Signs you may need this
- Ponding water that sits on the roof for days after rain
- Blistering, cracking or splits in the surface
- Damp patches on the ceiling below, especially after heavy rain
- Edges lifting or trims that have come loose
- Roof is over 15 to 20 years old and made of traditional felt
Flat roofs that stay watertight
Flat roofs fail for a short list of reasons: age, standing water, poor detailing at the edges and upstands, and damage from foot traffic or debris. A good flat roof needs a sound deck, the right fall to drain water, a quality waterproof membrane and neat finishing at every edge and junction. The membrane is only as good as the details around it.
We repair small areas where that makes sense, and strip and replace the whole roof where the deck has gone or the covering is past saving.
Flat roof systems we fit
- EPDM rubber: a single-piece rubber membrane that is flexible, long lasting and low maintenance. A good choice for larger roofs because there are very few seams.
- GRP fibreglass: a seamless, rigid finish that is tough and neat, popular on extensions, balconies and dormers.
- Modern torch-on and cold-applied felt systems: multi-layer high-performance felt that is a good-value option when installed to a high standard.
We explain the strengths of each in plain terms and recommend what suits your roof's size, shape, use and budget.
What a proper replacement involves
- Strip the old covering and inspect the deck, replacing any wet or rotten boards.
- Add insulation to the current building regulations requirement where it applies, and lay new decking and firring pieces to create a proper fall to the gutter.
- Fit the waterproof membrane, with upstands, edge trims and drip details finished correctly.
- Replace or refit the gutter, fascias and any rooflights so they work with the new surface.
Why flat roofs leak so often
Most failures begin at the edges, around rooflights and pipes, or where the roof meets a wall. Ponding water speeds up the ageing of the surface. Cheap patch repairs over wet or blown areas tend to fail within a season or two, so we aim to repair what is actually wrong, or advise a replacement when that is the sound choice.
Maintaining a flat roof
Keep it clear of leaves and debris, make sure outlets are not blocked, and avoid walking on it with sharp or heavy loads. A quick check once or twice a year, especially after autumn leaf fall, catches problems early. If you would like us to look at it, we offer an inspection with photos.
Questions about flat roofs
How long does a flat roof last?
It depends heavily on the system and installation. Traditional felt roofs often need replacing after around 15 to 20 years, while good EPDM and GRP roofs are commonly expected to last considerably longer when fitted and maintained properly.
Can you repair my flat roof or does it need replacing?
If the leak is from a localised split, a failed joint or a poorly sealed upstand, a repair may be enough. If the deck is wet, the surface is crazed or blistered across a wide area, or it has been repaired repeatedly, replacement is usually the better value.
Why does water collect on my flat roof?
Often the roof was laid with too little fall, or the deck has dipped over time. Ponding is bad for the membrane. When we replace a roof we build in a fall so water drains away to the gutter.
Do you need planning permission for a flat roof replacement?
Replacing like with like generally does not need planning permission. Building regulations can apply, particularly to insulation when a roof is stripped and re-covered. We advise on what is likely to apply to your project.
Can I walk on my flat roof?
Not unless it is designed for it. Occasional light foot traffic for maintenance is usually fine, but regular use, furniture and planters can damage a membrane. If you want a roof terrace, tell us at the quote stage so we can specify it for the job.
Related advice
Where we work
We carry out flat roofs across Hampshire and the south of England, from our base in Farnborough to Aldershot, Fleet, Camberley, Farnham, Hook, Basingstoke, Guildford, Woking, Reading, Winchester, Andover, Alton, Southampton, Bournemouth, London. Not on the list? Call 07498170924 and we will tell you straight away.