12x18 Shed Material List: Lumber, Sheets and Hardware

Last updated October 16, 2026

A 12×18 shed material list for a gable shed on skids comes to 155 2x4s (139 for framing, 16 for bracing), 20 treated 2x6s, 7 treated 4x4s, 7 sheets of floor plywood, 10 of OSB, 20 of T1-11 and 11 shingle bundles. It assumes 94 1/2 in walls, a 6/12 roof and 16 in spacing.

Every count and cut length here comes from the 3DSHEDPLANS plan generator, software that models each board and counts what to buy. Its audit checks every roof sheet joint lands on a rafter and that the model matches the list. The list covers one 60 in double door and two 36 x 36 in windows.

What this 12×18 shed material list assumes

The generator ran a shed 12 ft deep and 18 ft wide, with 216 sq ft of floor and the ridge running the 18 ft way. These are its settings:

• Walls: 94 1/2 in tall including the bottom plate and double top plate, so wall studs are cut to 90 in (7′ 6″).
• Spacing: studs, floor joists and rafters all at 16 in on center.
• Roof: 6/12 pitch, 2×4 rafters, a 2×6 ridge board, 8 in eave overhang and 4 in rake overhang, about 276 sq ft of roof.
• Floor: four pressure-treated 4×4 skids 18 ft long, about 47 in apart (46.8 in), with 2×6 joists cut to 11′ 9″ at 16 in on center and 3/4 in tongue and groove plywood.
• Pad: crushed stone 20 x 14 ft (12 in wider than the shed on every side) and 4 in deep.
• Loads: the 2×4 rafters pass a span table check at 30 psf ground snow (SPF #2 at 16 in, 72 in run). If your snow load may be higher, check your local permit office before you buy rafter stock.
• Openings: a 60 in double door on 76 1/2 in trimmers in the 18 ft front wall, and one 36 x 36 in window in each 12 ft gable wall. The 18 ft back wall has no openings.

Our catalog has a 12×18 lean-to shed plan on the same footprint. Its PDF has its own printable list for its own layout, so if you build that plan, shop from the plan’s list.

Shopping list by stage

Lumber sizes are nominal. A 2×4 measures about 1 1/2 x 3 1/2 in, as the American Wood Council explains. Check the grade stamp on plywood and OSB; the APA trademark guide shows how to read it.

Totals at a glance

Material	Total
2×4 framing boards, all lengths	139
2×4 for temporary braces, ridge post, stakes and cleats	16
Pressure-treated 2×4 x 14 ft (skid splice scabs)	2
Pressure-treated 2×6 (16 joists at 12 ft, 4 rim boards at 10 ft)	20
Pressure-treated 4×4 (four 18 ft skids from 7 boards)	7
2×6 (ridge and window headers)	4
2×8 (door header)	1
3/4 in T&G plywood sheets (floor)	7
7/16 in OSB sheets (roof)	10
5/8 in T1-11 sheets (walls, gables, door leaves)	20
1/2 in plywood sheets (soffit, header fillers)	2
3-tab shingle bundles	11

Floor

Item	Qty	Used for
Pressure-treated 4×4 x 8 ft	2	Skid pieces
Pressure-treated 4×4 x 12 ft	4	Skid pieces
Pressure-treated 4×4 x 14 ft	1	Skid pieces
Pressure-treated 2×4 x 14 ft	2	Eight 3′ 0″ splice scabs, both sides of each skid joint
Pressure-treated 2×6 x 12 ft	16	15 floor joists plus a second joist at the rim joint, all cut to 11′ 9″
Pressure-treated 2×6 x 10 ft	4	Two 18′ 0″ rim joists, two boards each
3/4 in T&G plywood, 4×8 sheet	7	Floor decking (216 sq ft)
1×4 x 8 ft	(3 of the 12 on the trim list)	Decking filler strip, three 6′ 0″ pieces ripped to 1 1/2 in
Crushed stone 3/4 in, loose	4.2 cu yd	Gravel pad, measured loose before tamping
Deck screws 2 in (or 6d ring-shank nails), rated for treated lumber	6 lb	Decking
Construction adhesive, 10 oz tube	10	Joist, rim and door-frame beads

The three filler pieces come from 3 of the twelve 1×4 x 8 ft boards on the trim list, so they are not extra boards. For blocks, piers or a slab instead of skids, see shed foundation options; for leveling and framing the stone pad, see our gravel shed foundation guide. Square the deck before the decking goes on: the diagonals of the 12 x 18 ft frame should both be about 21′ 7 5/8″.

Walls and roof framing

Item	Qty	Used for
2×4 x 8 ft	103	Wall studs, rafters, fly rafters, cripples, sills, gable studs, vent framing, lookout and frieze blocks, some plate and cap pieces
2×4 x 10 ft	6	Back wall plate piece, collar ties
2×4 x 12 ft	11	Wall plates and cap plates, gable end studs
2×4 x 14 ft	19	Rafter ties, door and window trimmers, front plate piece, frieze blocks
2×6 x 8 ft	2	Window headers
2×6 x 10 ft	2	Ridge board (18′ 8″, spliced)
2×8 x 12 ft	1	Door header
Hurricane ties, H2.5A type or equal	30	Rafter to plate
2×4 x 12 ft, temporary braces	12	2 plumb braces per wall section plus a diagonal, reused later
2×4 x 12 ft, temporary ridge post	1	Under the ridge joint, reused later
2×4 x 8 ft	3	Eight 24 in stakes and eight 12 in deck cleats for the braces

Add the 16 temporary boards to the 139 framing boards for 155 plain 2x4s in all. The three header filler strips of 1/2 in plywood are ripped from a soffit sheet, so buy the soffit plywood with the wall lumber.

Roof covering

Item	Qty	Used for
7/16 in OSB, 4×8 sheet	10	Roof sheathing
15 lb felt, 400 sq ft roll	1	Underlayment
3-tab shingles, 26 per bundle	11 bundles	Roof, starter course and ridge cap
Drip edge, 10 ft	8	Eaves and rakes
Roofing nails 1 1/4 in galvanized	9 lb	Shingles
Roofing cap nails 1 in	2 lb	Felt
Roofing cement, 10 oz tube	2	Roofing
Louvered gable vent, 8 x 12 in	2	One in each gable
Insect screen, 2 ft x 25 ft	1 roll	Vent holes and gaps at the eaves

Siding and trim

Item	Qty	Used for
5/8 in T1-11, 4×8 sheet	16	Walls (480 sq ft of wall, before the door and window cut-outs)
5/8 in T1-11, 4×8 sheet	2	Both gable triangles
5/8 in T1-11, 4×8 sheet	2	Door leaves (one per leaf)
1/2 in plywood, 4×8 sheet	2	Eave soffit and header fillers
Z-flashing, 10 ft	3	Wall siding to gable siding joint
Drip cap, 10 ft	2	Over the door and window head casings
1×6 x 10 ft	4	Eave fascia (two 18′ 8″ runs, spliced)
1×6 x 8 ft	4	Rake fascia
1×4 x 16 ft	2	Corner trim on the eave walls
1×4 x 14 ft	4	Door casing sides, door stiles, Z braces
1×4 x 12 ft	1	Door rails
1×4 x 8 ft	12	Gable-wall corner trim, decking filler strip, door head casing, window casings
1×2 x 8 ft	2	Door stop and astragal
Exterior paint and primer in one	6 gal	Two coats over about 685 sq ft
Exterior caulk	3 tubes	Trim

Hardware and windows

Item	Qty
Framing nails 3 1/2 in (16d), hot-dip galvanized (about 1,469 nails plus 10 percent)	41 lb
Siding nails 2 1/2 in (8d), hot-dip galvanized	18 lb
Sheathing nails 2 1/2 in (8d) for OSB	9 lb
Connector nails 1 1/2 in for the ties	3 lb
T-strap door hinges	6
Door handle and latch set	1
Barrel bolts for the fixed leaf	2
Exterior screws 1 1/4 in (door frame to T1-11)	1 lb
Exterior screws 2 1/2 in (hinge straps into framing)	1 box
Prefabricated window, 36 x 36 in rough opening	2
Flashing tape 4 in	1 roll
Wood shims	1 bundle

Cut list highlights

Most of the 12×18 cut list is square cuts: 50 wall studs at 7′ 6″ and 16 floor joists at 11′ 9″. The parts below need angle cuts, splices or more than one length.

Part	Lumber	Cut length	Qty
Rafter (board length, see below)	2×4	7′ 6 3/8″	30
Fly rafter (rake)	2×4	7′ 6 3/8″	4
Ridge board (spliced)	2×6	18′ 8″	1
Rafter tie (interior pairs, at the plates)	2×4	12′ 0″	13
Collar tie	2×4	4′ 4 9/16″	7
Lookout block (rake overhang)	2×4	2 1/2″	20
Frieze block (top beveled)	2×4	1′ 1″ (24), 1′ 1 3/4″ (2), 4 1/4″ (2)	28
Skid (spliced)	PT 4×4	18′ 0″	4
Skid splice scab	PT 2×4	3′ 0″	8
Rim joist (spliced)	PT 2×6	18′ 0″	2
Front and back wall plate (spliced)	2×4	18′ 0″	4
Front and back cap plate (spliced)	2×4	17′ 5″	2
Side wall plate	2×4	11′ 4 7/8″	4
Side wall cap plate	2×4	12′ 0″	2
Door header (2×8 doubled + 1/2 ply)	2×8	5′ 3″	2
Door trimmer	2×4	6′ 4 1/2″	2
Window header (2×6 doubled + 1/2 ply)	2×6	3′ 3″	4
Window trimmer	2×4	6′ 1″	4
Center gable stud (under the ridge)	2×4	2′ 8 3/4″	2
Gable end studs	2×4	7 1/8″, 1′ 3 1/8″, 1′ 11 1/8″ and 2′ 7 1/8″	4 each
Gable vent sill and header	2×4	1′ 2 1/2″	4

Rafters. The 7′ 6 3/8″ figure is the board each rafter needs, measured long point to long point on the top edge from the ridge plumb cut to the tail plumb cut, including the 8 in eave overhang. That is about 90 3/8 in, so each rafter and fly rafter comes out of one 8 ft 2×4 with about 5 5/8 in left over.

Mark the plumb cuts with a speed square pivoted to 6 on the common scale (26.6 degrees). The birdsmouth seat is 2 1/2 in, which makes the notch about 1 1/8 in deep, inside the generator’s one-third-of-depth limit. Cut one pattern rafter, test it at both ends and the middle of the shed, then trace the other 33 (29 rafters and 4 fly rafters).

Ridge. The ridge is 18′ 8″, not 18′ 0″, because it runs 4 in past each gable wall to carry the fly rafters. It goes up as two 9′ 4″ pieces cut from 10 ft 2x6s, joined 112 in from one end so the joint centers on a rafter pair. Stand the temporary 2×4 ridge post under that joint until the rafter pairs on both sides are nailed.

The 18 ft runs. Skids, rims, front and back plates, cap plates, ridge and eave fascia are all longer than the lumber on the list, so each is two pieces, joined at these points:

• Skids: the joints fall 80 in from one end on two skids and 128 in on the other two, so neighbors are 48 in apart. Each joint sits under a joist, stays 16 in or more from the rim joint, and gets a 3 ft treated 2×4 scab on both sides.
• Rims: each rim joint lands 111 1/4 in from the end, on the seam between a layout joist and the extra second joist the list buys for it.
• Plates: the front plate joint is 75 3/4 in from the end and the back plate joint 96 in, both centered on a full-height stud. The cap plate joints (140 1/4 in front, 144 in back) sit at least 48 in from the plate joints below.

Headers. The 60 in door opening gets a doubled 2×8 header with a 1/2 in plywood filler on 6′ 4 1/2″ trimmers, with four 6 1/4″ cripples above it. The bottom plate is cut out of the doorway after the wall is up. Each window gets a doubled 2×6 header on 6′ 1″ trimmers, two 11 1/2″ cripples above, a 3′ 0″ sill and two 2′ 11 1/2″ cripples below.

Gable studs. Each 12 ft gable has one 2′ 8 3/4″ center stud plus eight end studs in four lengths, from 7 1/8″ to 2′ 7 1/8″. At 6/12 each stud 16 in further from the corner is 8 in taller. The gable vent goes in the bay between the third and fourth studs from the corner, framed with a flat 1′ 2 1/2″ sill and header.

Side plates. The side wall plates are 11′ 4 7/8″, which is 1/8 in short of the gap between the front and back walls so the side walls drop in. The 12′ 0″ side cap plates lap over the front and back walls and lock the corners.

Gable vs lean-to: what changes

We ran the same 12×18 footprint as a lean-to (single-slope) roof at 3/12, with an 80 in low back wall, the door in the high front wall and one window in the back wall. The gable run passed all 99 audit checks and the lean-to run all 80.

Item	Gable (6/12)	Lean-to (3/12)
Rafters	30 2×4 at 7′ 6 3/8″ + 4 fly	15 2×6 at 13′ 10 1/4″ + 2 fly
Ridge board	2×6, 18′ 8″ from two 10 ft boards	None
Wall studs	7′ 6″ on all four walls	9′ 2 5/8″ front, 6′ 3 1/2″ back, 10 stepped studs per side
2×4 framing boards bought	139	65
Plain 2×6 boards bought	4	24
T1-11 sheets	20, all 4×8	18: seven 4×10, two 4×9, nine 4×8
Roof OSB sheets	10	10
Shingle bundles	11	9
Felt	1 roll	2 rolls, laid double below 4/12
Windows	2	1
Framing nails	41 lb	29 lb
Fascia	1×6	1×8
Extra hardware	3 Z-flashing, 2 gable vents	4 twist straps at the wall corners
Soffit plywood	2 sheets	1 sheet
Temporary braces	12	15
Ladder the audit checks	16 ft	20 ft
Floor	4 skids, 16 joists, 7 sheets	4 skids, 16 joists, 7 sheets

On a 12 ft deep shed the lean-to rafters must be 2×6: the generator checks a 137 in span against a 143 in limit for 2×6 at 30 psf. That is why the lean-to buys 24 plain 2x6s (17 of them 14 ft rafter stock) and less than half the 2x4s. Each side wall has 10 studs stepping from 6′ 5 3/8″ to 9′ 3 1/4″. Ask the yard about 4×9 and 4×10 T1-11 early, since many stock only 4×8.

At 3/12, read the minimum slope on the shingle wrapper and follow the maker’s low-slope steps; ARMA’s low-slope guide explains the double underlayment. For a lean-to on this footprint, see the 12×18 lean-to shed plan, all lean-to shed plans and our gable vs lean-to vs hip roof comparison.

Where the waste goes

• Wall studs: 90 in from a 96 in board leaves about 6 in each.
• Rafters: about 90 3/8 in from a 96 in board leaves about 5 5/8 in, so do not mis-cut one; there is no second rafter in the offcut.
• Floor joists: 11′ 9″ from a 12 ft board leaves 3 in for squaring the ends.
• Rafter ties: the thirteen 12′ 0″ ties come from 14 ft boards, leaving about 2 ft each.
• Ridge: two 9′ 4″ pieces from 10 ft boards leave about 8 in each.
• Rims and eave fascia: two 10 ft boards make 20 ft, so each 18′ 0″ rim leaves about 2 ft and each 18′ 8″ fascia run about 16 in.
• Skid scabs: four 3 ft scabs per 14 ft treated 2×4 leave about 2 ft per board.
• Side plates: 11′ 4 7/8″ from a 12 ft board leaves about 7 in. The 12′ 0″ side cap plates use a full 12 ft board, so check that the factory ends are square at the yard.
• Floor decking: 7 sheets give 224 sq ft for a 216 sq ft floor, 8 sq ft over, so there is no spare sheet; one bad cut means a trip back to the yard. Three full rows of 47 1/2 in net plus the 1 1/2 in filler strip make the 144 in joist span.
• No spares for rejects: sight down each board at the yard and pass on any with a bow or crown you can see from end to end. Adding 4 spare 2×4 x 8 ft (one per wall) is worth it; that is our tip, not a generator count.

The longest boards bought are 16 ft: the two corner trim boards for the eave walls. Everything else is 8, 10, 12 or 14 ft stock.

Tools for a 12×18 build

• Circular saw, speed square and framing square for 50 stud cuts and 34 rafters; cut the 2 1/2 in lookout blocks from a long clamped stick with a stop block, never as loose scraps
• Framing hammer or framing nailer, and a drill/driver for the screws
• 4 ft level, 25 ft tape for checking that the floor diagonals match, and a string line for the 18 ft rims and plates
• A 16 ft extension ladder (the generator checks it reaches about 4 ft past the roof edge at a 4 to 1 setup)
• A hand tamper or rented plate compactor for 4.2 cu yd of gravel, laid in two layers, and one helper: the heaviest bare wall frame, the front wall, weighs about 240 lb, a two-person lift
• A dust mask for cutting the treated skids, scabs, rims and joists, plus eye and ear protection for the saw

Common mistakes

• Mixing up 12×18 and 18×12. Here the ridge runs along the 18 ft side and the door sits in an 18 ft wall. Turn the ridge the other way and each rafter’s run grows from 72 in to 108 in, which changes the rafter check, the ridge length and the gable height.
• Lining up the splices. If the skid, rim, plate and cap joints all fall at one spot, the floor and walls get a hinge line. Use the joint positions above, and do not plan to drag a shed on spliced skids later.
• Skipping the second rim joist. The 16th joist on the list is there so the rim joint lands on two joists, not one. Leave it out and one end of the rim has nothing to nail into.
• Forgetting the door sheets. The siding cut out of the doorway is 76 1/2 in tall, shorter than the 77 1/4 in door leaf, so each leaf needs its own new T1-11 sheet.
• Skipping rafter ties. A ridge board is not a beam. The 13 rafter ties at the plates stop the 18 ft walls from spreading; the 7 collar ties higher up do not replace them.
• Untreated wood near the ground. Skids, scabs, rims and joists are pressure treated. Buy ground-contact rated stock for the skids, and consider it for the joists and rims too, since they sit only 3 1/2 in off the gravel. Use hot-dip galvanized or treated-lumber rated fasteners in treated wood. The USDA Wood Handbook covers why wet, untreated wood decays.
• Leaving the siding bottom bare. On the 12 ft side walls the T1-11 laps the floor framing by only about 3/4 in. Prime or seal the bottom edge of each panel before you hang it (do not caulk it shut, which traps water), and keep the gravel graded away from the walls.
• Forgetting the ramp. The floor sits on skids and joists above the gravel, so a 60 in double door usually needs a ramp for a mower or wheelbarrow; see how to build a shed ramp. The ramp is not on this list.
• Swapping materials without recounting. This list is for 3-tab shingles and T1-11. Architectural shingles, metal roofing or lap siding cover differently, so recount from the coverage printed on the bundle or the maker’s guide.

Whether a 216 sq ft shed needs a permit, and what setbacks and tie-downs apply, varies by town, so check your local permit office before you order. Our shed permit checklist lists what to ask.

Before you order:

• Read our shed material list guide for how to check a list like this one.
• Set a rough budget with how much it costs to build a shed, then price this list at two yards.
• Building another size? The shed material calculator covers other sizes.

Get the full plan

3DSHEDPLANS does not sell a 12×18 gable plan, so this free list is the gable version for this size. The nearest gable PDFs are the 12×16 gable shed plan and the 12×20 gable shed plan, with matching free lists for a 12×16 shed and a 12×20 shed.

On the exact 12×18 footprint, the 12×18 lean-to shed plan is a 3DSHEDPLANS PDF with step-by-step 3D images and its own printable material list. Want to see the format first? Download the free 12×18 lean-to shed plan preview PDF. Compare every gable shed plan or browse all sizes on the shed plans page.

Frequently asked questions

What is on a 12×18 shed material list?

For a 12×18 gable shed with 94 1/2 in walls and a 6/12 roof, our generator lists 155 2x4s (139 framing, 16 temporary), 20 treated 2x6s, 7 treated 4x4s, 7 sheets of 3/4 in plywood, 10 of OSB, 20 of T1-11, 2 of 1/2 in plywood and 11 shingle bundles, plus trim, nails and hardware.

How many 2x4s do I need for a 12×18 shed?

139 2×4 framing boards for a 12×18 gable shed with a 60 in double door and two windows: 103 at 8 ft, 6 at 10 ft, 11 at 12 ft and 19 at 14 ft. Add 16 more for temporary braces, a ridge post, stakes and deck cleats, and 2 treated 2x4s for the skid splices.

How many sheets of plywood, OSB and T1-11 does a 12×18 shed need?

7 sheets of 3/4 in tongue and groove plywood for the floor, 10 sheets of 7/16 in OSB for the roof, 20 sheets of 5/8 in T1-11 for the walls, gables and door leaves, and 2 sheets of 1/2 in plywood for the soffit and header fillers.

How many bundles of shingles for a 12×18 shed roof?

11 bundles of 3-tab shingles for the 6/12 gable roof, which comes to about 276 sq ft with an 8 in eave and 4 in rake overhang. That count includes the starter course, the ridge cap and about 10 percent extra.

Is there a 12×18 shed plan with a material list?

Yes, but the 12×18 plan 3DSHEDPLANS sells is a lean-to, and its PDF has its own printable material list. There is no 12×18 gable plan in the catalog, so this page is a free gable list, and the 12×16 and 12×20 gable plans are the nearest PDFs.