How to Build the Gambrel Garage Part 2 of 3

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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.

 

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Overview

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.

What You'll Need

Tools:

circular saw
drill
tape measure
hammer
caulk gun
level

Materials:

Foundation

Drainage material 1.75 cu. yds. Compactible gravel

Concrete slab 2.5 cu. yds. 3,000 psi concrete

Mesh 144 sq. ft. 6 x 6", W1.4 x W1.4

welded wire mesh

Wall Framing

Bottom plates 4 @ 12' 2 x 4 pressure-treated

Top plates 8 @ 12' 2 x 4

Studs 47 @ 925⁄8" 2 x 4

Headers 2 @ 10', 2 @ 6' 2 x 8

Header spacers 1 @ 9', 1 @ 6' 1⁄2" plywood—7" wide

Angle braces 1 @ 4' 2 x 4


Gable Wall Framing

Plates 2 @ 10' 2 x 4

Studs 7 @ 10' 2 x 4

Header 2 @ 6' 2 x 6

Header spacer 1 @ 5' 1⁄2" plywood—5" wide


Attic Floor

Joists 10 @ 12' 2 x 6

Floor sheathing 3 sheets @ 4 x 8' 3⁄4" tongue-&-groove ext.-grade plywood


Kneewall Framing

Bottom plates 2 @ 12' 2 x 4

Top plates 4 @ 12' 2 x 4

Studs 8 @ 10' 2 x 4

Nailers 2 @ 14' 2 x 8


Roof Framing

Rafters 28 @ 10' 2 x 4

Metal anchors—rafters 20, with nails Simpson H2.5

Collar ties 2 @ 6' 2 x 4

Ridge board 1 @ 14' 2 x 6

Lookouts 1 @ 10' 2 x 4

Soffit ledgers 2 @ 14' 2 x 4

Soffit blocking 6 @ 8' 2 x 4

Exterior Finishes

Plywood siding 14 sheets @ 4 x 8' 5⁄8" Texture 1-11 plywood, grooves 8" O. C.

Z-flashing—siding 2 pieces @ 12' Galvanized 18-gauge

Horizontal wall trim 2 @ 12' 1 x 4 cedar

Corner trim 8 @ 8' 1 x 4 cedar

Fascia 6 @ 10', 2 @ 8' 1 x 6 cedar

Subfascia 4 @ 8' 1 x 4 pine

Plywood soffits 1 sheet @ 10' 3⁄8" cedar or fir plywood

Soffit vents 4 @ 4 x 12" Louver w/ bug screen

Z-flashing—garage door 1 @ 10' Galvanized 18-gauge


Roofing

Roof sheathing 12 sheets @ 4 x 8' 1⁄2" plywood

Shingles 3 squares 250# per square (min.)

15# building paper 300 sq. ft.

Metal drip edge 2 @ 14', 2 @ 12' Galvanized metal

Roof vents (optional) 2 units


Window

Frame 3 @ 6' 3⁄4 x 4" (actual) S4S cedar

Stops 4 @ 8' 1 x 2 S4S cedar

Glazing tape 30 linear ft.

Glass 1 piece—field measure 1⁄4" clear, tempered

Exterior trim 3 @ 6' 1 x 4 S4S cedar

Interior trim (optional)3 @ 6' 1 x 2 S4S cedar


Door

Frame 3 @ 8' 1 x 6 S4S cedar

Door sill 1 @ 6' 1 x 6 S4S cedar

Stops 1 @ 8', 1 @ 6' 1 x 2 S4S cedar

Panel material 4 @ 8' 1 x 8 T&G V-joint S4S cedar

Door X-brace/panel trim 4 @ 6', 2 @ 8' 1 x 4 S4S cedar

Exterior trim 1 @ 8', 1 @ 6' 1 x 4 S4S cedar

Interior trim (optional) 1 @ 8', 1 @ 6' 1 x 2 S4S cedar

Strap hinges 4


Garage Door
Frame 3 @ 8' 1 x 8 S4S cedar
Door 1 @ 8' x 6' - 8" Sectional flush door w/2" track
Rails 2 @ 8' 2 x 6

Trim 3 @ 8' 1 x 4 S4S cedar



Fasteners

Anchor bolts 16 3⁄8" x 8", with washers & nuts, galvanized

16d galvanized common nails 2 lbs.

16d common nails 17 lbs.

10d common nails 2 lbs.

10d galvanized casing nails 1 lb.

8d common nails 3 lbs.

8d galvanized finish nails 6 lbs.

8d box nails 6 lbs.

6d galvanized finish nails 20 nails

3d galvanized box nails 1⁄2 lb.

7⁄8" galvanized roofing nails 21⁄2 lbs.

21⁄2" deck screws 24 screws

11⁄4" wood screws 48 screws


Construction adhesive 2 tubes


Silicone-latex caulk 2 tubes



Foundation

Drainage material 1.75 cu. yds. Compactible gravel
Concrete slab 2.5 cu. yds. 3,000 psi concrete
Mesh 144 sq. ft. 6 x 6", W1.4 x W1.4
welded wire mesh

Wall Framing

Bottom plates 4 @ 12' 2 x 4 pressure-treated
Top plates 8 @ 12' 2 x 4
Studs 47 @ 925⁄8" 2 x 4
Headers 2 @ 10', 2 @ 6' 2 x 8
Header spacers 1 @ 9', 1 @ 6' 1⁄2" plywood—7" wide
Angle braces 1 @ 4' 2 x 4

Gable Wall Framing

Plates 2 @ 10' 2 x 4
Studs 7 @ 10' 2 x 4
Header 2 @ 6' 2 x 6
Header spacer 1 @ 5' 1⁄2" plywood—5" wide

Attic Floor

Joists 10 @ 12' 2 x 6
Floor sheathing 3 sheets @ 4 x 8' 3⁄4" tongue-&-groove ext.-grade plywood

Kneewall Framing

Bottom plates 2 @ 12' 2 x 4
Top plates 4 @ 12' 2 x 4
Studs 8 @ 10' 2 x 4
Nailers 2 @ 14' 2 x 8

Roof Framing

Rafters 28 @ 10' 2 x 4
Metal anchors—rafters 20, with nails Simpson H2.5
Collar ties 2 @ 6' 2 x 4
Ridge board 1 @ 14' 2 x 6
Lookouts 1 @ 10'
Soffit ledgers 2 @ 14' 2 x
Soffit blocking 6 @ 8' 2 x 4
Exterior Finishes
Plywood siding 14 sheets @ 4 x 8' 5⁄8" Texture 1-11 plywood, grooves 8" O. C.
Z-flashing—siding2pieces @ 12' Galvanized 18-gauge
Horizontal wall trim 2 @ 12' 1 x 4 cedar
Corner trim 8 @ 8' 1 x 4 cedar
Fascia 6 @ 10', 2 @ 8' 1 x 6 cedar
Subfascia 4 @ 8' 1 x 4 pine
Plywood soffits 1 sheet @ 10' 3⁄8" cedar or fir plywood
Soffit vents 4 @ 4 x 12" Louver w/ bug screen
Z-flashing—garage door 1 @ 10' Galvanized 18-gauge

Roofing

Roof sheathing 12 sheets @ 4 x 8' 1⁄2" plywood
Shingles3 squares 250# per square (min.)
15# building paper 300 sq. ft.
Metal drip edge 2 @ 14', 2 @ 12'Galvanized metal
Roof vents (optional) 2 units

Window

Frame 3 @ 6' 3⁄4 x 4" (actual) S4S cedar
Stops 4 @ 8' 1 x 2 S4S cedar
Glazing tape 30 linear ft.
Glass 1 piece—field measure 1⁄4" clear, tempered
Exterior trim 3 @ 6' 1 x 4 S4S cedar
Interior trim (optional)3 @ 6' 1 x 2 S4S cedar

Door

Frame 3 @ 8' 1 x 6 S4S cedar
Door sill 1 @ 6' 1 x 6 S4S cedar
Stops 1 @ 8', 1 @ 6' 1 x 2 S4S cedar
Panel material 4 @ 8' 1 x 8 T&G V-joint S4S cedar
Door X-brace/panel trim 4 @ 6', 2 @ 8' 1 x 4 S4S cedar
Exterior trim 1 @ 8', 1 @ 6' 1 x 4 S4S cedar
Interior trim (optional)1 @ 8', 1 @ 6' 1 x 2 S4S cedar
Strap hinges 4

Garage Door

Frame 3 @ 8' 1 x 8 S4S cedar
Door 1 @ 8' x 6' - 8"Sectional flush door w/2" track
Rails 2 @ 8' 2 x 6
Trim 3 @ 8' 1 x 4 S4S cedar

Fasteners

Anchor bolts163⁄8" x 8", with washers & nuts, galvanized
16d galvanized common nails 2 lbs.
16d common nails 17 lbs.
10d common nails 2 lbs.
10d galvanized casing nails 1 lb.
8d common nails 3 lbs.
8d galvanized finish nails 6 lbs.
8d box nails 6 lbs.
6d galvanized finish nails 20 nails
3d galvanized box nails 1⁄2 lb.
7⁄8" galvanized roofing nails 21⁄2 lbs.
21⁄2" deck screws 24 screws
11⁄4" wood screws 48 screws
Construction adhesive 2 tubes
Silicone-latex caulk 2 tubes



Foundation

Drainage material 1 cu. yard Compactible gravel

Skids 3 @ 10' 6 x 6 treated timbers

Floor Framing

Rim joists 2 @ 10' 2 x 6 pressure-treated

Joists 9 @ 8' 2 x 6 pressure-treated

Joist clip angles 18 3 x 3 x 3" x 18-gauge galvanized

Floor sheathing 3 sheets @ 4 x 8' 3⁄4" tongue-&-groove
ext.-grade plywood

Wall Framing

Posts 6 @ 8' 4 x 4 rough-sawn cedar

Window posts 2 @ 4' 4 x 4 rough-sawn cedar

Girts 2 @ 10' 2 @ 8' 4 x 4 rough-sawn cedar


Beams 2 @ 10' 2 @ 8' 4 x 6 rough-sawn cedar


Braces 8 @ 2'
4 x 4 rough-sawn cedar

Post bases 6, with nails Simpson BC40

Post-beam connectors 8 pieces, with nails Simpson LCE

L-connectors 4, with nails Simpson A34

Additional posts 6 @ 8' 4 x 4 rough-sawn cedar

Roof Framing

Rafters 12 @ 7' 2 x 4

Collar ties 2 @ 10' 2 x 4

Ridge board 1 @ 10' 2 x 6

Metal anchors—rafters 8, with nails Simpson H1

Gable-end blocking 4 @ 7' 2 x 2


Exterior Finishes

Siding 2 @ 14'
8 @ 12'
10 @ 10'
29 @ 9' 1 x 8 V-joint rough-sawn cedar



Corner trim 8 @ 9' 1 x 4 rough-sawn cedar

Fascia 4 @ 7'
2 @ 12' 1 x 6 rough-sawn cedar


Fascia trim
4 @ 7'
2 @ 12' 1 x 2 rough-sawn cedar


Subfascia 2 @ 12' 1 x 4 pine

Plywood soffits 1 sheet 4 x 8' 3⁄8" cedar or fir plywood

Description


Soffit vents (optional) 4 @ 4 x 12" Louver with bug screen

Flashing (door) 4 linear ft. Galvanized—18 gauge

Roofing

Roof sheathing 6 sheets @ 4 x 8' 1⁄2" ext.-grade plywood


Cedar shingles 1.7 squares


15# building paper 140 sq. ft.


Roof vents (optional) 2 units


Door

Frame 2 @ 7'
1 @ 4' 3⁄4 x 41⁄4" (actual) S4S cedar


Stops
2 @ 7'
1 @ 4' 1 x 2 S4S cedar


Panel material 7 @ 7' 1 x 6 T&G V-joint
rough-sawn cedar

Z-brace 1 @ 8' to 2 @ 8' 1 x 6 rough-sawn cedar


Strap hinges 3


Trim 5 @ 7' 1 x 3 rough-sawn cedar

Flashing 42" metal flashing


Fasteners

60d common nails, 16 nails

20d common nails 32 nails


16d galvanized common nails 31⁄2 lbs.


10d common nails 1 lb.


10d galvanized casing nails 1⁄2 lb.


8d galvanized box nails 11⁄2 lbs.


8d galvanized finish nails 7 lbs.


8d box nails 1⁄4 lb.


6d galvanized finish nails 40 nails


3d galvanized finish nails 50 nails


11⁄2" joist hanger nails 72 nails


21⁄2" deck screws 25 screws


11⁄2" wood screws 50 screws


7⁄8" galvanized roofing nails 2 lbs.


3⁄8" x 6" lag screws, w/washers 16 screws

1⁄4" x 6" lag screws, w/washers

Construction adhesive 4 tubes





 

Step 1

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.


Step 2

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.


Step 3

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".


Step 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).


Step 5

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.


Step 6

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.


Step 7

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.


Step 8

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.


Step 9

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.


Step 10

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.


 
 

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