Roof Recover Eligibility Checker

Sometimes, and the code sets the conditions rather than leaving it to preference. The baseline in IRC Section R908.3 is that a roof replacement removes the existing layers down to the deck. Section R908.3.1 then permits a recover in defined cases — most commonly where the new covering's manufacturer's approved instructions allow it, where the new system is a complete and separate one such as a standing-seam metal roof transmitting loads directly to the structure, for certain coverings over existing wood shake, and for recoating certain membrane systems. Outside those cases the default stands.

Because they win. The permissions in R908.3.1 and the prohibitions in R908.3.1.1 are separate lists, and a prohibition is not relieved by a permission. A manufacturer's instructions permitting installation over an existing covering do not make a recover lawful on a roof that already carries two layers, or on tile, or on a deteriorated deck. Testing the prohibitions before reading any permission is the order the code itself implies, and reversing it is how people arrive at the wrong answer confidently.

Section R908.3.1.1 rules out a recover where the existing roof already has two or more applications of any type of roof covering. That is a prohibition on adding a third rather than a permission to have two — the baseline in R908.3 remains removal down to the deck. The wording is worth reading closely: two or more applications of any type, so a layer of shingles over a layer of roll roofing counts the same as two layers of shingles. Jurisdictions amend Chapter 9 and some are stricter.

Because the code names the material directly. Section R908.3.1.1 prohibits a recover where the existing covering is slate, clay, cement or asbestos-cement tile, and it is an unconditional prohibition — it does not depend on the tile's condition, on the number of layers, or on what the new covering's instructions permit. The practical consequence is that a tile roof at the end of its service life is always a tear-off, which is worth knowing before an array is fastened to one.

It means the question has not been answered by somebody who could answer it, which is a different state from a no. The deck-condition prohibition is the one that most often sits unanswered, because it requires an assessment of the existing roof and covering by somebody who has been on the roof rather than a look from the ground or a photograph. Treating an unanswered prohibition as a no is the most common way a recover gets quoted that should not have been, so the tool reports it as undetermined rather than resolving it in either direction.

Section R908.3 carries an exception for this. Where the existing roof assembly includes an ice barrier membrane adhered to the roof deck, that membrane is permitted to remain in place and be covered with an additional layer of ice barrier membrane in accordance with Section R905. It is a narrow exception about one specific component adhered to the deck, not a general permission to leave material behind, and it does not turn a tear-off into a recover.

It does not change what the code permits, but it changes the economics and the timing decisively. Panels have to come off before a covering underneath them can be replaced and go back on afterwards, which is a separate scope with its own cost and its own liability boundary. That makes the roof's remaining service life something to settle before the array goes up rather than years into it. A second layer also changes the attachment, because the mount has to reach a structural member through whatever is on the deck.

No. It reproduces the structure of IRC Section R908 as commonly adopted, and the authority having jurisdiction decides. Jurisdictions adopt different editions of the code and amend Chapter 9 freely, section numbering moves between editions, and some departments are stricter than the model text. Use this to know which questions decide the answer and which evidence you need, then confirm with the building department that will issue the permit.