Ask who handles the building warrant
Every garage conversion in Scotland needs a building warrant. Ask directly whether the builder prepares the drawings and submits the application themselves, or whether that's left to you to arrange separately. A specialist handles it as part of the job because they do it on every project, not occasionally.
Ask for the damp-proofing specification in writing
A generalist builder describes the work as 'damp-proofed and insulated' without specifics. A specialist names the actual build-up — a membrane lapped into the wall DPC, the insulation type and thickness, and how the wall lining is constructed for your specific wall type (single-skin masonry needs a different answer than a cavity wall).
If the answer is vague, that's a sign the specification will be decided on site rather than planned — which is how skipped details happen.
Compare itemised quotes, not just totals
- —A proper quote separates the warrant fee and drawings, structural and infill work, damp-proofing and insulation, electrics, and finishes.
- —Ask whether the warrant fee is included or additional — this varies between builders and changes what looks like the cheapest quote.
- —Be cautious of a quote significantly below others for the same brief; the saving usually comes from the insulation or damp-proofing specification, which is invisible once the room is finished.
Ask about your specific garage type
A single-skin masonry garage, a cavity-wall garage, an integral garage and a detached garage all need different approaches. Ask what specifically changes in their specification for your garage — a generic answer suggests limited experience beyond the most common case.
What guarantee to expect
Expect a written workmanship guarantee, plus the building warrant's own completion certificate as the formal record that the work meets Scottish building standards. Ask when in the process the completion certificate is submitted and confirm it's included as part of the job, not an optional extra.