Blog Archives

F. Diagonal Percent Method

Posted by on 15/ 11/ 15

The length of a rafter can be found by determining the horizontal length (run) that it covers, and the pitch of the roof. The constant relationship

between these factors is defined as the diagonal percent. This percent is constant for any common or jack rafter on any roof that has the same pitch. To find the length of a rafter, multiply the length of the run by the diagonal percent. For example, if you have a roof with a 6/12 pitch and a run of 6′-111/4", you multiply 6′-111/4" by 1.118 (diagonal percent for a 6/12 pitch) and find that your rafter length is

7′-91/16". With a construction calculator, enter 7′ x 1.118, and it will read 7′-91/16". The illustration below provides the diagonal percent for common pitch roofs...

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Carpentry

Posted by on 15/ 11/ 15

This chapter od, the king

of building materials. Built amid virgin forests, the first wood houses were fashioned from mas­sive ax-hewn timbers that took half a neighbor­hood to raise. Because iron was scarce, those great post-and-beam frames were joined without nails. Instead, they were fitted tightly and then fastened with whittled wooden pegs. The technol­ogy was crude, but the houses survived, in large part because of the mass and strength of wood.

Early in the nineteenth century came plentiful iron nails and circular-sawn lumber of uniform, if smaller, dimensions. Although such lighter components needed to be spaced closer than rough-hewn timbers, their reduced weight made it possible for three or four people to raise a wall. Balloon framing was the earliest of milled lum­
ber house...

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Urban hydraulics in the Mycenaen palaces

Posted by on 15/ 11/ 15

The centers of Mycenaen power are in strongly fortified palaces (Figure 4.6), with an architecture that has been described as cyclopean due to its use of huge stone blocks. At Mycenae in the palace of Agamemnon, at Pylos homeland of Nestor, and at Tiryns, one finds bathing rooms equipped with permanent bathtubs of terra cotta that sometimes

Urban hydraulics in the Mycenaen palaces

Figure 4.6 Sites of the great hydraulic developments in the Greek world before Alexander.

were equipped with a drain. Complex systems of drainage sewers in the floors of the palace drained both rainwater and wastewater, including water from the bathing rooms. At Pylos, stone drains collect wastewater and dump it into collectors large enough for a
man to stand in.[148]

Like the Cretans, the Mycenaens bring water to their palaces using aqueducts...

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Beef Up Your Old Insulation without Tearing into Walls

Posted by on 15/ 11/ 15

■ BY JUSTIN FINK

W

hen it comes to insulating floors, walls, and ceilings, nothing makes it easier than working with the blank canvas of a newly framed house. The walls are wide open, so contractors can add any type of insulation they want to achieve the best pos­sible thermal performance.

What about the rest of us, though? Those of us living in houses built with minimal
insulation, or none at all? The ones who don’t have the luxury of gutting their walls? The ones who work on or live in houses that hemorrhage heat in the winter and bake like an oven during the summer? What can we do to improve the thermal performance of these homes?

A lot. Techniques and materials for retro­fitting insulation in old walls have improved

Balsam wool Urea-formaldehyde foam

 

Vermiculite

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How to Build a House on Wheels

Posted by on 15/ 11/ 15

The Foundation and Framing

With little exception, my first portable house was built by using the most stan­dard methods of construction. Like any other mobile home, my structure sit on a steel chassis – in this case, a 7’ x 14’ flatbed, utility trailer. I took most of the wooden deck off to save weight and put aluminum flashing over the gaps to safeguard against mice. The floor framing was laid on top of that. I used two-by-fours spaced about 24 inches apart on center.

Once that framing was assembled, I filled the cavities between the boards with foam board insulation and spray foam and capped the whole thing off with some %-inch plywood subflooring.

The walls were framed right over the wheel wells using headers just as you would over any other opening...

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Probability Estimates for Data Series: Plotting Positions (Rank-order Probability)

Posted by on 15/ 11/ 15

As stated previously, the objective of frequency analysis is to fit geophysical data to a probability distribution so that a relationship between the event magnitude and its exceedance probability can be established. The first step in the procedure is to determine the type of data series (i. e., event magnitude) to be used. In order to fit a probability distribution to the data series, estimates of probability (or equivalent return period) must be assigned to each magnitude in the data series.

Consider a data series consisting of the entire population of N values for a particular variable. If this series were ranked according to decreasing magni­tude, it could be stated that the probability of the largest variate being equaled or exceeded is 1/N, where N is the total number of variates...

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Blowing Insulation Is a Team Effort

Posted by on 15/ 11/ 15

A

division of labor keeps insulation flowing. One person handles the hose, and the other feeds the blowing machine. The most critical job is at the machine (see the top left photo below and the bottom right photo), where the steady rate of insulation flow is controlled by the operator. At the other end of the hose, it’s best to start at the farthest point and work back to the attic access. A slight upward hose angle helps to spread the insulation more evenly.

Fiberglass made easier

Owens Corning® (www. owenscorning. com) has introduced AttiCat®, a rental system that processes and distributes bales of fiberglass. The packaging is stripped as the bale is pushed into the hopper. Then the machine agitates the fiberglass and blows it out through the hose...

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STEP 6 Raise the Walls

Posted by on 15/ 11/ 15

STEP 6 Raise the WallsПодпись:
As with barn raisings of yore, it takes a few warm bodies to raise framed walls. Let one person be the team leader and encourage everyone to work together (see the photo below). Remind people to lift with their legs, not with their backs. In many areas, builders put a heavy bead of caulk or a roll of foam

(polystyrene) on the floor or slab under the bottom plate before raising a wall. This helps keep out cold air as well as any bugs that may want to migrate inside. To ensure that the wall wont slip over the outside edge of the build – ingas it’s being raised, nail pieces of 2x stock to the rim joist so they stick up a few inches above the floor to catch and hold the bottom plate (see the top photo at right ). On a slab, bolts hold the bottom plate in place.

Raise exterior through walls ...

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Teaching By Example

Posted by on 15/ 11/ 15

Embracing less in a culture founded on the precept of more is counter-cul­tural, but it need not be self-consciously so. To do what we know to be right takes effort enough. There is no need to waste our much-needed energy on actively trying to change this spendthrift society. The tangible happiness of a life well lived is worth a thousand vehement protests.

Magazines, television and billboards incessantly insist that the cure for what ails us will be revealed by earning and spending more and increasing square footage. But the security and connectedness we seek are unobtainable so long as we continue to surround ourselves with these symbols of security and connectedness. Our desire for that which pretends to be success and our fear of not having it bar us from feeling genuinely fulfilled...

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Return Period

Posted by on 15/ 11/ 15
Return Period Подпись: 1 1 - P (X < xT) Подпись: (3.1)

Hydrosystems engineers have been using the concept of the return period (or sometimes called recurrence interval) as a substitute for probability because it gives some physical interpretation to the probability. The return period for a given event is defined as the period of time on the long-term average at which a given event is equaled or exceeded. Hence, on average, an event with a 2-year return period will be equaled or exceeded once in 2 years. The relation­ship between the probability and return period is given by

in which xT is the value of the variate corresponding to a T-year return period. For example, if the probability that a flood will be equaled or exceeded in a single year is 0.1, that is, P (X > xT) = 0.1, the corresponding return period is 1/P (X > xT) = 1/0...

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