Renovimo
A dimensioned staircase drawing on drafting paper with a wooden model stair rising out of it

Engineering

Engineering calculators

The material calculators tell you how much to buy. These tell you how to build it: the geometry worked out from your measurements, a dimensioned drawing you can print and take to the job, a 3D model, every code limit checked, and the lumber list.

Scale drawing

Side elevation with every dimension in feet, inches and sixteenths, ready to print on Letter paper.

3D model

Turn the build around before you cut a board, in the finish you plan to use.

Code checks

Each IRC 2021 limit as a pass or fail, with the section it comes from.

Cut and buy list

Pieces, the stock lengths to buy them from, and the hardware.

Structural element

These figures follow the IRC tables and typical practice; they are not an engineered design. Check sizes, fastening and permits with a licensed engineer or your local building department before you build.

Engineering calculators by project

Stairs

Every stair layout, each on its own page.

Stair Calculator Risers, treads, stringer layout, floor opening and code checks, drawn to scale and in 3D Open calculator L-Shaped Stair Calculator Two flights and a landing: risers, treads, stringers, landing size and the L footprint, drawn in plan and 3D Open calculator U-Shaped Stair Calculator Two parallel flights and a half-turn landing: risers, treads, stringers, landing size and the U footprint, drawn in plan and 3D Open calculator

On the way

  • Winder stairs
  • Spiral staircases
  • Ship ladders and alternating tread stairs
  • Curved stairs
  • Steps on a slope

Roofs

Pitch, rafters and trusses for the common roof shapes.

Gable Roof and Rafter Calculator Common rafter length, birdsmouth and ridge cuts, rafter count, ridge board, ties and roof area for a gable roof, drawn and in 3D Open calculator Roof Pitch Calculator Pitch in inches per foot, angle, slope, rafter length and roof area, with a gable drawing and a 3D house Open calculator

On the way

  • Roof trusses
  • Hip roofs
  • Gambrel roofs

Ramps

Slope, length and landings to the ADA rules.

Wheelchair Ramp Calculator Ramp length and slope, landings, handrails and the framing and lumber list, checked against the ADA and drawn in 3D Open calculator

Framing

Span tables and the cuts that go with them.

On the way

  • Headers and beams
  • Floor joists
  • Octagons and gazebos
  • Miter and crown molding angles
  • Pergolas
  • Shed framing

What makes a calculator an engineering one

A paint or tile calculator ends at a quantity. An engineering calculator ends at a layout: the numbers you mark on the lumber. For a stair that is the riser and tread you clamp on the framing square, the length of 2 × 12 to buy for each stringer, how long the floor opening has to be for headroom, and whether the flight passes the residential code.

The limits come from the 2021 International Residential Code, which most US states and towns adopt, sometimes with local changes. The calculators check against it and name the section, but they do not replace a permit or an inspection, and where a part carries a load they say so.

Want a quantity rather than a layout? The material calculators cover paint, flooring, drywall, concrete, decking and more.