When a commercial roof reaches the end of its life, the first big decision is whether the new roof can go over the old one or whether the old one has to come off. A recover saves money and disruption. A tear-off fixes what is hidden underneath. Which one your building needs depends on things you can't see from the surface.
What each one is
Full replacement (tear-off) strips the roof down to the deck: membrane, insulation and all. The deck is inspected and repaired, then a complete new system goes on. A recover leaves the existing roof in place and installs a new system over it, usually starting with a cover board or new insulation to create a clean, flat, dry base.
When a recover is allowed
Ohio's commercial building code is based on the International Building Code, which generally does not allow a recover when:
- The existing roof or its insulation is water-soaked or deteriorated to the point that it isn't a sound base
- The existing roof already has two or more layers of roof covering
- The existing covering is slate, clay or concrete tile, or asbestos-cement tile (rare on low-slope commercial roofs)
Your local building department has the final word, and manufacturers have their own requirements for warranted recovers.
Roof leaking right now?
Dayton Commercial & Flat Roofing repairs, coats and replaces commercial and flat roofs across Dayton and the Miami Valley, with a written price before any work starts. Call (937) 669-7303 to request service.
How the decision gets made
- Count the layers. Core cuts show how many roofs are already there. Many older Dayton-area buildings are already on their second.
- Check for moisture. An infrared scan or moisture meter survey, confirmed with cores, maps the wet insulation. A little can be cut out and replaced; a lot means tear-off.
- Check the deck. Rusted steel or rotted wood has to be replaced, and that means opening the roof.
- Check drainage and height. A recover raises the roof surface. Flashings, door thresholds, rooftop unit curbs and edge metal have to work at the new height, and ponding has to be fixed, not buried.
Recover vs. tear-off at a glance
| Recover | Tear-off | |
|---|---|---|
| Typical cost | $4 – $8 / sq ft | $6 – $13 / sq ft |
| Disruption and noise | Less | More, with debris removal |
| Landfill waste | Minimal | The whole old roof |
| Hidden problems fixed | Only where found | All of them; deck fully exposed |
| Drainage correction | Possible with tapered insulation | Easiest |
| Next re-roof | Must be a tear-off of both layers | Recover may be possible |
The third option: restoration
If the roof isn't finished yet, with a dry base and a membrane that is aging but intact, a coating may give it another 10 to 20 years before either of these. See are roof coatings worth it?
The bottom line
A recover is a good deal when the existing roof is one dry layer over a sound deck. Otherwise, tear it off. Core cuts and a moisture survey make that call, not a sales pitch. See our roof replacement service and the cost guide.