CSLB C-39 Roofing ContractorLow-Slope RoofingMedium
An inspector is checking a termination bar securing the top edge of a mechanically attached TPO membrane at a wall termination. Per typical manufacturer specifications, fasteners in the termination bar should be spaced no more than how far apart on center?
- A24 inches
- B3 inches
- C12 inches
- D6 inches
Show answer & explanationAnswer & explanation
Correct answer: C. 12 inches
Standard single-ply manufacturer specifications typically require termination bar fasteners spaced at a maximum of 12 inches on center to provide adequate holding power and prevent membrane pull-out at wall terminations, with tighter spacing at corners.
Why the other options are wrong
- A. 24 inches spacing is too wide and would risk membrane pull-out under wind load.
- B. 3 inches is far tighter than standard field spacing requirements.
- D. 6 inches is sometimes used at corners but is not the typical field maximum.
Termination Bar Fastening
A metal bar mechanically fastened over the top edge of single-ply membrane at wall or curb terminations to secure and seal the membrane edge, typically fastened at 12 inches on center maximum.
- Standard max spacing is 12 inches on center
- Tighter spacing (6 inches) often required at corners
- Sealant is applied above the bar to prevent water intrusion
Memory trick: A foot apart keeps the membrane from tearing off the wall.