In short: An HMO extension adds space to a shared house, usually a ground-floor bedroom with ensuite or a bigger communal kitchen. Across Caerphilly, the work is planned around Wales’s HMO rules and the standards the local council publishes.
- Nation
- Wales
- Pricing region
- Wales
- Postcode areas
- CF
- Main towns
- Caerphilly, Gelligaer, Blackwood, Bargoed, Nelson (Caerphilly)
What do extensions for extra rooms in Caerphilly involve?
- Party wall coordination where needed
- Ensuite drainage and extraction
- Planning route check and drawings
- Heating, insulation and glazing
- Fire separation and detection extended to the new space
- Building control completion
Which rules apply in Caerphilly?
- 3–6 sharers is use class C4, and in Wales changing a house to C4 always needs planning permission; only C4 back to C3 is permitted development.
- Building regulations cover structural work, partitions, drainage, fire-resisting construction and electrics; confirm with building control whether the conversion is a material change of use.
- Council HMO standards and the fire risk assessment set detection, fire doors and escape routes.
- Kitchen and bathroom ratios are set in each council’s HMO standards.
- More than 6 sharers is a sui generis HMO and needs planning permission; councils such as Cardiff apply concentration limits.
Welsh councils set their own HMO standards and may run additional licensing. In Wales, changing a house to a C4 HMO always needs planning permission, so check planning first.
How much do extensions for extra rooms cost in Caerphilly?
| Item | UK typical | Local guide | Per |
|---|---|---|---|
| Single-storey extension, about 15 m² | £35,000 – £60,000 | £32,900 – £56,400 | project |
| Single-storey extension per m² | £1,800 – £4,000 | £1,700 – £3,750 | m² |
Typical time on site: 8–14 weeks. For a figure for your house, try the guide-price tool.
Extensions for extra rooms by town in Caerphilly
Questions about extensions for extra rooms in Caerphilly
Can I extend an HMO under permitted development?
Some extensions to houses are permitted development, but rules differ for HMOs and by nation and council. We check the address before design.
Is a kitchen extension worth it?
Often, when the existing kitchen limits how many people the council will allow. A bigger kitchen can unlock an extra room.
Do you carry out extensions for extra rooms across Caerphilly?
Yes, across the whole of Caerphilly, including Caerphilly, Gelligaer, Blackwood.
Who licenses HMOs in Caerphilly?
Caerphilly council licenses HMOs in its area. Landlords must also register with Rent Smart Wales.
Other HMO services in Caerphilly
- Loft conversions for extra rooms in Caerphilly
- Communal kitchen refits in Caerphilly
- Layout changes and room reconfiguration in Caerphilly
- Large HMO conversions (7+ sharers) in Caerphilly
- Ensuite installation in Caerphilly
- House to HMO conversion in Caerphilly
- Sound insulation in Caerphilly
- Bedroom upgrades and room refits in Caerphilly