Recognizing a drain that no longer drains
The drain is the part that all flat roof drainage depends on. A blocked drain gives three clues, and none of them requires climbing.
- a stain on the ceiling of the top-floor dwelling, near the drain pipe
- water running down the wall, below the overflow opening
- seen from a higher window, if there is one, a large pond around the drain whose level barely drops
A single one of these clues is reason enough to have us look at the roof. No one should push a rod or a handle into the drain. The clog may get packed tighter, or a joint further down may come apart.
When ice gets involved
During a winter thaw, the snow on the roof melts and the water runs toward the drain. If the top of the pipe has stayed cold, the water freezes there in thin layers that build up. An ice plug ends up closing the passage.
This ice is not broken with tools, and you do not go up to look at it. An impact can crack the drain body or puncture the membrane around it. The roofer has safer methods, steam for example. When the drain freezes every winter, ask us to find the cause.
Four parts, from the roof down
A roof drain is like a floor drain, only sturdier.
- The body. This metal or plastic bowl is set into the roof at its lowest point.
- The clamping ring. A ring clamps the membrane onto the body. The watertightness of the connection depends on this ring.
- The strainer. This dome or mesh basket sticks up above the surface. Water gets through, leaves stay behind.
- The pipe. This pipe runs through the building from top to bottom.
Why the mesh basket stays on
Without its strainer, a drain lets everything lying on a roof go down the pipe: leaves, twigs, a stray ball. The clog then forms far from the surface, where it is hard to reach.
Debris held at the surface is removed in a few minutes during a maintenance visit. A clog lodged in the pipe calls for a plumber. The strainer stays in place in every season.
Two visits a year
Drain care is part of the maintenance visits, in spring and fall. At each visit:
- We pick up what has collected around the strainer, especially once the leaves have fallen.
- We check that the strainer is not broken and we do not remove it.
- We examine the membrane around the drain, which must lie flat, with no wrinkle and no crack.
This is not the owner's work. The danger of falling is very real, even on a flat roof.
Frequently asked questions
How many times a year should a roof drain be cleaned?
A roof drain should be cleaned at least twice a year, in spring and fall. If tall trees surround the roof, an extra visit after the leaves fall can be useful.
Can boiling water or salt thaw a drain?
No, boiling water and salt are not ways to thaw a drain. You would first have to walk on an ice-covered roof, which is dangerous. If the plug holds, the hot water freezes again further down. De-icing products can also damage the membrane and the metals. This work calls for an equipped roofer, so write to us through the form.
Is it a job for the roofer or the plumber?
The roofer takes care of what is on the roof: strainer, drain body, connection with the membrane. The plumber steps in when the clog is in the pipe or when the pipe leaks inside the building.