Roofing Inspection Checklist for Contractors

The roof is the building's primary defence against water, and roofing defects are among the most expensive and disruptive to put right after the fact — because by then they're causing leaks, damp, and damage to the finishes below. A thorough roofing inspection at the right stages catches problems while access is easy and before the roof is relied upon.

This checklist covers the main roofing inspection points for contractors. Work to the specification, manufacturer's instructions, and relevant standards, which govern the detail.

Structure and substrate

Roof structure (trusses, rafters, joists) installed per design, correctly spaced and fixed.
Adequate bracing and restraint.
Substrate/decking sound, correctly fixed, and to the right falls (especially flat roofs).
No damage or deflection.

Underlay and breather membrane

Correct membrane type used per specification.
Laid with adequate laps and in the right direction.
Continuous and undamaged, dressed correctly into gutters and at edges.
Fixed/battened correctly.

Battens (pitched roofs)

Correct size and grade of batten.
Gauge (spacing) correct for the covering and pitch.
Securely fixed, with staggered joints over supports.

Coverings (tiles/slates)

Correct tile/slate type, laid to the specified gauge and lap.
Set out evenly, lines straight, no excessive cutting at edges.
Each unit fixed/clipped as required by spec and exposure.
Ridge, hip, and verge details correct and secured.
No cracked, chipped, or slipped units.

Flat roof coverings

Membrane/covering laid per manufacturer's instructions.
Laps, welds, or bonding continuous and sound.
Upstands and detailing at the correct height.
Falls achieve drainage with no ponding.

Flashings and weatherproofing

Flashings at abutments, chimneys, and penetrations correctly formed and dressed.
Soakers, valleys, and secret gutters correct.
All junctions and penetrations weathertight — the most common source of leaks.

Rainwater goods

Gutters and downpipes correct size, fixed, and to fall.
Connected and discharging correctly.
No blockages or debris.

Insulation and ventilation

Insulation correct type and thickness, continuous, no gaps.
Ventilation provision adequate (eaves, ridge) to prevent condensation.
Vapour control layer correct where specified.

Safety and access

Edge protection and access in place during inspection.
Permanent fall-protection/anchor points installed where specified.

Why timing matters

Many roofing elements are concealed by later layers — membrane under battens, battens under tiles, insulation under the covering. Inspect each layer before the next covers it. Once the roof is complete, the only evidence of what's underneath is the photos you took at each stage.

Capturing it digitally

Roofs are awkward to inspect and the evidence (especially of concealed layers and flashing details) is critical. A site inspection app lets you work through the roofing checklist on a tablet, photograph each layer and detail before it's covered, and hold the record against the project — so weatherproofing details are documented even after the roof is finished.

Key takeaways

A roofing inspection should cover structure and substrate, underlay, battens, coverings, flat-roof membranes, flashings, rainwater goods, and insulation/ventilation — inspecting each layer before the next conceals it. Flashings and junctions are the leak hotspots, so check them closely. Photograph concealed layers as you go; it's the only record you'll have.