Insights — 14 October 2026

A flat roof inspection checklist for property and facility managers

If a flat roof only gets attention when a ceiling tile stains, the water has already found a path, and the path does not always start directly above the stain. A regular walk-over can find problems while they are still small, and a written record turns a leak into something a contractor can diagnose.

This checklist is what we look at on an inspection, set out so a property or facility manager can do a first pass and know what to send us. Roof access carries fall hazards: go up only if your building’s safety procedures allow it and you are trained and equipped for it under WorkSafeBC requirements, or have someone qualified do the walk-over.

On the roof

Eight places to look

What to look for, and why it matters
Where	What to look for	Why it matters
Drains and scuppers	Debris, missing or damaged strainers, water standing around the outlet	A blocked drain turns a roof that drains into one that holds water
The field of the roof	Blisters, splits, cracks, bare or worn patches, loose granules, soft spots underfoot	Local defects are repaired before a restoration; widespread ones point towards replacement
Seams and laps	Open, lifting or wrinkled laps	An open lap lets water under the roofing
Flashings and upstands	Cracked, split or separated flashing at walls, parapets, curbs and roof edges	Where the roof turns up a wall it changes direction and material, and it needs its own detail
Penetrations	Cracked sealant, gaps or displaced collars at pipes, vents, conduits and equipment supports	Every penetration is a hole in the roof that depends on its detail
Expansion joints	Split, missing or displaced joint covers or sealant	Joints move, and they need a joint detail of their own
Equipment and walkways	Worn tracks where crews walk, damage around rooftop units	Areas with regular foot traffic need a traffic-rated surface
Ponding	Water still standing well after the rain has stopped; dirt rings or growth where it sits	A coating does not fix ponding; the drainage is corrected first

Inside the building

When a leak shows up tells you as much as where

Note every stain, drip and damp patch with its location, and when it appears: during rain, some hours after it, only in wind-driven rain, or when snow melts. A leak that appears only in driving rain may point to a different source, sometimes a wall or parapet rather than the roof, than one that appears after every shower, and the timing is one of the most useful things a manager can tell a contractor.

Look at the underside of the deck where it is visible, and at the tops of exterior walls. Water can travel along the deck and the structure before it drips, so the stain marks where the water came out, not necessarily where it went in.

What to record

The record we ask for when you call

Photographs.
A wide shot of each roof area, close-ups of every defect, every drain, and the stains inside, each with its location.
A sketch.
A simple plan of the roof with the drains, the equipment, and each defect and ponding area marked.
The history.
The roof’s age and type if they are known, past repairs and who made them, and any earlier reports or drawings.
The weather.
When it last rained and how heavily, so standing water can be read against it.
How the roof is used.
Equipment that is serviced from the roof, routes crews walk, and any terrace or seating area.

Reading the results

What the findings mean

Local defects on a roof that is dry, bonded and drains, such as a few open laps, a cracked flashing or a blocked drain, are repair work, and they may make the roof a candidate for restoration under a new membrane. Widespread blisters, soft spots underfoot or roofing that has lost its bond across the field point towards replacement, or at least towards a closer investigation. Our article on restoring or replacing a commercial flat roof sets out how that decision is made.

Ponding is its own finding: the drainage is corrected before any coating goes on. Wear along the routes crews walk means those areas need a traffic-rated surface. Any of these is worth photographing and sending before the next season of rain.

When to look

Make it routine

How often depends on the roof and how it is used. A practical routine is a walk-over in spring and autumn, and after a major storm or once heavy snow has melted, so that a blocked drain or an opened seam can be caught before the next storm finds it. Keep each record with the building’s maintenance file, so the next inspection can be read against the last.

If your inspection turns up something you want looked at, our flat roof coating and restoration service starts with an inspection and an adhesion test patch. The way the membrane itself is built is explained in our article on fabric-reinforced liquid roof membranes.

Questions we get asked

Flat roof inspection checklist: FAQs

How often should a flat roof be inspected?

It depends on the roof and how it is used. A practical routine is a walk-over in spring and autumn, and after a major storm or once heavy snow has melted, so that a blocked drain or an opened seam can be caught before the next storm finds it.

What counts as ponding on a flat roof?

Water that is still standing well after the rain has stopped. Dirt rings or growth on the roof show where it sits even when the roof is dry. A coating does not fix ponding, so the drainage is corrected first.

Should I patch a blister or a split myself?

A temporary patch can slow a leak, if roof access is safe for you. Tell your contractor what was used and where: the area is cleaned and repaired before the adhesion test patch, and the test patch confirms that the new membrane bonds to the roof, patched areas included.

What should I send a contractor after an inspection?

Photographs of each roof area, every defect, every drain and the stains inside; a simple sketch of the roof; its age, type and repair history if known; when it last rained; and how the roof is used.

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