Why a Utility Room Makes Sense in a London Extension
Many London terraced houses have the washing machine in the kitchen, a tumble dryer balanced on top, and no dedicated space for ironing, cleaning products, or outdoor coats and shoes. A utility room — even a small one — relocates these functions and transforms the kitchen into a cleaner, quieter, more focused cooking space.
In the context of a rear extension, a utility room is often positioned at the back of the original kitchen footprint or as a separate room adjoining the new extension. Because it typically connects to the existing drainage and services position, it minimises new service runs.
Minimum Sizes and Layouts
A utility room can function effectively in as little as 2.5–3 square metres if planned carefully. Common configurations:
Galley Utility (1.8m × 1.4m minimum)
Units on a single wall: washing machine, tumble dryer, tall storage. Sink in the corner. Door at one end.
L-Shape Utility (2.0m × 2.5m)
Washing machine and tumble dryer under-counter on one wall. Sink, storage, and space for ironing board on return wall.
Full Utility (3.0m × 2.5m)
Space for washing machine, tumble dryer, utility sink, fridge-freezer, boiler cupboard, boot storage, and drying rack or airer.
Key Design Elements
Plumbing
A utility room requires:
- Cold water supply (for the washing machine and sink)
- Hot water supply (for the sink)
- Waste connection (washing machine waste and sink waste)
Position the units against the wall closest to the existing drainage to minimise pipe runs.
The washing machine trap should be at 650mm height for direct connection from the machine's outlet hose.
Drainage
Most utility rooms drain by gravity to the existing drainage system. If the extension is at a lower level than the existing drainage, a pump may be required.
Where the room connects to the rear garden, a floor drain with a trap is useful — it allows the room to be hosed out and prevents flooding if the washing machine floods.
Ventilation
Tumble dryers require ventilation unless you are specifying a heat pump (condenser) dryer, which produces no duct requirement:
- Vented tumble dryer: Requires a 100mm duct through the external wall
- Heat pump tumble dryer: No external vent — recirculates air internally. Preferred in an extension where external ducting would complicate the wall build-up.
Utility rooms also produce moisture from wet laundry, washing machines, and sinks. A mechanical extractor (continuous running at low rate) helps control condensation.
Electrical
A utility room typically requires:
- Double sockets at 200mm above worktop height for appliances
- A dedicated 16A or 20A circuit for the washing machine
- A separate dedicated circuit for the tumble dryer (if electric vented) or combined with the washing machine if heat pump type
- A socket for the iron at a convenient height
- Lighting (LED downlights or surface fitting)
All electrical work must comply with Part P Building Regulations.
Flooring
Utility rooms need a practical, water-resistant floor. Options include:
- Ceramic or porcelain tile (hardwearing, water-resistant, easy to clean)
- Vinyl or LVT (warmer underfoot, comfortable to stand on for ironing)
- Concrete screed (can be sealed or painted)
Avoid engineered timber or laminate — spills and moisture will damage them over time.
Storage
The utility room works best with:
- Full-height larder-style storage for cleaning products, laundry items, and consumables
- A coat hook rail and boot storage bench near an external door connection if the utility links to the garden
- Overhead cupboards above the worktop for infrequently used items
- A hanging rail for air-drying delicate items
Sink
A deep Butler or Belfast sink is functional and popular in utility rooms — large enough for soaking, cleaning mops, or filling buckets. A single-bowl is sufficient for most households.
Utility Room as Boiler Cupboard
Where the extension relocates the boiler (as often happens when the kitchen moves), the utility room is a natural home for the boiler. Ensure:
- Adequate ventilation for the boiler (if required — most modern sealed-system boilers are room-sealed)
- Access for boiler maintenance
- Condensate pipe route to drainage
RCB Design & Build
RCB designs and fits out utility rooms as part of extension projects, coordinating the plumbing, electrical, and fitting specifications within the main contract. We help clients maximise the function of even small utility footprints with practical layout planning.