CSLB C-39 Roofing ContractorLow-Slope RoofingMedium
A building owner has a low-slope roof section prone to persistent ponding water that has damaged prior asphalt BUR systems. A roofing consultant recommends a coal tar pitch built-up roof for this area instead of asphalt. What property of coal tar pitch makes it better suited to standing water conditions?
- ACoal tar pitch is lighter in weight, reducing structural dead load
- BCoal tar pitch is self-healing and highly resistant to moisture penetration due to its chemical structure
- CCoal tar pitch cures faster than asphalt, shortening installation time
- DCoal tar pitch has a lower melting point, making it easier to apply cold
Show answer & explanationAnswer & explanation
Correct answer: B. Coal tar pitch is self-healing and highly resistant to moisture penetration due to its chemical structure
Coal tar pitch has a unique self-healing property where minor cracks reflow and seal under warm conditions, and it exhibits excellent resistance to moisture penetration, making it historically favored for roofs subject to ponding water.
Why the other options are wrong
- A. Weight is not significantly different and is not the reason for selecting coal tar pitch.
- C. Cure time is not the relevant advantage; both materials cure similarly as built-up systems.
- D. Coal tar pitch actually requires higher kettle temperatures than asphalt, not lower.
Coal Tar Pitch BUR
A bituminous roofing material with self-healing properties and superior resistance to standing water, traditionally used on flat roofs prone to ponding.
- Requires higher kettle temperatures than asphalt
- Self-heals minor surface cracks under heat
- Fumes are more hazardous, requiring stricter ventilation controls
Memory trick: Tar heals itself when water just won't leave.