COMMERCIAL DECISIONS
Restore or replace a commercial flat roof in Ontario?
Choose by condition rather than age: a sound membrane, mostly dry insulation and limited ponding usually leave a commercial flat roof suitable for restoration instead of replacement. Restoration on commercial low-slope roofs typically costs about half as much as tear-off and replacement, except when a built-up roof needs rebuilding.
Start with condition, not the roof's age
The installation date is useful background, not a verdict. Look at how much membrane remains sound, how far moisture has spread through the insulation, where water lingers and whether leaks are isolated or widespread.
Wet insulation is the biggest single factor. Its extent is checked during the on-roof assessment; an owner who has not had it checked should treat it as unknown, not assume it is dry.
Signs a roof is a restoration candidate
These observations follow the roof scorecard criteria. They help frame the assessment rather than replace it.
| Observation | What it suggests | Next step |
|---|---|---|
| Sound membrane | The existing covering may be suitable to retain. | Confirm the insulation, drainage and leak findings on the roof. |
| Cracking or blistering in areas | Restoration may remain possible with repairs. | Identify the affected areas and define the repair scope. |
| Splits, detached or missing membrane sections | Affected sections may require replacement. | Assess how much membrane needs removal before considering restoration elsewhere. |
| No known wet insulation or only small known areas | A mostly dry assembly may support restoration; small wet areas still need attention. | Check moisture extent on the roof and specify localized removal where needed. |
| Large areas of wet insulation | Replacement is likely to be the appropriate direction for the affected roof. | Map the wet areas at the assessment and establish the replacement scope. |
| Water pooled 48 hours after rain in a few spots | Limited ponding may leave a restoration pathway open. | Review those low areas and the preparation or repairs they require. |
| Water pooled 48 hours after rain across large areas | Broad ponding needs further assessment before a restoration decision. | Determine the extent of persistent water and the work required. |
| No leaks or a few known leak spots | Targeted repairs may allow the sound remainder to be restored. | Locate each known leak and include its repair in the scope. |
| Widespread leaks | The problem may call for replacement rather than coating alone. | Assess the affected sections together with membrane and insulation condition. |
When replacement is the right call
Leaks throughout the roof, extensive saturated insulation, or membrane that is split, detached or missing are reasons to consider replacement. Coating over those conditions is not the same as restoring a qualifying roof.
The assessment can separate failed sections from serviceable ones, helping the owner avoid removing more roof than necessary. A qualifying restoration scope can still include localized removal and repairs before coating begins.
Built-up roofs are the exception
Built-up, or gravel, roofs need a case-by-case specification. If the assembly must be rebuilt, the usual restoration-versus-replacement cost comparison no longer applies.
For a qualifying built-up roof, the commercial approach uses Bleed Blocker as the base layer beneath a reflective top coat, with fabric reinforcing the low areas. Suitability and required preparation come first.
What restoration includes
Restoration starts with assessment and required repairs, followed by cleaning and surface preparation. Details are reinforced and the coating is built to the specified thickness, rather than treated as a cosmetic finish.
Qualifying roofs can receive a manufacturer system warranty of 10, 15 or 20 years. The specified coating thickness sets the term. Review the warranty requirements and written terms alongside the proposed scope.
Your next step
Take the 2-minute scorecard to organize what you know about the roof, then explore the commercial restoration approach. NanoGuard's commercial roof assessment is free and checks the conditions that decide the scope.
Questions
Is restoration cheaper than replacing a flat roof?
For commercial low-slope roofs, restoration typically comes in at about half the cost of tear-off and replacement. A built-up roof that requires rebuilding falls outside that comparison; its scope must be priced case by case.
Can a roof with leaks be restored?
A few identifiable leaks can leave a repair-and-restoration option open when the remaining membrane is sound and insulation is mostly dry. Widespread leaks, extensive wet insulation or split, detached or missing membrane sections point toward replacement of the affected roof sections. An on-roof assessment defines the scope.
Does roof age decide restore or replace?
Age provides context, but it does not settle the decision. Membrane condition, the extent of wet insulation, persistent ponding and the spread of leaks determine whether restoration remains suitable.