How to Build the Gambrel Garage Part 2 of 3
Following classic barn designs, this 12 x 12-ft. garage-size storage shed has several features that make it a versatile storage shed or workshop.
Following classic barn designs, this 12 x 12-ft. garage-size storage shed has several features that make it a versatile storage shed or workshop. The garage’s 144-square-foot floor is a poured concrete slab with a thickened edge that allows it to serve as the building’s foundation. Designed for economy and durability, the floor can easily support heavy machinery, woodworking tools, and recreational vehicles.
The garage’s sectional overhead door makes for quick access to equipment and supplies and provides plenty of air and natural light for working inside. The door opening is sized for an 8-ft.-wide x 7-ft.-tall door, but you can buy any size or style of door you like—just make your door selection before you start framing the garage.
Another important design feature of this building is its gambrel roof, which maximizes the usable interior space (see The Gambrel Roof). Beneath the roof is a sizeable storage attic with 315 cubic feet of space and its own double doors above the garage door. Note: we added a patio section to the front of this shed. This optional slab will appear throughout the how-to photos.
How to Build the Gambrel Garage - Step 1
Snap a chalk line across the sidewall studs, level with the ends of the rafters. Cut two 2 x 4 soffit ledgers at 160" and fasten them to the studs on top of the chalk lines, with their ends overhanging the walls by 8". Cut 24 2 x 4 blocks to fit between the ledger and rafter ends, as shown in the EAVE DETAIL. Install the blocks.
How to Build the Gambrel Garage - Step 2
Frame the gable overhangs. Cut 12 2 x 4 lookouts at 5" and nail them to the inner overhang rafters as shown in the LEFT and RIGHT SIDE FRAMING ELEVATIONS. Install the inner overhang rafters over the common rafters, using 10d nails. Cut the two front (angled) overhang rafters; see the GABLE OVERHANG RAFTER DETAILS. Install those rafters; then add two custom-cut lookouts for each rafter.
How to Build the Gambrel Garage - Step 3
To complete the gable walls, cut top plates to fit between the ridge and the attic kneewalls. Install the plates flush with the outer common rafters. Mark the stud layout onto the walls and gable top plate; see the FRONT and REAR FRAMING ELEVATIONS. Cut the gable studs to fit and install them. Construct the built-up 2 x 6 attic door header at 62 1⁄2"; then clip the top corners to match the roof slope. Install the header with jack studs cut at 40 1⁄4".
How to Build the Gambrel Garage - Step 4
Install siding on the walls, holding it 1" below the top of the concrete slab. Add Z-flashing along the top edges, and then continue the siding up to the rafters. Below the attic door opening, stop the siding about 1⁄4" below the top wall plate, as shown in the ATTIC DOOR SILL DETAIL. Don’t nail the siding to the garage door header until the flashing is installed (Step 20).
How to Build the Gambrel Garage - Step 5
Mill a 3⁄8"-wide x 1⁄4"-deep groove into the 1 x 6 boards for the horizontal fascia along the eaves and gable ends (about 36 linear ft.); see the EAVE DETAIL. Use a router or table saw with a dado-head blade to mill the groove, and make the groove 7⁄8" above the bottom edge of the fascia.
How to Build the Gambrel Garage - Step 6
Install the 1 x 4 subfascia along the eaves, keeping the bottom edge flush with the ends of the rafters and the ends flush with the outsides of the outer-most rafters; see the EAVE DETAIL. Add the milled fascia at the eaves, aligning the top of the groove with the bottom of the subfascia. Cut fascia to wrap around the overhangs at the gable ends but don’t install them until Step 17.
How to Build the Gambrel Garage - Step 7
Add fascia at the gable ends, holding it up 1⁄2" to be flush with the roof sheathing. Cut soffit panels to fit between the fascia and walls, and fasten them with 3d galvanized nails. Install the end and return fascia pieces at the gable overhangs. Enclose each overhang at the corners with a triangular piece of grooved fascia (called a pork chop) and a piece of soffit material. Install the soffit vents as shown in the EAVE DETAIL.
How to Build the Gambrel Garage - Step 8
Sheath the roof, starting at one of the lower corners. Add metal drip edge along the eaves, followed by building paper; then add drip edge along the gable ends, over the paper. Install the asphalt shingles. Plan the courses so the roof transition occurs midshingle, not between courses; the overlapping shingles will relax over time. If desired, add roof vents.
How to Build the Gambrel Garage - Step 9
Cover the Z-flashing at the rear wall with horizontal 1 x 4 trim. Finish the four wall corners with overlapping vertical 1 x 4 trim. Install the 2 x 6 rails that will support the garage door tracks, following the door manufacturer’s instructions to determine the sizing and placement; see the GARAGE DOOR TRIM DETAIL.
How to Build the Gambrel Garage - Step 10
For the garage doorframe, rip 1 x 8 trim boards to width so they cover the front wall siding and 2 x 6 rails, as shown in the GARAGE DOOR TRIM DETAIL. Install the trim, mitering the pieces at 22.5°. Install the 1 x 4 trim around the outside of the opening, adding flashing along the top; see the FRONT ELEVATION.