Category RENOVATION 3

Even though clapboard nailing isn’t rocket science, four carpenters will give you five opinions on how to do it. Here’s what you need to know:

► Place clapboard nails roughly l1/ in. from the bottom so they don’t enter the tip of the clapboard underneath, especially if you’re installing 1×8 clapboards or wider. Wide clap­boards are particularly likely to split if they are inadvertently nailed at top and bottom.

► Nail clapboards to stud centers. For guidance, snap vertical chalklines on the building paper over the stud centers; offset the clapboard butt joints by at least 32 in.

Lined-up nails look better, especially if you’re using a clear finish.

► Carpenters set nails; painters fill and paint them. Setting nails makes painters cranky, and if there are 1,000 to set, painters will miss some.

Rain-Screen Walls

In humid regions where housewrap and back – primed siding are not enough to prevent rotted siding, some builders have retrofitted rain-screen walls to remedy paint failure and soaked sheathing. Basically, rain-screen walls employ furring strips to space clapboards out from the building-paper membrane, allowing air to circulate freely behind the siding and dry it out. The reasoning is sound, and field reports are encouraging.

As sensible as this solution is, it’s not for every renovation. Rain screens require careful detailing and a skillful crew. For example, if furring strips raise the siding roughly 3/ in., existing trim needs to be oversize already (5/4 stock) or built up to compensate for the increased thickness of siding layers. Another option: Home Slicker®, or CedarBreather, a thin layer of nylon mesh, raises siding off the building paper and doesn’t need furring strips.

As with any horizontal siding, level each course of clapboards. Note that the corner board is installed long; it will be trimmed flush with the bottom courses of siding after the two adjacent walls have been sided.

Rain-screen walls allow air to circulate behind the siding, thereby allowing its back face to dry thoroughly. Here, thin wood furring strips raise the siding above the building paper; each strip is centered over a stud.

STUCCO REPAIRS

Stuccoing a whole house requires skills that take years to learn, but stucco repairs are well within the ken of a diligent novice. If you spend a few hours watching a stucco job in your neighbor­hood, you’ll pick up useful pointers.

A basic description. Stucco is a cementitious mix applied in several layers to a wire-lath base over wood-frame construction or to a masonry surface such as brick, block, or structural tile. Like plaster, stucco is usually applied in three coats: (1) a base (or scratch) coat approximately h in. thick, scored horizontally to help the next coat adhere; (2) a brown coat about % in. thick; and (3) a finish coat (called a dash coat by old – timers) % in. to 14 in. thick. For repair work and masonry-substrate work, two-coat stucco is common.

The mix. The mix always contains Portland cement and sand, but it varies according to the amount of lime, pigment, bonders, and other agents, which are described in the following text. See "Stucco Mixes,” below, for standard mixes.

The consistency of a mix is easy to recognize but hard to describe. When you cut it with a shovel or a trowel, it should be stiff enough to retain the cut mark yet loose enough so it slumps
into a loose patty when dropped from a height of 1 ft. It should never be runny.

Building paper. Stucco is not waterproof. In fact, unpainted stucco will absorb moisture and wick it to the building paper or sheathing under­neath. Always assume that moisture will be pres­ent under stucco, and apply your building paper accordingly.

Basically, you want to cover the underlying sheathing with two layers of building paper before attaching the metal lath. Two layers of Grade D building paper will satisfy most codes, but you’re better off with two layers of a fiber­glass-reinforced paper such as Super Jumbo Tex 60 Minute. Although 60-minute paper costs more, it’s far more durable. Typically, the stucco sticks to the first layer of paper, exposing it to repeated soakings till it largely disintegrates; the second layer is really the only water-resistant one, so you want it to be as durable as possible.

Take care not to tear the existing paper around the edges of the patch. Tuck the new paper under the old at the top of the patch, over­lapping old paper at the sides and bottom of the patch. If the old paper is not intact or the shape of the patch precludes an easy fit, use pieces of reinforced flashing paper as "shingles,” slipping them up and under the existing stucco and paper and over the new. Caulk new paper to old at the edges to help keep water out.

Lath. Metal lath reinforces stucco so it’s less likely to crack and also mechanically ties the stucco to the building. Lath is a general term; it encompasses wire mesh or stucco netting (which looks like chicken wire) and expanded metal lath (heavy, wavy-textured sheets). When nailing up wire mesh, use galvanized furring nails with a furring "button” that goes under the mesh. When you drive these nails in, you thus pinch the wire mesh between the nail head and the button, creating a space behind the mesh, into which the scratch coat oozes, hardens, and keys. Note: Don’t use aluminum nails, because cement corrodes them. Use about 20 nails or staples per square yard of lath, spacing nails at least every 6 in. Overlap mesh at least 2 in. on vertical joints, and extend it around corners at least 6 in.

Expanded metal lath is a thicker, stronger lath used in situations requiring greater strength—for example, to cover soffits, where you’re fighting gravity while applying stucco. That is, expanded metal lath won’t sag. It typically comes in 2-ft. by 8-ft. sheets, is somewhat more work to install, and costs more. Expanded metal lath is stapled or nailed up; no need for furring nails because it’s self-furring.

Base coat. Here’s how to apply the base (scratch) coat:

1. Cover the sheathing with building paper and attach the lath.

2. Establish screed strips, which are guides for the stucco’s final surface thickness. Screeds can be existing window edges, corner boards, or strips manufactured for this purpose.

3. Mix and trowel on a thick first coat, press­ing it to the lath.

4. When the mud has set somewhat, screed it (meaning get it to a relatively uniform thickness) using screed strips as thickness guides.

5. Even out the surface further with a wood – or rubber-surfaced float.

6. Press your fingertips lightly against the surface; when it is dry enough that your fingers no longer sink in, steel trowel the surface. Steel troweling compacts the material, setting it well in the lath and driving out air pockets.

7. Scratch the surface horizontally.

Brown coat. Installing the brown (second) coat requires the most skill, care, and time because this stage flattens the surface and builds up the stucco to within Z in. of its final thickness.

To apply the brown coat, trowel on the stucco, screed it to a relatively uniform thickness, float the surface further, and steel-trowel to improve the uniformity. Then roughen the surface slightly with a wood or rubber float. As the stucco sets up, you will be able to work it more vigorously to achieve an even, sanded texture that will allow the finish texture coat to grab and bond. Do not leave the brown coat with a smooth, hard – troweled surface. Otherwise, the finish coat won’t stick well.

Finish coat. The finish coat is about!/ in. thick, and textured to match the rest of the building.

I Stucco Details

When attempting to match an existing texture, you may need to experiment. If at first you don’t achieve a good match, scrape off the mud and try again until you find a technique that works. Textures are discussed at the end of this stucco­ing section.

Stucco trim. If doors or windows in stucco walls are cased with wood trim, flash their head cas­ings with self-adhering flexible flashing. Metal windows in stucco usually have no casing to dam up water and so need no head flashing; metal windows usually have an integral nailing flange that serves as flashing after being caulked. If you need to cut back stucco siding to repair rot or install a new window, install flexible flashing over the head casing, and install fiberglass-reinforced paper along the sides and under the sill.

Helpful materials. The following materials are particularly useful for repair work and are avail­able from any masonry supplier.

► Weep screed is a metal strip nailed to the base of exterior walls, providing a straight edge to which you can screed stucco. Because it is perforated, it allows moisture to "weep" or migrate free from the masonry surface, thus allowing it to dry thoroughly after a rain.

Weep screeds are an easy way to make the bottom edge of stucco look crisp and clean.

And because the weight of the stucco flattens the screed down against the top of a foundation, the screed provides a positive seal against termites and other pests. (Stucco’s tendency to retain moisture makes rot and insect infestation particular problems.) Weep screed is also a good solution for the frequently rotted intersection of stucco walls and porch floors.

Weep screed isn’t difficult to retrofit, but you’ll need to cut away the base of walls 6 in. to 9 in. high in order to flash the upper edge of

g STUCCO PROBLEMS

the screed strip properly. Cut the screed with aviation snips, and fasten it with large-head 8d galvanized nails.

► Wire corners are preformed corners (also called corner aid) that can be fastened loosely over the wire lath with 6d galvanized nails.

Set the corner to the finished edge, taking care to keep the line straight and either plumb or level.

► Latex bonders resemble white wood glue. They are either painted into areas to be patched or mixed into batches of stucco and troweled onto walls. To ensure that the mixture is dis­tributed uniformly, stir the bonder into water before mixing the liquid with the dry ingredi­ents. Reduce the amount of water accordingly, as recommended by the manufacturer.

To ensure that a patch will adhere well, brush bonder full strength all around the edges of the hole or crack you’ll fill with new stucco. Merely applying patch stucco without bonder creates a "cold joint," which is likely to frac­ture. In most cases, you must apply new stucco before the bonder dries; otherwise, the joint won’t be as strong, although products such as Thorobond® and Weldcrete® will reemulsify when moistened by the next stucco coat.

► Prepackaged stucco mix is helpful because it eliminates worry about correct proportions among sand, cement, and plasti­cizing agents. However, you will need to add bonder to the mix.

► Color-coat pigment (also known as LaHabra™ color or permanent color top coat), is a pigmented finish coat, available in a lim­ited range of colors. Its principal advantage is its ease of mixing and its depth of color, which is as deep as the finish layer. But precolored top coats usually aren’t of much use to reno­vators because their colors aren’t likely to match older colors on a house. Yet, if a house is already painted white, white pigmented stucco will require fewer coats of paint to blend in.

► Masonry paint and primer, which is alkali resistant, can be used on any new masonry surface. You should still wait at least 2 weeks or 3 weeks for the stucco to "cool off" before painting it. (Follow the manufacturer’s recommended wait times.) Use two coats of primer and two coats of finish paint.

The repair. Before repairing damaged areas, first diagnose why the stucco failed. Then deter­mine the extent of the damage by pressing your palms firmly on both sides of the hole or crack. Springy areas should be removed. Continue pressing till you feel stucco that’s solidly

attached. When removing damaged areas, be deliberate and avoid disturbing surrounding intact stucco. Avoid damaging existing lath so you can attach new lath to it. Also avoid ripping the old building paper if possible. Safety note: Whether removing old stucco or mixing new, wear eye protection, heavy leather gloves, and at least a paper dust mask.

You can use a hammer and a cold chisel to remove a small section of damaged stucco. But for larger jobs, rent an electric chipping hammer with a chisel bit. Important: The bit should just fracture the stucco, not cut through it. Ideally, the underlying wire mesh and building paper will remain undamaged.

Let’s say you’re removing stucco to expose a rotted mudsill. Using a chipping hammer, fracture the stucco surface in two roughly parallel lines. On the first pass, delineate the top of the stucco to be removed. Then make a second pass, 6 in. lower. Basically, you’ll eventually demolish all the stucco below the top cut-line and restucco it after you replace the mudsill. But if you carefully remove the top 6 in. of the damaged stucco, you’ll preserve the wire mesh in that section, giving you something to tie the new mesh and stucco to.

Cut through the wire mesh exposed by the second pass, insert a pry bar under the stucco, and pry up to detach the stucco from the sheath­ing. Because the first pass of the chipping hammer separates damaged stucco from intact stucco, prying up this 6-in. corridor of stucco will not disturb the solid areas above it.

Now the strenuous work begins. Using a mason’s hammer or a beat-up framing hammer, carefully pulverize the corridor of pried-up stucco.

Stucco is hard stuff, so whacking it in place with a hammer is more likely to drive it into the wood sheathing than to pulverize it. However, if you pry up the stucco slightly, you can slide a hand sledge under it to serve as an anvil. Then, between a hammer and a hard place, the stucco will shatter nicely. After you’ve removed all old chunks of stucco, you’ll have a 6-in.-wide section of unen­cumbered wire mesh and, ideally, a layer of largely intact building paper under that. Once you’ve replaced the rotted framing (and sheathing), insert new paper, tie new mesh to the old—just twist the wire ends together—and nail both to the sheathing. Now you’re ready to apply the new scratch coat.

If only the finish coat is cracked, wire brush and wet the brown coat, apply fresh bonding liq­uid, and trowel in a new finish coat. But if the cracks are deeper, the techniques for repair are much the same as those for patches, except that you need to undercut the cracks. That is, use a cold chisel to widen the bottom of each crack. This helps key in (hold) the new stucco. Chip away no more than you must for a good mechan­ical attachment. Then brush the prepared crack well with bonding liquid.

Texturing and finishing. To disguise new stucco patches, it’s often necessary to match the texture of the surrounding wall. Before texturing the fin­ish coat, steel-trowel it smooth and let it set about a half hour—although the waiting time depends on temperature and humidity. Cooler and more humid conditions delay drying. Stucco allowed to cure slowly is far stronger than fast – cured stucco. So, after applying the finish coat, use a hose set on a fine spray to keep the stucco

damp for 3 days. Here are descriptions of the three com­mon textures:

► Stippled. For this effect you’ll need rubber gloves, an open-cell sponge float like those used to spread grout in tiling, a 5-gal. bucket, and lots of clean water.

After dampening the sponge float, press it into the partially set finish coat and quickly lift the float straight back from the wall. As you lift the float, it will lift a bit of the stucco material and so create a stippled texture looking somewhere between pebbly and pointy. Repeat this process over the entire surface of the patch, feathering it onto surround­ing (old) areas as well, to blend the patch in.

Rinse the float often. Otherwise, its cells will pack with stucco, and the float won’t raise the desired little points when you lift it. Equally important, the sponge should be damp and not wet. If you want a grosser texture than the float provides, use a large open-cell natural sponge. If you notice that the new finish is more pointy than the old surrounding stucco, that’s probably because the old finish has been softened by many layers of paint. To improve the match, knock the new texture down a little by lightly skimming it with a steel trowel.

► Swirled. Screed (level) the patch’s finish coat to the surrounding areas, and feather it in. After you’ve made the patch fairly flat, comb it gently with a wet, stiff-bristled brush. For best results, use a light touch and rinse often; otherwise you’ll drag globs of stucco out of the hole. By varying the pressure on the brush, you can change the texture.

► Spanish stucco or skip troweled. Visually, this texture looks rather like flocks of amoebas or clouds. To achieve this look, screed off the patch so it’s just Иб in. below the level of surrounding areas. Then, using a steel trowel, scoop small amounts of stucco off a mortarboard and, with a flick of the wrist, throw flecks at the wall. Skim the flecks with a swimming pool trowel because its rounded edges are less likely to gouge the stucco as you flatten the flecks slightly.

Ideally, this will give you an irregular pat­tern of miniature mesas, matching that of the original surface. Another approach is to use a
wet, sandy mix and load it onto your steel trowel unevenly. (Beforehand, coat the hole well with bonder so the new material adheres well.) Again, using a swimming pool towel, you’ll see the material "skipping" over the sand particles, leaving flattened patches of texture and gaps. To get the right texture, you’ll need to experiment with trowel pres­sure, mix stiffness, and wrist movement.

Before you start shingling, make sure that win­dows and doors are correctly flashed, that sheathing is covered with building paper—most pro shinglers prefer 15-lb. felt paper—and that exterior trim is installed.

Materials. For best results, use No. 1 grade cedar shingles. For a standard 5-in. shingle expo­sure, figure four bundles per square (100 sq. ft.). Always inspect the visible shingles on a bundle to make sure they’re uniformly thick (3з8 in.) at butt ends, of varying widths (on average, 6 in. to

CUTTING SHINGLES CROSS-GRAIN

12 in.), knot free, and reasonably straight grained. Installing shingles requires a lot of trim­ming, so you don’t want to be fighting knots and wavy grain. Shingle butts should also be cut cleanly and squarely across, not angled or ragged. Send back bundles that look inferior or contain mostly narrow shingles.

To save a little money, however, you might want to use No. 2 shingles for the bottom layer of doubled starter courses. In this case, order one bundle per 50 lineal (lin.) ft. of wall. Typically, the starter course of shingles along the bottom is doubled, with vertical joints between the two shingle layers offset by at least 1 h in.

Also, pick up a bundle to see how dry it is. Relatively wet shingles are fine, as long as they’re good quality, but they’ll shrink. In fact, most shingles shrink. Though how-to books are fond of telling you to leave a!4-in. gap between shin­gles during installation, many shinglers don’t bother; unless the shingles are bone-dry, installers assume that all shingles will shrink some.

Use two 1 f4-in. galvanized nails or staples per shingle, whatever its width. Because nails must be covered by the course above, place shingle nails in M in. from either edge and 1 in. above the eventual butt line of the course above. Where nails will be visible—say, on interwoven corners or the top course below a window—use sili­conized bronze ring-shank nails or stainless-steel nails. Again, 1!4-in. nails are fine, unless you’re also nailing through a gypsum layer to reach the sheathing on a fire-rated wall.

Installation. If you’ve got a water table (see p. 132), set your first course of shingles atop it, even if it’s not level. That way you eliminate unsightly gaps along the trim, and it’s easy
enough to level the next course of shingles. If there are corner boards, snap chalklines between them to mark shingle courses, and off you go. However, if there are no corner boards, weave shingles at the building corners, alternating shin­gle edges every other course. This requires more skill and patience than just butting shingles to the boards but produces corners that are both handsome and weather-tight. Weave the corners first; then nail up the shingles in between. Because the starter course overhangs the bottom of the sheathing 12 in. to 1 in., measure down that amount at each corner, using a laser level to establish level. After establishing the correct exposure, as described above, shingle up each corner. As you work up the wall, snap a chalkline from corner to corner to line up shingle butts.

As you did on the first course, offset the verti­cal shingle joints at least Ш in. between courses. If you have a partner, you’ll find it easier if each of you works from a corner toward the middle. Only the last shingle will need to be fitted.

Wood Shingle Details

Fit shingles closely to window and door cas­ings. The top of the shingle course under a win­dowsill should butt squarely to the sill. Because this course needs to be shortened and will be sus­ceptible to splits, caulk the back sides. It’s also wise to caulk the shortened top course of shingles under the eaves. Ideally, the tops of those shingles

will also be protected by a rabbeted-out or built – up frieze.

If you need to angle cut shingle butts for use along gable-end walls and dormers or need to angle cut shingle tops to fit under rake trim, use an adjustable bevel to capture the roof angle and transfer it to shingles. Such angle cuts are best

made all at once, on the ground, using a table saw. To notch shingles around windowsill ears and the like, use a cordless jigsaw. Finally, leave a Я-in. gap beneath dormer-wall shingles and adja­cent roofing; otherwise, shingles resting directly on roofing can wick moisture and rot.

INSTALLING CLAPBOARDS

The following discussion assumes that you’ve read this chapter’s earlier sections on layout and that you’ve installed door and window flashing, building paper, and exterior trim. It also assumes that the building has corner boards that you can butt the clapboards to. Otherwise, the clapboard corners will require compound-miter joints, which is a considerable amount of work.

Materials. Clapboards are a beveled siding milled from redwood, red cedar, or spruce; for best results, use Grade A or better. Preprimed finger-jointed clapboards are a cost-effective alternative, joining shorter lengths of high-quality wood. Clapboards come in varying widths and thickness, but all are nominally 1-in.-thick boards that have been planed down. Thus a 1 x6 is actually Я in. thick (at the butt) by 5!4 in. wide; a 1×8 is actually Я in. by 7h in., and so on. Traditional clapboards come in varying lengths, whereas finger-jointed prod­ucts are manufactured in 16-ft. lengths; all are sold by the lineal foot.

To estimate the amount you need, calculate the square footage of your walls, less window and door openings. Then consult the table below, which assumes Я in. of overlap for 1×4 clap­boards and 1-in. to 1 J/8-in. overlap for all other sizes. It also factors in 5 percent waste. Order preprimed (or prestained) clapboards. Pre­priming seals out moisture, saves tons of time otherwise lost to priming and waiting for primer to dry, and keeps the job moving. You will need a small amount of primer on hand to touch up newly cut ends.

Shingles

If you split a shingle while installing it (or if you need to remove shingles to install an exhaust vent for a fan), break out the shards, hammer down the nail heads, and replace the shingle. To remove a few damaged shingles on an otherwise intact wall, use a shingle ripper (also called a slate hook), shown in the photo on p. 121. Slide its hooked head up under surrounding the shingles till you can feel it hook around a nail shank. Then hammer down on the tool’s handle till the hook cuts through the shank. To avoid damaging the replacement shingles as you drive them into place, hold a scrap block under the shingle butt to cushion the hammer blows.

Nails. Buy 5d stainless-steel, ring-shank siding nails, whether you’re painting the clapboard or not. True, stainless-steel nails cost four or five times as much as galvanized nails, but that pre­mium buys you peace of mind. Galvanized nails are fine 99 percent of the time. But if their coat­ing breaks off, the nail will rust. Moreover, the tannins in cedar and redwood can chemically react with galvanization, which causes staining. Same with galvanized staples. For every 1,000 lin. ft. of siding, buy 5 lb. of 5d nails.

Installation. Worth repeating: Standard clap­board exposure is 4 in. for 1×6 clapboards (actual width, 5Я in.), but you may want to vary that exposure by І4 in. or less between courses to help align the clapboards with the window and door casings.

The first course of clapboards typically sits atop a water table. First flash the top of the water table with metal drip-edge to forestall rot. To establish the correct pitch for that first course, rip a 1 Я-in.-wide beveled starter strip from the top of a clapboard. (Save the 4-in.-wide bottom waste rip for the top of a wall.) Tack the strip atop the water table, and you’re ready to nail up the first course. The water table may not be level, but that’s okay; better to avoid a noticeable gap between a level first course and an off-level water table. In that case, take pains to level the second and all successive courses.

Start at one corner board and work all the way across the wall, nailing clapboards to each stud center they cross. All butt joints should be square cut and centered over a stud so that the ends of both boards can be securely nailed.

I Clapboard Details

Position clapboard joints over stud centers.

For the most weathertight joints, bevel-cut ends. Note: For clarity in this drawing, building paper between clapboards and sheathing isn’t shown.

Homemade

Remember to stagger joints by at least 32 in. To further weatherproof the joints, back them with strips of building paper; the paper overlaps the top of the clapboard beneath by ‘A in.

For clean, square cuts, rent or buy a 10-in. radial-arm saw with a 40-tooth or 60-tooth carbide-tipped blade. And be prepared to recut joints. When fitting the second board of a butt joint, leave it a little long till you’re satisfied with the joint. If it isn’t perfectly square on the first try, you’ll have excess to trim.

When butting clapboards to corner boards and jamb casings, use the homemade gauge shown below at left. Using the gauge to hold the clapboard tight to the trim, scribe the cutoff line with a utility knife. Never fit clapboards so tightly to the casing that you need to force them into place: Too tight trim can cause window sashes to bind. Where top courses abut the underside of eave or rake trim, rabbet or build out the trim to receive the top edges of the clapboards, as illus­trated on p. 133. Caulk all building joints well with latex acrylic or urethane caulk before nail­ing up the top course of clapboards.

For clapboards and shingles, the two most important parts of the layout are establishing level for the bottom course and varying the expo­sure of subsequent courses so that they align with door or window trim, if possible. If a leveled water table has already been installed, skip the next section.

Establishing level. If there’s no water table on the house (see p. 132), the bottom of the first course of siding typically overhangs the sheath­ing by % in. to 1 in. Because the bottom edge of sheathing is seldom level, use a laser level or a water level to establish a level base line. Simple tripod-mounted laser levels are relatively inex­pensive and offer quick layout over long dis­tances without needing a helper. When set up correctly, they’re also quite accurate, usually within Уз in. in 100 ft.

Lay out the front of the building first. Pencil in an appropriate siding overhang on one corner board. Then, using the level, transfer that mark to all the other corner boards. When you’re done, use a combination square to draw light lines through your pencil marks, across the faces of the corner boards. These lines indicate cut-off lines for the corner boards and the bottom of the first course of siding. To align that first course of sid­ing, stretch a chalkline through the marks and snap it onto the building paper. Or, if you’ve used housewrap, which won’t chalk well, drive a nail into a pencil line at each corner and stretch a taut line between them. Place clapboards or shin­gle butts slightly above, but not touching, the line so it won’t be distorted.

Varying subsequent courses. By aligning siding courses to window and door trim, you can mini­mize funky-looking notch cuts at door and window

corners. (But when installing wide-board siding, notch cuts are sometimes unavoidable.) Achieve these alignments by increasing or decreasing the exposure of individual courses. Of course, there are physical restrictions. For example, clapboards must overlap at least 1 in. But as long as exposure adjustments are no more than ‘/ in. between courses, they’ll look evenly spaced.

The following steps refer to the illustration above:

1. Measure the full height of the wall, from the cutoff at the base of a corner board to the underside of the soffit. Let’s say the height is 10 ft. 2 in. (for calculation purposes, 122 in.). Because shingle exposures are customarily 5 in., that wall will have roughly 24 courses.

2. The wall has three windows and a door. Fortunately, their head casings happen to align 84 in. above the base line. This creates three sep­arate areas for which shingle exposures need to be adjusted, as shown in the drawing: (A) from the top of head casings to the soffit, 38 in.; (B) from the top of the window head casing to the bottom of sills, 45 in.; and (C) from the bottom of windowsills to the base line, 39 in. Total: 122 in.

3. Calculating exposure adjustments is easy. Round off each measurement to the nearest increment of 5 in. Then increase or decrease the shingle exposure accordingly. Thus area A yields a 4%-in. exposure (38^8 = 4%); area B is exactly 5 in. (45^9); and area C is roughly 418 in.

The easiest way to keep track of such meas­urements and adjustments is by penciling them onto a story pole, a long straight board (a 1×2 is fine) whose length equals the distance between the top of the water table (if any) to the underside of the soffit or frieze. First mark the tops and bot­toms of window and door casings onto the story pole, then the adjusted course heights between.

As you work around the house, align the bot­tom of the story pole to each corner board and transfer marks from the pole to each board. If the house has windows set at varying heights, story – pole marks will better align with casing on some walls than on others; give precedence to the house’s most prominent facade. Where courses just won’t line up with casing joints, notch the siding around them.

Although it may be tempting to rip out exterior trim that’s badly weathered or rotten, repair is often a better option if replacement trim would be expensive or difficult to remove. Before decid­ing either way, survey the extent of the rot and address its cause. Otherwise you’re treating only the symptom.

Replacing rotted sections is a good option when the bottom of an otherwise sound trim board has rotted away. Flat and square trim is easier to replace and match than molded trim. Rotted bottoms of corner boards and splash­boards are usually easy to cut free and replace, whereas punky doorsills or windowsills are prob­ably best repaired in place, using epoxy, as described in the next section.

Replacing the bottom of a rotted board is straightforward. Draw a line across the face of the board, 6 in. above the bad section. After setting your circular-saw blade to the thickness of the board, use a Speed Square to guide the saw shoe, making a 90° cut. Wear goggles and use an old blade because it may hit nails. The replace­ment piece should be the same thickness, width, and—preferably—species as the original trim.

To join the new section to the old, use a router with a slot-cutting bit to cut a biscuit slot in both board ends. Dry-fit everything, prime all surfaces with epoxy primer, and allow the primer to dry well. Then epoxy the pieces together. Hold the boards in place with a piece of scrap screwed to both. Give the epoxy a day to cure (or whatever the manufacturer suggests), and you’re ready to sand and paint.

In-place epoxy repairs are appropriate when the rotted area is relatively small (epoxy is expen­sive!) and the trim would be difficult or costly to replace. Rotted windowsills or sashes are tough to remove because both are captured by sur­rounding elements. Epoxy applications vary con­siderably, so visit the manufacturers’ Web sites (try Abatron®, ConServ®, and Advanced Repair Technology®, for example) for specifics or get recommendations at your local home center.

Use a chisel or awl to dislodge loose, crum­bling wood. Suck up debris with a shop vacuum. Allow the wood to dry thoroughly before proceed­ing. Although it’s desirable to cut back to solid wood, soft punky wood can often be reinforced by impregnating it with a liquid consolidant. Typi­cally, you’d drill a series of small-diameter holes into the wood and then inject consolidant into them till the wood is clearly saturated. In time, the impregnated wood will become as hard as a rock.

But, for the best bond between the consoli – dant and the two-part epoxy filler that follows, apply the putty-like filler while the consolidant is still tacky. Avoid getting epoxy on your skin, and by all means wear a respirator mask with replaceable filters when applying or sanding it. After the filler dries and you’ve sanded it to its final shape, prime and paint it. Though other­wise tough, some epoxies are degraded by UV rays, and whatever original wood remains still needs protection from the elements.

Siding

This section addresses installation of the three most common traditional sidings: wood shingles, clapboards, and stucco. Vinyl and aluminum sid­ings are cost-effective alternatives to traditional sidings; they’re also durable and virtually maintenance-free if correctly installed. But they’re normally a whole-house job most effi­ciently handled by specializing contractors and so aren’t further addressed here. Aesthetics are another consideration. Although popular in new construction and renovation, faux-grained vinyl looks phony to traditional­ists. If that’s your reaction, too, consider untextured sidings, which, when painted, more closely resemble painted wood.

The information that follows assumes that building paper or plastic housewrap covers the wall sheathing and that win­dows, doors, and exterior trim are already installed.

The water table is horizontal trim running around the base of a building below the siding, and not all houses have it. Depending mostly on regional preferences, the water table takes sever­al forms. In the West, it typically looks like win­dowsill ears (the parts that stick out) and is often used to separate different types of siding materi­als, such as shiplap siding from wood shingles above. This strip-like water table usually runs continuously around the building and is mitered at the corners. It often has a rabbeted heel, which fits over the top of the wood siding below, and a

beveled top, which is overlain with shingles or clapboards.

In the East, water tables are also called splashboards; they usually are 1-in. boards 8 in. to 12 in. wide and may be capped to shed water. Splashboards are most common in wet regions, where roof runoff often splashes back along the base of a house. (Some primal carpenter may have reasoned it would be easier to replace a sin­gle rotted board than to disturb several courses of siding or that a thicker board would simply last longer.)

Whatever shape of water table you prefer, flash its top with a metal drip-edge that extends at least 12 in. beyond the face of the board. The section where corner boards sit atop the water board is especially rot prone. Prime and paint the boards thoroughly.

CORNER BOARDS

Corner boards are usually 1-in. boards butted together. Siding is then butted against them, making an attractive and weathertight corner.

Not all buildings have horizontal trim below the bottom of the siding. For example, the first (bottom) course of shingles is often doubled and
overhangs the sheathing slightly. In that case, run corner boards 2 in. to 3 in. below the bottom edge of the sheathing; then, after you nail up the first course of shingles, trim the corner board ends level to the shingles’ butts. If the house has a water table or splashboard, measure from its top edge up to the underside of the soffit to deter­mine the length of the corner boards.

If you’re installing shingles, whose overlap­ping courses have a higher profile than clap­boards, use 5/4 corner boards, which are full 1 in. thick. To give the illusion that corner boards are the same width at each side, rip down the overlapped board by the thickness of the stock. And for a crisp, straight corner, preassemble corner boards before installing them, as explained earlier.

Occasionally, corner boards are nailed over sid­ing. This can be a problem because nails driven through the trim are likely to split the thinner siding. Besides, corner boards can’t seal well if nailed over an irregular surface. This method was commonly used on Victorian homes with flat, shiplap siding. Careful nailing and liberal doses of caulk will help ensure a weathertight seal. To minimize splits, predrill the board nails.

A strip of continuous screen in the soffit allows you can create ventilation channels behind the frieze by

air to circulate into the attic. The rabbeted frieze spacing it out 3/4 in., using blocks spaced every 16 in. on center.

conceals and protects the top of the siding. This also conceals the top of the siding.

The corner boards described thus far cover outside corners. Inside corners aren’t as exposed to weather, so wide boards aren’t necessary. Instead, nail 1-in. by 1-in. strips (or 114-in. by 114-in. strips) to the inside corners, and butt the siding to that. That’s much faster than cutting compound miters in the clapboards or inter­weaving shingles.

Exterior trim can be applied in many different ways, depending on the design of the house and the type of siding. For wood shingles or clap­boards, use trim boards that are thicker than the siding, and apply trim to the sheathing before putting up the siding. For flat shiplap and board- and-batten sidings, apply trim boards over the siding. In general, try to use the same materials and installation methods that were used on the house originally.

Solid-wood exterior trim should be a rot – resistant species such as redwood, cedar, or hard pine and sufficiently dry to avoid shrinkage, cup­ping, and checking. For those reasons, avoid sugar pine, knotty pine, hemlock, fir, and the like. If you’ll be painting the trim, you may find it cost effective to use finger-jointed trim stock fabricated from shorter lengths of high-grade wood. Such stock is widely available and can be durable if you keep it sealed with paint. For best results, specify vertical-grain heartwood grade because it

Eaves Trim___________

Fascia, soffit, and frieze boards are collectively called the eaves trim.

resists decay, holds paint well, and is the most stable dimensionally. Caution: If this trim is allowed to absorb moisture, its finger joints may separate.

BACK-PRIMING AND PAINTING

Apply primer to all faces and edges of exterior wood (and engineered wood) siding and trim, including the back faces. Back-priming is critically important because wood will cup (edges warping up) when the sun dries out the exposed front face, while the back unexposed face retains mois­ture. The greater the moisture differential between front and back faces, the more likely the cupping.

While cutting trim or siding, keep a can of primer and a cheap brush nearby to seal the ends after every cut; unprimed end grain can absorb a lot of moisture. (It’s especially easy to forget to prime cut edges when you’re using preprimed trim.) Ideally, apply at least two top coats of acrylic latex paint after priming to seal trim and siding. If you want stained or clear-finished trim or siding, use cedar or heart redwood.

ATTACHING TRIM

As a rule, for best attachment, secure exterior trim to framing. In those rare instances where you have only sheathing to nail to, angle the nail so that it will be less likely to pull out.

Choosing attachers. Pick a nail meant for exte­riors. If you’ll be using a transparent finish, mak­ing nail heads visible, stainless-steel nails are the premier choice; though expensive, they won’t

rust. Aluminum nails won’t stain but are some­what more brittle and more likely to bend. Galvanized nails are the most popular because they’re economical, stain minimally, and grip well. Many nail types (including stainless) also come in colors matched to different wood types—cedar, redwood, and so on. Ring-shank nails hold best.

For stained exteriors, some contractors prefer galvanized finish or casing nails because their heads are smaller and less visible. Box nails are a good compromise. Their larger heads hold better than finish nails, yet their shanks are smaller than those of common nails, making box nails less likely to split wood. There are also “splitless” siding nails that come with preblunted points to minimize splits. (The blunt point smashes through wood fibers, rather than wedging them apart.)

Where trim is exposed—say, at cap trim atop a half wall—and you want maximum grip, use stainless-steel trim-head screws instead of nails.

drive nails quickly and accurately, reducing splits and eliminating errant hammer blows that mar trim. After setting the trim with finish nails, you can always can go back and hand nail with headed nails to secure the trim further. Or you can use headed siding nails in the nailer.

Nailing schedules. To face-nail nominal 1-in. trim (actual thickness, % in.), use 8d box nails spaced every 16 in. Nail both edges of the trim board to prevent cupping, placing nails no closer than h in. to the edge. If the trim goes over sid­ing, say, at corners, use 8d to 10d box nails. To draw board edges to each other, use 6d nails spaced every 12 in., and drive them in a slight angle. If you’ll be painting the trim, also caulk this joint or glue it using an exterior urethane glue, such as Gorilla Glue®.

rior Trim tips

About nail heads. Taking the time to line up nail heads makes the job look neater. For example, when nailing up jamb casing, use a combination square to align nail pairs. If you’re putting up a long piece of trim that runs perpendicular to studs, snap chalklines onto the building paper beforehand so that you’ll know stud positions for nailing. If the trim will be painted, take the time to set the nail heads slightly below the surface, using a flathead punch. Then use exterior wood filler to fill the holes. If you don’t set the heads slightly, they may later protrude as the wood shrinks, compromising the paint membrane and admitting water. On larger jobs, carpenters are usually expected to set nail heads. Painters fill and paint them.

EAVES TRIM

Because eaves trim is often complex and can impact framing, roofing, ventilation, and the house’s aesthetic integrity, draw a cross-section of it as early as possible.

There is no single correct way to construct the eaves, but the boxed eaves on the facing page are a good place to start. First, a fascia board that overhangs a soffit by % in. to in. enables you to hide rafter irregularities—rafters are rarely per­fectly straight or cut equally long. Second, that overhang accommodates a rabbeted fascia-soffit joint, which protects the outer soffit edge, even if the wood shrinks slightly. Third, if you rabbet out the back edge of a frieze board or build it out using blocks, the frieze will conceal the top edge of the siding. A built-out frieze also creates an inconspicuous space to install an eave vent.

Ventilation channels at eaves allow air to flow up under the roof and exit at ridge or gable-end vents. This airflow is beneficial because it lowers
attic temperatures and helps remove excess mois­ture from the house, thus mitigating mold, ice dams, and a host of other problems. To keep insects out, soffits need screening. In a wide sof­fit, there’s plenty of room for screened vents in the middle. In a narrower soffit, you may need to leave a M-inch space at the front of the soffit or at its back, hidden behind a built-out frieze board.

If the house has exposed rafter tails rather than soffits, cut down the blocking between rafters so air can flow over the top. Again, staple fine mesh screen or corrugated vent strips behind ventilation passages to keep insects out.

Flashing paper is available in several forms, the most convenient being fiberglass-reinforced rolls either 6 in. or 9 in. wide. (These strips are some­times called felt splines.) There’s also a plethora

of peel-and-stick flexible flashings; but because they’re expensive, they tend to be used mainly as cap flashing for the tops of doors and windows. Foil-faced flexible flashings like Polyken® Foil- astic, for example, adhere aggressively and seal head joints so water can’t back up behind them.

Uncased windows are commonly used in reno­vation when it’s desirable to install casing that matches an existing style. Since precased units offer a limited range of casing styles, many builders install uncased windows and buy appro­priate casing from a local mill.

Flash the rough sill before installing an uncased window. Tuck the paper into the kerf at the bottom of the sill (if there is a kerf) or fold the paper into the RO, caulk its edge, and set the sill onto it. This provides an unbreachable seal, and apron casing or siding will cover the edge of the paper later.

To seal side jambs, consider the double­caulking method shown above. Caulk each jamb edge, embed a flashing-paper spline in the caulk, and then run another bead of caulk atop the spline before installing the jamb casing. This caulk-and – spline sandwich stops infiltration effectively. Finally, caulk the edge of the head jamb before installing the head casing, but do not insert a spline between the head jamb and the casing— that could direct water behind the head casing.

After the window is cased, add the (metal) cap flashing over the head casing. Before installing flashing paper over metal flashing, careful
builders first caulk the upper flange of the flash­ing. This will prevent water that gets under the siding from wicking back up under the paper when it hits the window head. This is especially important with stucco siding, which is water per­meable and often collects water between the stucco and the building paper. Chapter 6 offers more specifics about cap flashing.

Should jamb flashing go over or under the building paper covering the sheathing? It doesn’t really matter because the strip flashing is extra protection. But under the windowsill, leave the lower edge of the flashing spline unstapled so it can overlay the building paper or housewrap below.

Windows and doors with integral nailing flanges require slightly different detailing. If the flanges are metal, apply fiberglass-reinforced flashing paper along the bottom and sides of the RO first. Then apply a bead of exterior caulk around the perimeter of the paper—close to the edges of the opening—and set the unit over the flashing paper. Position and shim the unit; then nail or screw through the flanges, into the sheathing. Install cap flashing (some units have an integral cap flashing) over the head of the unit, caulk its upper flange; then install flexible flashing over that cap flange. Building paper above will overlay the flexible flashing. Note: Most flanged windows don’t have casing per se. Unlike wood-cased windows, flanged units have jambs that protrude above the surface of the

sheathing, so siding (or casing) is butted to the sides of these protruding jambs.

Exterior Trim

In appearance, exterior trim is sometimes ornate and complex, but its basic function is to cover critical building seams.

Installation techniques for housewrap and build­ing paper are much the same; in this chapter, both materials are often referred to generically as building paper.

Before starting, survey the sheathing and knock down protruding nail heads and wood sliv­ers that could puncture the paper and admit water.

Installation is two-person job, especially if you’re working with 9-ft.-wide rolls of Tyvek. As one person unrolls the material, the other aligns and staples it. Start at the bottom of the wall, overhanging the bottom edge of the sheathing by about 1 in. Position the building paper, tack an upper corner in place, roll out about 8 ft., and raise or lower the roll till the edge of the building paper is roughly parallel to the bottom edge of the sheathing. When it’s in position, staple the paper every 16 in. along the edges and every 24 in. in the field; use!4-in. or Мб-in. staples. Thereafter, roll out 3 ft. to 4 ft. at a time, stapling as you go. Trim the 1 in. overhang later.

As you roll out the building paper, make sure it lies flat to the sheathing. Otherwise, puckers can elevate the siding or trim applied over them, compromising weather tightness. Typically, the person holding the roll maintains a slight tension on the building paper to prevent puckers. Also, take care to avoid tearing the membrane while handling and stapling it—more of a problem with paper than with plastic housewrap, which stretches.

Overlapping and taping seams. Overlap verti­cal end seams by 4 in. to 6 in.; overlap horizontal seams 6 in. to 8 in. As you work up the wall, applying courses of building paper, upper courses should always overlay those below so any water that gets behind the siding is directed out and down, away from the sheathing. Building paper should also overlay any flashing, especially cap flashing over doors and windows.

Seal building-paper seams, tears, and punc­tures with seam tape; smooth down the tape to make sure it adheres well. If you’re installing plastic housewrap, use a seam tape recommended by the manufacturer. If you tear building paper, just staple a patch of the same material over it and apply caulking over the top edge. Last, install siding as soon as possible after installing the building paper because wind can lift and stretch it, especially plastic housewraps.

Corners and rough openings. Take special pains with corners. Although a 4-in. overlap is often adequate for corners, you’ll be safer to over­lap outside corners by 1 ft. In addition, many builders reinforce corners with a self-adhering flexible flashing to keep water out should corner boards or siding gap. To prevent the material’s bunching in inside corners—a common problem with building paper—use a straight furring strip to press the paper into the corner before stapling it. That done, tape the corner seams immediately— before wind has a chance to lift the paper.

Builders installing plastic housewrap usually roll it right over rough openings (ROs) for win­dows and doors, cutting an Xin the middle of the opening and folding the housewrap into the sides of the framing. Well, that method can’t hurt. But it’s doubtful that it truly waterproofs the opening. If you’re installing metal windows, maybe a layer of housewrap will isolate the moisture that con­denses on cold metal. But if flashing paper is correctly installed about the perimeter of the window or door, water shouldn’t enter the RO in the first place.

The exterior і multi­

layered membrane, weatherproofing the house much the way a roof does. In addition to protect­ing underlying elements from damage by sun and wind, the exterior intercepts and directs water away from the underlying sheathing and fram­ing. The visible exterior layer consists of siding and trim. Beneath the siding, ideally, is either building paper or plastic housewrap, which is relatively water repellent. In addition, flashings seal transitions from one material to another or redirect water around potential dams, such as window and door headers, vent fans, and outdoor outlets. Finally, various sealants fill gaps, adhere materials, or cut air infiltration. Of course, win­dows and doors are exterior elements, too. But as “openings” in the exterior, they are the principal subjects of Chapter 6.

Although drain gutters may be considered part of the roof, they are discussed at the end of this chapter because gutters “attach to” and pro­tect the exterior. Gutters also direct water away from foundations, thus reducing moisture there and mold in basements and crawl spaces while preventing excess water from undermining foundations.

As with other building systems, maintenance is crucial. Each autumn after the leaves have fallen and each spring, clean gutters and downspouts; if needed, do this more often to keep them flowing freely. Every year, survey and recaulk building seams as needed. Paint or stain wood siding peri­odically. Trim trees and shrubs so they don’t retain moisture next to the siding or restrict air circulation. Slope the soil away from the founda­tion to help direct water away. Adjust lawn sprin­klers so they don’t spray siding.

Weatherproofing Windows

WOOD-CASED WINDOW

Weather Barriers

No matter how well siding is installed, sooner or later water will work its way behind. Typically this happens when storms drive rain into build­ing seams or gaps around doors or windows. But water can also be drawn inward and even upward by capillary action before trickling down behind siding. For these reasons, builders protect exterior sheathing with building paper (15-lb. building paper is most common) or plastic housewraps such as Tyvek® or R-Wrap® to repel water.

Both building paper and plastic housewrap do a good job of reducing air infiltration. That is, both are permeable enough to allow excessive moisture behind the siding to escape, and both are sufficiently water repellent to protect sheath­ing from wind-driven rain. Bottom line: It doesn’t matter whether you use building paper or house – wrap, as long as it’s correctly installed and con­forms to local building codes, which may require
that they are compatible with finish materials. For example, beneath stucco, many building codes require a double layer of Grade D kraft paper or a fortified paper such as Fortifiber’s Super Jumbo Tex® 60 Minute.

Typically, this weatherproofing membrane is installed after windows and doors have been installed and their perimeters weatherproofed with fiberglass-reinforced flashing paper. As shown in "Wood-cased window,” above, building paper overlays cap flashing and fits under the sill flashing. Cap flashing, also called head flashing, is especially important because it redirects water that might otherwise dam behind a door or window head casing, leading to stains and mold on interior surfaces, swollen sashes, peeling paint, and rot.

Replacing all siding, flashing, and building paper is the surest way correct such water-related damage, but if that’s not in your budget, retro-

fitting flashing around individual windows and doors may do the trick. In that case, cut back the siding far enough around the perimeter of the door or window to install 6-in.-wide flashing paper, as described next.

Follow the manufacturer’s instructions when installing and flashing your skylight, so the war­ranty will be honored should the unit leak. Installations shown are fairly typical.

Screw the mounting brackets to the sides of the skylight curb; most brackets are adjustable. Then, with one worker on the roof and one in the attic, pass the skylight out through the opening. As the worker outside raises or lowers the brack­ets till the top and bottom of the unit are level, the worker inside centers the unit in the opening.

Different skylight, same installer. Here, he frames out the lightwell before cutting a hole in the ceiling because it was raining. First he headered off the ceiling joists, then the rafters around the roof opening, before angle cutting the studs between the two openings. (He cut the four corner studs first.)

The same lightwell after the roof has been opened: Note the doubled headers around all sides of the opening. Because all walls flare, this is a complicated piece of framing.

Skylight Framing

In addition to doubling headers at the ends of rough openings, double up rafters and joists running along the sides of openings. Framing out a lightwell will be somewhat easier if side walls and the lower end wall of the lightwell are plumb.

That done, the outside installer screws the bot­tom legs of the brackets to the sheathing.

Wrapping the curb with building paper or self­adhering membrane underlayment gives you an extra layer of protection before installing the unit’s apron, side flashing, and head flashing. Apply four 12-in.-wide strips of underlayment, one on each side, folding each so that it runs up onto the curb about 2 in. Apply the bottom piece first, which overlaps the shingles below; then place the side pieces and, finally, the top piece. If possible, slide the top piece of self-adhering membrane up under the building paper so you adhere it directly to the sheathing. Slit the folded strips where they overlap the curb corners so the strips lie flat, and apply a dab of roofing cement to adhere the slit pieces.

Install the apron flashing first, which runs along the lower edge of the skylight and overlaps the shingles below it. Holding the apron snug against the curb, attach it to the curb—not the roof—using a single screw (or nail) on each side. Although it’s usually not necessarily to caulk under the apron’s lower flange, follow the manu­facturer’s advice for your unit. Ideally, the apron will line up with a course of shingles, but in reno­vation that’s not always possible.

Install step-flashing along the sides, weaving the L-shaped flashing between the shingle courses. Ideally, shingle courses should stop 14 in. shy of the curb so that water can run freely along the sides. The vertical leg of each piece of step-flashing
should extend up high enough so it will be pro­tected from rain by curb caps; the horizontal leg should extend under the shingles at least 4 in. As with all flashing, avoid nailing in the channel where water will run. Rather, nail overlapping pieces of step-flashing to the curb only and high enough so the nails will also be protected by curb caps. If necessary, trim the last (uppermost) pieces of step-flashing so they don’t extend beyond the curb.

Install the head flashing by slipping its upper flange under the next full course of shingles above and pressing the head flashing snug to the curb. Attach the head flashing to the curb with one screw or nail at each corner. Then install a strip of building paper—or a second strip of self­adhering membrane—over the head flashing’s flange before shingling over it. Note: Stop the flashing strip and shingles 2h in. to 4 in. above the skylight curb, so there is a clear expanse of metal to clear leaves and accelerate runoff.

Installing cladding (curb caps) is the last step. These pieces cover and seal the tops of apron and side (step-) flashing and, on some models, the top of the head flashing as well. Follow your sky­light’s installation guide religiously. In some fixed models, the head flashing is the last piece to go on, covering the upper ends of the side cladding pieces. Details vary, but caps snap or screw on. Note: Better-quality units have self-sticking foam gaskets that are applied to the top of the curb before the caps are installed, which reduces air and dust infiltration.

Once the unit’s mounting brackets are screwed to the sheathing, wrap the curb with building paper or self­adhering membrane as described in the text. (Note: Because rain began falling during this photo session, the curb wasn’t wrapped until later.) Here, the apron’s bottom flange overlays the shingles below.

Working from the bottom up, apply L-shaped step flashing along the side. Each overlaps the one below and is nailed with a single nail to the side of the curb. The last pieces of step-flashing slide up under the head flashing. When all the step-flashing is placed, counterflashing strips fit down over them, sealing the unit.

I Skylight Cladding

Cladding covers and seals the top legs of apron and step-flashing and—on some operable models—it covers the head flashing as well. Read installation instructions closely. Numbers on the cladding indicate the installation sequence.

Finish off with a couple more tasks. To reflect light, lightwells should be covered with drywall and painted a light color. Insulate around the lightwells to reduce heat loss and condensation. Because condensation is common around sky­
lights, cover the lightwell with water-resistant (WR) drywall, often called greenboard for its color. Stiffen the well’s outside corners with metal cornerbeads.