Pooling means the water has nowhere to go. The cause is usually the slope, a blocked outlet or a soft deck, and each one calls for a different fix.
A flat roof should shed water, even if it is almost level. When puddles sit there a day or more after rain, something is wrong. On Hanham's extensions, garages and porches, there are a handful of common reasons, and finding the right one decides whether you need a clean-out, a repair or something bigger.
Falls that are too shallow
Flat roofs are never truly flat. They are built with a slight fall towards a gutter or outlet. If the fall is too gentle, or the deck has dipped over time, water gathers in the low spots. Some older roofs were laid with almost no slope at all. Correcting this means altering the deck with firrings or new boards, not just patching the covering.
Blocked outlets and gutters
Leaves, moss, grit and debris can block a gully, outlet or gutter at the edge. The water backs up and spreads across the roof. This is the easiest cause to cure, but it is also a symptom. If the outlet clogs often, the roof may be sitting under trees, or the outlet may be too small for the area it drains.
- Leaves and silt blocking gullies and outlets.
- Gutters at the edge sagging or falling the wrong way.
- Outlets too small for the roof area.
- Trees close by dropping debris regularly.
A soft or sagging deck
Where water has been coming through for a while, the boards below weaken and sag. The sag then holds more water and the problem feeds itself. Pressing on a spongy patch tells us a good deal. If the deck is soft, the covering must come off and the damaged boards be replaced before a new surface is laid, otherwise the dip simply returns.
What pooling does to the covering
Standing water wears out any flat roof surface faster. Sun, frost and algae work on the same spots, and joints and seams soften or open. A pool near an upstand or a wall junction is especially risky. Where the covering is still sound and the cause is minor, we repair and clear. Where wear is widespread, replacing makes better sense.
- Seams and joints opening under standing water.
- Blisters and cracks forming in the low area.
- Moss and algae building up in the damp.
- Leaks showing in the ceiling below.
What to look at from indoors
Without going up, you can check the ceiling beneath the flat roof for new stains, bubbling paint or a damp smell, and look from an upstairs window for puddles after rain. Photos of the pool the morning after a shower help us. Please leave the roof itself to us, since flat roofs can be slippery and weak in places.
Frequently Asked Questions
Is a little puddle normal?
A shallow film that dries within a day is common and not a worry. Deep pools that stay for days are a problem. They load the roof, speed up wear and often point to poor falls or a blocked outlet.
Can pooling be fixed without replacing the roof?
Sometimes. If the cause is a blocked outlet or a small dip and the covering is still sound, a repair may do. Where the deck is soft or the fall is wrong across the roof, replacement is usually needed.
Does a pool always mean a leak?
Not always, but it raises the risk. Water standing on a covering finds any weakness over time. We check the roof and the ceiling below, and tell you whether it is already getting through.
Talk to our team about flat roofing in Hanham
Every roof is different — the fastest way to get an accurate answer is a quick chat with our team.