Siding calculator

Type the house and its openings. You get lap siding boards counted course by course around the doors and windows, house wrap and corner boards, from the same siding engine as the whole-house takeoff. Nothing leaves your browser.


  

Add siding to a whole-house framing takeoff

The method

  1. Courses. The wall height divided by the exposure, rounded up.
  2. Runs. Each course is as long as the wall, cut where a door or window crosses it.
  3. Boards. All the runs are packed into stock boards by first fit decreasing, so the offcut of one course starts another; waste is added on top.
  4. House wrap. Wall area less openings plus a lap allowance, in rolls of 1,350 sq ft.
  5. Corners. Two corner boards per outside corner, full height.

Questions

How much siding do I need for a 40 x 30 ft house?

For a 40 x 30 ft rectangle with 8 ft walls, one 3 ft door and two 3 x 4 ft windows, 7 in exposure and 12 ft boards, the calculator counts 56 courses, 176 boards with 10% waste, 1 roll of house wrap and 9 corner boards of 10 ft. Change any figure to match your plan.

How do I calculate lap siding from the exposure?

Each course covers one exposure (the reveal, for example 7 in for an 8 in board over a 1 in lap), so the courses are the wall height divided by the exposure, rounded up. The length of every course, cut around doors and windows, is packed into stock boards, and waste is added. This is more exact than dividing square feet by a coverage figure.

Does a siding calculator subtract windows and doors?

Yes. An opening that cuts through a course splits that course's run, so the boards it removes are not counted, but the offcuts are carried into the next course the way a crew works. House wrap is the wall area less the openings plus a lap allowance.

What is not counted?

Soffit and fascia, sill and jamb flashing, nails, caulk and paint. Exposure, board length and waste are figures you type from the product you buy, and the result is an estimate to check against your supplier's own takeoff.