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 — answers 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.

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