A downstairs cloakroom is one of the most practical additions you can make to a family home. It takes pressure off the main bathroom during busy mornings, impresses visitors, and adds genuine value to your property. Yet many homeowners overlook the possibility because they assume they do not have the space, or that it will be too expensive or complicated.
In reality, a cloakroom conversion can be achieved in a surprisingly small footprint, is relatively straightforward when the drainage situation is favourable, and offers an excellent return on investment. Having fitted cloakrooms across Surrey, Sussex and Kent, here is everything I know about making it work.
Minimum Space Requirements
The most common question is: do I have enough space? The short answer is probably yes, if you have an under-stair cupboard or a redundant ground-floor storage room.
The absolute minimum for a functional cloakroom is 900mm wide by 1200mm deep. This is tight, but achievable with the right compact fixtures. A wall-hung toilet with a concealed cistern (which sits inside the wall thickness rather than protruding into the room) combined with a small corner basin can fit into this footprint.
A more comfortable cloakroom is 1000mm wide by 1500mm deep or larger. This gives enough room to move easily, fit a slightly larger basin with storage below, and have proper ventilation. The most popular conversion in my experience is the under-stair cupboard — typically around 1200mm wide and 1500–2000mm deep — which is ideal.
The angled ceiling in an under-stair space needs thought: you need at least 2000mm of clear head height over the toilet position, and the sloped section can be put to use as a recessed shelf or coat hook area.
What Does a Cloakroom Conversion Involve?
Converting a cupboard or storage space into a cloakroom is a multi-trade project. The main elements are:
- Drainage — connecting a new toilet waste pipe and basin waste to the existing soil stack or ground-level drainage. This is the most variable element. If the space is close to an existing soil stack, drainage is straightforward. If the stack is on the other side of the house, longer waste runs add cost and complexity.
- Water supply — running cold water (and hot if needed) from the nearest pipe. Usually relatively simple.
- Stud walling — if the space is open, a new partition wall creates the enclosure and houses the concealed cistern frame (if using a wall-hung toilet).
- Electrical — a fused spur for the extractor fan, lighting, and potentially a heated towel rail. All bathroom electrical work must comply with Part P building regulations.
- Ventilation — a cloakroom with no external window requires mechanical ventilation. Building regulations require a minimum extract rate of 6 litres per second for an intermittently used WC. This is usually achieved with a small inline fan venting to outside.
- Finishing — tiling, plastering, painting, and fitting the sanitaryware, basin, mirror, and accessories.
Typical Cloakroom Conversion Costs in 2026
Costs vary depending on drainage complexity, the fixtures chosen, and the amount of structural work required. Here is a realistic guide for the Surrey, Sussex and Kent area:
| Item | Typical Cost | Notes |
|---|---|---|
| Drainage and plumbing | £500 – £1,200 | Depends on proximity to soil stack |
| Stud walling & boarding | £300 – £600 | Includes frame for concealed cistern |
| Electrical (fan, lighting) | £250 – £500 | Must be Part P certified |
| Sanitaryware (toilet & basin) | £200 – £800 | Wide range; wall-hung costs more |
| Tiling (floor & walls) | £300 – £700 | Includes tiles and labour |
| Labour (fitting) | £600 – £1,200 | 3–5 days for a standard conversion |
| Total (typical range) | £2,500 – £5,000 | Most cloakroom conversions fall here |
A higher-end cloakroom with premium sanitaryware (branded wall-hung toilet, designer basin and mixer tap, bespoke tiling) can reach £6,000–£8,000. The biggest single variable is usually drainage — if the space requires a macerator pump (Saniflo-type system) to pump waste uphill to the soil stack, add £600–£900 for the unit and installation.
Space-Saving Fixtures
The right fixtures make a compact cloakroom both functional and comfortable. These are the options worth knowing about:
Wall-hung toilets with concealed cisterns are the gold standard for small cloakrooms. The pan projects roughly 500mm from the wall (compared to 700mm+ for a close-coupled toilet), which recovers meaningful floor space. The cistern sits inside the wall within a steel frame, making cleaning easy and giving the room a sleek, minimal appearance.
Corner basins mount diagonally across a corner, making use of space that would otherwise be wasted. They are typically smaller than wall-hung basins but perfectly functional for hand-washing. Combined with a mixer tap that folds flat, they can fit into very tight spaces.
Wall-mounted basins without a pedestal or vanity below create a sense of more floor space in a small room. A simple shelf or small wall cabinet above provides somewhere to place soap and a hand towel without taking up floor area.
Slimline heated towel rails (300mm wide) provide warmth and somewhere to hang a hand towel without projecting far into the room.
Ventilation Requirements
Ventilation is non-negotiable in a cloakroom, and Building Regulations Approved Document F sets out the requirements. A WC without openable windows must have mechanical extract ventilation capable of at least 6 litres per second. In practice, this means a small axial fan (or a larger inline fan venting through the ceiling or wall to outside) that activates when the light is switched on and runs on a 15–20 minute overrun timer.
Failing to install adequate ventilation leads to condensation, mould, and potential building regulations issues if you sell the property. It is a modest addition to the project cost and absolutely worth including.
Tiling and Decoration Ideas
A cloakroom is a small canvas, which means you can afford to be bolder with the design than you might be in a larger room. Dark walls, patterned floor tiles, and statement mirrors all work well in a compact space where the effect is absorbed quickly rather than becoming overwhelming.
Popular approaches we have fitted recently include: full-height subway tile with a contrasting dark grout; large-format matt stone-effect porcelain floor with a painted and panelled wall; and encaustic-style patterned floor tile with simple white wall tiles that let the floor do the talking.
Mirrors are particularly useful in a small cloakroom. A large mirror above the basin bounces light around the room and makes it feel significantly less confined. Backlit LED mirrors add a practical and atmospheric element.
Does a Cloakroom Conversion Add Value?
Yes, measurably. Estate agents consistently report that a downstairs WC is one of the features buyers prioritise in family homes. In the Surrey and Sussex property market, where competition for well-presented homes is strong, a cloakroom can add between 1.5% and 5% to a property's value — often significantly more than the cost of the conversion itself. It also makes the property easier to sell and helps it stand out to buyers with children or elderly relatives.
Planning Permission and Building Regulations
For most cloakroom conversions within the existing footprint of a house, no planning permission is required. It falls under permitted development. The exception is listed buildings or properties in conservation areas, where you should check with your local planning authority before starting work.
Building regulations approval is required for the drainage connection and electrical work. Your fitter can arrange a building notice submission as part of the project, or apply for approval through a private approved inspector. The cost is usually modest and is included in a good fitter's quote. A completion certificate, issued when the work passes inspection, is important for your records and will be requested by solicitors when you sell the property.
Cloakroom Conversion: Key Checks Before You Start
- Measure the space carefully — minimum 900mm wide by 1200mm deep, ideally larger. Check ceiling height over the toilet position.
- Locate the nearest soil stack — the closer, the simpler and cheaper the drainage run.
- Check for a nearby cold water pipe — usually straightforward to extend.
- Confirm ventilation options — where can a fan vent to? Through an external wall or up through the ceiling?
- Consider a wall-hung toilet — the space saving is significant in a compact room and it looks considerably better than a traditional close-coupled unit.
- Budget for building regulations — a building notice and completion certificate protect you when you sell.
Thinking About Adding a Cloakroom?
HGN Bathrooms offers free site visits and no-obligation quotes for cloakroom conversions across Surrey, Sussex and Kent. Haydn will assess the space, discuss your options, and give you a clear, itemised quote. Call 01293 804 790 or use the form below.