CSLB C-39 Roofing ContractorSteep-Slope RoofingMedium
A roofer is preparing to install standard concrete roof tile on a new residential structure. Per manufacturer and code standards, what is the minimum roof slope for a standard tile installation without requiring special low-slope modifications such as double underlayment?
- A6:12
- B4:12
- C2:12
- D3:12
Show answer & explanationAnswer & explanation
Correct answer: B. 4:12
Standard concrete and clay tile installations require a minimum slope of 4:12; roofs between 2.5:12 and 4:12 require special low-slope applications with double underlayment and reduced headlap to compensate for slower water shedding.
Why the other options are wrong
- A. 6:12 exceeds the minimum requirement but is not the threshold itself.
- C. 2:12 is below even the low-slope minimum and unsuitable for tile.
- D. 3:12 falls within the low-slope range requiring special modifications.
Minimum Tile Roof Slope
The lowest roof pitch at which standard tile installation methods can be used without additional waterproofing measures.
- 4:12 is standard minimum slope for tile
- 2.5:12-4:12 requires double underlayment (low-slope application)
- Below 2.5:12 tile is generally not permitted
Memory trick: Four-twelve keeps tile happy and dry.