ContractorHandbook

Siding for a 2,500 Square Foot House

Siding needed

22.5 squares

200 ft perimeter, 9 ft walls, two 38 ft gables at 6/12, 16 windows, 3 doors, 6 corners, 12% waste.

It does not stop at a number.

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wall length, ftheightgable = width x rise / 2net area with waste / 100 = squares
Siding is quoted in squares of a hundred square feet, and the gable is the piece people leave out. Openings only come off at half, because the cut piece around a window is rarely long enough to use anywhere else.

How that number is worked out

These are the figures this page was built with and every line the calculator produces from them. Change anything above and all of it moves.

  • Wall perimeter200 ft
  • Wall height to the eave9 ft
  • Gable ends2 each
  • Gable width38 ft
  • Roof pitch, rise per 12 in6 /12
  • Windows16 each
  • Doors3 each
  • Outside corners6 each
  • Waste allowance12 %

Siding needed22.5 squares

Wall area1,800 sq ft
Gable area361 sq ft2 gables at 6/12
Openings deducted at half152 sq ftof 303 sq ft total
Net area2,010 sq ft
With 12% waste2,251 sq ft
Squares22.5
Vinyl cartons at 2 squares12
Starter strip200 ft
J channel310 ftaround windows and doors

The material list this produces

Siding, cartons at 2 squares12
Starter strip, ft200
J channel, ft310
Outside corner posts, 10 ft6
Undersill trim, ft200
House wrap, sq ft2,161
Siding nails, lb6

Roof pitch compared

Pitch only moves the gable triangles, but it moves them fast. Going from 4/12 to 12/12 triples the gable area on the same house, which is about three extra squares of siding on a 30 foot wide elevation and closer to six on a 40 foot one.

Roof pitchSiding neededGable area
4/1221.2 squares241 sq ft
6/1222.5 squares361 sq ft
8/1223.9 squares481 sq ft
10/1225.2 squares602 sq ft
12/1226.5 squares722 sq ft

What else matters here

Twenty two and a half squares, twelve cartons. The six outside corners in this one are not decoration: a house this size rarely comes as a plain rectangle, and every corner is a post and a run of cut siding that produces offcuts.

The 361 square feet of gable here is three and a half squares from two triangles. On a house with cross gables or a dormer there will be more of them, and each one is another width squared over 48 to add.

Twelve percent waste holds on a straightforward elevation. If the house has a cut up front, a wrapped bay or shake courses in the gable, take the waste to 15 and expect to use it.

What this calculator assumes

  • A gable is a triangle, so its area is the width squared times the pitch divided by 48. Two gables on a 30 foot wide house at 6/12 add about 225 square feet, which is more than two squares of siding that people routinely forget.
  • Openings are deducted at half, not in full. You still cut siding around a window and the offcut is usually scrap, so the trade rule is to take off half the opening and leave anything under 10 square feet in.
  • 12 percent waste is normal for vinyl on a straightforward house. Lap siding, a cut up elevation or a staggered shake course runs higher.
  • A carton of vinyl siding covers two squares, 200 square feet. Fiber cement and wood lap are sold by the piece, so use the square figure and convert at your supplier's coverage.

Questions people ask

How many boxes of vinyl siding for a 2,500 square foot house?

About twelve, at two squares per carton, for a 200 foot perimeter with nine foot walls and two 38 foot gables. Count the actual gables on the house rather than assuming two.

Do you subtract windows and doors from siding?

At half, not in full. You still cut siding around every opening and the offcut usually cannot be used anywhere else, so the trade rule is to take off half the opening area and leave anything under about 10 square feet in the number entirely.

How many squares are in a box of vinyl siding?

Two. A standard carton covers 200 square feet, which is why siding is quoted in squares rather than square feet. Fiber cement and wood lap are sold by the piece, so take the square figure here and convert at whatever coverage your supplier lists.

Different numbers?

The siding calculator takes any dimensions you like and hands back the same list.

Other common sizes