Markham Commercial Roofing for Business Parks and Offices

Start by mapping which tenant spaces sit below each roof zone and which rooftop units or outside-air intakes serve them. Markham office buildings often stay occupied during reroofing, but the project should be sequenced around tenant hours, air-intake locations, parking and loading access, and any noise-sensitive uses. Define daily work zones that can be made watertight before the crew leaves, agree on when noisier removal or fastening can occur, and coordinate any temporary air-intake protection with building operations before work reaches that zone. The goal is not simply to keep the doors open; it is to keep each tenant's normal operations predictable while the roof is renewed above them.

Persistent ponding in a single area is worth investigating even when the current membrane appears intact there. The question is whether the ponding is caused by a blocked drain, compressed insulation from a previous saturation event, structural deflection, or original slope deficiency. A blocked drain clears with maintenance. Compressed insulation from previous saturation needs to be replaced to restore drainage slope. Structural deflection and original slope issues are addressed at time of reroofing with tapered insulation. Understanding the cause before next winter is worthwhile, because sustained water contact against membrane seams and details accelerates the deterioration that eventually results in a leak.

Start with the curb flashing immediately around the new unit's roof penetration. Many mechanical contractors install rooftop units competently from an HVAC standpoint but leave the curb-to-membrane interface in a condition that depends on sealant rather than proper flashing. Confirm that the membrane has been correctly terminated at the top of the curb, that the interior of the curb is sealed, and that the unit's condensate drain is discharging appropriately. Also check whether the installation involved any foot traffic across the membrane between the roof hatch and the new unit, impact or abrasion damage along that route is a common secondary source of leakage near new equipment.

Verify that each quote addresses the same scope, specifically, whether existing insulation is being removed or reroofed over, what insulation thickness is being installed, which membrane product and thickness is specified, and how the perimeter flashings and penetrations are being handled. A quote that omits insulation removal, installs thinner insulation or specifies a lighter-gauge membrane will be less expensive and will underperform against one that does the work correctly. Ask each contractor to identify the warranty they are offering and whose signature covers it, a manufacturer warranty, a contractor warranty, or both.

The primary risk is escalating repair costs combined with decreasing repair effectiveness. A membrane that has been patched repeatedly across multiple zones reaches a point where new repairs cannot achieve reliable tie-ins to the surrounding membrane, and the repair spend in any given year approaches what a replacement section would have cost. There is also the risk of insulation saturation, wet insulation is not visible from the surface and can extend well beyond the visible repair zone, so the actual replacement scope grows while the building owner is deferring the decision. On occupied Markham office buildings, there is an additional risk: a significant leak event in a technology or professional services environment can cause business disruption that far exceeds the cost of the replacement that was deferred.

Coordinate unit locations, curbs, service paths and roof protection before roof work begins. Ask the roofer how equipment disconnects and reconnects will be handled and by whom. Protect the membrane with walkways where technicians travel often.