Why can't a carpenter price rot repair until the Ottawa wall is open?

Rot in a wall can run beyond the piece you can see. Until the drywall or plaster comes off, nobody can tell how far the damage has spread, which members are affected, or what the repair actually involves.

Here is what changes once the wall is open.

The extent of the rot. A single soft spot on a sill plate can turn out to be one short section or the full length of the plate, depending on how long moisture was present and where it came from. The carpenter cannot measure what is hidden.

Which members need replacing. A rotted sill can mean rotted stud bases beside it, a compromised bottom plate, or a floor joist end sitting in the same wet pocket. Each additional member is separate labour and material.

Whether the repair is structural. The City of Ottawa lists structural repairs or alterations as permit work. If the carpenter opens the wall and finds that a load-carrying member is compromised, a qualified, registered designer (BCIN), an engineer, or you for a house you own, may need to specify the repair before work continues. That is a cost that cannot be known in advance.

What material is behind the wall. On an older home, plaster, old paint and other materials may contain lead or asbestos. Health Canada notes that homes built before 1960 probably contain lead-based paint, and lists plaster and related materials as potentially containing asbestos. Testing before disturbance is a separate line item, and the contractor has worker-safety duties regardless.

What a fair quote for rot repair should include, once the scope is known: design if a structural member is involved, the building permit if the City requires one, materials for every affected member, labour for removal and replacement, patching and finishing to close the wall again, disposal, and testing if old paint or plaster is disturbed.

Ask whether the quote comes in two stages: a first price to open and assess, and a revised price once the full picture is clear. Get both stages in writing, and make sure the written agreement covers what happens if the scope grows after opening.

Ask the carpenter to walk you through exactly what they will assess when the wall is first opened, and to put the criteria for a scope change in writing before any work starts, so there are no surprises about what triggers a revised price.