HMO conversion cost calculator
HMO conversions are the most complex — and most scrutinised — refurb deals. Estimate yours below including the fire-safety and licensing items valuers check, then build the full schedule of works with the compliance pack auto-included.
How to cost an HMO conversion
- 1Size the works to the rooms
Each lettable room carries a share of strip-out, layout reconfiguration, electrics, plastering and decoration. Add en-suites per room where the market supports it.
- 2Add the compliance pack
Fire doors to every bedroom plus communal and escape-route doors, a fire alarm to the correct grade, emergency lighting on 3+ storeys, a fire risk assessment, signage and an EICR.
- 3Size the kitchen to occupancy
Councils set minimum kitchen facilities per sharer — extra units, worktop, hob rings and fridge/freezer capacity. Budget for a larger kitchen than a standard BTL.
- 4Include licensing and contingency
Add the HMO licence fee (varies by council) and a 15% contingency for the unforeseen — HMO conversions carry more structural and compliance surprises than a plain refurb.
The difference between a profitable HMO and a stalled one is usually the items investors forget to budget: the jump from a Grade D1 to a Grade A alarm on a three-storey property, the fire-stopping and compartmentation behind the walls, the en-suite drainage runs, and the council’s kitchen amenity standards. These aren’t optional extras — a valuer or licensing officer will expect them, and a lender wants them costed.
ScopeWise auto-includes the full HMO compliance pack and warns you if any mandatory category is missing, so nothing falls through. Remember the prompts are guidance — HMO standards vary by authority, so confirm the detail with your council before you rely on the numbers.
Typical HMO compliance & conversion items
| Item | Indicative cost | Driver |
|---|---|---|
| FD30(S) fire door (fitted) | £320–£650 each | Per bedroom + communal/escape |
| Fire alarm — Grade D1 (small HMO) | £900–£1,600 | Mains interlinked, ≤6 occupants |
| Fire alarm — Grade A (3+ storey) | £3,500–£6,000 | Panel, sounders, certified |
| Emergency lighting | £80–£180/fitting | Escape routes, 3+ storeys |
| En-suite shower room | £2,200–£4,500 each | Per room |
| HMO kitchen (occupancy-sized) | £3,500–£8,000 | Per kitchen |
| Fire risk assessment | £150–£500 | Per property |
| HMO licence fee | £500–£1,600 | Per council (5-year licence) |
Indicative figures — HMO standards and fees vary by local authority. Confirm with your council.
Frequently asked questions
How much does it cost to convert a house to an HMO?+
As a rough guide, a typical 5–6 bed HMO conversion runs from around £40,000 to £100,000+ depending on the starting condition, number of en-suites, storeys (which drives the alarm grade) and region. Use the calculator above for a figure tailored to your property, then build the itemised schedule.
What fire safety do I need for an HMO?+
Generally: FD30(S) fire doors to bedrooms, kitchen and the protected escape route; an interlinked fire detection system to the right grade (Grade D1 for smaller HMOs, Grade A for larger/3+ storey under BS 5839-6); emergency lighting where escape routes lack borrowed light; fire-stopping/compartmentation; signage, a kitchen fire blanket and extinguishers; and a fire risk assessment. Your council's standards govern the detail.
Do I need planning permission for an HMO?+
A small HMO (up to 6 occupants, use class C4) is often permitted development from C3 — but many councils have an Article 4 Direction removing that right, meaning you need planning permission. Larger HMOs (sui generis) usually need planning. Always check your council and any Article 4 area.
When do I need an HMO licence?+
Mandatory licensing applies to HMOs with 5 or more occupants forming 2 or more households. Many councils also run additional or selective licensing covering smaller HMOs. Fees and conditions vary by authority.
Related tools & guides
Cost figures shown are indicative estimates, not quotations. You are responsible for verifying all costs (obtain contractor quotes) and any figures submitted to a lender. ScopeWise is a documentation tool, not financial, tax, structural or planning advice. HMO compliance prompts are guidance only — confirm requirements with your local council, as standards and licensing vary by authority.