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Recover or tear off? How to decide on a low-slope roof replacement

A recover puts a new roof over the existing one; a tear-off removes the old roof down to the deck. Under the building code, a recover is not allowed when the existing roof is water-soaked or deteriorated, or when it already has two or more roof coverings. Testing answers those questions: an infrared survey with test cuts shows wet insulation, pull tests show what the deck will hold, and an asbestos survey shows how the old materials must be handled.

By Veteran Rep Group of Ohio ·

What the code allows

The reroofing section of the International Building Code, which the 2024 Ohio Building Code is based on, does not allow a recover in two situations that matter on most commercial roofs:

  • the existing roof or roof covering is water-soaked, or has deteriorated to the point that it is not adequate as a base for the new roof;
  • the existing roof already has two or more applications of any type of roof covering.

So the first two questions are simple: how many roofs are already up there, and how wet is what is under the membrane?

What a recover saves, and what it risks

A recover skips most of the tear-off labor and disposal, and the building stays covered while the new roof goes on. The risk is what gets trapped underneath. Wet insulation left in place has lost much of its insulating value, adds weight, and can keep a steel deck and its fasteners damp for years. A recover also adds load to the structure and has to be compatible with the old surface, usually with a recover board between the two.

The tests that decide it

  • Infrared moisture survey and test cuts. A night-time infrared scan maps wet insulation; ASTM C1153 calls for confirming it with cuts. A roof with wet areas scattered across it may still be recovered after those areas are replaced. A roof that is wet throughout points to a tear-off.
  • Fastener pull tests. A recover is usually fastened through the old roof into the existing deck. ANSI/SPRI FX-1 pull tests show what the deck will hold, which sets the fastening pattern for wind uplift, or shows that the deck needs attention first.
  • Adhesion tests. If the new system will be adhered, ANSI/SPRI IA-1 testing shows whether the adhesive bonds to what is actually there.
  • Asbestos survey. Older felts, flashings, mastics and coatings can contain asbestos. In Ohio, work that falls under Ohio EPA’s asbestos rules needs a survey and written notice at least 10 working days before it starts. Know before you choose, because it changes both the schedule and the budget of a tear-off.
  • A structural check. If a recover adds weight, have the design professional confirm the structure can carry it.

When a tear-off is the better buy

Even when a recover is allowed, a tear-off can be worth it. It is the time to fix drainage with tapered insulation, replace a deck that failed its pull tests, bring insulation up to what the owner wants for energy costs, and start fresh with a system and warranty that are not built on top of an old one. Ask the design professional how the energy code applies when insulation is replaced.

Start with the facts

Every one of these questions is answered by testing, not by looking at the surface. Veteran Rep Group of Ohio offers infrared scanning, pull tests, adhesion tests and asbestos testing and helps design teams turn the results into a specification. Call 216-258-3834.

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