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Downstairs Toilet Building Regulations Explained

Design Ideas

Adding a downstairs toilet was one of the best changes I made to our house last year.

Our guests were thankful, as they no longer had to open all the doors on the first floor before finding the bathroom.

More importantly, it has also helped save quite a few accidents for my kids.

The most complicated part of the process was understanding the relevant downstairs toilet building regulations.

I thought a brief summary of the building regulations might help those of you thinking about installing one yourselves.

A picture of a Colourful Down Stairs Toilet
Why not add the wow factor to your downstairs toilet with a little colour?

1. Building Regulations vs Planning

1.1. Planning permission

Planning Permission deals with both the appearance and design of the proposal, and the effect it will have on your house and neighbouring properties. It may be that in some cases you require both planning and building regulations approval, but the planning stage would typically come first.

When it comes to a downstairs toilet, if you’re planning on installing it within your house with no exterior changes, this would not require planning permission. If you want to include a new downstairs toilet as part of an extension you may require planning permission. If you’re not sure, you should ask for expert advice, as understanding downstairs toilet building regulations is key to knowing whether you need planning permission or not.

1.2. Building regulations

Building Regulations or Building Control Approval deals with the technical details of building works to ensure the health and safety of those in and around the building.

All new downstairs toilets require building regulations approval.

2. Downstairs Toilet Building Regulations

A picture of a modern and compact downstairs toilet
Less is more when it comes to downstairs toilets

2.1. Accessibility

A downstairs toilet should be fully accessible to anyone in a wheelchair. The minimum size is 70cm x 130cm. However, please bear in mind this is just a minimum standard. If you have a little bit more space to accommodate your downstairs toilet, our philosophy is, the bigger the better!

As downstairs toilets tend to be on the smaller side, we would always suggest that the toilet door opens outwards. A great alternative is also a pocket door. As these slide from side to side rather than opening outwards, they take up far less space.

2.2. Location

The previous rules stated that a downstairs toilet could not lead directly to a kitchen or living room, but these rules have now been relaxed. This is now permitted as long as the toilet includes a sink for handwashing (which the majority do). Ideally however, we would always advise that downstairs toilets lead out into your hallway even though downstairs toilet building regulations no longer demand it.

If your new downstairs toilet is being located under your stairs, make sure there is sufficient head height to stand up. We know some people are taller than others but we recommend the minimum height for the tallest wall to be 215cm. This will allow guests to use the space comfortably without stooping down.

2.3. Ventilation

Building regulations for downstairs toilets state that any bathroom must have a window, ventilation, or both. Given the nature of the space, downstairs toilets can be damp & humid places. From a practical point of view, it is therefore very important that any downstairs toilet is well ventilated.

Proper ventilation will not only limit condensation, but it will also help prevent the appearance of mould, which can lead to nasty health implications. Mould can also mean a lot more time spent cleaning, which is something we always like to avoid.

The final benefit of good downstairs toilet ventilation is that it also extends the longevity of both the paint and plaster. If this space is damp with poor airflow, the paint and plaster can begin to come away over time.

2.4. Drainage

Toilets also have to be connected to a waste pipe so, if possible, it will save labour by fitting the toilet to an outside wall so it can more easily be connected to the existing drainage system. Your Building Control Inspector will want to see that you have investigated where the drains are and that you have ensured that you have connected the waste from your new loo and sink, into a drain which is large enough to cope with the increased flow.


If you’re looking to create a new downstairs toilet but have questions about the best layout, design or downstairs toilet building regulations, why not arrange a free 30- min consultation with one of our architects?

We’re a super creative team and are always on hand to talk about your ideas and answer any questions you might have.

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