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A 12×20 shed material list for a gable shed on skids is 154 2x4s (146 for framing, 8 for braces), 20 treated 2x6s, 8 treated 4x4s, 8 sheets of 3/4 in plywood, 11 of OSB, 20 of T1-11 and 12 shingle bundles. It assumes 94 1/2 in walls, a 6/12 roof and 16 in spacing.

Every quantity and cut length on this page comes from the 3DSHEDPLANS plan generator, our software that models each board of the shed and counts what to buy. This 12×20 build passed all 62 checks of our framing audit. The list covers one 60 in double door and two 36 x 36 in windows.

What this 12×20 shed material list assumes

The generator ran a shed 12 ft deep and 20 ft wide, with 240 sq ft of floor and the ridge running the 20 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. The roof works out to about 305 sq ft.
  • Floor: four pressure-treated 4×4 skids 20 ft long, about 47 in apart (46.8 in), on a crushed stone pad 22 x 14 ft and 4 in deep (12 in wider than the shed on every side), with 2×6 joists cut to 11′ 9″ at 16 in on center and 3/4 in tongue and groove plywood.
  • Loads: the 2×4 rafters pass a span table check at 30 psf ground snow (SPF #2 at 16 in, 72 in run). That is the generator’s design assumption; if your area’s snow load may be higher, check your local permit office before you buy rafter stock.
  • Openings: a 60 in wide double door on 76 1/2 in trimmers in the 20 ft front wall, and one 36 x 36 in window in each 12 ft gable wall. The 20 ft back wall has no openings.

Our 12×20 gable shed plan uses the same footprint. The plan PDF has its own printable list, and its counts can differ a little from this generator run, so shop for the plan from the plan’s own 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 boards, all lengths (framing and braces) 154
Pressure-treated 2×6 x 12 ft (16 joists, 4 for the two rims) 20
Pressure-treated 4×4 x 12 ft (two per 20 ft skid) 8
2×6 (ridge and window headers) 4
2×8 (door header) 1
3/4 in T&G plywood sheets (floor) 8
7/16 in OSB sheets (roof) 11
5/8 in T1-11 sheets (walls, gables, door leaves) 20
1/2 in plywood sheets (soffit, header fillers) 2
3-tab shingle bundles 12

Floor

Item Qty Used for
Pressure-treated 4×4 x 12 ft, tagged for ground contact 8 Four 20′ 0″ skids, two boards each
Pressure-treated 2×6 x 12 ft 16 Floor joists, cut to 11′ 9″
Pressure-treated 2×6 x 12 ft 4 Two 20′ 0″ rim joists, two boards each
3/4 in T&G plywood, 4×8 sheet 8 Floor decking (exactly 240 sq ft)
Crushed stone 3/4 in, loose 4.6 cu yd Gravel pad, measured loose before tamping
Deck screws 2 in (or 6d ring-shank nails), rated for treated lumber 6 lb Decking

Walls and roof framing

Item Qty Used for
2×4 x 8 ft 106 Wall studs, rafters, fly rafters, cripples, window sills, gable studs, lookout and frieze blocks
2×4 x 10 ft 8 Front and back cap plates, collar ties
2×4 x 12 ft 15 Wall plates, side wall cap plates, one gable stud
2×4 x 14 ft 17 Rafter ties, door and window trimmers
2×6 x 8 ft 2 Window headers
2×6 x 12 ft 2 Ridge board (20′ 8″, spliced)
2×8 x 12 ft 1 Door header
Hurricane ties, H2.5A type or equal 32 Rafter to plate
Temporary braces 2×4 x 12 ft 8 Wall bracing, reused later

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. Add the 8 temporary braces to the 146 framing boards for 154 2x4s total.

Roof covering

Item Qty Used for
7/16 in OSB, 4×8 sheet 11 Roof sheathing
15 lb felt, 400 sq ft roll 1 Underlayment
3-tab shingles, 26 per bundle 12 bundles Roof, starter course and ridge cap
Drip edge, 10 ft 8 Eaves and rakes
Roofing nails 1 1/4 in galvanized 10 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 (512 sq ft, 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 1 Over the door and window head casings
1×6 x 12 ft 4 Eave fascia (two 20′ 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 9 Gable-wall corner trim, door head casing, window casings
1×2 x 8 ft 2 Door stop and astragal
Exterior primer and paint 4 gal Two coats (rough-sawn T1-11 soaks up more, so check the coverage on the can)
Exterior caulk 3 tubes Trim

Hardware and windows

Item Qty
Framing nails 3 1/2 in (16d), hot-dip galvanized 30 lb
Siding nails 2 1/2 in (8d), hot-dip galvanized 20 lb
Sheathing nails 2 1/2 in (8d) for OSB 10 lb
Connector nails 1 1/2 in for the ties 3 lb
Construction adhesive, 10 oz tube 6
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 12×20 cut list is square cuts: 52 wall studs at 7′ 6″ and 16 floor joists at 11′ 9″. The parts below have angles, overhangs, splices or stacked sizes.

Part Lumber Cut length Qty
Rafter (board length, see below) 2×4 7′ 6 3/8″ 32
Fly rafter (rake) 2×4 7′ 6 3/8″ 4
Ridge board (spliced) 2×6 20′ 8″ 1
Rafter tie (interior pairs, at the plates) 2×4 12′ 0″ 14
Collar tie 2×4 4′ 4 1/2″ 7
Lookout block (rake overhang) 2×4 2 1/2″ 20
Frieze block (over the eave walls, top beveled) 2×4 1′ 0 1/4″ to 1′ 1 3/4″ 30
Skid (spliced) PT 4×4 20′ 0″ 4
Rim joist (spliced) PT 2×6 20′ 0″ 2
Front and back wall plate (spliced) 2×4 20′ 0″ 4
Front and back cap plate (spliced) 2×4 19′ 5″ 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

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 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. The generator keeps the notch to a third of the rafter’s depth or less, so do not cut it any deeper. Cut one pattern rafter, test it at both ends and the middle of the shed, then trace the other 31.

The 4 fly rafters hang off the 2 1/2 in lookout blocks and the ridge extension, not a wall, so they get the ridge plumb cut but no birdsmouth.

Ridge. The ridge is 20′ 8″, not 20′ 0″, because it runs 4 in past each gable wall to carry the fly rafters. The list buys two 2×6 x 12 ft for it, so it goes up in two pieces. Put the joint at a rafter pair so both ends of the splice are nailed through rafters, and support the ridge at both gables and the joint while you set the first pairs.

The 20 ft runs. The skids, rim joists, wall plates, cap plates, ridge and eave fascia are all longer than the 12 ft and 14 ft stock on the list, so every one of them is two boards. Stagger the joints. Land each skid joint on firm, tamped gravel right under a floor joist, and offset the joints of neighboring skids by 4 ft or more. Put each rim joint at a floor joist so both ends get nailed into it.

Headers. The 60 in door opening gets a doubled 2×8 header with a 1/2 in plywood filler, on trimmers cut to 6′ 4 1/2″, with four 6 1/4″ cripples above it. The bottom plate is cut out of the doorway after the wall is up, so the door leaves swing over the floor. 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, so the four lengths step 8 in apart. Measure each one off your actual end rafter before cutting. Two T1-11 sheets cover both gable triangles.

Plates. The front and back walls have 20′ 0″ bottom and top plates with 19′ 5″ cap plates, and the side walls have 11′ 5″ bottom and top plates with 12′ 0″ cap plates. The side caps lap over the front and back walls, which locks the corners together. Land every plate joint over a stud, and keep each cap plate joint at least 4 ft from the top plate joint under it.

Gable vs lean-to: what changes

We ran the same 12×20 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 skids, joists and decking stay the same; the studs, rafters and siding change.

Item Gable (6/12) Lean-to (3/12)
Rafters 32 2×4 at 7′ 6 3/8″ + 4 fly 16 2×6 at 13′ 10 1/4″ + 2 fly
Ridge board 2×6, 20′ 8″ from two 12 ft boards None
Wall studs 7′ 6″ on all four walls 9′ 2 5/8″ front, 6′ 3 1/2″ back, stepped on the sides
2×4 framing boards bought (plus 8 braces in both) 146 67
2×6 boards bought (not treated) 4 23
T1-11 sheets 20, all 4×8 18: seven 4×10, two 4×9, nine 4×8
Roof OSB sheets 11 11
Shingle bundles 12 10
Felt 1 roll 2 rolls, laid double below 4/12
Windows 2 1
Extra hardware 3 Z-flashing, 2 gable vents 4 twist straps at the wall corners
Floor 4 skids, 16 joists, 8 sheets 4 skids, 16 joists, 8 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 23 plain 2x6s (18 of them 14 ft rafter stock) but far fewer 2x4s. Each side wall has 10 studs stepping from 6′ 5 3/8″ to 9′ 3 1/4″ under an 11′ 9 1/4″ sloped top plate.

The 9′ 2 5/8″ front studs come out of 10 ft boards, and the high wall takes 4×10 siding sheets, which some yards have to order. At 3/12, read the minimum slope on the shingle wrapper and follow the maker’s low-slope instructions. For single-slope layouts, see the 12×24 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: 90 3/8 in from a 96 in board leaves about 5 5/8 in each, 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 fourteen 12′ 0″ ties come from 14 ft boards, leaving about 2 ft each. Cut the 8 brace stakes (about 2 ft) from these.
  • 20 ft runs: two 12 ft boards make 24 ft, so each 20′ 0″ skid, rim and wall plate leaves about 4 ft, and the 20′ 8″ ridge and eave fascia leave about 3′ 4″. Two 10 ft boards for each 19′ 5″ cap plate leave about 7 in.
  • Plates: the 11′ 5″ side plates leave about 7 in. The two 12′ 0″ side cap plates use a full 12 ft board with no trim room, so measure the boards at the yard and check that the factory ends are square before you set them.
  • Floor decking and wall siding: 8 floor sheets cover exactly 240 sq ft and 16 wall sheets cover exactly 512 sq ft, so a damaged sheet means a trip back to the yard.
  • No spares: the counts include nothing for rejects. Pick straight stock at the yard, and add a few 2×4 x 8 ft if you expect to cull warped or split boards.

The longest pieces 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 12×20 build

  • Circular saw, speed square and framing square for 52 stud cuts and 36 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 20 ft rims and plates
  • A rented plate compactor for 4.6 cu yd of gravel, laid in thin layers, plus two helpers to raise the 20 ft walls and set the spliced ridge

Common mistakes

  • Mixing up 12×20 and 20×12. In this list the ridge runs along the 20 ft side and the door sits in a 20 ft wall. Turn the ridge the other way and each rafter’s run grows from 72 in to 120 in, which changes the rafter span check, the ridge length and the gable height.
  • Lining up the splices. Every 20 ft member here is two boards. If the skid, rim, plate and cap plate joints all fall at the same spot, the floor and walls get a hinge line. Stagger them, and do not plan to drag a shed on spliced skids to a new spot later.
  • Forgetting the door sheets. The generator measures the siding cut out of the doorway at 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 14 rafter ties at the plates stop the 20 ft walls from spreading. The 7 collar ties, higher up on interior pairs, hold the rafter pairs together near the ridge; they do not replace the rafter ties.
  • Deep birdsmouths. A full 3 1/2 in seat would notch a 2×4 rafter past the generator’s one-third limit, so keep the seat at 2 1/2 in.
  • Too few skids. The generator keeps skids no more than 48 in apart. Four under a 12 ft floor land about 47 in apart; three would land past that limit.
  • 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 install guide.
  • Untreated wood near the ground. Skids, rims and joists are pressure treated; plain framing lumber there rots. Use ground-contact rated wood for the skids, and hot-dip galvanized nails and treated-lumber rated screws in treated wood. The USDA Wood Handbook covers why wet, untreated wood decays.

Whether a 240 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.

For how to read any list like this one, see our shed material list guide. For the base under the skids, see shed foundation options. For a rough budget, see how much it costs to build a shed; price this list at two yards before you order.

Get the full plan

The 12×20 gable shed plan is a 3DSHEDPLANS PDF with 40+ steps, 3D images and its own printable material list. Want a hip roof on the same footprint? See the 12×20 hip roof shed plan. For the nearest sizes, see the 10×20 gable shed plan and the 16×20 gable shed plan, or compare the 12×16 shed material list and the 10×16 shed material list.

Want to see the format first? Download the free 12×20 gable shed plan preview PDF. Need more or less room? Compare all gable shed plans or browse every size on the shed plans page.

Frequently asked questions

What is on a 12×20 shed material list?

For a 12×20 gable shed with 94 1/2 in walls and a 6/12 roof, our generator lists 154 2x4s incl. braces, 20 treated 2x6s, 8 treated 4x4s, 8 sheets of 3/4 in plywood, 11 of OSB, 20 of T1-11, 2 of 1/2 in plywood and 12 shingle bundles, plus trim, nails and hardware.

Is there a 12×20 shed plan with a material list?

Yes. The 3DSHEDPLANS 12×20 gable shed plan PDF includes a printable material list with quantities, and a free 12×20 preview PDF shows the format first. This page lists the generator's shopping list and the key cut lengths.

How many 2x4s do I need for a 12×20 shed?

154 in all for a 12×20 gable shed with a 60 in double door and two windows. That is 146 framing boards (106 at 8 ft, 8 at 10 ft, 15 at 12 ft, 17 at 14 ft) plus 8 boards at 12 ft for temporary wall braces.

How many sheets of plywood, OSB and siding does a 12×20 shed need?

8 sheets of 3/4 in tongue and groove plywood for the floor, 11 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 12×20 shed roof?

12 bundles of 3-tab shingles for the 6/12 gable roof, which works out to about 305 sq ft with an 8 in eave and 4 in rake overhang. The count includes the starter course, ridge cap and about 10 percent extra.

Shed building guides