Built-Up Roofing (Flat) Materials Calculator
Calculate area, waste factor (5%), and cost per square ($400-$800) for your built-up roofing (flat) roof.
- Estimated Packs
- 9 packs
- Effective Area per Shingle
- 784 sq in
- Waste Factor Used
- 10%
Enter your values and press Calculate to see your result.
About Built-Up Roofing (Flat)
Traditional hot-tar-and-gravel system for flat or low-slope roofs.
When measuring for a built-up roofing (flat) roof, it's critical to account for the correct waste factor. The typical waste factor for this material is 5%, which ensures you have enough material to cover hips, valleys, and starter strips without running short.
How it works
Follow the exact steps to get your result instantly and privately.
Step 1: Wood Shingle Roofing
Wood shingles are thin, tapered pieces of wood which are treated with fire retardant. They are used because of their beautiful loo...
Step 2: Clay Tile Roofing
Clay tile roofing is maybe the oldest form of roofing. We find clay tiles as early as the 3rd millennium BC in ancient Mesopotamia...
Step 3: Metal Roofing
Metal roofing is also an old solution - we find it in 27 B.C. with Romans using copper for the Pantheon. It has a few advantages l...
Step 4: Asphalt Shingle Roofing
Asphalt roofing is one of the most common forms of roof covering because it is cheap, easy to install and easy to maintain. Typica...
Step 5: Slate Roofing
Slate is a natural stone created by intense heat and pressure produced by ancient seas. The stone can be split into thin sheets, i...
Step 6: Flat Roof Covering Solutions
There are more types of flat roof coverings like PVC, rubber, bitumen, and tar and gravel. PVC or vinyl is very light, long-lastin...
Step 1: Wood Shingle Roofing
Wood shingles are thin, tapered pieces of wood which are treated with fire retardant. They are used because of their beautiful look, durability and high-wind resistance. Calculating materials requires accounting for the specific reveal and overlapping nature of wood shakes.
Frequently asked questions
A roofing square is a unit of measurement used by contractors and manufacturers. One square equals 100 square feet of roof area. Materials like shingles, underlayment, and nails are all calculated and sold based on how many squares your roof is.
The industry standard waste factor is 10% for a simple gable roof. If your roof is complex with multiple valleys, dormers, and hips, you should increase the waste factor to 15%. For extremely complex roofs, a 20% waste factor is recommended to ensure you don't run short.
Most standard architectural and 3-tab asphalt shingles are packaged so that 3 bundles equal one square (100 square feet). However, heavier premium shingles may come in packages of 4 or even 5 bundles per square due to their weight. Always check the manufacturer's specifications.
Your home's footprint (length × width) only gives you the flat ground area. Because the roof is angled (pitched), its actual surface area is larger than the footprint beneath it. The steeper the pitch, the larger the surface area. We use a 'pitch multiplier' to accurately convert the flat footprint into the true roof area.
For standard asphalt shingles in normal wind areas, 4 nails are required per shingle. This equates to roughly 320-350 nails per roofing square. If you live in a high-wind area, building codes typically require 6 nails per shingle, pushing the count to about 480-500 nails per square. A 5lb box of standard 1-1/4" roofing nails contains approximately 900 nails.