An extension or loft conversion can add real value to a home you're buying — provided the work was done properly and documented. Missing paperwork isn't necessarily a deal-breaker, but it's something to understand before you commit. Here's what to ask for, with an important caveat about whose advice to rely on.
In short
If a home you're buying has been extended or converted, it's worth checking the paperwork behind that work — planning permission or a lawful development certificate, building-regulations completion certificate, and any structural or service certificates. This is general information, not legal or conveyancing advice: your solicitor is the right person to act on it. SC Design can help you understand the drawings and physical work.
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Reviewed by Sean Corser, SC Design & Construction. Sean Corser helps Wirral homeowners with architectural design and drawing packs for extensions, loft conversions, planning and building regulations.
Last reviewed June 2026
This guide is general information to help you ask the right questions. It is not legal, conveyancing or structural advice, and it doesn't replace your solicitor or conveyancer — they are the people who should review documents and advise on the purchase.
Treat the points below as a checklist to raise with your solicitor and the seller, not as a substitute for professional advice.
Depending on the work, useful documents include any planning permission or Lawful Development Certificate, a building-regulations approval and completion certificate, structural calculations for beams or new floors, and certificates for electrical and gas work.
It's also worth asking for the approved drawings and any planning conditions, plus warranties for elements like flat roofs or windows where they exist.
For an extension, look for the planning position (permission or an LDC), building-regulations completion certificate and any structural calculations. For a loft conversion, building regulations almost always apply to habitable space, so a completion certificate and the fire-safety and structural details matter.
For a garage conversion, habitable space normally needs building-regulations approval, so again a completion certificate is the key document to ask about.
Missing documents don't automatically mean the work is unsafe, but they can create questions on a future sale. GOV.UK notes that without building-regulations approval, a homeowner may not have the certificates of compliance a buyer's solicitor expects. Where works were lawful, an LDC can sometimes confirm the planning position, and a building-control regularisation route can exist for some situations — but those are matters to explore with the council and your solicitor, not from a guide.
We can help you understand the drawings and the physical work — what was built and how — which can inform the questions you and your solicitor ask. The legal and conveyancing side stays firmly with your solicitor.
A few details are enough for an honest first view — with no obligation:
Need planning & building regulations? We can prepare them — clear, coordinated and ready for builders and building control.
External links open in a new tab. Always confirm your specific project with the relevant authority.
Send Sean a few photos and a short description of what you'd like to do. You'll get an honest first view with no obligation.