Get the water off the roof
Roof drains and scuppers
A flat roof works only if water has somewhere to go. When a drain blocks, cracks or sits above the roof surface, the roof becomes a shallow pool.
- Clearing and repair
- Interior drains and scuppers
- Starting price listed
Two kinds of outlet
Interior drains sit in the field of the roof and send water down pipes inside the building. Scuppers are openings through a parapet wall that let water spill out the side, often into a downspout. Both do the same job, and both fail in similar ways.
Because snow melts and rain pools, drains do the most work in spring and in summer storms. A blocked one leaves that water, and its weight, sitting on a roof that was not built to hold it.
What goes wrong
Blockage
Leaves, seeds, grit and plastic gather at the strainer. See clogged drains.
Drain set too high
If the drain body sits above the surface, water stays around it. This can be fixed when the roof is re-done, and it often explains ponding.
Cracked or loose clamping ring
The seal between the drain and the membrane opens, and water enters beside the pipe.
Frozen pipes and ice
Water in the drain line freezes and splits it or backs up. See ice and snow damage.
Scupper too small or too high
Water cannot leave fast enough, or leaves only after depth builds on the roof.
No overflow route
If a drain blocks, there must be a second place for water to go. Many older roofs have none.
What the service involves
Look and test
Check strainers, flow, pipe condition and how the roof slopes toward each drain.
Clear
Remove debris and flush the line where accessible.
Repair or replace
New strainers, re-sealed clamping rings, a re-flashed drain body or a lowered sump if the membrane is open.
Improve flow
Where water still sits, we propose tapered insulation or an added drain.
Tell you what else
Notes on interior pipes, which are a plumber's job, and overflow arrangements.
Drain and scupper pricing
| Item | Starting price |
|---|---|
| Roof drain or scupper repair | from $800 per drain |
| Maintenance visit (drains, seams, flashings, photos) | from $295 per visit |
| Small leak repair (patch, seam or puncture) | from $350 per repair |
Starting prices in CAD before 13% HST, based on typical Ontario contractor rates (mostly Toronto and the GTA). The final price depends on roof size, access, the layers to remove, the membrane, drains and flashings, and is confirmed in your written quote.
New drains, cutting through the deck and interior plumbing work are quoted separately.
Questions about roof drains
How often should drains be cleared?
At least twice a year, and more often if trees overhang the roof. The maintenance checklist lists the dates to remember.
Do condos have to keep drains clear?
Responsibility depends on your declaration and by-laws. Boards usually include drain clearing in the roof maintenance plan. See condo roof planning.
My roof has no drains, only an edge. Is that a problem?
Not necessarily. Edge-drained roofs rely on slope toward the edge and on gutters or downspouts. We check that water actually reaches them.
Can you add a drain to an existing roof?
Often, if the structure allows a new opening and there is a place for the pipe to go. It needs an assessment of the deck and the interior route first.
Leak, damage or an old flat roof?
Send a few details and photos. We reply by email with next steps and a written quote.