How to Tell If a House Is Non-Standard Construction (2026)
What counts as standard construction?
Lenders treat "standard" construction as the low-risk default. Anything else is "non-standard", which doesn't mean bad — many non-standard homes are perfectly sound — but it does affect how easily the property can be mortgaged, insured and therefore sold.
How to tell if a house is non-standard construction
- Look at the walls — smooth render, concrete panels or metal sheeting rather than visible brick can indicate PRC or steel frame.
- Check the roof — flat roofs or unusual materials are a flag.
- Read the Home Report — the surveyor usually states the construction type in the Single Survey.
- Look for a steel frame — visible around windows, or a regular grid of vertical joints (common in BISF houses).
- Research the estate — many councils built identifiable prefab estates; neighbours and local records help.
Common types of non-standard construction in Scotland
| Type | What it is | Mortgage outlook |
|---|---|---|
| BISF (steel frame) | Post-war British Iron and Steel Federation homes | Mortgageable with some lenders |
| PRC (pre-cast reinforced concrete) | Concrete-panel homes, some 'designated defective' | Hard unless repaired to an approved scheme |
| Timber frame | Frame of timber; modern is fine, some older types aren't | Often fine; depends on type/cladding |
| Prefab / system-built | Cornish, Airey, Wates and similar designs | Varies; many need specialist lenders |
| Single-skin / cob / thatch | Period and rural construction | Specialist lenders only |
Key takeaways
- Standard = brick/stone walls with a pitched, tiled roof.
- Non-standard includes steel frame, concrete (PRC), timber and prefab systems.
- The construction type is usually stated in the Home Report.
- Non-standard construction narrows the mortgage and buyer pool — not the value.
- Auction to cash buyers is the fastest, most certain way to sell these homes.
Why it matters for mortgages and selling
Many mainstream lenders are cautious about non-standard construction, which shrinks the number of buyers who can get a mortgage on it. A property designated 'defective' (such as some PRC types) may be unmortgageable unless it's been repaired to an approved scheme and certified — for example a PRC Homes Ltd certificate. This is the single biggest reason these homes can sit unsold on the open market.
The best way to sell non-standard construction
Because so many buyers depend on mainstream mortgages, non-standard homes often sell best at auction, where cash buyers, investors and developers compete without mortgage constraints. Competitive bidding among buyers who actively want these projects regularly achieves a strong, fast result.
Learn more in our guides to non-standard construction and BISF houses, or get a free as-is valuation.
Founder & Director of Scotland Property Auction. Julie has spent over a decade helping Scottish homeowners, landlords and executors sell property quickly at auction — covering Home Reports, missives, repossession and the modern method of auction.
More about Julie →✔ Last reviewed June 2026 by Julie McAndrews. We keep our guides current with Scottish property law and market conditions.