Garage Shower Room and WC Conversions in Liverpool

When does a garage shower room make sense?

Most requests for a shower room or WC in the garage come with another change. A ground-floor bedroom for a relative who can no longer manage the stairs needs a bathroom close by. An annexe needs its own facilities. A busy family with one upstairs bathroom wants a downstairs WC. Someone converting the garage into a gym wants to shower afterwards. In each case, the bathroom has to fit around the other room rather than take the best space.

Planning it as part of the wider design, rather than squeezing it in later, is something we do on many garage conversions in Liverpool and Merseyside. See our garage to bedroom and garage annexe pages if the bathroom will serve one of those rooms.

Drainage decides where the bathroom goes

A WC needs a large-diameter waste pipe with a steady fall to the drains, and showers and basins need their own trapped wastes. The questions we ask at the visit are:

• Where does the existing soil stack or drain run, and how far is it from the garage?
• Is there enough depth for the pipe to fall all the way, allowing for the new floor build-up?
• Is there a manhole or inspection chamber nearby that a new branch could join?
• Does any shared drain run under the garage, which may need checking with the water company?

Raising the garage floor to the house level often helps, because it creates space under the floor for the pipes to fall. Where gravity drainage is not possible, a pump-assisted macerator is sometimes used for a WC, but it has limits and building control should be asked before it is chosen. All new drainage is part of the Building Regulations approval under Part H. Our plumbing and heating page covers the pipework in more detail.

Extract ventilation and condensation

A shower room or WC needs mechanical extract ventilation, and building control will confirm the requirements. The fan needs a duct route to outside, through the infill wall, an existing wall or the roof, which is easiest to plan before ceilings and linings go up. In a garage, the walls and roof must also be well insulated, otherwise warm, damp air from showers will condense on cold surfaces and cause mould. That is one of the most common faults we find in older conversions, as our garage conversion problems guide explains.

Electrics in a shower room

Bathrooms are treated as special locations in the wiring regulations (BS 7671), with zones around the shower that limit what can be fitted where and require suitable protection. Lighting, an extract fan, a heated towel rail, a shaver socket or an electric shower all need to be planned around those zones. This is notifiable work under Part P, carried out by a registered electrician who issues an Electrical Installation Certificate. Our electrics for conversions page explains the paperwork.

Waterproofing, floors and level access

A shower tray needs a waterproof seal to the walls, and a wet room needs the whole floor and lower walls tanked with a waterproof membrane, with the floor laid to fall towards the drain. In a garage the new floor build-up of membrane, insulation and screed or timber can be designed to allow for this. A level-access shower is worth considering for anyone with limited mobility, and wider doors and space for grab rails later can be planned at the same time.

Hot water and heating

A new shower draws on the hot water supply. With a combi boiler, the flow rate matters: a boiler that copes well with one upstairs shower may struggle if two are used at once. With a cylinder system, the stored volume matters. An electric shower is sometimes chosen to avoid relying on the boiler, but it needs its own dedicated circuit. A heated towel rail or radiator from the existing system keeps the room warm. Any gas work must be done by a Gas Safe registered engineer.

Windows and privacy

A shower room in the garage is often at the front of the house, where the garage door used to be. Obscure glass in the new window gives privacy while still letting in light, and it needs to open for ventilation. A shower room is not usually an escape route, so the escape window rules that apply to bedrooms do not normally apply here, but building control will confirm for your layout.

Homes where this works well

Larger homes in Southport's suburbs and in West Kirby and Bebington often have a side garage close to the kitchen drains, which keeps the waste run short. Detached garages need more work because new drainage has to cross the garden. If the shower is for after exercise, our garage to home gym page covers combining the two.