A square of shingles covers a 100 square foot area This is a
A square of shingles covers a 100 square foot area. This is a 10 foot by 10 foot area. One square of shingles usually comes in 3 bundles for standard duty or 4 bundles for heavy duty shingles. 80 square would be a big roof, and would represent 8000 square feet. You want to replace the shingles on your home. The house is a 24 feet by 32 feet ranch style home with a 12:12 pitch roof. The roof has one foot overhangs all around. The lowest cost you can find for shingles is $40 per square. Calculate the cost of replacing the shingles on your house.
Solution
The house is a ranch style. That\'s important to figure
 out what the roof looks like. I\'m thinking the long side
 faces the street and the roof pitches to the sides.
 One edge of the roofline is the 24\' dimension, and the other
 is the sloping dimention
 (1/2)*32 = 16 is the \"run\" of the roof measured along the front
 16 would also be the \"rise\" That would mean the roof measures
 16*sqrt(2) from outside wall to peak, since rise and run are equal
 The roof area would be
 16*sqrt(2)*24*2 = 1086.12 The factor of 2 is for both sides of the roof.
 To account for the dripedge, (2)*(24)*(1) = 48
 1086.12 + 48 = 1134.12. The number of squares would be this
 divided by 100, or 11.34. At $40 per square,
 (40)*(11.34) = $453.64 to shingle the roof

