When the wall is placed on concrete or masonry, the bottom plate must be a naturally durable wood (for example, red- wood) or pressure-treated wood. A sealing material, such as Sill Seal, is often placed below the bottom plate of exterior walls when the walls bear on concrete or masonry. When the wall is placed on a wood floor, the bottom plate is of the same lumber as the studs. For the bottom plate, the door openings are not deducted from the length because the bot- tom plate is run through the opening and is cut out after the framing is complete. This helps ensure that the walls are framed straight.
Bearing walls require two top plates. Nonbearing walls may be built with one top plate, but they are often built with two top plates to allow the same length of studs to be used for both the bearing and nonbearing walls. Top and bottom plates are taken off in the same way that sills are taken off.
The following formulas need to be entered into the associated cells:
Cell Formula
B4 =ROUNDUP(B2/4,0) B5 =CEILING(B1/8,1/3) B7 =ROUNDUP(B4*B5,0)
The data for the floor is entered in Cells B1 and B2. The spreadsheet assumes the sheets are 4 feet by 8 feet and the long direction of the sheet is run parallel to the length of the building. The number of rows is rounded up to the next whole sheet, and the number of columns is rounded up to the next one-third of a sheet using the CEILING function, which equals the distance covered by three joists when the joists are spaced at 16 inches on center. The data shown in the foregoing figure is from Example 8-5.
EXAMPLE 8-7
How many feet of treated plate and untreated plate are needed to construct the walls shown in Figure 8-5? The walls are constructed of 2⫻ 4s and the exterior walls are sheathed with 7>16-inch OSB. The wall bears on a concrete floor.
Solution: The thickness of the exterior walls is 4 inches, and the thickness of the interior walls is 3 1>2 inches. The total length of the walls is calculated as follows:
Because the walls bear on a concrete floor, the bottom plate needs to be constructed of treated plate; therefore, 142 feet of treated plate are needed. The top requires a double top plate of untreated lumber; therefore, 284 feet (2⫻ 142 ft) of untreated
plate are needed. 䊏
Studs
Precut studs are available for 8- and 9-foot ceilings. Precut studs for an 8-foot ceiling are 92 5>8 inches long, and when used with a single bottom plate and double top plate, they provide a rough ceiling height of 97 1>8 inches. The extra 1 1>8 inches allows for floor and ceiling finishes. Precut studs for a 9-foot ceiling are 104 5>8 inches long, and when used with a single bottom plate and double top plate, they provide a rough ceiling height of 109 1>8 inches.
The number of studs in a wall is determined by the stud spacing and the number of ends, corners, intersections, openings, and hold-downs. The number of studs needed to meet the spacing requirements is determined by Eq. (4-2). When a wall ends without forming a corner, an additional stud is needed, as was shown in Chapter 4. This is to take the
⫽ 141 ft 11 inches
Length⫽ 2(22 ft) ⫹ 3(24 ft 4 in) ⫹ 2(11 ft 5 in) ⫹ 2 ft 1 in
end conditions into account. When the wall forms a corner, the end condition will be accounted for with the corner.
Two extra studs are needed at corners. One of these studs provides for the end condition, and the other stud pro- vides backing for the interior finish. Two methods of fram- ing a corner are shown in Figure 8-6. The difference in these two corners is how the backing stud is placed. In this book, two additional studs are added for each corner.
FIGURE 8-5 Wall Layout
FIGURE 8-8 Framing of a Door Opening
When walls intersect, backing is needed for the interior finish and to secure the intersecting walls together. Two methods of framing an intersection are shown in Figure 8-7. The top method requires two additional studs to be pro- vided for each intersection. The bottom method requires a
wider stud (a 2⫻ 6 for a 2 ⫻ 4 wall or a 2 ⫻ 8 for a 2 ⫻ 6 wall) be provided for each intersection. In this book, two addi- tional studs are added for each intersection.
Each opening requires additional studs. A typical door opening is shown in Figure 8-8. Narrow openings require a jack stud and a king stud on both sides of the opening. The jack studs are used to support the header. Wider openings may need two or three jack studs on each side of the open- ing to support the header, depending on the load sup- ported by the header and the width of the opening. The number of jack studs should be determined by the design professional or the building code when it has not been specified by the design professional. For the opening shown in Figure 8-8, two additional studs are needed be- cause two of the studs needed to meet the spacing require- ments have been deleted and two king studs and two jack studs have been added. The actual number of additional studs will vary based on the location of the door. If the opening in Figure 8-8 were moved a few inches to the right, the right king stud would meet the stud spacing require- ment, and only one additional stud would be needed. For wider openings a greater number of studs will be replaced by the openings; however, this is often offset by the need for a greater number of jack studs. In this book, two addi- tional studs are added for each doorway.
Window openings are similar to door openings except that there is framing below the opening that reduces the deletion of the regularly spaced studs. The framing of a win-
dow opening is shown in Figure 8-9. Cripple studs and a sill are used to frame the wall below the opening. A cripple stud is lo- cated at each end of the sill, and cripple studs are placed under the sill to maintain the regular spacing of the studs. The num- ber of additional studs that are needed will change depending on the location of the opening, the height of the opening, and the width of the opening. If the opening in Figure 8-9 were moved a few inches to the right, the right king stud would meet the stud spacing requirement and reduce the number of addi- tional studs by one. Less material is required for the cripple studs in taller openings than in shorter openings. For example, if the top of the sill in Figure 8-9 was below 49 inches, two crip- ple studs could be cut from one 92 5>8-inch stud and two studs would be required for the cripple studs. If the top of the sill were above 49 inches, four studs would be required for the cripple studs. Wider openings may need additional jack studs. For an opening up to 8 feet wide with single jack studs, up to seven additional studs may be needed to frame the opening. If the opening required double jack studs, up to nine additional studs may be needed to frame the opening. In this book six ad- ditional studs are added for each window opening that requires only two jack studs; eight additional studs are added for each window opening that requires a pair of jack studs on each side. Posts or doubled or tripled studs are needed wherever a hold-down occurs. If the hold-down occurs at the edge of a door or window, the hold-down may be attached to the jack and king studs. When a hold-down occurs at a corner, an
additional stud is needed to form a solid blocked corner as shown in Figure 8-10. When a hold-down occurs at other places, up to three additional studs are needed. In this book no studs are added when a hold-down occurs at the edge of a door or window opening, one additional stud is added for each hold-down located at a corner, and three additional studs are added for all other hold-downs.
The quantity takeoff for studs is shown in the following example.
EXAMPLE 8-8
How many studs are needed to frame the wall in Figure 8-5? The stud spacing is 16 inches on center. Allow for one additional stud for each wall that does not have a corner; two additional studs for
FIGURE 8-9 Framing of a Window Opening
each corner, intersection, or doorway; six additional studs for each window less than 6 feet in width; eight additional studs for each window 6 feet or more in width; and one additional stud for each hold-down located at a corner. Do not add additional studs for