1. Check the address before you commit
- England: 3–6 sharers is use class C4, usually permitted development from a family house unless an Article 4 direction applies. 7 or more normally needs planning permission. Check for additional licensing too.
- Wales: a change from a house to a C4 HMO always needs planning permission, and councils may run additional licensing.
- Scotland: every HMO needs a licence; planning policy is set by each council.
- Northern Ireland: all new HMOs need planning permission and building control approval, and licensing runs through the NI HMO Unit.
2. Measure every room
In England, licensed HMOs must meet national minimum bedroom sizes (6.51 m² for one person aged 10 or over, 10.22 m² for two), with floor under a 1.5 m ceiling excluded. Councils can set larger sizes, and the other nations rely on council or national standards of their own. A measured survey before you design saves rebuilding later.
3. Design to the council’s standards
Councils publish HMO standards for kitchens, bathrooms, WCs and room sizes. Kitchens and bathrooms are usually the biggest cost drivers, because ratios often step up at 5 and 6 sharers.
4. Plan fire safety with the risk assessment
Detection, fire doors, a protected route and fire stopping are set by the fire risk assessment and council guidance. Three storeys and larger houses usually need more.
5. Building control
Partitions, drainage, fire-resisting construction and electrics must meet the building rules, and the conversion may count as a material change of use. Confirm the route with building control before work starts.
6. Works, certificates and the licence
At handover you need electrical and alarm certificates, gas safety records, building control completion where relevant and evidence of fire works for the licence application.
Questions
How long does an HMO conversion take?
Most three or four-bedroom conversions take 6–14 weeks on site after approvals.
Can I start letting before the licence is granted?
Rules differ by nation and council. Letting a licensable HMO without a licence or valid application is an offence, so check with the council first.
Do I need an architect?
For layout changes, planning or building control applications, drawings are needed. We can build from your architect’s drawings or arrange them.
Checked 31 October 2026. General information for landlords planning works, not legal advice. Check the council’s pages for the exact address.