How to Build the Gambrel Garage - Part 3 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. 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.

 

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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.
The Gambrel Roof

The gambrel roof is the defining feature of two structures in American architecture: the barn and the Dutch Colonial house. Adopted from earlier English buildings, the gambrel style became popular in America during the early 17th century and was used on homes and farm buildings throughout the Atlantic region. Today, the gambrel roof remains a favorite detail for designers of sheds, garages, and carriage houses.
The basic gambrel shape has two flat planes on each side, with the lower plane sloped much more steeply than the upper. More elaborate versions incorporate a flared eave, known as a “Dutch kick,” that was often extended to shelter the front and rear facades of the building. Barns typically feature an extended peak at the front, sheltering the doors of the hayloft. The main advantage of the gambrel roof is the increased space underneath the roof, providing additional headroom for upper floors in homes or extra storage space in outbuildings.

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

Install the garage door in the door opening, following the manufacturer’s directions.


Step 2

How to Build the Gambrel Garage - Step 2

Build the window frame, which should be 1⁄2" narrower and shorter than the rough opening. Install the frame using shims and 10d galvanized casing nails, as shown in the WINDOW JAMB DETAIL. Cut eight 1 x 2 stop pieces to fit the frame. Bevel the outer sill stop for drainage. Order glass to fit, or cut your own plastic panel. Install the glazing and stops, using glazing tape for a watertight seal. Add the window trim.


Step 3

How to Build the Gambrel Garage - Step 3

For the attic doorframe, rip 1 x 6s to match the depth of the opening and cut the head jamb and side jambs. Cut the sill from full-width 1 x 6 stock; then cut a kerf for a drip edge (see the ATTIC DOOR SILL DETAIL). Fasten the head jamb to the side jambs and install the sill at a 5° slope between the side jambs. Install the doorframe using shims and 10d casing nails. Add shims or cedar shingles along the length of the sill to provide support underneath. The front edge of the frame should be flush with the face of the siding. Add 1 x 2 stops at the frame sides and top, 3⁄4" from the front edges.


Step 4

How to Build the Gambrel Garage - Step 4

Build the attic doors as shown in the ATTIC DOOR ELEVATION, using glue and 11⁄4" screws. Each door measures 28 5⁄8" x 38", including the panel braces. Cut the 1 x 8 panel boards about 1⁄8" short along the bottom to compensate for the sloping sill. Install the door with two hinges each. Add 1 x 4 horizontal trim on the front wall, up against the doorsill; then trim around both sides of the doorframe. Prime and paint as desired.


 
 

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