Flat roofing · A focused guide
What should I record when water remains on a flat roof?
Published by Big Ben Roofing Ltd
Record where the water remains and how its visible extent changes after rainfall, using only a safe existing viewpoint. Standing water raises a drainage question but does not identify the cause by itself. Outlets, roof geometry and the supporting deck may need different checks. Ask the assessor to explain the findings and whether the proposal addresses drainage as well as the covering. Do not walk onto the roof to measure the pool or attempt to release water yourself.
Give the observation a time and location
An image taken immediately after rain has a different context from one taken later in a dry interval. Include the approximate time, the nearby roof edge or rooflight and any visible outlet. State when the view is incomplete. Avoid estimating depth from a reflection or assuming that a darker patch is always water; the record should describe what is actually visible.
Ask what would change the drainage route
Bauder identifies several possible reasons for poor drainage, including design and deck-related issues. A professional proposal should explain the relevant findings for this roof rather than select a remedy from a photograph. If renewal is planned, ask how retained levels, outlets and adjoining details constrain the options, and whether the quoted work includes a drainage improvement or only a new surface.
Useful details to record
- Record the time since rain and the visible area.
- Locate nearby outlets and roof openings in the image.
- State which parts cannot be seen safely.
- Ask whether drainage changes are included in the proposal.
Use information already available from indoors or ground level. Do not climb onto the roof or disturb materials to complete this checklist.
Will replacing the membrane automatically remove a low spot?
A new waterproof covering does not itself establish a new roof shape or outlet arrangement. Ask what causes the low area and which parts of the proposed build-up address it, including any limits imposed by the existing roof and adjoining details.
Background reading
General guidance helps frame the questions. The cause, suitable materials and scope depend on inspection of the particular roof.
Related questions
How should a suspected blocked flat-roof outlet be assessed?
Report a visible obstruction and ask how the outlet, connected pipework and surrounding roof area will be included in the proposed work.
Why should new roof drainage be planned before the covering is fitted?
Coordinate outlets, gutters and connected rainwater routes early so a new roof specification includes how water leaves the building.
Discuss what you have noticed
Include your postcode, the affected roof section and when the concern appears. The team will review the enquiry and confirm the next step, scope and availability.
Request a roofing assessment