About House Extension Expert
A feasibility-first extension site: the rules and the realistic numbers before anyone tries to sell you anything.
Why this site exists
We run a quote tool for extension work, so we see what people actually ask before they hire. Over a recent 90-day window, of the homeowners who told us where they were up to: roughly 54% said they were still planning and researching rather than ready to hire, 27% did not know whether they needed planning permission, and 58% had no drawings. Two thirds wanted a single-storey rear extension.
Almost every extension site answers “what does it cost and who can do it”. Very few answer “am I allowed to build this, and is it the right thing for my house” — which is what most people are actually asking at that point. That gap is the whole reason this site is here.
How we write
- Every regulatory statement is sourced and dated. Planning and Building Regulations content comes from the Planning Portal and GOV.UK, and each page carries the date it was last checked. Where the rules differ in conservation areas, on listed buildings, or outside England, we say so rather than quietly generalising.
- Every cost range names its source. The figures come from BestBuilders’ 2026 regional cost model — published national cost guides multiplied by a regional labour index and averaged across 519 UK towns. They are indicative ranges, not quotes, and we say so on the page. We do not hold the prices builders actually quote, so we never present anything as if we did.
- No invented trust signals. No star ratings, no review counts, no “trusted by thousands”, no fabricated author credentials. Pages are written and checked by our editorial team; when a page is reviewed by a named professional, it will carry their name and their credentials, and not before.
- Hand-written, not generated at scale. There is no daily page routine and no town × service matrix here. Pages are added one at a time when there is something worth saying.
What we are not
We are not a builder, an architect, a surveyor or a planning consultant. We do not carry out work, draw plans or submit applications, and nothing on this site is professional advice for your specific property. For anything that turns on your particular site — a boundary, a tree, a covenant, an Article 4 direction — you need your local planning authority or a professional you have appointed.
Who runs it
House Extension Expert is operated by SharpCode Ltd, a company registered in England and Wales (number 16031384), registered office Suite 6585, Unit 3a, 34–35 Hatton Garden, Holborn, London EC1N 8DX. We also run BestBuilders.co.uk, which is where the regional cost model is maintained; we cross-reference it rather than pretending the two are unrelated.
General enquiries and corrections: [email protected], or use the contact page. If you think something on this site is wrong or out of date, please tell us — we would rather fix it than leave it.