Perhaps you have  a cupboard under the stairs that doesn’t get much use and you’re tempted to install a downstairs toilet? Perhaps you have an especially large master bedroom and you fancy an ensuite bathroom? If this sounds familiar, read on!

While we know that adding a bathroom can make you some serious money in a matter of days, it’s also important to do your research so you’ll know what to consider before taking the plunge.

Converting a cupboard under the stairs into a downstairs

  • Potential value added: £26,700 to an averagely priced home in Surrey
  • Time taken to complete: Seven days
  • On average, it will cost: £2,600

What to think about before you start

Is it viable?

An under stairs toilet can be squeezed into surprisingly small cupboards, but before getting carried away you’ll need to see if the plumbing is viable in your cupboard. A plumber will be able to tell you where your current soil pipes are and whether a new pipeline will be necessary to link it up correctly. It pays to be in the know about this as you might have to lift up floor boards to link your pipe. Alternatively, you could install a more expensive macerating toilet which allows the unit to be linked to a normal pipe that's been tied into the main drain line.

Head room

Under the stairs, the ceiling height may be limited. A good tip is to position the basin against the tallest wall and place the toilet under the slope of the stairs.

Is there room for a door?

Many under stairs cupboards open on to narrow hallways. If your door swings open on a hinge this will take up valuable hallway space. Instead you could opt for a sliding door which can either roll into a space in the wall next to your cupboard or across to one side.


According to building regulations, all toilets need to have ventilation. Without a window, you will need to install an extractor fan.


In small spaces such as cupboards under the stairs, should consider using light, bright colours for your walls to give the appearance of a bigger space. Mirrors above the sink also give an impression of a larger space. Good lighting will also help to keep the room feeling bright and airy. Tiles can be wiped clean and are therefore a practical surface to have around the basin to avoid splashing the walls. A good space-enhancing tip is to keep the same flooring that is in the hallway into the toilet.

Converting part of the master bedroom into an ensuite

  • Potential value added: £14,500 to an averagely priced home in London
  • Time taken to complete: Eleven days
  • On average, it will cost: £4,700

What to think about before you start

Do you have the space?

An ensuite can be a fantastic and luxurious addition to a master bedroom. You should weigh up space and practicality before embarking on this project. We know from speaking to various estate agents that sectioning off part of your master bedroom to form an ensuite is only advisable if your room is very large. You will not add any value to your house if you leave a very small master bedroom.

Consider alternative space

If you’re concerned that sectioning off part of your bedroom will leave two very small rooms, perhaps consider sacrificing another part of your home for an ensuite instead. If you have a small spare unused room or box room next to your bedroom, the space might be handier as a bathroom that is used every day.

Keep it light and bright

If you’re set on sectioning off part of your bedroom to form an ensuite and are left with a bathroom without a window, frosted glass could stop the room feeling dark. A wall of opaque glass between the bedroom and the bathroom will allow maximum daylight while maintaining privacy.

The logistics

You may not need planning permission to fit an ensuite but it will more than likely need Building Regulations approval to make sure wiring, windows, ventilation and drainage comply. Much like in an under stairs toilet, you will also need to think about plumbing. Look into how simple it is to redirect supply and waste pipework.

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