The house's size, wall height, stories, roof pitch and openings in. Squares of siding, the trim by the foot and the house wrap out.
Result
The house takes 13 squares of siding.
1,155 sq ft of wall to cover, with 10% waste: 12.7 squares.
What to buy
13 squares of siding, 100 sq ft a square
134 ft of starter strip along the bottom of the walls
260 ft of J-channel around the doors and windows and up the gable rakes
32 ft of outside corner: 4 corners 8' 0" tall
1,345 sq ft of house wrap
The walls
Walls
1,120 sq ft
Gable ends
225 sq ft
Doors and windows
190 sq ft
To cover
1,155 sq ft
A side wall over an end wall. The length is the long wall, the width the end wall under the gable, and the wall height is one story, floor to the top of the wall.
How the siding is counted
Walls are the distance around the house times the wall height and the stories. A 40 by 30 foot house with 8 foot walls has 2 × (40 + 30) × 8 = 1,120 sq ft of wall.
Gable ends are the triangles under the roof on the width. Each is half the width times the rise, and the rise is half the width times the pitch over 12: at 6/12 on a 30 foot house, 7.5 feet. The two come to 30 × 7.5 = 225 sq ft.
Doors and windows come off at 20 sq ft a door (3' by 6' 8") and 15 sq ft a window (3' by 5').
Squares are the area to cover plus waste, divided by 100. Siding is sold by the square; the box says how many squares it holds.
Trim is by the foot: starter strip around the bottom of the walls, less the doors; J-channel around each window, up the sides and across the top of each door, and up the rakes of each gable; and outside corners at the four corners, as tall as the walls.
House wrap is counted over the whole wall, openings included; it's cut at the openings once it's up. The code calls for a water-resistive barrier behind siding (IRC R703.2).
What the count leaves out
Inside corners, where an L-shaped house turns in.
Soffit and fascia under the eaves, priced by the foot of eave.
Utility trim under the soffit and under the windows, where the siding is cut.
Garage doors and wide windows, which take off more than a standard opening.
Common questions
How many squares of siding for a 2,000 sq ft house?
It depends on the walls, not the floor. A two-story house of 2,000 square feet, 40 by 25 with 8 foot walls and 6/12 gables, has 2,046 sq ft of wall to cover after two doors and ten windows: 23squares with 10% waste.
How much does a square of siding cover?
100 square feet of wall. Many boxes of vinyl siding hold two squares; the label on the box says.
How much waste for siding?
About 10% on a plain house. Add more for many windows, tall gables, dormers and short walls, where more of each panel is cut off.
What does siding cost installed?
The vinyl siding cost guide has the range for a typical house and by state, with the tear-off, house wrap, overhead, profit and sales tax.
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