A lumbered slope framed over a flat roof deck to move water toward the drains, with a two-ply system installed over it.
Lumbered Slope Build and Two-Ply System, Toronto
Open Lumbered Slope Build and Two-Ply System, Toronto
Flat roofing in Oshawa, Durham Region
Oshawa Flat Roof Repair, Installation, and Replacement
We repair, replace and install flat roofs across Oshawa in Durham Region. Free no-obligation quotes, warrantied workmanship and 24/7 emergency response.
What you get from Flat Roofs Toronto
24/7 Emergency Response
Leaks do not wait for business hours.
Free No-Obligation Quotes
Scope, system and number, in writing, first.
Manufacturer & Workmanship Warranties
The materials and the installation are both covered.
Flat Roofs Only
Low-slope work is the whole business, not a sideline.
Flat Roofs in Oshawa, Up Close
Oshawa carries the roofing legacy of a manufacturing town. Industrial and supplier buildings hold big low slope fields, some of them still on built up tar and gravel under a patch history nobody kept a record of. The older downtown blocks are two and three storey commercial buildings with flat roofs sitting behind parapets, and those parapets, along with the party walls between attached buildings, are where the water actually gets in. There is also a deep stock of older housing carrying flat rear wings and porch decks, plus campus and institutional buildings with mechanically loaded decks. Age, not design, is the common thread across all of it.
What We Do on Oshawa Roofs
Oshawa jobs run from parapet and party wall flashing rebuilds on a downtown block to full tear off of an old gravel roof on an industrial building. We also do leak tracing, seam and membrane repair, drain and scupper replacement, skylight flashing, roof hatch details, and 24/7 emergency flat roof repair.
Where Oshawa Sits in Our Service Area
The plan opens on this part of the GTA. Every city we cover in the region is in the legend beside it.
Select a region on the plan
Systems That Suit Oshawa
Old built up tar and gravel comes off and is normally replaced with two ply SBS modified bitumen on smaller downtown roofs, where parapet detailing matters, or TPO on large industrial fields. Cold applied liquid systems suit tight awkward areas around old chimneys and party walls. Compare every flat roofing system.
Two Ply
Modified Bitumen
Torch-applied or self-adhered SBS in two plies, with a granule-surfaced cap. The default on Toronto houses because it handles tight perimeters, curbs and wall terminations without a wide sheet.
- 15 to 20 year service life
- Redundant second ply
- Repairs patch cleanly
Torch Free
Cold-Ply
The same two-ply build assembled in cold adhesive rather than with an open flame. It is what we specify over occupied buildings, beside vinyl siding and anywhere a torch is not welcome.
- No open flame on the roof
- Low odour on occupied buildings
- Granule-surfaced cap
Single Ply
TPO and PVC
Hot-air welded thermoplastic sheet, laid in wide rolls with far fewer seams. It suits large commercial fields, and the reflective white surface keeps a warehouse roof cooler through a Toronto summer.
- Welded rather than glued seams
- Reflective white surface
- Fast over large areas
Rubber
EPDM
A synthetic rubber membrane that stays flexible through freeze thaw movement and takes ponding better than most. Common on garages, additions and small commercial decks.
- Flexible in cold weather
- Tolerates standing water
- Simple to detail and repair
Local Considerations in Oshawa
The conditions that decide how long a roof here lasts, and what we detail differently because of them.
- Attached downtown buildings share party walls, so a failed flashing on one roof turns into a stain on the top floor next door, and repairs often have to be coordinated across both.
- Parapets take weather on two faces and move differently from the deck, which is why cap flashing and the membrane upturn behind it fail before the field does.
- Industrial fields that have been patched repeatedly hide wet insulation, and a core cut is the only honest way to find out how much of the assembly is still dry.
Recent Flat Roofing Projects
Real jobs photographed on site by the crews who did them.
Flat Roof Application Detail, Toronto
A detail from a flat roof membrane application, showing the finished surface of the system.
Attic Inspection and Blown-In Insulation, Toronto
Inspection of a flat roof attic space followed by blown-in insulation. The cavity is checked before any insulation is added.
Flat Roofing Advice
What we have written about keeping a low-slope roof watertight in this climate.
Flat Roof Replacement in Oshawa: Costs and Options
Flat roof replacement in Oshawa: 2026 cost ranges, membrane options, insulation and drainage rules, permit basics, and how to choose the right contractor.
Flat Roofing in Oshawa: Best Systems for 2026
Flat roofing in Oshawa for 2026: compare TPO, EPDM, PVC and modified bitumen, installed costs per square foot, code rules, permits and maintenance advice.
Commercial Flat Roofing in Oshawa: An Owner Guide
Commercial flat roofing in Oshawa: 2026 costs, membrane options, permits, drainage and maintenance guidance for plaza, office and industrial building owners.
Oshawa Flat Roofing Questions
Straight answers to what people ask us about a roof on this street.
My Oshawa building has a tar and gravel roof. Does all of it have to come off?
Usually yes. Gravel surfaced built up roofing cannot be reliably overlaid, and on Oshawa buildings of that age there is often a second layer under it already. We core the assembly first to see what is there and how wet the insulation has gone. If the deck is sound, tear off and a new membrane over fresh insulation is the honest fix and gives you a clean start.
Can you fix a leak coming through a parapet on an Oshawa storefront?
That is one of the most common calls we get in Oshawa. Water enters through open cap flashing joints, cracked masonry or a failed membrane upturn behind the parapet, then runs down inside the wall and shows up metres from the actual entry. We open the detail, rebuild the upturn and counterflashing, and seal the cap properly rather than smearing sealant over the symptom.
Do you offer emergency flat roof repair in Oshawa overnight and on weekends?
Yes, 24/7. When a seam opens in a storm or a drain backs up and water is coming into an Oshawa building, we attend, find the entry, clear or bypass the blocked outlet and dry in the breach with material compatible with the existing membrane. We return in working conditions to complete the permanent repair and check the surrounding area for wet insulation.
What does a commercial flat roof replacement cost in Oshawa?
Replacement generally sits around $8 to $15 per square foot. On an Oshawa commercial building the number moves with how many layers come off, disposal, deck condition, the insulation thickness required, and how much curb, drain and parapet detailing is involved. Access and staging on a downtown block also affect it. We walk the roof and give a free no-obligation quote.
Nearby Areas We Also Cover
Flat roofing in the streets either side of Oshawa:
Whitby • Ajax • Pickering • All of Durham Region
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Get a Free Flat Roof Quote in Oshawa
Free, no-obligation quotes across Oshawa and the rest of Durham Region, and a 24/7 emergency line on (647) 333-3528.