12x20 Shed Material List
Quick Answer
A 12x20 gable shed with 8 ft walls, 16 inch on center framing, 4/12 roof pitch, pressure treated floor framing, OSB or plywood sheathing, and a basic double door requires substantial materials due to its size. This is a large structure commonly used as a workshop, garage overflow, storage building, or hobby space.
See all shed material lists by size
You will need:
- Heavy pressure treated lumber for the floor system
- Standard 2x4 wall framing
- 2x6 roof framing for the wider span
- Full sheathing on walls and roof
- Panel or lap siding
- Asphalt shingles and underlayment
- Reinforced door framing
- Large quantities of fasteners and hardware
In 2026 pricing, expect a realistic total material cost of: $5,500 to $9,000
This assumes a gravel base, basic finishes, and no electrical or interior work.
Need a smaller option? See our 14x16 shed material list. Want a larger build? See our 10x24 shed material list.
Full Material List
Quantities reflect 8 ft walls, 16 inch on center spacing, and one large double door on a gable end.
Floor Framing
A 12x20 shed spans far enough that floor strength matters. Many builders upgrade joists to 2x8 for stiffness, but 2x6 can work for light-duty use.
Gravel Base
- 6 to 8 cubic yards of compacted 3/4 inch crushed gravel
Floor Frame (Pressure Treated)
Perimeter
- 2x8x20 PT – 2 (long rim joists)
- 2x8x12 PT – 2 (end band joists)
Floor Joists (16 inch OC across 12 ft span)
- 2x8x12 PT – 16 to 18
Using 2x8 joists reduces bounce and increases load capacity for workshop use.
Floor Sheathing
- 3/4 inch tongue and groove plywood or OSB – 8 sheets
Fasteners
- 3 inch exterior screws or galvanized framing nails
- Joist hangers recommended for strength
Wall Framing
All walls framed 16 inch on center.
- 2x4x8 studs
- 120 to 135 total
- Includes perimeter walls
- Additional studs for corners and door framing
- Waste allowance
Plates
- 2x4x20 – 6 (long walls, double top plates + bottom plates)
- 2x4x12 – 6 (end walls)
If 20 ft boards are unavailable, use shorter lengths spliced over studs.
Double Door Framing
Typical opening: 60 to 72 inches wide.
- 2x8x8 – 2 (header material)
- 1/2 inch plywood spacer
- Additional jack studs and king studs (included in stud count)
Roof Framing
A 12 ft span typically requires 2x6 rafters minimum.
Rafters (4/12 pitch, 16 inch OC)
- 2x6x12 – 30 to 34
Approximately 15 to 17 rafter pairs.
Ridge Board
- 2x10x20 – 1
Collar Ties or Ceiling Joists
- 2x4x12 – 15 to 17
Sheathing
Large sheds require significant sheathing quantities.
Wall Sheathing
- 7/16 inch OSB or plywood – 20 to 24 sheets
If using panel siding like T1-11, separate wall sheathing may not be needed.
Roof Sheathing
- 7/16 inch OSB or plywood – 12 to 14 sheets
Siding
Panel siding is common for sheds of this size.
T1-11 or LP SmartSide Panels
- 20 to 24 sheets
Alternative siding options (vinyl, lap siding) require additional trim, starter strips, and sometimes foam board.
Roofing
Roof area is large enough that roofing becomes a major cost component.
Underlayment
- 2 rolls synthetic underlayment
Drip Edge
- 10 to 12 pieces (10 ft lengths)
Shingles
- Approximately 2.5 to 3 squares
- 9 to 12 bundles depending on waste and brand
Roofing Nails
- 10 lb box
Hardware and Fasteners
- 16d framing nails or structural screws
- 8d nails for sheathing
- Exterior construction screws
- Construction adhesive (4 to 6 tubes)
- Hurricane ties recommended
- Double door hinge set (3 hinges per door)
- Heavy-duty shed door latch or lockset
- Padlock hardware
- Flashing for door opening
Estimated Cost Breakdown
Prices reflect typical 2026 material costs and vary by region.
- Gravel Base: $350 to $700
- Pressure Treated Floor Framing: $900 to $1,500
- Wall Framing Lumber: $900 to $1,500
- Roof Framing Lumber: $700 to $1,200
- Sheathing (walls and roof): $1,200 to $1,900
- Siding: T1-11: $900 to $1,400; LP SmartSide: $1,600 to $2,500; Vinyl system: $2,200 to $3,500
- Roofing: $600 to $1,000
- Hardware and Fasteners: $250 to $500
Total Estimated Range
With basic panel siding: $5,500 to $7,000
With upgraded siding: $7,000 to $9,000
Costs increase sharply compared to smaller sheds because of:
- Much larger floor area (240 sq ft)
- Longer walls requiring more studs and plates
- Wider roof span needing stronger framing
- Increased sheathing and siding coverage
- Higher quantities of hardware and fasteners
- Heavier door framing requirements
- Material handling and delivery costs may also increase
If you want exact cut diagrams, printable framing layouts, and step-by-step blueprints for this 12x20 shed, detailed plans eliminate guesswork and reduce lumber waste.
Get the Complete 12x20 Shed Plans Here
Tools Required
Standard framing tools plus equipment capable of handling large components.
Essential tools:
- Circular saw
- Miter saw
- Drill and impact driver
- Framing hammer
- 4 ft or longer level
- Speed square
- Tape measure
- Chalk line
- Ladders
- Shovel and rake
- Plate compactor or heavy hand tamper
Helpful for large builds:
- Pneumatic framing nailer
- Roofing nailer
- Laser level
- Sawhorses
- Clamps
Assistance is typically required. Handling 12 ft boards, long wall sections, and roof components alone is difficult and unsafe.
Step-by-Step Build Overview
High-level sequence only.
- Prepare and compact gravel base. Ensure level across full footprint.
- Build pressure treated floor frame. Square carefully.
- Install floor sheathing.
- Frame walls on the ground. Include double door opening.
- Raise walls with assistance. Brace securely.
- Install double top plates tying all walls together.
- Install ridge board and rafters.
- Add collar ties or ceiling joists.
- Install roof sheathing.
- Install drip edge and underlayment.
- Install shingles.
- Install wall sheathing if not using panel siding.
- Install siding.
- Build and hang double doors.
- Install trim and hardware.
- Maintain square throughout the build. Check measurements frequently.
Common Mistakes
- Insufficient foundation support. A large shed needs a well-compacted base. Soft spots cause sagging.
- Using undersized floor joists. Leads to bounce and long-term structural issues.
- Underestimating material quantities. Running short mid-build causes delays and mismatched lumber.
- Attempting to lift walls alone. Large wall sections are heavy and dangerous.
- Weak door framing. Double doors need strong headers and proper support.
- Skipping structural connectors. Wind loads are higher on larger buildings.
- Poor squaring practices. Errors compound across long walls and roof lines.
- Inadequate roof framing. Wider spans demand proper lumber sizing and spacing.
Is It Worth Building Yourself?
DIY material cost: $5,500 to $9,000
Typical prebuilt 12x20 shed delivered in 2026: $9,000 to $16,000 depending on construction and finishes.
DIY savings can exceed $4,000 to $7,000.
However:
- Construction time may be 4 to 7 full days with help
- Transportation logistics become significant
- Structural mistakes are costly at this scale
- Permits may be required in some areas
For homeowners comfortable with framing and heavy materials, DIY is usually financially worthwhile. If you need fast installation, warranty coverage, or lack assistance, a prebuilt structure may be the better option despite the higher price.
Get Exact Cut Diagrams and Printable Plans
This material list provides realistic quantities and cost expectations for a 12x20 shed.
It does not include:
- Exact rafter angle calculations
- Stud-by-stud wall layouts
- Header engineering details
- Precise overhang measurements
- Optimized cut lists to reduce waste
- Printable construction diagrams
On a structure this large, layout mistakes can waste hundreds of dollars in lumber and significantly slow construction.
Detailed blueprints with exact measurements, framing layouts, and printable cut sheets simplify the process, reduce material waste, and help ensure structural accuracy.
For a one-time build, complete plans typically save more time and money than they cost by preventing errors and rework.