Building a garage is similar in many ways to building a shed. Aside from the excavation and foundation work, which is best left to specialist contractors, if you are a handy do-it-yourself you should be able to complete most of the work involved in this major project and so add to the resale value of your home.
The following steps describe how to build a 16' × 22' garage. They provide the main guidelines and give an idea of the skill level required to undertake such a project.
Roof trusses, frames composed of structural members, are designed and built in a special manufacturing facility to the exact specifications of the garage plan. Roof trusses are designed to withstand vertical pressure only. For this reason, they should never be lifted horizontally or laid flat across exterior walls.
1.1 Stake out the boundaries of the garage area. Call in a surveyor to establish the exact location for the garage and the precise dimensions of the area to dig.
1.2 Hire a contractor to excavate the area to the depth required.
1.3 A specialized contractor should also be called in to do the foundation work. The steps are: footing, concrete walls, backfill, and finally, the floor slab. Set anchor bolts in the poured concrete every 4', centre to centre.
Assemble the wall frames flat on the ground using lumber with less than 19% moisture content. All the exterior walls are made of 2" x 4" lumber except for the wall with the garage door opening which is made from 2" x 6". The studs – vertical members – must be spaced 16" apart. The bottom plate at the base of the walls is the same width as the studs, i.e. 4". TIP: Build the longest wall first and erect it.
2.1 Lay the bottom or "sill" plate in the future location of the wall base.
2.2 Drill holes in the plate every 4' to line up with the anchor bolts set in the foundation.
2.3 Nail the studs to the plate at right angles, spacing each one 16" apart, centre to centre.
2.4 Nail together two pieces of 2" × 4" to form a double top plate. Use 2" × 6" pieces for the top plate on the wall with the garage door opening.
2.5 Fasten the top plate to the top of the studs.
The door opening is framed on either side by two studs nailed together. These are the door jambs. Another stud is attached to the inside of each jamb and supports the door lintel or header. The header transfers its load onto the double studs on either side of the opening.
3.1 Determine the location of the door in the wall.
3.2 Install double 2" × 4" studs on either side of the door opening. These exterior or "king" studs rest on the sill plate, while the interior or "trimmer" stud rests on the ground and is shorter, since it supports the header.
3.3 Install the header. Fasten one piece of 2" × 10" onto one side of the wall and another piece to the other side. The gap between the two pieces will be filled with insulation material.
The window opening is framed on either side by two studs nailed together. Interior trimmer studs support the rough sill and header. The rough sill runs across the base of the window to support the window. The header at the top transfers its load onto the double studs on either side of the opening.
4.1 Determine the location of the window in the wall.
4.2 Install a 2" × 4" stud on either side of the window opening. These two king studs rest on the bottom (sill) plate of the wall frame.
4.3 Fasten a 2" × 4" trimmer stud to the inside of the king studs up to the height of the rough sill.
4.4 Place the rough sill on the trimmer studs and nail it to them.
4.5 Fasten a 2" × 4" trimmer stud to the inside of the two king studs from the rough sill up to the header. These trimmer studs rest on the rough sill.
4.6 Install the header. Fasten one piece of 2" × 10" onto one side of the wall and another onto the other side. The gap between the two pieces will be filled with insulation material.
5.1 Determine the location of the overhead garage door.
5.2 Install triple 2" × 6" studs on either side of the door opening. The ends rest on the floor. The inside trimmer studs are shorter, to support the header.
5.3 Nail three pieces of 2" × 10" together to form the header.
5.4 Rest the header on the studs and nail it to them.
The sheathing consists of large rigid 4' × 8' panels, which act as a wind and rain barrier. The suggested sheathing material for this project is tarred fibreboard. The air barrier is a thin plastic membrane. TIP: Lay the sheathing materials flat – first the fibreboard sheathing, then the air barrier.
6.1 Lay the tarred fibreboard panels over the wall framing and fasten them to the studs with large-head nails.
6.2 Spread out the air barrier sheet and fasten it down with nails or staples.
6.3 Install furring strips vertically every 16" opposite the studs.
7.1 Make sure that the sill plate is properly positioned on the ground before raising the wall frame, which you will need to do with the help of several people.
7.2 Immediately attach a bracing plank at one end of the wall. Then nail the wall to the brace to hold the structure upright while you continue working.
7.3 Build the second wall frame and erect it.
7.4 Check that the two walls are square and level. Secure them temporarily with diagonal braces attached to the top and bottom of the walls at the ends.
7.5 Once all the walls are upright and in position, check that they are square with each other and plumb.
7.6 Nail the walls together at the corners and join the top plates.
7.7 Once the walls are up, seal the air barrier membrane with adhesive tape, following the manufacturer's recommendations.
7.8 Fasten furring strips to the stud wall for the exterior cladding.
Close the roof as soon as possible to avoid rain or wind damage. Roof trusses are designed and pre-built by specialized manufacturers to the exact specifications of your garage plans. Trusses are designed to withstand vertical pressure only. They have clearly defined support points, which makes them easier to anchor onto the exterior walls.
8.1 Before installing the trusses, mark their position on the top plates every 24". Begin the installation at one end of the roof.
8.2 Lift the trusses with a rope and pulley or hoisting equipment. Do not raise them horizontally or lay them flat across the tops of the walls.
8.3 When the roof trusses are in position, nail a brace to each one to hold them in place temporarily.
8.4 Nail the roof edging around the perimeter. You will need additional lengths of wood for the cornices.
8.5 Build the cornices directly at each end of the roof as shown on the plan; this completes the framework.
8.6 Cover the sides of the gable trusses with 7/16" tarred fibreboard.
The roof sheathing consists of ½" plywood panels. Sturdy, durable, non-slip and easy to install, they are what give the roof its rigidity.
9.1 Lay the panels across the trusses, perpendicular to the rafters.
9.2 Stagger the joints of each course and ensure that the ends of the panels meet over the centre of a truss.
9.3 Leave a small gap between the panels to allow for expansion of the material. Depending on the truss spacing, the horizontal edges of the panels are attached only every 24".
9.4 Attach the sheathing panels with metal "H" clips between the trusses to prevent sagging.
9.5 Nail metal drip edge around the roof and eaves to prevent water intrusion and the formation of ice dams. If the roof edge is particularly long, overlap each section by 2". Cut the corners with tin snips.
9.6 Install waterproof self-adhesive membrane (between 36" and 72" wide depending on the applicable building regulations) along the roof edges. The membrane should overlap the metal drip edge by 3/8". Overlap each section of membrane by at least 12".
9.7 Install flashing along valleys, over the top of the membrane.
9.8 Cover the entire roof surface with felt paper.
9.9 Draw a guide line to ensure perfectly straight rows when laying the shingles.
9.10 Lay the first row of shingles, tabs pointing upwards. The first row must overlap the roof edges by approximately 3/8". Nail the shingles at least 6" from the roof edge.
9.11 Install the subsequent courses and cover the whole roof up to the ridge.
9.12 Cover the ridge, overlapping the courses of shingles to hide the nails.
The procedure for hanging an exterior door is generally always the same, but you should follow the manufacturer's specific instructions.
10.1 Apply sealer to the threshold on the ground and place the door in the opening.
10.2 Adjust the door threshold and insert shims as needed.
10.3 Fasten the door firmly in place. Drive the screws through the shims next to the hinge. The shims on the other side must be at the same height.
10.4 Nail the door jambs and exterior trim.
10.5 Cut the shims, insulate the door frame and caulk the exterior frame.
10.6 Install the handle, lock and inside frame.
11.1 Working from the outside, place the window in the opening.
11.2 Insert shims all the way around and make sure the frame is plumb and level.
11.3 Fasten the window frame to the garage framing with long galvanized screws.
11.4 Insulate the window around the frame with mineral wool and neoprene foam strip. Caulk.
11.5 Install the flashing, drip edge and J-channels.
Installing an overhead garage door is a challenge and requires some expertise. If you do not feel you have the DIY know-how to tackle this job, it may be best to have it done by a professional installer.
12.1 Lay out the door sections on the ground so they are straight and correctly arranged, with their exterior side face down. Align and centre the hinges.
12.2 Centre the bottom section in the door opening and find the exact point at which to screw the vertical track onto the inside jamb.
12.3 Screw the vertical track to the door jamb, making sure it is straight and ½" off the ground, and leave ½" between the track and the end of the door section.
12.4 Place the rollers in the track and in the hinges, starting with the bottom section.
12.5 Install the horizontal tracks and the top brackets at the front and back.
12.6 Install the extension spring(s) and the cable(s), depending on the door type.
This step involves covering all the outside surfaces of the garage.
13.1 Install all the necessary moulding for the exterior vinyl siding, e.g. corner moulding, moulding around the door and window, and starting moulding.
13.2 Cover the outside walls with the vinyl siding.
13.3 Install the roof edging on the edge of the roof, the mouldings for the soffit, and the soffit under the cornice.
13.4 Caulk around all the openings, especially around the door and the window.
14.1 Insert wool insulation between the studs.
14.2 Close the walls with fibreboard panels covered with a vapour barrier.
14.3 Attach furring to the studs and fasten drywall panels over the top.