TURNING CORNERS IS TRICKY WORK

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Combining an enclosed soffit with a gable-end roof overhang means that you need to con­struct a boxed return. The return creates the nailing surfaces required to bring the soffit and fascia trim around the corner of the house. Here’s how to do the job:

TURNING CORNERS IS TRICKY WORK

1. Use 2x lumber to make the framing for the boxed return, which consists of a triangular piece cut to match the roof’s pitch and a straight board that vertically extends to the gable wall.

2. Fasten this assembly to the bottom edge of the barge raf­ter and the back wall. The soffit paneling must be attached prior to the aluminum cladding.

TURNING CORNERS IS TRICKY WORKTURNING CORNERS IS TRICKY WORK

3. Run electric cable through the corner soffit for an outdoor light. Slip the gutter board cladding under the roof’s drip edge trim, then bend it at a 90-degree angle to cover the end of the soffit. Test-fit the cladding for the return before you nail the prebent piece in place.

4. To install gable-end siding panels, nail white J-channel trim along the rake. Trim the panel ends to match the roof’s pitch.

We have to set up scaffolding to finish the siding and soffit work; by this time, the house is really looking great.

After a break to admire our progress (and clean up the spare pieces of vinyl siding), we start to cut and bend the aluminum cladding that will cover the fascia boards and the barge rafters.

A big bending tool, called a brake, creases the aluminum perfectly straight.

TURNING CORNERS IS TRICKY WORKWhen it slides into place over the wood, it looks like it be­longs there.

TURNING CORNERS IS TRICKY WORK

Clad the fascia. The top edge of fascia cladding must slide underneath the metal drip edge that extends from the roof. Install the cladding with special nails colored to match the prefinished aluminum.

 

TURNING CORNERS IS TRICKY WORK

Bend the aluminum cladding. Borrow or rent a large sheet-metal brake—it’s the only way to make precise bends in aluminum cladding. The brake clamps the coil stock in a straight line while you move a lever to make the bend.

 

TURNING CORNERS IS TRICKY WORK

Put on the finishing touches. Barge-rafter cladding is installed last. For an attractive appear­ance and weather-tight construction, the alumi­num overlaps at the peak, with the topmost piece showing a plumb cut.

 

TURNING CORNERS IS TRICKY WORK

The cladding that covers the boxed return is a bit more complex, but the bends can be made with a hand brake. At the ridge peak, run one piece of aluminum past the centerline, then cut the second piece plumb to give the trim a finished appearance.

Any time you use aluminum to cover gut­ter boards, posts, or beams, make absolutely sure that no water can get behind the alumi­num. You can do this by overlapping adjacent sections of cladding by 3 in. to 4 in. and by ensuring that a higher section of cladding (on a barge rafter, for example) always overlaps a lower section.

Median Barrier Transitions

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Transition sections are used between adjoining median barriers having significantly different deflection characteristics, between a semirigid median barrier and a rigid barrier (such as a bridge rail), and in similar situations. The transition sections should provide impact performance similar to standard sections, and emphasis should be placed on designs to avoiding vehicle snagging. Structural details of special impor­tance include the following:

• Rail splices should develop the tensile strength of the weaker rail.

• Use a flared or sloped connection if the connection could snag an opposite-direction vehicle. Use a standard terminal connector to attach a W-beam or thrie-beam rail to a rigid bridge railing or parapet, or provide a recessed area in the parapet wall to receive the rail.

• In cases such as a strong-post W-beam transition to the concrete safety shape, use a blockout design and consider adding a rub rail or using a thrie-beam instead.

• Use a transition length 10 to 12 times the difference in lateral deflection of the two systems under consideration.

• Increase stiffness gradually from the weaker to the stronger system by means such as decreasing the post spacing, increasing the post size, and using nested sections of W-beam or thrie-beam.

Median Barrier Transitions
Remarks: The concrete safety shapes are the only operational rigid barriers. The lower-sloped face redirects vehicles without damage under low-impact conditions. During moderate to severe impacts, some energy is dissipated when the vehicle is lifted off the pavement. The loss of tire contact with the pavement also aids redirection.

The details of the shape are critical. The distance from the pavement to the break between the upper and lower slopes should be kept at 13 in or below. Barrier performance under moderate to severe impact conditions is not significantly affected by overlays on the lower-sloped face, The overall height of the barrier, however, needs to be maintained at a minimum of 29 in.

The safety-shape barrier is suitable for narrow medians. Both faces can be flared away from the centerline to provide room for rigid objects to be installed in the medians.

*Very severe hits may destroy the barrier. Reinforcing is recommended to prevent shattering of concrete where the top of the barrier has a width less than 1 ft.

FIGURE 6.31 Concrete safety-shape median barrier. Conversion: 1 in = 25.4 mm. (From Roadside Design Guide, AASHTO, Washington, D. C., 2002 and 2004, with permission)

STEP 7 FINISH THE SOFFITS

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Vinyl soffit material has small holes to allow air to enter freely. Before attaching this material along eave walls, make sure that all the baffles between rafters are in place to keep insulation out of the eaves and allow airflow into the attic. On this house, we cut the vinyl soffit sections into short lengths that overlap each other and ran them perpendicular to the siding. Insert the ends of each soffit panel into vinyl J-channel trim nailed to the wall and nail the other end to the bottom edge of the gutter board.

Gable-end soffit details

Soffit work is also required to finish off the un­derside of the roof overhang on the gable ends of a house. Remember the J-channel trim that you installed along the rake to house the ends of the gable-wall siding panels? The inboard edge of the soffit trim can rest right on top of that J-channel. This detail is shown in the illustration on p. 149. The outboard edge of each soffit piece is nailed to the 2 x2s fastened along the barge rafter.

It’s common practice for some builders to build boxed returns at the bottom corners of the roof to bring the soffit around the corners of walls. One part of the return (made from 2x material) is cut to match the angle of the roof’s pitch and is fastened to the underside of the barge rafter. The other part of the return should then be fastened to the angled piece and to the wall (see the sidebar on the facing page).

STEP 8 COVER EXTERIOR TRIM WITH ALUMINUM CLADDING

Aluminum trim, often referred to as coil aluminum because it comes in a coil or roll, can be shaped and used to cover rough exte­rior trim, such as gutter boards, barge rafters, and beams. This sheet metal comes in various widths and colors. The small nails used to install the material are available in matching colors. Softer than steel, coil aluminum can be cut with tinsnips or a utility knife. The same long, flat worktable that was used during vinyl siding installation is just as valuable for sheet – metal work. To make the precise bends that give the finished cladding its clean-lined ap­pearance, you’ll need a hand brake as well as a large sheet-metal brake, which you can borrow or rent (see the bottom right photo on p. 174).

To wrap a 2×4 gutter board, cut a 6-in.-wide strip of aluminum and bend it at 4 in. into a 90-degree angle. The 4-in. leg slips under the roof’s drip cap and covers the front of the gutter board. Attach it with matching l-in.-long nails every 24 in. along an imaginary centerline (see the left photo on p. 174). The 2-in. leg fits over the vinyl soffit, covering the nails used to secure the soffit to the bottom of the gutter board. Be careful not to drive nails so hard that you leave a hammer imprint in the metal.

Building Code Load

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Conventional and nonconventional codes regulate the strength needed in the walls, floors, roofs, and connections to resist the forces on buildings. The conventional code describes a prescriptive standard to resist the forces. The standard applies to simple buildings using common construction methods. The nonconventional code is a performance-rated system and provides non-prescriptive engineering
guidelines that can be applied to more unusual or more difficult buildings.

Prescriptive Format

The prescriptive format has specific requirements, such as the size of studs needed or the type of wall bracing. If you build the structure following these requirements, then the building meets the minimum code standards for a safe building. The prescriptive codes are covered in more detail in Chapter 10.

Framers meet prescriptive code requirements on a regular basis, sometimes without even knowing it. As they brace their walls, block and nail their floor system, nail their walls to the floors, and bolt the building to the foundation, they are creating a load path that transfers the forces of nature to the ground-in ways that are prescribed by the code.

Non-Prescriptive Code

The performance, or non-prescriptive, code provides for free design, as long as it stays within certain code standards. Performance designing is different for each building, and the engineer or architect must specify and detail all aspects of the design.

A special design might be needed because a building is in a high-earthquake or a high-wind zone, because it requires large open spaces or window walls, or to resist other forces. The most common forces affecting buildings are shown in the illustration “Forces on Buildings."

Forces on Buildings

A

Snow load Gravity

A Very Hot Bed

Posted by on 20/ 11/ 15

Prior to purchasing a home, a family contacted John to conduct radon testing with electronic monitors, following the EPA’s protocol. Closed – house conditions were established 12 hours prior to testing and were maintained throughout the tests. During the testing, one of the electronic monitors located in the dining room indicated 12.5 picocuries of radon per liter of air, while a monitor elsewhere showed close to normal levels. The client was advised that the electronic read­ings were suspicious and that additional testing was necessary. As the investigation proceeded, it became clear that there was a radon source at one end of the home. In fact, the radon result for a test conducted on a night table in the guest bedroom was 27.0 picocuries, while that for the family room a short way down the hall was 7.0 picocuries. The farther the monitors had been placed from the guest bedroom, the lower the radon value.

Upon visual examination of the guest bed­room, it was noted that the headboards for the two beds were made of rock that appeared to be granite. The headboards were later tested with a small Geiger counter. While normal radioactive background levels away from the headboards were approximately 12 radioactive counts per minute, the counts close to the headboards were over 300. It was clear that the headboards were at least one source of radon in the room.

The headboards were in fact a decorative granite rock imported from Italy. Each headboard weighed several hundred pounds. The floors and walls had been especially constructed to hold the extra weight. It took six strong men to remove each of the headboards to a detached garage. The radon tests were repeated throughout the home with all values now under 1.0 picocurie. The home was given a radon clearance, contingent upon the proper disposal of the headboards.

Discussion

This was the first home John inspected in which a radon source was caused by a building material or furnishing. Although radon from the soil is the most common cause of elevated radiation levels in a home, there are many other possible sources. Since granite rock is sometimes high in uranium, it must be considered a potential source of radon when used in construction. Rock can be a superb building material, but it should always be tested prior to use for the rare possibility of radiation.

Installing the top piece of eave-wall siding

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The last piece of siding at the top of an eave wall can be fastened in different ways. If the eaves will be left open, use strips of undersill trim and cut and fasten the final panel in the same way as the one under the window. If the eaves will be closed with soffit material (as was done on this house), then the uppermost siding panel can simply be nailed in place above the level of the soffit. The

J-channel trim for the soffit, and then the soffit itself, will cover the top siding panel.

Siding gable-end walls

Begin by nailing 2×2 blocking between the lookouts and along the barge rafter. This allows J-channel to be nailed up the rake, where it can receive the angled ends of the siding panels. Some builders prefer to hold the J-channel /4 in. down so the soffit pieces can simply lie on top of it.

To ensure accurate angled cuts where the siding panels meet the rake, make a pattern from a short scrap of vinyl siding, with the angle cut to match the roof’s pitch. If you really want to save time, however, set up a circular saw guide at the proper angle on the worktable.

As you cut and fit these pieces on the gable end, be sure to leave a /4-in. space between the siding and the inside of the J-channel. If there are gable-end vents, cut and fit pieces around the vents, just as you did for those around the windows and doors. The last small piece at the peak can be cut and secured to the wall with a small screw or nail.

MAKING AN OUTLET-BOX CUTOUT

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Precise cutouts are sometimes required for certain situations, such as fitting siding panels over vents or electrical outlet boxes. Careful layout is the key here.

MAKING AN OUTLET-BOX CUTOUTMAKING AN OUTLET-BOX CUTOUT

1. Place the siding panel directly below where it will be in­stalled. Mark where the sides of the box hit the panel.

2. Reposition the panel to one side of the box, clipping it into the panel just below the box. Mark where the top and bottom of the box hit the panel.

MAKING AN OUTLET-BOX CUTOUT

4. The panel is now ready to install.

 

MAKING AN OUTLET-BOX CUTOUT

3. Outline the cutout where the horizontal and vertical lines intersect, then cut the opening with a sharp utility knife.

Подпись: Install J-channel for the soffit. The top course of vinyl siding on eave walls extends behind the J-channel that holds the soffit panels. Install the J-channel by nailing it to the bottom chords of the roof trusses.

more than 1 in. to fit, you must fur out or shim the undersill trim. The deeper the notch in the siding, the thicker the shim you’ll need. By fur­ring out the undersill trim, you can prevent the surface of the siding from bowing in beneath the window. Try not to have any joints between panels located beneath or above windows.

To determine a notch’s location horizontally in the panel beneath a window, measure from the last piece of siding to the opening and mark it on the panel (don’t forget to add 1 in. for the overlap). For an accurate height measurement vertically, lock a scrap of siding into the nail flange of the piece below, then slide the scrap against the window edge. Mark where the scrap hits the bottom of the window and transfer the mark to the panel you’re cutting. Finally, measure the length of the opening and transfer it to the siding, leaving /4 in. on each side for ex­pansion. These notched cuts can be made with a utility knife, a hacksaw, or tinsnips. Use a snap-lock punch to create crimps, or tabs, /4 in. down from the top edge of the notched siding and make crimps every 6 in. across the length of the window. The crimps must face out to lock into the undersill trim.

The panels that fit over the tops of windows and doors are marked and notched in the same way as those on the bottom. The horizontal part of the siding slips down into the J-channel. To make cutouts where the siding fits over a dryer vent, an electrical outlet box, or another protru­sion, use the techniques discussed here and on the facing page.

FRAMING

Posted by on 20/ 11/ 15

Buildings are naturally affected by the forces of nature, and also by artificial forces. Elements such as gravity, wind, snow, earthquakes, retained soil, water, impact by an object, and mudslides can all have negative effects on a building.

This chapter will give you a basic understanding of the forces that affect buildings, and some helpful information on the framing methods used to resist those forces.

Although you may not be responsible for designing structural requirements for buildings, it is important to have some understanding of a building’s structural loads. When you are aware of the reasons behind the decisions engineers and architects make, it is easier to interpret the plans, and to make sure that the structure is built accordingly.

The Strength of Good Framing

The forces of nature can have devastating effects on buildings. The following photo shows an example of how destructive the elements can be. This photo is quite dramatic; you can see that the ground literally fell out from under the house. But the photo also shows the strength of good framing— the house stayed together even though the ground collapsed under it.

Source: APA, The Engineered Wood Association

Understanding

Structural Loads

^■

As the forces of nature contact a building, they travel throughout seeking a weak link. Ultimately, if a weak link is not found, the force or energy will be transferred to the ground, which will absorb the force. Each component of the building must be strong enough to transfer the load in a path to the ground. The components are:

• Foundations

• Walls

• Floors

• Roofs

• Connections

To achieve the strength needed, a building’s walls, floors, and roof must work together as a unit.

The vertical elements that are used to resist forces are commonly called shear walls, and the horizontal elements (like floors and roofs) are called diaphragms. The path of energy to the ground is called the load path. The diagram on the next page shows the load path for transferring the forces to the ground.

STEP3 Set the Windows and Doors

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The setting process anchors the windows and doors in their final positions. Complete installation happens later, when we move inside the house and work on the interior trim. The windows and doors used in afford­able housing are mainly vinyl and vinyl clad, though aluminum-clad frames are still installed in some areas. Some codes require that window frames be clad with white vinyl; check with your local building department. Dark-colored vinyl absorbs more solar heat and, as a result, tends to deteriorate faster. On the other hand, dark-colored aluminum cladding holds up well in sunny areas.

Both vinyl and aluminum-clad windows come with a nailing flange on the outside of the window frame; the flange greatly simplifies the installation process. The most popular styles are single hung (the bottom sash moves up and down), double hung (both sashes move up and down), and sliding (one sash slides to the side). Windows with a built-in 1-channel, or channel surround, make it easy to hide the ends of vinyl and other siding without the use of extra trim.

Windows in affordable houses should definitely be double-glazed. The heat loss and gain through single-glazed windows is considerable. In very cold or very hot cli­mates, windows with low-E coatings offer even more energy savings. For more infor­mation on energy-efficient glazing, see Resources on p. 278.

Setting a window

Flanged windows are the easiest windows to install, but windows that come with exterior trim instead of flanges are fairly easy as well. The main difference is that you nail through the exterior trim instead of through the flanges. No matter which type of window you use, its good to have two people for this job—one inside the house and one outside. There are three basic steps involved in setting a window:

Подпись:Подпись: Lighten the load. Before installing windows, you can substantially lighten their load by removing one or more sash members. It's also wise to store all screens in a safe place until the house is finished. 1. Caulk the flange. Squeeze a generous bead of exterior caulk or sealant on the back of each window flange (see the left photo on p. 156).

STEP3 Set the Windows and Doors
3 • Nail the flange to the wall. Secure the window by driving іИ-in.-long galvanized roofing nails at each corner of the window flange and every 8 in. elsewhere. Be careful not to damage the vinyl frame by hitting it with your hammer. When I’m building in rainy climates, I make one more seal all around the windows by running a strip of waterproof tape over the flange and onto the housewrap. It may be overkill, but who wants to tear off siding to repair a leaky window in the middle of a rainstorm?

Setting a prehung exterior door

Exterior doors are often prehung units that include jambs, a threshold, and wood exterior trim. I buy doors predrilled for both the house lockset and the deadbolt. Given the option, I also choose a door with a double-glazed glass window to bring more light into the house.

Take note of which way the plans say the door should open, and make sure the door you ordered swings the right way (see the illustra­tion at bottom right). Most exterior doors open inward. Also, make sure the door jamb is the proper width for the wall. A 2×6 wall takes a wider jamb than a 2×4 wall does. There are four basic steps involved in setting a pre­hung door:

1. Flash the doorsill. The sides and top of the rough opening can be flashed in the same way as a window. With an exterior door, sill flash­ing is essential if you want to prevent rot beneath the threshold. I prefer to use 12-in.- wide aluminum flashing for this application.

Cut the flashing about 6 in. longer than the width of the rough opening so it can cover the threshold area completely and extend several inches up each trimmer stud. Cut the flashing as necessary to create ears that fold onto the subfloor and over the exterior wall sheathing. You can keep the flashing in place with a few galvanized roofing nails.

2. Test-fit the door. When working with a prehung door, your primary concern is to set itsothat it opens and closes with ease. Fortu­nately, this is pretty easy to do. Once you’ve removed any materials used to protect the door during shipping and any device used to hold the door secure in its jamb, check the fit of the door in its opening. It should fit easily see the photo on p. 158).

Подпись:

3. Set the door in place. Run a bead of sealant on the back of the door trim and a couple of heavy beads across the bottom of the rough opening on the flashing where the threshold will sit. Then set the frame in its opening. From the inside, adjust the frame so that there’s a gap of about A in. all the way around the door. This will allow the weatherstripping on the door frame to seal properly. Secure the door in the opening by driving a 16d finish nail through each corner of the exterior trim and into the sheathing and studs. (Alterna­tively, you can drive З-in.-long trim-head screws.)

4# Finish fastening the door. Check the door again to see that it opens and closes with ease. If it does, then drive more 16d finish nails (or screws) 2 ft. o. c. all the way around the trim. Set all nails or screws about A in. below the
surface of the wood so they can be hidden by putty and covered with paint. Drive 8d finish nails or 2-in.-long screws through the hinge side of the jamb and into the trimmer near each hinge. If the jamb is not tight against the trimmer, slip in a shim to prevent the jamb from bowing. Shim and nail through the jamb on the lock side next, but be sure to keep nails away from the lock and deadbolt area. Finally, drive the long screws that are included with the door frame through the hinges and the jamb and into the trimmer. These help hold the entire assembly in place.

Installing panels around windows, doors, outlets, and vents

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Strips of undersill trim must be installed beneath windowsills. This special trim covers the horizontal edge of a siding panel and locks the panel in place. Cut each trim piece to fit between the two side J-channels, then nail it flush against the underside of the window. If the panel beneath a window needs to be notched