Brandon Roofers explains exactly what happens during a flat roof replacement in Thetford, from the initial inspection through to clearing the site at the end.
A flat roof replacement is not a complicated job when done properly, but the quality of each stage directly affects how long the finished roof performs. Understanding what should happen - and in what order - means you can ask the right questions when speaking to roofers and spot a quote that has cut corners before you commit to it.
Below is a straightforward account of how a flat roof replacement should run on a typical domestic property.
Before any price is agreed, a roofer should inspect the existing roof properly. That means walking the surface where it is safe to do so, checking the falls towards the outlet, examining every flashing and edge detail, and pressing the deck to check for softness or delamination. Internal signs of damp - staining on ceilings, peeling paint, soft plasterboard - should also be noted.
A roofer who quotes from the ground or from a photograph alone is guessing at the deck condition. The deck is the part most likely to hold hidden costs, and it cannot be fully assessed without getting on the roof. Ask whether the inspection price is absorbed into the job cost if you proceed - most roofers work this way, but it is worth confirming.
The existing membrane and any insulation board beneath it are stripped back to expose the deck. On older properties this often means removing several layers of felt that have been built up over decades of patch repairs. All stripped material goes into a skip or is bagged for disposal - the site around the property should be protected with boards or sheeting before work starts to prevent debris falling onto glazing, gutters or garden areas.
Once the surface is stripped, the deck is inspected again in detail. What looked sound from above sometimes reveals soft sections or delaminated chipboard once the weight of the old felt is removed. Any damaged decking is cut back to the nearest joist and replaced with exterior-grade plywood before the build-up begins. This is not optional - a new membrane laid over a soft deck will fail within a few years.
The roof outlet - the point where water drains away - should be checked as a matter of course during a replacement. The outlet should sit at the lowest point of the roof, which means the deck needs adequate fall towards it. The standard minimum fall for a flat roof is 1:80, or roughly 12mm of drop for every metre of run. Where falls are insufficient, tapered insulation boards can be used to create the correct slope without raising the overall height of the roof significantly.
Outlets that are corroded, blocked or positioned incorrectly should be replaced or relocated at this stage. Fitting a new membrane over a faulty outlet defeats the purpose of the job.
A modern warm roof build-up on a domestic flat roof typically runs as follows:
Each layer is fixed or bonded correctly before the next goes down. On an EPDM installation, the membrane is rolled out across the deck, bonded fully using contact adhesive, and then trimmed and dressed into all upstands and edge trims. The bond to the deck and to every upstand is critical - a membrane that has lifted away from the deck at any point will trap water and fail at that location.
Flashings are fitted once the membrane is in place. Where the roof meets a wall or parapet, lead is cut and dressed to overlap the membrane below and tuck into a raked mortar joint above. The mortar joint is then re-pointed to seal the flashing in place. Edge trims at the perimeter of the roof are fixed before the membrane is turned up and bonded to them.
Any rooflights, pipes or other penetrations through the membrane are sealed using compatible collars or flashing patches. These details take time to do properly and are the areas most often skimped on by roofers working too quickly. A sound flashing should not flex or lift when pressed by hand.
Once the membrane is down, water should be run across the surface - or the roof checked after rain - to confirm that it drains fully to the outlet with no low spots where water can collect. If ponding water remains after 48 hours, the falls need attention before the job is signed off.
At the end of the job, all stripped material, packaging and debris should be removed from site. Gutters adjacent to the work area should be cleared of any grit or off-cuts that have dropped in. You should be able to walk around the property and inspect the finished roof from ladder height if you wish - a roofer who is unhappy with this inspection is a roofer worth questioning.
Ask for a brief written record of what was done, what decking was replaced and what materials were used. This information is useful if you sell the property or need follow-up work in future.
We cover Thetford and the surrounding area from our base in nearby Brandon. If you have a flat roof that needs replacing or repairing, call us to arrange a proper inspection - not a quote based on a glance from the pavement.
No obligation · We usually respond within 2 hours
Storm damage, active leak, damaged ridge - we aim to be on-site within 24 hours.
