En-suite bathrooms
Command £50 - £100 more per room each month and cut disputes over shared bathrooms.
HMO Investment
HMO refurbishment costs & ROI in Cardiff
What a Cardiff HMO conversion really costs, where the money goes, what actually adds value, and the room standards you have to hit - with a quick budget estimator.
Budget around £10k - £15k per room
A useful benchmark for a Cardiff HMO conversion is roughly £10,000 to £15,000 per room - so a typical project lands between £40,000 and £120,000 depending on the property's condition, the number of rooms and the spec you're chasing. A sound house needing only light work can come in lower; en-suite, premium conversions cost more. The trick is spending where it earns its keep.
Breaking that benchmark down reveals where the money tends to go. Fire safety works — alarms, emergency lighting, fire doors and intumescent strips — are non-negotiable in a licensed Cardiff HMO and typically account for 10 to 15% of the total budget. Kitchens, bathrooms and en-suites take the biggest share, often 25 to 30%, because shared wet rooms are the spaces tenants scrutinise most. Electrics, heating and plumbing follow, particularly if the property needs a consumer unit upgrade or a new gas-safe boiler. Professional fees — a building regulations application, a structural engineer where walls are removed, and a management fee for the project — add around 5% on average. Budget a contingency of at least 10% on top: older Cardiff terraces regularly surface surprises once walls and floors are opened up.
The return side of the equation is what makes the numbers attractive to investors. A well-converted, well-managed Cardiff HMO can generate significantly higher gross yields than an equivalent single-let — frequently cited in the 8 to 12% range, depending on the purchase price and the room rents achieved. The key driver is the rent-per-room model: Cardiff's student and professional tenant demand is deep enough, particularly in Cathays and Roath, that strong rooms let quickly and stay let. Investors who plan the refurbishment carefully — building compliance, room sizes and specification to the right level for their target tenant — consistently outperform those who cut corners on the fit-out and then struggle with voids.
Where the money goes
A typical refurb budget
Illustrative split of a Cardiff HMO conversion budget. Bathrooms and kitchens take the biggest share.
- Kitchens, bathrooms & en-suites30%
- Electrics, heating & plumbing20%
- Bedrooms & partitions20%
- Fire safety15%
- Communal areas & decor10%
- Fees & contingency5%
Try it yourself
Refurb cost estimator
A ballpark for budgeting. Pick the number of rooms and the spec to estimate the conversion cost.
Estimated conversion cost £0
A rough guide only - condition, layout and finishes all move the number. Ask us for a proper quote.
Spend where it counts
What adds the most value
Ranked by impact on rent, void periods and resale.
An extra lettable room
More rooms means more income from the same building - often the single biggest lever.
A bright, modern shared kitchen
The space viewers remember. A good kitchen lets rooms faster and holds tenants longer.
Storage and a desk in every room
Professionals and postgraduates expect it. Well-fitted rooms reduce voids.
Kerb appeal & communal space
First impressions and a usable lounge help rooms let quickly.
Cosmetic decor alone
Necessary and worth doing well, but won't move the rent on its own.
Hit the standards
Cardiff room & amenity standards
The minimums you have to meet for licensing. Build above them where you can.
6.51 m² Single room
Minimum for one adult. Aim for 10 - 12 m² to let faster.
10.22 m² Double / couple room
Minimum for two adults sharing.
25 m² External amenity
For up to 6 persons, plus 2.5 m² per extra person.
1 per 5 Shared facilities
Roughly one kitchen and bathroom set per five occupants.
Common questions
HMO refurb FAQs
How much does it cost to convert a property to an HMO?
Budget roughly £10,000 to £15,000 per room as a benchmark, so a typical conversion runs from around £40,000 to £120,000 depending on the property's condition, the number of rooms and the spec. A sound property needing light work can be nearer £8,000 to £12,000 per room; en-suite, premium conversions cost more.
Do en-suites add value to a Cardiff HMO?
Yes - they are usually the strongest value driver. An en-suite adds roughly £3,000 to £8,000 per room to the build cost but can command £50 to £100 more per room each month, lets rooms faster and reduces friction over shared bathrooms.
What are the minimum room sizes for a Cardiff HMO?
A single-occupancy bedroom must be at least 6.51 m², and a room for two adults at least 10.22 m². Rooms of 10 to 12 m² tend to let faster and stay occupied longer. Cardiff also sets external amenity space and shared-facility standards for licensing.
What return can I expect from an HMO refurbishment?
Done well, HMO conversions are often cited as delivering a 15 to 20% return, driven by higher per-room rents and, where a property is valued on a yield basis, an uplift in capital value. The actual return depends on your costs, the rents you achieve and how the property is valued - take advice before you commit.
Sources & method
Conversion cost benchmarks are drawn from 2026 UK HMO conversion cost guides; room sizes and amenity standards from Cardiff Council's HMO Licensing and Supplementary Planning Guidance (single room 6.51 m², couple room 10.22 m²). The budget split and estimator are illustrative - real costs depend on the property. Last updated 20 May 2026. General information, not a quotation or financial advice.
Planning a conversion?
Get the refurb right the first time
We help Cardiff investors spec, cost and manage HMO conversions that meet the standards and let fast. Tell us about the property.
Thank you for getting in touch
We've received your enquiry and a member of the team will be in touch shortly.