How it is built
The centrepiece of flat roof drainage, a roof drain looks like a floor drain, only sturdier. It has four parts.
- The body. This is a metal or plastic bowl set into the roof at the lowest point.
- The clamping ring. This ring presses the membrane against the drain body and makes the joint watertight.
- The strainer. This basket or mesh dome sticks up from the roof. The strainer lets water through and holds back leaves.
- The pipe. This is the pipe that runs down through the building.
What the strainer is for
Without a strainer, leaves, branches and stray balls go down the pipe and block it where no one can easily reach them. A clog at the surface is removed in a few minutes during maintenance. A clog in the pipe needs a plumber.
The strainer stays in place at all times.
Maintenance
Drain maintenance happens on the roof. It is our job, not yours. Ask for one visit in spring and another in fall. Here is what we do.
- We clear debris around the strainer, especially after the leaves fall.
- We check that the strainer is intact and leave it in place.
- We look at the membrane around the drain, which must lie flat, without wrinkles or cracks.
Do not go up to do it yourself. The risk of falling is real.
Signs of a clogged drain
The signs of a clogged drain can be seen without going up on the roof.
- a stain on the top-floor ceiling, near the drain pipe
- water running down the wall under an overflow scupper
- a wide puddle centred on the drain that drops very slowly, visible from a higher window
If you see one of these signs, write to us through the form. Nothing should be pushed into the drain with a stick. It can pack the clog tighter or undo a connection.
The frozen drain
In winter, during a thaw, meltwater reaches the drain. If the top of the pipe is cold, the water freezes there layer by layer until it forms a plug of ice.
Do not go up to break the ice. A blow from a tool can crack the drain body or pierce the membrane around it. Write to us. Thawing a drain is a roofer's job, done with safer means than a tool, such as steam. If the freezing comes back every winter, ask us to look for the cause.
Frequently asked questions
How often should a roof drain be cleaned?
A roof drain should be cleaned at least twice a year, in spring and in fall. A roof surrounded by tall trees may need an extra visit after the leaves fall.
Can I pour hot water or salt into a frozen drain?
No. You would first have to climb onto an icy roof, and that is dangerous. Hot water refreezes lower down if the plug does not give way, and de-icing products can damage the membrane and metal parts. Write to us. Thawing a drain is a roofer's job.
Who should I call, a roofer or a plumber?
For anything on the roof, meaning the strainer, the drain body and its connection to the membrane, write to us. For a clog in the pipe or a leak from the pipe inside, call a plumber.