Outdoor & Structural
Deck Calculator & Material Planner
Estimate the material a deck of a given size consumes — decking, framing, railing, stairs, and fasteners — so you can budget the project. This is material planning, not structural design.
Before you build
Material-planning estimate only. Structural requirements, footing sizes, spans, loads, permits, and code requirements vary by location and project. Verify structural design and local building requirements before construction.
Common questions
How much decking do I need for a 16 × 12 deck?
A 16 × 12 deck is 192 sq ft. With 5.5 in boards and a quarter-inch gap you need about 34 rows at 12 ft each — roughly 410 linear feet before waste. This planner works it out from your exact board width and gap.
How far apart should deck joists be?
Sixteen inches on centre is common for wood decking. Many composite products require twelve inches, and diagonal layouts require closer spacing still. Always follow the decking manufacturer's specification and your local code.
Do I need a permit to build a deck?
Usually yes, particularly for anything raised or attached to the house. Permits exist because deck collapses are almost always a ledger or footing failure. Check with your local building department before buying material.
Can ProjectKit design my deck structure?
No, and it should not try to. Joist spans, beam sizes, post spacing, and footing depth depend on load, lumber species, soil, and frost line. This planner estimates material quantities for budgeting — the structural design needs a span table, a designer, or your building department.
What usually comes next
Projects that tend to follow a deck job.
ProjectKit provides planning estimates only. Actual requirements, costs, installation methods, structural requirements, permits, safety requirements, and building codes vary. Verify critical specifications before purchasing materials or beginning work. Read the full terms.