You’re thinking of turning a family house into a house in multiple occupation (HMO), and you want to know what it will really cost. Done well, it pays: a 5-bed student or professional HMO in a northern city can deliver a higher net yield than a single-family let in the same postcode. The worked example below comes out at about 7.0% against 4.5%.
But the numbers only work if you go in with realistic costs and written quotes. An investor who pencils in £15,000 for "fire doors and a licence" can end up well over budget when planning, licensing inspections and LACORS fire standards hit.
This is the full 2026 breakdown: every line item with realistic ranges, planning risks by city, and honest yield maths.
Disclaimer: costs are indicative UK-wide averages for 2026. Always get written quotes and consult your local authority’s HMO standards.
Total cost ranges by scale
Representative conversion of a 3-bed semi into a 5-person HMO:
| Scope | Typical total |
|---|---|
| Minimal (already compliant) | £8,000–£15,000 |
| Standard 5-bed HMO conversion (north of England) | £25,000–£35,000 |
| Standard 5-bed HMO conversion (London / SE) | £35,000–£60,000 |
| Large HMO (7+ bed, sui generis) | £60,000–£120,000+ |
Add Article 4 planning fees (if applicable): the council’s planning application fee + £4,000–£15,000 for refused appeals / re-application.
Once the works are paid for, the return depends on every room staying let. From £7.99 a month, LetCompliance sets a rent and a deposit for each room, shows an empty room as vacant, and takes the next applicant through one shareable advert. Get started
Line-by-line cost breakdown
1. Planning (if Article 4 applies)
Article 4 directions now cover HMO areas in many cities. Check the council’s own planning pages for the exact boundary before you buy.
| Item | Cost |
|---|---|
| Planning application (C3 → C4) | Check the council’s planning fee |
| Planning consultant (recommended) | £1,500–£3,000 |
| Heritage / design statement (if needed) | £500–£1,500 |
| Refusal appeal (PINS) | Free application, but consultant + delay |
Pre-application advice from the council (£150–£400) is essential.
2. Fire safety (LACORS-equivalent)
The current industry standard is the LACORS Housing – Fire Safety Guide (2008), which most councils follow for HMO licence conditions.
| Item | Cost (5-bed example) |
|---|---|
| FD30 fire doors on habitable rooms opening to escape route (£350–£550 fitted × 6) | £2,100–£3,300 |
| Hard-wired interlinked smoke alarms (mains + 10-yr battery back-up) | £500–£900 |
| Heat detector in kitchen | £150–£250 |
| CO alarms (any room with a fixed combustion appliance, except gas cookers) | £60–£150 |
| 30-minute compartmentation (intumescent strips, plaster upgrades) | £1,500–£3,000 |
| Emergency lighting (HMO over 2 storeys) | £500–£1,500 |
| Fire-risk assessment (competent assessor) | £250–£450 |
| Total fire safety | £5,000–£9,500 |
3. Bathrooms and sanitary
| Occupants | Min bathrooms | Min WCs |
|---|---|---|
| Up to 4 | 1 | 1 |
| 5 | Check the council’s amenity standards | Check the council’s amenity standards |
| 6–7 | 2–3 | 2–3 |
Cost to add a second bathroom: £4,000–£9,000 depending on layout (stud walls, new plumbing, extractor, tiling).
4. Electrical and gas
| Item | Cost |
|---|---|
| EICR and C1/C2 remedial works | £300–£2,500 |
| Upgrade to 18th-edition consumer unit | £600–£1,200 |
| Gas Safety (new CP12) | £80–£150 |
| Additional sockets / PAT inspection | £200–£600 |
5. EPC upgrades
Under current MEES (min E), any property below E can’t be let. The Government plans to require all privately rented homes to reach EPC C by 1 October 2030 (not law yet; the earlier 2028 date for new tenancies was dropped). Even though the proposed deadline is 2030, it’s worth upgrading to C now.
| Item | Cost |
|---|---|
| Cavity-wall / loft insulation | £500–£2,500 |
| Double-glazing upgrade | £5,000–£12,000 |
| Boiler upgrade / smart controls | £2,500–£5,000 |
6. Licensing
| Licence type | Typical fee |
|---|---|
| Mandatory HMO (5+) | £500–£1,200 per property for 5 years |
| Additional HMO (3–4) | £500–£1,200 for 5 years |
| Selective (non-HMO rental) | £500–£900 for 5 years |
Plus inspection fees (£100–£300) in some councils.
7. Furnishing and kitchen
| Item | Cost |
|---|---|
| Kitchen refresh (paint, worktops) | £1,500–£4,000 |
| Kitchen replacement | £8,000–£15,000 |
| Furniture (5-bed, mid-market) | £4,000–£8,000 |
| Bedroom locks on doors | £200–£400 |
Yield maths: does HMO still stack up in 2026?
Scenario: 3-bed semi in Sheffield (Broomhill)
| Item | Figure |
|---|---|
| Purchase price | £220,000 |
| SDLT (5% additional-property surcharge, since Oct 2024) | £12,900 |
| Legal + survey | £1,800 |
| Conversion (fire, bathroom, kitchen, licence) | £35,000 |
| Total in | £269,700 |
Rent (5 single rooms @ £550 pcm all-inclusive): £2,750 / month
Operating costs:
- Utilities: £500/mo
- Management (if used, 12%): £330/mo
- Repairs / voids reserve: £250/mo
- Licensing / insurance amortised: £100/mo
Net operating income: £1,570 / month = £18,840 / year
Gross yield (on purchase price): £33,000 / £220,000 = 15.0%
Net yield (after all costs except mortgage): £18,840 / £269,700 = 7.0%
Compare to single-family let (3-bed at £1,150/month): gross yield ~6%, net yield ~4.5%.
HMO premium: ~2–3 percentage points of net yield.
Top 5 HMO conversion mistakes in 2026
- 1Buying in Article 4 without pre-app. Planning refusal kills the project. £400 for pre-app advice is the best spend you’ll make.
- 2Underspecing fire doors. A carpenter will sell you £200 "fire-check" doors that don’t meet FD30 certification. Use certified sets with correct ironmongery and intumescent strips. Council licensing inspection will fail on this.
- 3Not checking the bathroom count. Check the council’s amenity standards for your number of occupants before you plan the layout; adding a bathroom later costs more than fitting it first time.
- 4Missing the licence renewal date. Letting a licensable HMO without a licence can mean prosecution and an unlimited fine, or a civil penalty of up to £40,000, plus a rent repayment order of up to 2 years’ rent. Put the renewal date in LetCompliance, the HMO management software that also runs the rent for each room, and confirm annually.
- 5Buying in a saturated student market without demand evidence. Check university term-dates, 6-month void risk, and Rightmove comparables before committing.
Where to go next
- HMO compliance guide: all HMO rules in one place
- Selective licensing UK 2026: whether your street needs a non-HMO licence
- Smoke & CO alarm rules England: the stricter rules from 2022
Get started. Once the works are signed off, the house still has to be let and run room by room. LetCompliance tracks the HMO licence renewal, keeps the fire-risk assessment and LACORS evidence in the property’s documents, and shows rent and arrears for each room, with arrears chasing if you switch it on. If a room falls badly behind, the Section 8 builder (Form 3A, paid plans) works out the arrears for you.
Sources and scope
- GOV.UK: House in multiple occupation licence
- GOV.UK: HMO, fire safety
- LACORS Housing: Fire Safety Guidance (industry standard)
- GOV.UK: Article 4 directions (planning)
- Legislation: Housing Act 2004 Part 2 (HMO licensing)
Every figure on this page is cited to GOV.UK, legislation.gov.uk or HSE and reviewed against the live source every quarter. This is guidance, not individual legal advice.
New Tenancy Document Checklist
What to give a new tenant in England, and when: before the tenancy is agreed, before they move in, and within 30 days of taking the deposit. With the source and the penalty for each.
- Written statement of terms before the tenancy is agreed
- Gas, electrical and EPC certificates before move-in
- Deposit protection and prescribed information within 30 days
- What not to give a new tenant any more
Frequently asked questions
What is the typical total cost to convert a family house into a 5-bed HMO?
Indicative 2026 ranges: £25,000–£60,000 depending on council area, starting condition and whether you need planning (Article 4). A representative mid-market 5-bed HMO conversion in a northern city: £35,000 (fire doors, interlinked alarms, extra bathroom, EICR upgrade, HMO licence, kitchen refresh, furniture). London and Article 4 areas add £10k–£20k due to higher trades and planning fees.
Do I need planning permission to convert a C3 house to a 4-person HMO (C4)?
Only in areas with an Article 4 direction, which now covers HMO areas in many cities (check the council’s planning pages for the exact boundary). Outside Article 4, C3 to C4 is permitted development. For HMOs over 6 occupants (sui generis), planning is always required. Check local policy before buying.
What fire-safety works are legally required in an HMO conversion?
Minimum standard (LACORS guide, current industry baseline): FD30 fire doors on all habitable rooms opening onto the escape route; hard-wired interlinked smoke alarms (mains-powered, battery back-up) throughout; heat detector in the kitchen; CO alarm in any room with a fixed combustion appliance (except gas cookers); 30-minute compartmentation between floors; emergency lighting on escape routes in HMOs over 2 storeys; and a documented fire-risk assessment. Expect roughly £5,000–£9,500 for these works in a typical 5-bed house.
Is HMO conversion still profitable in 2026 given mortgage rates?
Yes, but margin has compressed. In this guide’s worked example (five rooms at £550 a month, £35,000 of conversion work on a £220,000 purchase, £269,700 all in), the gross yield is 15.0% on the purchase price and the net yield about 7.0% on the total cost, after bills, management, repairs and voids but before mortgage costs. The same house let to one family nets about 4.5%, so the HMO premium remains real. It holds only if you avoid planning refusal, overestimate voids, and keep fire-safety upgrades under control.
