Certified Roofing Contractor/Trade Knowledge

Low-Slope Systems

35% of this exam

Membrane roofing: built-up, modified bitumen, and the single plies (TPO, PVC, EPDM), plus the insulation, drainage, and detailing under and around them. The exam favors matching questions — which seam method, attachment method, or component goes with which system — and the drainage rules that keep water moving.

Core concepts

Know each membrane by its seams and application

BUR is multiple felt plies in hot bitumen. Mod-bit installs by torch, cold adhesive, or self-adhered depending on the product. TPO and PVC are thermoplastics — seams are hot-air welded into a fused joint. EPDM is a thermoset rubber that cannot be re-melted, so its seams use tape or splice adhesive.

Three ways to hold a single-ply down

Fully adhered (glued), mechanically attached (screws and stress plates in rows, usually in the seam laps, with tighter spacing at perimeters), or ballasted (loose-laid under stone or pavers). The attachment method comes from the tested, approved assembly.

The assembly under the membrane matters

Polyiso is the workhorse insulation — highest R per inch of the common boards. Tapered insulation builds slope on flat decks. A cover board over the foam protects against crushing, hail, and puncture. Humid-interior buildings (natatoriums) get a vapor retarder near the deck.

Water must always have two ways off

Design to at least 1/4 inch per foot toward drains — ponding kills membranes and voids warranties. Scuppers are openings through the parapet; parapet roofs on interior drains also need secondary overflow drainage in case the primaries clog. Walkway pads protect traffic routes; pitch pans are last-resort penetration seals.

Key facts to know cold

Minimum design slope1/4 inch per foot to drains — positive drainage, no ponding

Seam methodsTPO/PVC heat-welded; EPDM taped/adhered (thermoset); BUR/mod-bit bitumen-based

Single-ply attachmentFully adhered, mechanically attached, or ballasted

PolyisoMost common above-deck insulation; highest R-value per inch of common boards

Cover boardHard layer over foam for puncture, hail, and crush resistance

Overflow drainageSecondary scuppers/drains required where parapets could trap water

Where it lives in your books

The real exam is open book. Knowing which book and which tab answer this domain is worth as much as memorizing it.

manual

Roofing References

Florida roofing is code-first: product approvals, underlayment, and attachment requirements decide questions that would be judgment calls elsewhere. Tab the FBC roofing chapter before anything else.

7 recommended tabs

Lookup strategy

· Tab the NRCA low-slope sections by membrane type — BUR, mod-bit, EPDM, TPO/PVC — and answer 'which system does X' questions from the right section.
· Drainage and overflow requirements are code provisions; slope and secondary drainage questions check against the FBC, not just the manual.

Reading isn't learning. Retrieval is.

70 questions in this domain, each with an explanation and source.