Age and type of house
A 1930s garage in the garden is single-skin brick. Does its rating transfer to the cavity walls of the house?
No. A single-skin brick garage in a 1930s garden is not the cavity wall of the house, so its rating does not transfer. Single-skin means one leaf, often with no cavity at all. The house walls, where they are a true cavity, are a different element. An empty cavity in those house walls is not itself a defect. Describe the garage for cracks, a poor roof and damp at its slab. Do not rename the dwelling because the garage is only a half-brick thick.
Last reviewed 24 October 2026. Written for buyers in England and Wales unless this answer says otherwise. No named surveyor has signed this page. It is general guidance, not a report on your house, and not legal advice.
What is the fuller explanation?
Garden garages of this era are frequently half-brick, with a simple roof and a concrete floor, built as stores rather than as rooms. They crack at the door piers, let damp through the thin wall and rot their own roof timbers. None of that is a test of the house, which in a typical 1930s semi has two leaves and a cavity. The survey should already be separating them. If it has used one rating for 'walls', ask which walls. A hollow note on a garage gable is not a wall-tie survey of the front elevation.
An empty house cavity is not a defect by itself. Do not upgrade the garage finding into a storey about missing insulation or failed ties in the dwelling unless those were seen on the house. The garage roof is yet another element, often felt or asbestos-cement looking sheets. Do not call a cement-looking garage roof asbestos from appearance, and remember the surveyor is not an asbestos inspector. Keep the thin brick wall as thin brick. The house keeps the construction the house walls showed.
What should you ask your surveyor?
- Did you rate the garage brick separately from the cavity walls of the house?
- Is the house wall actually a cavity, and did you see that, or is the cavity only typical for the age?
- Are you avoiding any claim that an empty cavity is itself a defect?
What are the typical next steps?
- Repair notes for the garage should not be copied onto the house elevation.
- Do not call the house single-skin because the garage is.
- If a garage sheet looks like cement, do not label it asbestos and do not break it.
Costs vary with the building and with who you instruct. Where this page does not cite a published figure, ask the surveyor, a relevant specialist, or your solicitor for a written quote. Do not treat a forum average as the price.
Also asked about this
Is half-brick construction a defect when it is only the garage?
It is the way many garages were built. The survey should still describe cracks and damp. It should not export that build to the house.
Does a damp garage slab mean the house damp-proof course has failed?
No. The slab is the garage. House damp needs evidence on the house walls, not a wet outbuilding.