Flat & low-slope roofing
Flat roofs that actually drain
Modern Toronto architecture loves a flat roof. Toronto weather does not. Ponding water, ice lensing at drains and UV-baked membranes are the usual failures; every one of them is a design problem, and every one of them we design out.
Overview
Systems for houses, not warehouses
Most flat-roof contractors in the GTA are commercial roofers squeezing houses in between warehouse jobs. We treat a flat roof on a Forest Hill modern or a Leaside addition as part of the architecture: drainage designed with tapered insulation, terminations in metal rather than a bead of mastic, and a finish chosen because somebody looks at it from the bedroom window.
Our primary system is two-ply SBS modified bitumen (Soprema or IKO), torch-applied or self-adhered, with a granulated or reflective cap sheet. For roof terraces we install inverted assemblies with pedestal pavers; for large planes we offer 60-mil TPO and fully adhered EPDM.
Toronto fit
Where flat roofs fail in Toronto, and how we prevent it
Ponding & ice lensing
Tapered polyiso insulation gives a true 2% slope to every drain. Water leaves within 48 hours, so it can never freeze in place and lever the membrane.
Drain freeze-up
Insulated drain bowls, heated drain leads where needed, and secondary scuppers as overflow so a January freeze never floods the roof.
UV & heat
Reflective or granulated cap sheets rated for 70 °C surface temperatures; membranes carry a 20-year manufacturer system warranty, not a material-only warranty.
Scope
What a Ross the Roofer flat roof includes
- Removal to the deck; replacement of any damaged sheathing
- Vapour retarder and tapered polyiso insulation to R-31 or better (Ontario Building Code SB-12)
- Two-ply SBS modified bitumen, 60-mil TPO or 90-mil fully adhered EPDM
- Prefinished metal or copper parapet caps, drip edges and counter-flashings
- Insulated drains, overflow scuppers and leaf guards
- Optional pedestal-paver terrace, green roof tray system or architectural ballast
- Infrared moisture scan of the existing roof before scoping, so nothing is hidden
Questions
Flat roofing, answered
Can I use my flat roof as a terrace?
Yes, with the right assembly. An inverted roof with pedestal pavers protects the membrane from foot traffic and UV. We coordinate with your architect on guards, drainage and structural loading.
Should I choose modified bitumen, TPO or EPDM?
For most Toronto homes, two-ply modified bitumen offers the best combination of puncture resistance, redundancy and repairability in freeze-thaw. TPO suits large uninterrupted planes; EPDM is excellent where the roof will be covered by pavers or a green roof.
My flat roof holds water after rain. Is that normal?
No. Ponding that lasts more than 48 hours accelerates membrane ageing and is the leading cause of winter failure. It can usually be corrected with tapered insulation or additional drainage during a re-roof.
Begin
Let's talk about your roof
A consultation with a project director is complimentary and without obligation. We'll walk the property, survey the roof by drone and tell you honestly what it needs.