Where is the property?
Give your postcode and say whether the roof is over an extension, a terrace, a garage or part of a block. Mention any shared access.
Roofing advice for homeowners
Leaking Flat Roof? Causes, Repairs & Next Steps
Understand what may be causing a flat-roof leak, when a repair or renewal needs consideration, and what to check before agreeing work. Get practical guidance and request a free written roofing quotation.
Emergency calls answered 24/7. Attendance, safe access and any charge are agreed by phone.
Can a leaking flat roof be repaired?
Sometimes. A local defect may suit a targeted repair if the surrounding roof is sound. Wider deterioration, an unsuitable base or several failed details may need more extensive work. The cause and condition should be assessed before choosing a patch, an overlay or a full renewal.
Ask about a flat-roof repair quotation ↗Help us understand the leak
Four details to have ready when you call.
What is happening now?
Explain whether water is actively coming in, where it appears indoors and whether any rooms or electrical fittings are affected.
When does it happen?
Tell us whether it follows prolonged rain, wind from a particular direction or every shower. Mention when you first noticed it.
What has been done before?
Describe previous patches or roof work and any existing report. Only take photographs from a safe position; do not climb onto the roof.
Keep clear of unstable ceilings and affected electrics. An online form does not book an emergency visit; call to discuss an active leak.
By Avent Roofing · Homeowner guidance · Updated 21 October 2026
Record what you can see safely
Note which room is affected and when water appears. Does it happen during every shower, prolonged rain or rain from one direction? Photographs of the internal staining and safely visible roof areas can help. Keep clear of unstable ceilings or affected electrics and seek appropriate urgent help if the situation is unsafe. Do not climb onto a wet roof to investigate.
Why is my flat roof leaking?
A flat-roof leak can involve the covering, a junction or drainage details. Water can travel within the roof construction before it appears indoors. A patch directly above the visible stain may not address the entry point. A roofer may need to consider the waterproofing surface, outlets, rooflight upstands, wall junctions and penetrations together. Explain any recent work or previous attempts to stop the leak.
Why should I mention standing water and drainage?
If you can see water remaining on the roof from a safe vantage point, tell the roofer where it collects. Drainage condition and roof falls can affect the proposed remedy. A new coating alone does not establish that the underlying construction or drainage problem has been resolved. Avoid assuming that all visible water means the same defect.
Ask about the base before an overlay
An overlay depends on the existing roof being suitable for the specified system. Trapped moisture, an unsound deck or incompatible materials can change the recommendation. Ask what was assessed, what remains concealed and whether further investigation is required. Where stripping is needed, the quotation should explain the proposed replacement build-up.
Arrange the right next step
For an active leak, call with the postcode and explain the urgency. Availability, safe access and any attendance charge should be agreed before a visit. For planned work, request a free roofing quotation. If you need a written assessment of the whole roof, ask about a separate condition survey and its scope.
What should an assessment consider?
A useful assessment looks at more than the visible waterproofing. Relevant details can include the joins to walls, rooflights, drainage outlets, roof edges and signs of moisture within the roof. Tell the roofer which areas were inaccessible during any earlier visit.
Drone images can help show visible external details, but they do not reveal every concealed layer. Avent’s paid roof surveys combine internal and external checks, drone use where appropriate and moisture readings within an agreed scope, with a detailed written report.
Can the existing roof be coated over?
That needs an assessment. The proposed system must be compatible with its base, and the condition of the existing layers matters. Ask what checks support an overlay and whether any areas need removal or repair first. The Liquid Roofing and Waterproofing Association explains roofing overlays; the specification must still suit the individual roof.
Will a patch solve a recurring leak?
It may, if the fault is local and the repair addresses its cause. A recurring stain can also mean the entry point has not been found or that more than one detail needs attention. Ask what the repair is intended to resolve and what remains uncertain. Our repair or replacement guide helps you compare the next steps.
What happens after an urgent visit?
Ask whether the proposed work is a temporary measure or a lasting repair, and what follow-up is needed. For planned renewal, use our quotation checklist to check the preparation, drainage details, access and exclusions.
What affects the cost of a flat-roof repair?
The roof area, access and the work needed at outlets, rooflights and wall junctions all affect the quotation. A local repair and a renewal involving removal of existing layers are different scopes. Concealed damage or moisture may require further investigation before the extent of work can be confirmed.
Ask for a written quotation identifying the roof area, preparation, proposed materials, access, exclusions and how any additional work will be agreed. Avent’s roofing quotations are free; a formal condition survey and written report is a separate paid service. See our roofing quotation checklist when comparing proposals.
How Avent can help
Avent project · Mayfair
Water ingress from a balcony into an office below
At this Mayfair property, water ingress from the balcony was affecting the office below. Avent renewed the balcony and added an anti-slip finish.
A balcony, terrace and other flat-roof area can have different requirements for waterproofing and use. This photograph records one completed job; the appropriate work for your roof depends on its assessment.
Discuss your leaking flat roof ↗
See the Mayfair project photograph in detail ↗
For another example, see the before-and-after liquid roof renewal in Golders Green.
Start with a conversation
Get a free quotation for your roofing work.
Tell us the property’s postcode, where water appears and any previous repairs. We’ll discuss the assessment needed for a written roofing quotation. Sending the form does not book a visit or commit you to work.
Speak to the team020 8485 9967
Email your enquiryinfo@aventroofing.co.uk
Tell us about your roof
Your postcode and a few details are all we need to start.