Roofing Advice
Common Flat Roof Problems and How to Spot Them
Flat roofs need different maintenance to pitched roofs. Here's what to watch for and when to call a roofer.
Flat roofs are common on extensions, garages, outbuildings and some older properties in Ayrshire. They're generally more prone to water ingress than pitched roofs, but many problems can be caught early if you know what to look for.
Common Flat Roof Problems
Ponding water
Flat roofs should drain fully after rain. If water pools and sits for more than 48 hours after rainfall, there's a drainage problem. Standing water accelerates deterioration and adds significant weight to the structure.
Blistering or bubbling surface
Blisters in the roof surface are caused by moisture or air trapped under the felt or membrane during installation. Small blisters can be repaired; widespread blistering often means the whole surface needs replacing.
Cracks and splits
Thermal movement — the roof expanding and contracting with temperature changes — eventually causes cracks. Scotland's variable climate means this is common. Any crack is a potential water entry point.
Failing or missing flashing
Where a flat roof meets a wall, parapet or upstand, it's sealed with flashing. If this peels away or cracks, water can run down the wall cavity. This is one of the most common sources of flat roof leaks.
Blocked outlets and drains
Flat roofs drain via outlets or internal drains. Leaves, debris and dirt can block these, causing water to back up across the roof surface. Regular clearing prevents bigger problems.
Deteriorated felt
Older felt flat roofs naturally deteriorate over time. Signs include cracking, shrinkage pulling away from edges, exposed chippings, and a generally worn appearance. Felt roofs typically have a shorter lifespan than modern alternatives.
Flat Roof Materials
Different flat roof materials have different characteristics and lifespans:
- Felt (built-up roofing): Traditional and relatively inexpensive. Typically lasts 10-15 years.
- EPDM rubber: Durable and well-suited to wet climates. Lasts 25+ years when properly installed.
- GRP fibreglass: Hard-wearing, seamless finish. Good for complex shapes. Long lifespan.
- Torch-on felt: Improved version of traditional felt. Better durability than standard felt.
When to Call a Roofer
Call a professional roofer if you notice:
- Any internal water ingress or damp associated with a flat roof
- Standing water that hasn't drained within two days of rain
- Visible splits, cracks or tears in the surface
- Lifting or missing flashing
- A roof that's 15+ years old and showing its age