1 · What the fire did, mechanically, to the assembly
Treat the roof as a stack: covering, underlayment, sheathing, framing, insulation, ceiling. Fire attacks it from below and, in wildland-urban cases, from above, and each layer fails differently.
Framing and sheathing. Wood under fire exposure pyrolyses from the surface inward, leaving a char layer that insulates the sound wood behind it. The Forest Products Laboratory's Wood Handbook documents the behaviour engineers rely on: char forms at a broadly predictable rate, and the uncharred core retains most of its mechanical properties. Residual capacity is therefore a measurement, not a guess — which is also why "it looks burned" is not a finding.
Underlayment and covering. Asphalt shingles and synthetic underlayment are hydrocarbon products; heat from below blisters and slumps them long before flame appears, and heat from an adjacent structure can do the same from above. Metal panels distort and lose their fastener seal; tile survives heat but cracks under thermal shock from hose streams.
Insulation. Loose-fill fiberglass and cellulose have enormous internal surface area. They do not so much burn as absorb: suppression water, then particulate, then the semi-volatile fraction of smoke that condenses as the attic cools. Wet, contaminated loose-fill is not cleanable in place and is normally removed.
Openings. Vertical ventilation — opening the roof above the fire so the hot gas layer can leave — is a core tactic described in NFPA 1700 and studied extensively in full-scale experiments by UL's Fire Safety Research Institute. The National Roofing Directory's reference on ventilation holes and fire department roof damage catalogues the openings an inspector should expect: inspection and kerf cuts, louver cuts with a hinged panel, vent holes laid out between rafters, trench cuts, and removed skylights and turbines. Overhaul adds ceilings pulled from below and insulation dragged out of the bays. All of it is deliberate, and all of it must be recorded as such.
2 · Inspection one: origin and cause
The fire marshal's investigator, or the carrier's retained investigator, works to NFPA 921. The product is a determination of where the fire began and what ignited it, supported by pattern analysis — including patterns on the roof framing, which can show direction of travel and duration of exposure. Two boundaries the property owner should understand: the investigation is not a structural evaluation, and the investigator's access to the roof happens before the scene is released, which means before anyone else's inspection can begin. Ask for the incident report and, if one is produced, the origin-and-cause report; both belong in the claim file.
3 · Inspection two: structural capacity
A licensed structural engineer answers the only question that matters for occupancy: can the assembly carry dead, live, snow and wind loads as it now stands, and if not, what changes that. The method is direct. Char is removed from each affected member, the residual section is measured, the member is checked against its required capacity, and a disposition is written: retain, sister, or replace. Cut members — a rafter sawn during a louver cut, a truss chord notched during overhaul — are evaluated the same way; trusses in particular are engineered as a system, and a cut chord usually requires a repair designed by an engineer, not a field fix. Delaminated sheathing is assessed for fastener holding and diaphragm action, since a deck that will not hold nails cannot take a new roof.
The engineer's letter is the controlling document. The roofer builds to it, the adjuster pays against it, and the hygienist's scope has to be sequenced around it, because attic cleaning is done to framing that is staying, not framing that is coming out.
4 · Inspection three: restoration scope
The restoration contractor — ideally one whose technicians hold the IICRC's Fire and Smoke Restoration Technician certification, which covers scoping, mitigation, cleaning, deodorization and documentation of fire-damaged structures — writes the scope under ANSI/IICRC S700. Where hose water saturated the assembly, S500 governs drying and the category of the water; where wet materials sat long enough, S520 governs mold. It is routine for a single attic to be all three losses simultaneously, and a scope that names only the fire standard is a scope that will be re-opened.
For the roof assembly the scope has a characteristic shape: removal and disposal of contaminated insulation; HEPA vacuuming and cleaning of framing and the underside of the sheathing; treatment of remaining odor reservoirs by sealing; replacement of the fire department's openings and of members the engineer condemned; and, only then, the new roof covering. The National Roofing Directory's article on smoke odor in roof decking and attic insulation explains why the sequence cannot be reversed: a new roof laid over an untreated deck seals the reservoir in.
5 · Inspection four: contamination sampling and clearance
This is the inspection the other three cannot substitute for and the one this library exists to explain. The question is not whether the attic smells; it is what is present, at what intensity, and where its boundary lies — the three things S700 asks an assessment to establish. The methods are the ones covered elsewhere on this site: tape lifts and wipe samples of the framing and deck, read by microscopy to distinguish soot, char and ash from ordinary dust; and, where odor is the complaint, air sampling for the volatile fraction, since the compounds that re-emit from warm wood are the ones the EPA groups as volatile organic compounds. Background samples from an unaffected space or outdoors anchor the comparison.
The same locations are sampled again after the work. A clearance report shows the before and after side by side, against background, with the chain of custody intact. That document is what closes the attic out of the claim and what a future buyer's inspector will ask for.
6 · Distinguishing char, heat effect and soot in the field
| Observation | Read it as | Discipline |
|---|---|---|
| Black layer with alligator cracking; probe penetrates; material crumbles | Char — loss of section | Engineer |
| Brown-to-black surface, sound underneath, no penetration | Heat effect / scorch — cosmetic unless extensive | Engineer confirms, hygienist samples |
| Grey or black deposit that wipes onto a cloth; natural wood color below | Soot — surface residue | Hygienist |
| Swollen, layered, soft OSB or plywood | Water damage to sheathing | Engineer (holding power), S500 (drying) |
| Sawn edges, hinged sheathing, rectangular geometry between rafters | Fire department opening, not fire damage | Roofer (repair), documented separately |
| Odor that returns on warm days after cleaning | Reservoir in porous material | Hygienist — sampling, sealing, clearance |
7 · The file that holds together
In sequence: the incident report and any origin-and-cause determination; photographs of every opening and every affected member before anything is touched; the engineer's letter with member-by-member dispositions; the restoration scope citing S700 and, where applicable, S500 and S520; the pre-remediation sampling report; the roofer's estimate keyed to the engineer's letter, with fire department openings itemised separately; and the clearance report. Every carrier communication in writing. A file built in that order tends not to be argued with, because each document answers the question the next one depends on.