How much does an HMO conversion cost in 2026?

HMO conversions are the highest-value, most complex deals most investors will run — and the ones where the budget most often goes wrong. The reason is almost always the same: the compliance pack gets under-costed.

Here's a realistic picture for 2026.

The headline number

For a typical 5–6 bed HMO conversion, expect somewhere between £40,000 and £100,000+, depending on the starting condition, the number of en-suites, the number of storeys (which drives the fire-alarm grade), and your region. That's a wide range because HMOs vary enormously — but the shape of the cost is predictable.

Use the HMO conversion calculator for a figure tailored to your property.

Where the money goes

Room works (~£12–15k per room). Strip-out, layout reconfiguration, electrics, plastering, flooring and decoration — a share of this lands on every lettable room.

En-suites (~£2,200–£4,500 each). They raise rents and valuation, but each one adds drainage runs and ventilation. Per-room en-suites are increasingly the market standard.

A kitchen sized to occupancy (~£3,500–£8,000). Councils set minimum kitchen facilities per sharer — extra units, worktop, hob rings and fridge/freezer capacity. Budget for more than a standard BTL kitchen.

The compliance pack — the bit people forget

This is where HMO budgets blow up. Valuers and licensing officers scrutinise it, so a lender wants it costed:

• FD30(S) fire doors (~£320–£650 fitted) to every bedroom plus communal and escape-route doors.
• Fire detection to the right grade. A smaller two-storey HMO might need a Grade D1 system (£900–£1,600); a three-storey property usually needs a Grade A system (£3,500–£6,000) with a panel, sounders and certification. That jump is the single biggest swing factor — see our HMO fire-safety cost guide.
• Emergency lighting on escape routes (commonly required on 3+ storeys).
• Fire-stopping and compartmentation, a fire risk assessment, signage and extinguishers.
• An EICR and the HMO licence fee (£500–£1,600+, varying by council).

Contingency and finance

Run a 15% contingency on an HMO — they hide more surprises than a plain refurb. And remember the holding cost: if you're on a bridge, every extra week on site is interest.

The bottom line

An HMO stacks up when the spec lifts the valuation (and the rent) by more than the cost — and when nothing in the compliance pack is forgotten. The investors who come unstuck are almost always the ones who budgeted a domestic smoke-alarm package and got a Grade A quote, or who missed the en-suite drainage.

ScopeWise auto-includes the full HMO compliance pack and warns you if a mandatory category is missing, then builds it into a lender-ready schedule. As always, confirm the detail with your local council — HMO standards vary by authority.