Standing water on a flat roof is a sign something is wrong with its slope, its outlets or the deck beneath. Here is what causes it on Ridgeway garages and extensions.
Garage and extension roofs are common in Ridgeway, and many of them hold a puddle for days after rain. A little shallow water is not always a fault, but deep or lasting pools usually point to a cause worth fixing. Here is what to look for, and what it means.
Falls that are too shallow
A flat roof is not meant to be flat. It should slope gently towards an outlet or gutter so water runs off. If the falls are too slight, or have been lost through settlement, water collects in the lower patches. Some older garage roofs were built with barely any fall at all.
Extensions and garages in this part of Bristol often went up in different eras from the house itself, with different builders and different standards. A roof built a long time ago may never have had proper falls, while a newer one may have lost them when the deck settled. Both look the same from the pavement.
Blocked or badly placed outlets
Even good falls fail if the outlet is blocked by leaves, silt or moss, or sits higher than the roof surface. A gutter that is full or poorly set also backs water up. From the ground you may see overflow staining on a wall below the edge, which is a clue worth telling us.
- Leaves and silt blocking the outlet or gutter
- Outlets set slightly above the lowest part of the roof
- Gutters that have sagged and no longer drain
- Overflow marks on the wall below the roof edge
A deck that has sagged
If the boards or joists beneath have weakened, the roof sags, and water follows. Rot, past leaks or an overloaded roof can all do this. A low, soft or springy area when seen from inside, or a ceiling beneath that bows, tells us the deck itself needs to be looked at.
What standing water does
Water that sits for long periods ages the covering faster, finds weak joints and seams, and can freeze and lift edges. Algae, dirt and moss thrive in damp areas, which in turn hold more water. Over time, a pool becomes a leak, which is why we do not ignore it. Slow drainage also loads the roof, which is not a good thing for an older garage deck.
What we do about it
We check the falls, clear and test outlets, and look under the covering where we can. Sometimes a repair and clearing is enough; sometimes new tapered insulation or a corrected deck is needed to create falls. Where the roof is worn, we recommend a new covering laid to proper falls.
If the roof is otherwise sound, we may be able to cure pooling by clearing the outlet, resetting a gutter or adding a small tapered section. If the covering is worn or the deck is soft, we say so honestly, as covering over a pool is only a short-term answer and does not remove the cause.
Frequently Asked Questions
Is a small puddle a problem?
A thin film that dries soon after rain is common and not usually harmful. A deep pool that stays for days is a different matter. If it returns in the same place each time, it is worth having looked at.
Can pooling happen on a new flat roof?
Yes, if the falls were not built in, or the outlet was poorly set. A new roof should drain properly. If yours does not, we can look at what is causing it and what correcting it would involve.
Will clearing the gutter solve it?
Sometimes, if a blockage is the only cause. If the water stays after the outlet is clear, the falls or the deck are likely at fault. We check both so you do not clear the gutter and still have the problem.
Talk to our team about flat roofing in Ridgeway
Every roof is different — the fastest way to get an accurate answer is a quick chat with our team.