What actually kills a commercial roof
Not age. Water that got in years ago and never left.
A low-slope roof is a system: deck, insulation, base sheet, membrane, surfacing. The membrane is the only part anyone looks at, and it is rarely the part that fails first. What fails is a detail — a base flashing at a parapet, a curb corner under an HVAC unit, a pipe boot that hardened in UV. Water enters there, travels through the insulation, and quietly destroys the thermal value and the deck fastening long before it ever shows up on a ceiling tile.
By the time you see the stain, the insulation has been wet for a season.
The three questions that decide everything
1. Is the deck sound?
If the deck has corroded or the fasteners have lost their grip, nothing installed above it will perform. This is why every honest assessment starts with core cuts, not with a proposal.
2. Is the insulation dry?
Dry insulation means restoration is on the table. Wet insulation means you are paying to coat over a problem. Infrared or nuclear moisture survey answers this; a walk-around does not.
3. Is the membrane aged, or has it failed?
Aged means chalked, weathered, granule loss, brittle at the laps. Failed means splits in the field, open laps, delamination. Aged can be restored. Failed is replaced.
Questions to ask before you sign anything
- Did you take core cuts? Can I see the photographs?
- How many roof layers are already on this deck, and what does code allow?
- Is the insulation wet, and how did you determine that?
- What is the ply count you are proposing, and what service life does it indicate?
- Who manufactures the system, and are you an approved applicator for it?
- What does the warranty cover — material only, or material and labor?
- What happens to ponding water on this roof after the work is done?
Not all roofing contractors are created equal. Make sure you have confidence in the company that is keeping your building watertight and your possessions dry.