How to add a loft en suite

A loft en suite will make a bedroom in a loft conversion far more practical and desirable. Renovation expert Michael Holmes offers advice on layout, lighting, ventilation, plumbing and heating

Loft en suite bathroom with an Optima bespoke shower by Coram Showers
(Image credit: Coram)

A loft en suite as part of a master bedroom is a brilliant use of space, sure to add to the value and appeal of your home. If you’re converting your loft space to create additional bedroom accommodation, it makes sense to incorporate en suite bathroom facilities on the same floor for convenience. This will also maintain a good bathroom to bedroom ratio as you up the number of rooms.

A bathroom need not take up much space, but it is important to make sure that the space allocated has sufficient headroom for features such as the WC, basin and shower to function comfortably.

Planning a loft en suite layout

Start your en suite project with a scale floorplan of the loft space and mark a dotted line showing where the ceiling height reduces down to 1.8m, 1.6m and 1.4m. This will enable you to plan where the bed and other furniture can go while leaving sufficient full-height space for you to move around and it will show the space left to create the bathroom.

Putting in a dormer window can create extra headroom, but if this is not possible, a rooflight can still add 150mm — which can make all the difference over a WC or basin.

When it comes to choosing sanitaryware, decor and bathroom storage, it may help to follow the same design principles as you would for a small bathroom.

  • The bathroom will typically be formed using timber studwork, clad in marine ply and tile backing board (inside) and plasterboard (outside), with the voids filled with acoustic insulation.
  • Metal frames are available to build into stud walls for a wall-mounted WC with a concealed cistern, or a wall-mounted basin.
  • The voids between the studs are ideal for concealing the plumbing, soil pipes, wiring, concealed cistern and mixers for taps and showers
  • You may even be able to use voids in stud walls for forming storage niches.

loft conversion bathroom with fittings from

(Image credit:

How much will a loft en suite cost?

A loft en suite may cost slightly more than your average bathroom as plumbing needs extending and waste pipes adding in. Remember to factor in added labour and material costs. 

Another factor that could impact the cost of your new loft bathroom is the need for fittings and sanitaryware that will work within an unusual footprint and with sloping ceilings. Find out how to cost your bathroom for more information.

How much space do you need for a bathroom?

A shower room will fit into a space measuring only 1m by 2.6m, with a WC, basin and a 900mm square shower tray – full headroom is required here, but the ceiling can start to slope down over the WC cistern. A bathroom will need at least 1.7m by 2.3m floor area to incorporate a WC, basin and standard bath. The ceiling height can be reduced over one end of the bath or the side of the bath, and behind the cistern, so it is sometimes easier to fit a bath into a loft room than a shower.

En suite lighting and ventilation

It is not essential to have a window in a bathroom, but if it is possible it is desirable. Planning permission isn’t usually an obstacle for a small dormer window or gable window, providing you use obscured glass and no part of the window opens below 1.7m. Ventilation is essential to meet the building regulations, so an extractor fan will be needed to provide both background and rapid extract ventilation.

loft en suite bathroom with grey and white chevron tiles and a blue freestanding bath

Worcestershire-based interior designers Cream & Black used a neutral backdrop and added accents of colour to make this en suite fun and playful. They combined contemporary finishes, such as the concrete basin from Kast Concrete Basins, with traditional style brassware and a cast iron bath painted in Farrow & Ball Pitch Blue no. 220

(Image credit: Cream & Black)

Planning the plumbing

Get to know your home's plumbing, then mark on your floorplan where any existing soil pipes for bathrooms on lower floors are located, as it will be easier to connect the new en suite to one of these than to put in a new soil pipe. Although this may also be possible, depending on the location of the drains outside — look for the inspection chambers or talk to a plumber. Our guide to bathroom plumbing will help you get to grips with any potential issues.

Connecting water and drainage

  • If you can’t connect into a soil pipe, you can still create a bathroom anywhere in the loft and connect it using flexible small bore waste pipes and a pumped unit with a macerator.
  • Hot and cold plumbing can be branched off from an existing bathroom on the floor below, and the pipes hidden in a service duct, or in the back of a cupboard. Flexible plastic plumbing can make retrofitting far easier than rigid copper pipe.
  • If your plumbing works from a header tank, this will need to be moved higher than the loft bathroom taps or showerhead to create pressure.
  • It is possible to use a flush shower tray, or walk-in shower tray in a loft bathroom, but the floor level may need to be built up to accommodate the waste trap.
  • For a walk-in shower, it is best to use a pre-formed tray with an integrated trap and to tank the whole floor, dressed up the walls by 100mm, so that the water can only escape down the trap.

You may need to fit a mains pressure plumbing system, with either a combi boiler providing instant hot water on demand, or a boiler and unvented cylinder. A mains pressure system requires at least 1 bar of pressure — enough to lift water 10m. If the local mains pressure isn’t adequate, water could be pumped from a coffin tank to create the necessary pressure.

Heating for loft bathrooms

A radiator towel rail is usually sufficient to heat a small bathroom, but it is nice to have underfloor heating too, especially if your floor is tiled. Electric underfloor heating mats are inexpensive (around £100 for 6m²) and will only raise the floor level by 3-4mm, so they can be laid beneath tiles.

Read more about bathroom design: