Lesson 4.1 Framing Members
The primary objective of good construction is to erect a building that is structurally sound. The structure should withstand such forces as wind and vertical loads.
Wall framing consists of studs, plates, braces, cripples, trimmers, headers, and fire blocks. It is supported by the floor system. Prefabricate the members of the frame wall on the floor of the building. Then raise the members into position and brace, nail, or bolt them in place.
Studs are closely spaced vertical members that support the weight of the upper floors. They provide a framework for exterior and interior finishes. Main studs can be spaced at 12, 16, or 24 inches on center. Lay out studs by measuring from one corner the distance the studs are to be spaced. Make a tick mark on the plate at the proper measurement (see Figure 2-1 ). After the window and door openings are determined, the studs are paced and nailed through the existing plates with 16d or 20d nails.
Figure 2-1. Tick marks on the plate
To gain the proper location and width of window and door openings you will need additional studs. Fasten the new studs to the plates in the same way as the previously installed studs. The new studs are not framed at 12, 16, or 24 inches on center (see Figure 2-2 ).
There are two types of plates--top and bottom (sole). The plates are laid out so the competed frame wall can be lifted easily and directly into place with the least amount of movement of the wall.
Top Plates. A horizontal member of a partition or frame wall is called a top plate. It serves as a cap for the studs and a support for the joist, rafters, and studs. Top plates tie the studs together at the top and ensure that the studs are aligned. They provide support for structural members above the plates and also provide a base for the roof rafters which tie the roof and walls together. To be effective, top plates should be doubled at the top of the walls and partitions and should have their joints staggered. (Double top plats are discussed in paragraph 2-9.)
Figure 2-2. Placement of other studs
Sole Plates. Use a sole plate (with dimensions not less than the studs) where the walls do not rest on a sill, girder, or beam. Install the studs or corner posts at intervals that are evenly spaced except where partitions or walls are intersected.
2-3. Door and Window Openings
When framing door openings, it is desirable to double the studs. Cut short studs or trimmers the size of the opening and nail them to the inside face of the new studs (see Figure 2-3 ).
Figure 2-3. Frame for a door opening
Headers. Use 2 by 4 or 2 by 6 lumber to make a header. Double the header when this size of lumber is used. The size and the amount of lumber to be used in a header is determined by the width of the opening and the bearing load.
Subsill. When making a window opening, install a header over the window in the same way you would install a header over the door. A subsill must be framed between the trimmers and the cripples. The subsill can be either single or double. When doubled, nail the bottom piece to the outside studs at the proper height. Then nail the top piece of the sill to the bottom section (see Figure 2-4 ).
Figure 2-4. Frame for window opening
Cripples. Place the cripple or jack studs under and over the window and over door openings (see Figure 2-5 ). Cripples are placed at the same intervals as the ordinary studs and are installed after the openings are framed. These serve the same purpose as studs in the rest of the wall.
Figure 2-5. Cripples
Bracing is used to stiffen framed construction and make it rigid. Bracing is also used to resist winds, storms, twists, or strains. Good bracing keeps corners square and plum Bracing prevents warping, sagging, and shifting that could otherwise distort the frame and cause badly fitting doors and windows. The three methods commonly used to brace frame structures are let-in, cut-in, and diagonal-sheathing bracings. In some cases, temporary bracing may be used instead.
Let-In Bracing. Let-in bracing is set into the edges of studs, flush with the surface. The studs are always cut to let in the braces; the braces are never cut (see Figure 2-6 ).
Figure 2-6. Let-in bracing
Cut-In Bracing. Cut-in bracing is toenailed between studs. They are inserted in diagonal progression between studs running up and down from corner posts to the sole plate, top plate, or sills (see Figure 2-7 ).
Figure 2-7. Cut-in bracing
Diagonal-Sheathing Bracing. The strongest type of bracing is diagonal sheathing (see Figure 2-8 ). Each board braces the wall. If plywood sheathing 5/8 inch thick or more is used, other methods of bracing may be omitted.
Figure 2-8. Sheathing used as diagonal bracing
Temporary Bracing. Temporary bracing is placed at intervals small enough to hold the wall straight (see Figure 2-9 ). Bracing placed diagonally on the studs running from the sole plate to the top plate will increase the strength of the wall against horizontal stress (see Figure 2-10 ).
Figure 2-9. Temporary bracing
Figure 2-10. Temporary diagonal bracing
2-5. Fire Blocks
Fire blocks are short pieces of 2 by 4s cut to fit snugly between the studs. They are placed midway up the wall, between the studs to prevent the spread of fire inside the wall. The use of fire blocks will differ according to local building codes. Figure 2-11 shows the proper placement of fire blocks.
Figure 2-11. Fire block placement
2-6. Post Construction
Where partitions meet other walls and at the corners, the studs are built-up using three or more regular 2 by 4s to provide greater strength. Corner posts and T-posts are the most frequently used.
Corner Post. A corner post forms an inside corner and an outside corner, which provides a good nailing base for inside wall coverings. The studs used at the corners of fame construction are usually built up from three or more ordinary studs to provide greater strength. These built-up assemblies are called corner posts. They are set up, plumbed, and temporarily braced. Corner post may also be made in any of the following ways (see Figure 2-12 ).
Figure 2-12. Corner-post construction using both 2-inch and 4-inch lumber
A 4 by 6 with a 2 by 4 nailed on the board side flush with one edge (see Figure 2-12 , A). This type of corner is for a 4-inch wall. Where walls are thicker, heavier timber is used.
A 4 by 4 with a 2 by 4 nailed to each of two adjoining ides (see Figure 2-12 , B).
Two 2 by 4s nailed together with blocks between them and a 2 by 4 flush with one edge (see Figure 2-12 , C). This is the most common method.
A 2 by 4 nailed to the edge of another 2 by 4, the edge of one flush with the side of the other (see Figure 2-12 , D). This type is used extensively in the theater of operations, where no inside finish is needed.
T-Posts. Whenever a partition meets another wall, a stud wide enough to extend beyond the partition on both sides is used. This provides a solid nailing base for the inside wall finish. This type of stud is called a T-post and is made in any of the following ways (see Figure 2-13 ):
Figure 2-13. T-post construction
A 2 by 4 may be nailed and centered on the face side of a 4 by 6 (see Figure 2-13 , A).
A 2 by 4 may be nailed and centered on two 4 by 4s nailed together (see Figure 2-13 , B).
Two 2 by 4s may be nailed together with a block between them and a 2 by 4 centered on the wide side (see Figure 2-13 , C).
A 2 by 4 may be nailed and centered on the face side of a 2 by 6, with a horizontal bridging nailed behind them to give support and stiffness (see Figure 2-13 , D).
2-7. Plumbing Posts
There are two methods for plumbing posts.
Method 1. To plumb a corner with a plumb bob:
(1) Attach a string to the bo The string should be long enough to extend to or below the bottom of the post.
(2) Lay a rule on top of the post so that 2 inches of the rule extend over the post on the side to be plumbed.
(3) Hang the bob line over the rule so that the line is 2 inches from the post and extends to the bottom of it. Refer to Figure 2-14 .
Figure 2-14. Plumbing a post
(4) With another rule, measure the distance from the post to the center of the line at the bottom of the post. If it does not measure 2 inches, the post is not plum
(5) Move the post inward or outward until the distance from the post to the center of the line is exactly 2 inches, then nail the temporary brace in place.
(6) Repeat this procedure from the other outside face of the post. The post is then plum
Follow this process for each corner post of the building. If a plumb bob or level is not available, use a rock, half-brick, or small piece of metal.
Method 2. An alternate method of plumbing a post is shown in the inset in Figure 2-14 . To use this method--
(1) Attach the plumb-bob string securely to the top of the post to be plumbed. Be sure that the string is long enough to allow the plumb bob to hang near the bottom of the post.
(2) Use two blocks of wood, identical in thickness, as gauge blocks.
(3) Tack one block near the top of the post between the plumb-bob string and the post (guard block 1).
(4) Insert the second block between the plumb-bob string and the bottom of the post (gauge block 2).
(5) If the entire face of the second block makes contact with the string, the post is plum
The term bridging is used to refer to a system for bracing joists and studs. Frame walls are bridged in most cases, to make them more sturdy. Two types of bridging are diagonal and horizontal.
Diagonal Bridging. Diagonal bridging is nailed at an angle between the studs (see Figure 2-15 ). It is more effective than the horizontal type because it forms a continuous truss and keeps the wall from sagging. Whenever possible, both interior partitions and exterior walls should be bridged alike.
Figure 2-15. Diagonal bridging
Horizontal Bridging. Horizontal bridging is nailed between the studs horizontally and halfway between the sole and top plates. This type of bridging is cut to fit between the studs. The measurements should be taken at the sole plate in case the studs are warped. Such bridging not only stiffens the wall but also helps to straighten the studs. Notice that the bridging is staggered in Figure 2-16 .
Figure 2-16. Horizontal bridging
2-9. Double Top Plates
After the frame walls are assembled and set in place, they must be tied together. Use a double top plate to interlock exterior walls at the comer and load-beading partition walls. Overlap the double top plates at the corners (see Figure 2-17 ). Tie load-bearing partition walls into the exterior walls by leaving an opening in the top plate of the outside wall. This allows the double top plate to fit into place. Or cut out a piece of the double top plate to allow the overlap to fit (see Figure 2-18 ).
Figure 2-17. Lapped at the corner
Figure 2-18. Lapped at the partition wall
2-10 Hasty Wall Construction
Hasty wall construction less material and requires less time. The panels used most are end wall and sidewall.
End-Wall Panels. The walls at the end of the building have studs that extend to the rafters and do not require a top plate (see Figure 2-19 ).
Figure 2-19. End-wall panels
Sidewall Panels. Place studs from 2 to 10 feet apart, with girts placed horizontally between the studs to construct sidewalls (see Figure 2-20 ). Vertical siding is normally used in this type of construction.
Figure 2-20. Sidewall panels