Question 1

How do I measure roof area?

Accepted Answer

Multiply building footprint by roof pitch factor or measure each plane and sum; include overhangs.

Question 2

What is a roofing square?

Accepted Answer

A roofing square is 100 square feet; shingles and underlayment are often sold by the square.

Question 3

How much waste should I add?

Accepted Answer

Add 10-15% for cuts and starter/hip/ridge shingles; complex roofs may need more.

Question 4

Which pitch factor do I use?

Accepted Answer

Common factors: 4/12 ~ 1.054, 6/12 ~ 1.118, 8/12 ~ 1.202; steeper roofs have higher factors.

Question 5

What about underlayment and nails?

Accepted Answer

Include felt/synthetic underlayment area, ice & water shield for eaves/valleys, drip edge, flashing, and nails by the coil/box.

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