Siding for an 1,800 Square Foot House
Siding needed
18.7 squares
170 ft perimeter, 9 ft walls, two 32 ft gables at 6/12, 13 windows, 2 doors, 12% waste.
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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 perimeter170 ft
- Wall height to the eave9 ft
- Gable ends2 each
- Gable width32 ft
- Roof pitch, rise per 12 in6 /12
- Windows13 each
- Doors2 each
- Outside corners4 each
- Waste allowance12 %
Siding needed18.7 squares
| Wall area | 1,530 sq ft |
|---|---|
| Gable area | 256 sq ft2 gables at 6/12 |
| Openings deducted at half | 119 sq ftof 237 sq ft total |
| Net area | 1,668 sq ft |
| With 12% waste | 1,868 sq ft |
| Squares | 18.7 |
| Vinyl cartons at 2 squares | 10 |
| Starter strip | 170 ft |
| J channel | 244 ftaround windows and doors |
The material list this produces
| Siding, cartons at 2 squares | 10 |
|---|---|
| Starter strip, ft | 170 |
| J channel, ft | 244 |
| Outside corner posts, 10 ft | 4 |
| Undersill trim, ft | 170 |
| House wrap, sq ft | 1,786 |
| Siding nails, lb | 5 |
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 pitch | Siding needed | Gable area |
|---|---|---|
| 4/12 | 17.7 squares | 171 sq ft |
| 6/12 | 18.7 squares | 256 sq ft |
| 8/12 | 19.6 squares | 341 sq ft |
| 10/12 | 20.6 squares | 427 sq ft |
| 12/12 | 21.5 squares | 512 sq ft |
What else matters here
Eighteen point seven squares, ten cartons. Wall area is 1,530 and the gables add 256, with 119 square feet coming back off for the openings at half.
Ten cartons, because you cannot buy three fifths of one. That rounding is worth noticing: the last carton is what covers the mistakes, and returning an unopened one is usually easy while getting a matching one three weeks later is not.
Also order the trim by the takeoff rather than by eye. This house wants 170 feet of starter, 244 feet of J channel and four corner posts, and running short on J channel halfway through a window wrap stops the job.
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 squares of siding for an 1,800 square foot house?
About 18.7 squares, ten cartons of vinyl, on a 170 foot perimeter with nine foot walls and two 32 foot gables at 6/12.
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.
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.
The siding calculator takes any dimensions you like and hands back the same list.