What Are The Most Common Flat Roof Problems I See in Sussex?
After 18 years on roofs across Brighton, Hove, and Worthing, I’ve seen it all. Flat roofs have a bad reputation, but it’s usually because they were either installed poorly or have simply reached the end of their life. The damp, windy coastal weather here in Sussex really puts them to the test. Here are the top five issues I get called out for, and my blunt, honest advice on what’s really going on.
1. The dreaded ‘blistering’ and ‘bubbling’
What you see: Large, squishy bubbles or blisters appearing on the surface of your felt roof, especially after a sunny day.
The hard truth: This is trapped moisture or air underneath the top layer of felt. As the sun heats the roof, this trapped pocket expands, creating a bubble. It’s a sign that water has got between the layers, meaning the bond is failing. Each blister is a potential leak waiting to happen.
Your DIY temptation: You might think about popping it and sealing it. Don’t. You’ll likely just create a hole that lets even more water in.
How I fix it properly: The only real fix is to cut out the blistered section entirely, ensure the timber decking underneath is bone dry and sound, and then apply a new, professionally torched-on patch with proper adhesion. If the blistering is widespread, it’s a clear sign you need a full replacement. A new surface is the only way to guarantee a long-term solution, which is central to my flat roof repair and replacement services.
2. Pooling or ‘ponding’ water
What you see: A persistent puddle of water on your roof that doesn’t drain away 48 hours after it rains.
The hard truth: Water is heavy. That constant weight is stressing the roof structure and accelerating the breakdown of the roofing material. It’s almost always caused by an incorrect fall (the slope of the roof) or a sagging roof deck. It can also be caused by blocked outlets.
Your DIY temptation: Trying to sweep it off or, even worse, pouring some liquid sealant or bitumen into the puddle to ‘fill it in’. This just adds more weight and makes the problem worse.
How I fix it properly: First, I check your drains and outlets. If they’re clear, the problem is structural. I need to assess the roof deck. Sometimes the solution involves installing tapered insulation boards or timber ‘firrings’ to create a proper slope before re-covering the roof. Ignoring ponding water is one of the fastest ways to guarantee a roof collapse or a major leak.
3. Cracks, splits, and tears in the felt
What you see: Obvious cracks or splits in the roofing material, often around the edges or on seams.
The hard truth: This is your roof’s final cry for help. Years of UV exposure and temperature changes make old felt brittle. Once a crack opens, it’s a direct channel for water into your home. This is how most urgent leaks start.
Your DIY temptation: Get a tin of Acropol or some roofing silicone and paint over the crack. Honestly, for a genuine emergency, this isn’t a terrible short-term fix to get you through a weekend storm. It can work for a few weeks or months. But it’s a plaster on a gaping wound. The material around the crack is just as old and brittle, and another will appear soon.
How I fix it properly: If I catch it early and the rest of the roof is sound, a professional heat-welded patch can seal a small split. However, 9 times out of 10, visible cracks mean the entire roof covering has failed. It’s time for a new one. If you’ve got water dripping through your ceiling right now, you need an emergency roof leak repair to stop the immediate damage.
4. Failed or leaking lead flashing
What you see: Damp patches on your internal walls, usually right where the flat roof meets the house wall.
The hard truth: The flashing is the waterproof seal between your roof and a vertical wall (like the side of your house or a chimney). When this fails, water runs straight down the wall and into your property. It’s one of the most common and damaging types of leaks.
Your DIY temptation: Squirting a load of silicone along the join. This almost never works. The surfaces are often dusty, damp, and the silicone just peels away after a few weeks, trapping moisture behind it.
How I fix it properly: There are no shortcuts here. I remove the old, failed flashing, grind out the mortar joint in the brickwork, and install new, correctly shaped lead flashing, securing it properly into the brickwork and dressing it down onto the roof. It’s a skilled job, and doing it wrong is a waste of time and money. My work on lead flashing repairs is built to last decades.
5. Moss, algae, and even plants growing on the roof
What you see: A green carpet of moss or even small weeds sprouting from your flat roof, particularly common on garage roofs.
The hard truth: This is not just a cosmetic issue. Moss and plants hold moisture against the roof surface constantly, which speeds up its decay. Their tiny root systems will work their way into any small imperfection, widening them into cracks that will eventually leak.
Your DIY temptation: Scraping it off with a wire brush or a shovel. You are very likely to gouge and tear the old, fragile roofing felt, causing a leak you didn’t have before.
How I fix it properly: The vegetation needs to be killed with a suitable treatment, then gently removed. But the key is to ask *why* it was growing there in the first place. It indicates the surface is old, porous, and retaining moisture. It’s often the first sign that your garage flat roof is nearing the end of its life.
Tired of Patching? Here’s the Real Fix.
Look, I understand the temptation to go for the quick, cheap fix. But I’ve been called back to too many jobs where a homeowner has spent a fortune on temporary patches over the years when a proper replacement would have saved them money and stress in the long run. My approach is simple: I give you a fixed-price quote so there are no surprises. I give you an instant online estimate to start. When I do the job, you get access to a private client portal with daily photo updates, so you see the progress for yourself. If you’re seeing any of the issues above on your roof in Brighton or Worthing, stop worrying and get a straight answer. Book a free, no-obligation roof inspection and I’ll tell you exactly what you’re dealing with.