Plataforma de procesamiento Seismic Unix (SU )
4.14. Est´ aticas residuales
4.15.2. Normal Move Out (NMO)
?4'- o"
c.'-o"
7'-01#
IZ'-111
center of a 2x4 (3Yz-in.) wall is 1 % in. from its edge, so this added to the given dimension is 1 2
ft.
8% in. Measure in this distance from the outside of the building and make a mark. Carpenters usually mark locations with an upSide-down V (sometimes called a "crow's foot") with the point of the V right on the required dimension. Alongside this mark make a1 2 It. 8% in .
Bedroom wall
.1
clear X, rather than a simple line, with keel to indi cate the location of the plate. This X is important. When it comes time to lay down the 2x plates, the
X will indicate on which side of the line to place them. So every time you make a mark for wall ioca tion, make an X right alongside it to indicate actual plate location.
Both ends of every interior wall have to be marked by measuring off the outside wall or another known point. Some interior walls will be laid out parallel to other interior walls. Once the end points are located, these marks are connected together with a chalkline to show the location of the bottom plate of a framed wall. Care must be taken to get the correct dimen-
sions from the plan and to be sure whether the mea surement is from outside to outside, outside to cen ter or center to center (see p. 1 4) .
It i s important t o follow plan dimensions care fully, but for most builders, plans are a guide, not a law from which they cannot deviate. For example, a wall between bedrooms might have a pipe coming up through it that has been installed off layout an inch or two. Rather than move the pipe, which is especially difficult on a concrete slab, move the wall a bit and make one bedroom a little larger. This "fudging" is not always possible, of course. For ex ample, exact measurements must be maintained when one wall has to be placed 60Y4 in. from an other to accommodate a bathtub. If a pipe were in stalled in the wrong place here, it's the pipe, not the wall, that would have to move.
One problem is that plans don't always have the exact measurements you need. They may show, for example, that the bathroom is 60 in. wide, when in reality it needs to be 60Y4 in. or more, so that the tub you are using can be installed with ease. (The tub supplier or manufacturer may be a more reliable source for such information than an architect's plans.) Hallways are another example. A hallway wide enough to accommodate a header and king studs for a 32-in. door needs to be 40 in. wide be tween walls.
At times when extra space is needed, walls can be made 1
�
in. wide by nailing the studs in flat instead of on edge. This is sometimes done at the back of a closet to add an extra 2 in. in depth.Very little attention need be paid to door and window locations at this point. All chalklines should be continuous, snapped straight through any wall opening. If you make a mistake in layout, make a clear correction. Rub out an erroneous chalkline with your foot or draw a wavy line through it before snapping another. Anytime you have something out of the ordinary, indicate what is to be done by writ ing on the floor with keel. For example, if you have a short wall, one that ends in the middle of a room, The location of interior walls may have to be
indicate that by writing "end" on the layout. If a 2x6 wall is needed in a bathroom in a house that is otherwise framed with 2x4s, write "2x6" right along side the chalkline (see the drawing on p. 67).
One of the principles of good layout is clarity. On some jobs, the people who do the layout may nev er see the people who do the plating. Any commu nication between them must take place in writing on the layout surface. And remember that too many marks can be just as confusing as too few. Keep things as simple yet as clear as possible.
Rake walls
A rake wall follows the slope of the roof. It is neces sary when the plans call for a cathedral ceiling. In a rake wall, each stud is a different length. The layout for a rake wall involves drawing a template on the deck, so that the framer can build the wall without having to make any further calculations.
There are two fairly easy ways to lay out a rake wall. The first way is to use a pocket calculator (or your head) to determine the difference in length be tween the shortest and the longest stud. The short est stud will normally be the standard wall-stud length (92Y4 in. for this calculation). To determine the length of the longest stud it is necessary to know the length of the rake wall. For example, if the building is 33 ft. wide and the rake wall runs up to the center or peak of the roof, then its highest point is midspan, that is, 1 6Yz ft. This figure multiplied by the roof pitch will give you the difference in length in inches between the shortest and longest studs. With a roof pitch of 4-in-1 2, for example, multiply 1 6Yz ft. by 4 in. for a result of 66 in. Now add this 66 in. to the length of the shortest stud (92Y4 in.