Flat roof repair, fixed at the cause and welded properly.

Four things, in roughly this order: seams that were lapped but never heat-welded; scuppers and drains that clog and back water onto the field; parapet walls waterproofed with a metal cap and nothing behind it; and penetrations — plumbing stacks, vents, skylight curbs, equipment supports — installed without the manufacturer's flashing detail. Snow load and ice build-up then make every one of those worse over a Richmond Hill winter.

Most can be repaired. Isolated seam failures, a split at a termination, a failed drain collar or a bad skylight curb are all localised faults on roofs with years of service left. Replacement becomes the right call when thermography shows saturated insulation across a large proportion of the field, when the membrane has shrunk to the point that new material won't bond at terminations, or when the deck below has lost structural integrity. We scan before we advise, because the difference is thousands of dollars.

Water still sitting 48 hours after rain is the standard definition of ponding, and yes. It accelerates membrane breakdown, magnifies UV damage, freezes and expands in winter, and adds structural load. More importantly it's a symptom: the slope or the drainage is wrong. Laying new membrane over a low spot produces a roof that ponds in exactly the same place, which is why we correct it with tapered insulation instead.

Emergency work, yes — the roof is secured and water entry stopped in any weather. Permanent repairs need a dry, clean, frost-free surface: torch-applied SBS needs the substrate dry to bond, adhesives have minimum application temperatures, and hot-air welding on TPO requires the membrane to be clear of ice and moisture. We'll say plainly whether a permanent repair will hold now or whether temporary protection until conditions improve gives the better result.

Usually because the patch addressed where water appeared rather than where it entered, or because sealant was applied over an open seam instead of the seam being welded. Caulking on a membrane lap is a temporary measure — it moves at a different rate from the membrane and opens again within a season or two. It's also common for the original leak to have been fixed while a second entry point, twenty feet away, was never found. That's what the thermal scan is for.

Correctly installed and drained: roughly 20–30 years for two-ply SBS, 20–30 for EPDM, and 20–30 for TPO and PVC. What actually shortens those numbers is almost never the membrane itself — it's drainage that was wrong from day one, and penetrations added afterwards without proper flashing.

Not if it's done to the manufacturer's published repair detail in matched material, which is how we work. Warranties are voided by incompatible products and improvised details — solvent mastic on a thermoplastic membrane, a generic patch over a proprietary seam. Bring us the warranty paperwork and we'll work within it.

Very often it isn't. Damp appearing during cold snaps with no precipitation, particularly above bathrooms, kitchens or a humidifier, usually indicates condensation forming inside the roof assembly rather than water entering through it. No amount of membrane work fixes that. We check humidity, dew point and vapour barrier before recommending roof repair, because getting this one wrong costs you the repair and leaves the problem.