12x18 Shed Material List

Quick Answer

A 12x18 gable shed with 8 ft walls, 16 inch on center framing, 4/12 roof pitch, pressure treated floor framing, OSB or plywood sheathing, a basic double door, and gravel foundation is a large backyard structure often used as a workshop, riding mower garage, hobby space, or general storage building. The 12 ft width requires stronger framing than smaller sheds, while the 18 ft length significantly increases total material needs.

See all shed material lists by size

You will need:

• Heavy pressure treated lumber for the floor system
• 2x4 wall framing
• 2x6 roof framing
• Extensive floor, wall, and roof sheathing
• Panel or lap siding
• Asphalt shingles and underlayment
• Reinforced double door framing
• Large quantities of fasteners and hardware

Realistic 2026 total material cost: $4,800 to $7,600

This assumes a gravel base and basic exterior finishes only.

Need a smaller option? See our 10x20 shed material list. Want more space? See our 14x16 shed material list.

Full Material List

Quantities assume 8 ft wall height, 16 inch on center spacing, and a standard double door on one gable end.

Floor Framing

A 12 ft span requires stronger joists to prevent floor flex, especially under equipment loads.

Gravel Base

• 5 to 7 cubic yards of compacted 3/4 inch crushed gravel

Floor Frame (Pressure Treated)

Perimeter

• 2x10x18 PT – 2 (long rim joists)
• 2x10x12 PT – 2 (end band joists)

If 18 ft boards are unavailable, splice sections over blocking.

Floor Joists (16 inch OC across 12 ft span)

• 2x10x12 PT – 13 to 14

Floor Sheathing

• 3/4 inch tongue and groove plywood or OSB – 7 sheets

Fasteners

• Exterior-rated screws or galvanized framing nails
• Heavy-duty joist hangers recommended

Wall Framing

Framed 16 inch on center.

• 2x4x8 studs
• 110 to 125 total
• Includes perimeter walls
• Additional studs for corners and door framing
• Waste allowance

Plates

• 2x4x18 – 6 (long walls, double top plates + bottom plates)
• 2x4x12 – 6 (end walls)

Splicing shorter boards is common for long walls.

Double Door Framing

Typical opening: 60 to 72 inches wide.

• 2x10x8 – 2 (header material)
• 1/2 inch plywood spacer
• Jack and king studs included in stud count

Roof Framing

A 12 ft span typically uses 2x6 rafters across a long ridge.

Rafters (4/12 pitch, 16 inch OC)

• 2x6x16 – 28 to 30
• Approximately 14 to 15 rafter pairs

Ridge Board

• 2x10x18 – 1

Collar Ties or Ceiling Joists

• 2x4x12 – 14 to 15

Sheathing

Large wall area significantly increases panel usage.

Wall Sheathing

• 7/16 inch OSB or plywood – 20 to 22 sheets
• Panel siding may eliminate separate sheathing

Roof Sheathing

• 7/16 inch OSB or plywood – 11 to 12 sheets

Siding

Panel siding is common for sheds of this size.

T1-11 or LP SmartSide Panels

• 20 to 22 sheets

Alternative siding systems require additional trim pieces and backing.

Roofing

Underlayment

• 2 rolls synthetic underlayment

Drip Edge

• 10 to 12 pieces (10 ft lengths)

Shingles

• Approximately 2.5 to 3 squares
• 9 to 11 bundles depending on waste

Roofing Nails

• 8 to 10 lb box

Hardware and Fasteners

• 16d framing nails or structural screws
• 8d nails for sheathing
• Exterior construction screws
• Construction adhesive (5 to 6 tubes)
• Hurricane ties recommended
• Heavy-duty hinges (3 per door)
• Exterior double-door latch or lockset
• Padlock hardware
• Flashing for door header

Estimated Cost Breakdown

Typical 2026 pricing ranges.

• Gravel Base: $300 to $600
• Pressure Treated Floor Framing: $1,100 to $1,800
• Wall Framing Lumber: $900 to $1,500
• Roof Framing Lumber: $700 to $1,100
• Sheathing (walls and roof): $1,300 to $2,100
• Siding (T1-11): $950 to $1,500
• Siding (LP SmartSide): $1,700 to $2,700
• Siding (Vinyl system): $2,200 to $3,500
• Roofing: $650 to $1,050
• Hardware and Fasteners: $300 to $550

Total Estimated Range

With basic panel siding: $4,800 to $6,200

With upgraded siding: $6,200 to $7,600

Costs increase compared to mid-size sheds due to:

• Larger floor area (216 sq ft)
• Stronger floor joists
• Longer wall runs
• Increased sheathing and siding quantities
• Greater roof coverage
• Reinforced double door framing
• Higher fastener usage
• Regional material pricing can significantly affect totals

If you want exact cut diagrams, printable framing layouts, and step-by-step blueprints for this 12x18 shed, detailed plans eliminate guesswork and reduce lumber waste.

Get the Complete 12x18 Shed Plans Here

Tools Required

Standard framing tools plus equipment suitable for larger components.

Essential tools:

• Circular saw
• Miter saw
• Drill and impact driver
• Framing hammer
• 4 ft or longer level
• Speed square
• Tape measure
• Chalk line
• Multiple ladders
• Shovel and rake
• Plate compactor or heavy hand tamper

Helpful tools:

• Framing nailer
• Roofing nailer
• Laser level
• Sawhorses
• Clamps

Assistance is recommended due to the size and weight of components.

Step-by-Step Build Overview

High-level sequence only.

• Prepare and compact gravel base across entire footprint.
• Build pressure treated floor frame and verify square.
• Install floor sheathing.
• Frame walls on the ground including double door opening.
• Raise walls with assistance, plumb, and brace securely.
• Install double top plates tying 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 required.
• Install siding.
• Build and hang double doors.
• Install trim and hardware.
• Verify square frequently to avoid alignment problems across long spans.

Common Mistakes

• Using undersized floor joists for heavy equipment loads. Causes floor deflection.
• Poor base preparation. Leads to uneven settling.
• Losing square across long walls. Affects roof and siding alignment.
• Attempting to raise large walls without help. Unsafe and difficult.
• Underestimating materials. Causes delays and additional costs.
• Weak door framing. Leads to sagging doors over time.

Is It Worth Building Yourself?

DIY material cost: $4,800 to $7,600

Typical prebuilt 12x18 shed delivered in 2026: $9,000 to $16,000

DIY savings typically range from $4,000 to $8,000.

Consider:

• Build time of roughly 4 to 7 days with help
• Handling heavy materials
• Need for accurate layout
• Possible permit requirements

For homeowners comfortable with construction tasks, building yourself is usually financially worthwhile.

Get Exact Cut Diagrams and Printable Plans

This material list provides realistic quantities and cost expectations for a 12x18 shed.

It does not include:

• Exact rafter angle calculations
• Detailed wall framing layouts
• Header engineering details
• Precise overhang measurements
• Optimized cut lists
• Printable construction diagrams

On larger structures, layout errors can waste substantial time and material.

Detailed blueprints with exact measurements, framing layouts, and printable cut sheets simplify construction, reduce waste, and help ensure structural accuracy.

For a one-time large build, complete plans typically save more time and money than they cost by preventing mistakes and rework.

Get the Complete 12x18 Shed Plans Here