Where does the money go?
- Layout, linings, electrics and decoration: around £3,500–£6,500 per letting room.
- Ensuites: £4,000–£10,000 each.
- Shared bathrooms: £5,500–£9,000 each.
- A communal HMO kitchen: around £8,000–£18,000.
- Fire alarm: £800–£2,000 for a small HMO interlinked system; £1,750–£4,500 for a panel system.
- Fire doors: £300–£600 each into an existing frame; £600–£1,300 for a new doorset.
What pushes the price up?
- Three storeys or more, which usually means a bigger fire alarm and a protected route.
- Moving walls or kitchens, which brings structure, drawings and approvals.
- Pumped drainage for ensuites.
- A house in poor condition needing repairs first.
- London and the South East, typically 20–40% above the UK average.
What about VAT?
Work on existing homes is normally standard-rated. Some conversions and long-empty properties may qualify for a reduced rate under HMRC rules, but conditions apply, so confirm with HMRC or your accountant before relying on it.
See all guide prices or use the guide-price tool.
Questions
Is a per-room figure enough to budget?
It is a starting point. Kitchens, bathrooms and fire systems vary so much that an itemised price after a site visit is the only reliable figure.
Do your guide prices include VAT?
They are rounded budgets for planning. Some source guides include VAT and some do not say, so check the VAT line on your written quote. Insulation can be zero-rated until 31 March 2027 where conditions are met.
Can costs be phased?
Some can, such as room upgrades during voids, but conversions are usually best done in one go before letting.
Checked 31 October 2026. General information for landlords planning works, not legal advice. Check the council’s pages for the exact address.