Draw a set of plans to show the building inspector when you apply for a permit and for reference as you work. Start by drawing a simple floor plan on graph paper; indicate the overall dimensions of the structure, the distance between the center of each opening and the nearest corner of the building, and the size of each rough opening (usually specified by the manufacturer of the finished door or window). Then draw head-on views of the walls that have openings; indicate the height of the walls, the height and span of each opening and the sizes of the studs, posts, and headers that will support the roof.

Use the plan to determine exactly what materials you need when you order lumber. Studs—generally 2-by-4s cut 8 feet long at the sawmill—are usually spaced 16 inches apart. The 2-by-4 top plates should be straight pieces of structural-grade lumber at least 14 feet long.

Bracing the Walls

Plumb the walls accurately and brace them firmly. The temporary braces must hold the entire structure rigid while the roof trusses are put in. When the roof has been sheathed, remove the braces one by one as you apply the wall sheathing.

In the structure shown above, the studs are nailed to the bottom layer of the top plates then to the sole plates. The second layer of the top plates ties the walls together at the corners and at the joints in the first Temporary diagonal bracing holds the walls and corners plumb. The long span of the garage door is bridged with an LVL header supported by 4-by-4 posts. Horizontal 2-by-4 fire stops nailed between the studs are required in some areas; they add rigidity to the structure and provide a nailing surface for exterior sheathing.

Preparing the Sole and Top Plates

Holding the tongue of a carpenter’s square across the sole plate at the nail, run a pencil along both edges of the tongue, outlining the first stud location.

Hook a long tape measure on the nail and outline the next stud 16 inches from the first, while a helper holds the tape taut (left).

Mark the remaining stud locations at 16- inch intervals on all the sole plates. On each side of the garage door opening, mark the 4-by-4 posts.

 2. Marking the Top Plates.
Working with a helper, butt a top plate against the sole plate with the ends flush at a corner. Transfer the stud outlines from the sole plates to the top plates with a carpenter’s square (above).

With a circular saw, trim the ends of top plates in the middle of stud outlines to ensure that seams in the plate are centered over a stud.

Make sure that sections of the top plate abutting a corner are at least 8 feet long and perfectly aligned with the end of the sole plate.

Raising the Walls

 1. Nailing Studs to the Top Plate.
Build and raise the back and side walls (Steps 1-3) then the front one (Step 4).

Lay studs on edge on the slab—one for each outline on the sole plate—and position a top plate along the tops.

Stand on the stud and top plate, align the stud with its outline, and drive two 3 1/2-inch common nails through the plate into the stud. If a stud aligns with a seam in the top plate, center the joint on the stud, and angle the nails toward its middle.

For a stud that lines up with an anchor bolt in the sole plate, notch the stud with a chisel to fit over the bolt.

2. Preparing Corner Posts.
For each corner, sandwich three, evenly spaced 18-inch-long 2-by-4s between two studs and fasten the assembly together with 3 1/2-inch nails (right), making a corner post.

Nail the post to the end of one of the top plates at each corner (inset).

3. Erecting the Walls.
With one helper for every 8 feet of wall, tilt one wall upright.

Set the studs on their marks on the sole plate and brace the wall with long 2-by- 4s at 6-foot intervals, keeping the wall roughly vertical with a carpenter’s level.

Toenail each stud to the bottom plate with 3-inch nails, driving two fasteners from one side of the stud and one from the other.

At each corner, face-nail the outside stud of one wall to the corner post of the adjoining wall, tying them together.

4. Fashioning the Front Wall.
Assemble the front-wall sections on either side of the door, nailing studs to top-plate sections that extend over the door opening by at least 3 feet.

Cut two 4-by-4 posts to the height of the wall studs, less the height of the header for the door opening (page 113).

Fasten a stud along the inside edge of each post with 3 1/2-inch nails spaced 10 inches apart in a zigzag pattern (right).

Erect and brace the front wall sections as you did the other walls.

Aligning the Framework

1. Plumbing the Corners.
Hang a plumb bob from the top plate near a corner so the tip of the bob is slightly above the bottom plate.

Make a corner brace by mitering the ends of a long 2-by-4 at 45-degree angles. With a 3-inch common nail, secure the brace to the last stud of the wall being plumbed so one mitered end is flush with the outside edge of the stud.

With one helper supporting the wall and another eyeing the plumb bob, remove the exterior bracing you set up when raising the wall (above, Step 3). Have your helper tilt the wall so that the plumb bob aligns with the edge of the sole plate, then face-nail the brace to the sole plate of the adjoining wall, holding its bottom end against the slab (left).

Plumb the other walls the same way.

2. Straightening the Walls.
Nail a 2-by-4 block to the inside edge of the top plate at each end of one wall.

Drive a nail into one end of each block and stretch a string tautly between the nails and across the face of each block.

Working on a stepladder near the middle of the wall, hold a scrap 2-by-4 between the string and the top plate. If there is a gap between the string and the board, or if the board pushes out the string, have one helper tilt the wall as necessary while another reinstalls exterior bracing to hold the wall in position (right).

Straighten the other walls this way.

3. Completing the Top Plate.
To reinforce the corners, arrange the second top-plate layer so the boards overlap as shown at left.

Position a 2-by-4 over the first top-plate layer, aligning one end with the outside edge of the adjoining wall. Cut the other end so it is at least 4 feet from a joint in the first layer.

Nail the second top-plate board to the lower one with 3 1/2-inch common nails spaced every 8 inches in a zigzag pattern. At the corners, drive two nails where the top layer overlaps the bottom one of the adjoining wall (left).

Continue nailing the second top-plate layer around the perimeter, except over the door opening where the header must be installed first (opposite).

Nail the corner braces to every stud they cross with 3-inch nails.

1. Building the Header
For a span over 8 feet, cut a length of LVL lumber to fit between the studs at the edges of the door opening.

For a double header, you can nail two lengths of LVL together face to face, staggering 3 1/2-inch common nails along both sides at 10-inch intervals (right). Or, order an LSL (laminated structural lumber) beam as required for your span.

For a span up to 8 feet, build a header from a pair of 2-by-12s with a strip of 1/2-inch plywood of the same width and length sandwiched between them. Nail the header as you would a doubled LVL beam, adding construction adhesive to the surfaces that will be in contact.

2. Lifting the Header Into Place
With one helper for every 5 feet of header length, lift the header and slide it onto the posts at the edges of the door opening. The typical header is a manageable load for four people.

Have your helpers hold the ends of the header in place while you fasten it to the studs adjoining the posts, the posts themselves, and the top-plate sections with 3 1/2-inch nails.

Finish installing the lower top-plate layer, then nail the upper top-plate layer over the door opening.