Roofing a 400 sq ft Garage — 5/12 Pitch
A detached garage with a 400 sq ft footprint and 5/12 pitch needs approximately 14 shingle bundles.
How to use this tool
- Measure the building footprint (length x width) and total it across roof sections.
- Choose the pitch multiplier for your roof slope (1.118 for a 6/12 roof).
- Set a waste allowance — 10% for simple roofs, 15%+ for complex ones.
- Confirm bundles per square (3 for most shingles).
- Read the squares and total bundles to order.
Find out how many bundles of shingles to buy for a small detached garage roof replacement.
Frequently asked questions
- How many bundles of shingles are in a square?
- Most three-tab and architectural shingles pack three bundles per square (100 sq ft). Some heavy designer shingles use four or five bundles per square — check the wrapper.
- How do I account for roof pitch?
- Multiply the flat footprint by a pitch factor equal to the square root of (1 + (rise/run)^2). A 6/12 roof uses about 1.118, a 9/12 about 1.25, and a 12/12 about 1.414.
- How much waste should I add for roofing?
- Add roughly 10% for a simple gable roof and 15% or more for a complex roof with many hips, valleys, and dormers, plus starter and ridge courses.