There is no single best flat roofing material, only the best match for your extension. Here is how single-ply rubber, fibreglass and felt compare and what steers our advice.
Many homes in Bradley Stoke have had a kitchen extension, garage conversion or porch added to the original build, and those additions often finish in a flat roof. The material you pick matters, but the deck, falls and edge details under it matter just as much. A good covering laid on a poor base will still fail.
Single-ply rubber
EPDM is a large rubber sheet laid with few joins, which suits a plain rectangular extension roof well. With fewer seams there are fewer places for water to find. It copes with movement and is quick to lay. Detailing at corners, pipes and upstands still needs care, and we form those properly rather than relying on adhesive alone.
Fibreglass
GRP is laid in liquid form and sets hard, giving a seamless surface that follows awkward shapes. It suits roofs with bay tops, corners or lots of penetrations. It needs a firm, dry deck and clean edge trims, and it is not the best choice where the structure moves a great deal. We check the deck before suggesting it.
Felt systems
Modern felt systems are built up in layers and are a familiar, practical choice for garages, porches and small roofs. They suit a budget-minded job where the roof is simple. Seams and laps are the weak points, so the quality of the workmanship at the joins counts for a lot.
What decides the choice
We weigh the roof size, its shape, how much it is walked on, how it drains and what the deck is made of. We also look at insulation and falls, since an extension roof that holds water will wear any covering out early. The right answer depends on those details, not a catalogue.
A roof that joins a house wall also needs proper upstands and flashing, which is where many extension roofs first fail. We check that junction closely, because it is a detail that shows no problem at all until the first heavy rain finds it.
- Size and shape of the roof
- Condition and type of the deck
- Insulation and how water drains away
- How much foot traffic the roof gets
Questions to put to any installer
Ask what happens to the old covering and the deck beneath it, how the edges and upstands will be finished, and how the falls are set so water runs off. Ask for the material named in writing. Flat roof work may need planning or Building Regulations checks, and we advise before work starts.
Frequently Asked Questions
Is a flat roof extension a bad idea in our weather?
No. A well-built flat roof with correct falls, sound edges and good upstands performs well. Problems come from poor detailing or a neglected roof, not from the flat form itself. A yearly look keeps small faults from growing.
Can I put a new covering over the old one?
Sometimes, but only if the deck beneath is dry and sound. We check for soft spots and trapped moisture first. Where the old layers are damp or failing, stripping back to the deck gives a better base for whatever material goes on.
Does the material affect insulation?
The covering itself is only part of it. Warmth comes from the insulation layer in the roof build-up, which has to be thought about at the same time. Replacing the covering is a sensible moment to improve it, if the structure allows.
Talk to our team about flat roofing in Bradley Stoke
Every roof is different — the fastest way to get an accurate answer is a quick chat with our team.