The Cost of Installing a Downstairs Toilet

All you need to know about installing a downstairs toilet including costs of materials, labour and time frames.

installing downstairs toilet

What the job entails

Traditionally, if you want to add some value to your home then you would normally be considering an extension, a conservatory or upgrading the kitchen. However, many will be surprised to learn that adding a downstairs toilet can add as much as 5% on to the value of your home. Don't think that this means you'll have to start building an extension to accommodate the new toilet, as usually downstairs toilets utilise space that you already have, such as under the stairs or perhaps a small spare room. Even if you don't have much space to play with, there are stylish modern bathroom units available which feature basins that are placed on top of the cistern, meaning that downstairs toilets can be installed in very small spaces indeed.

The key to keeping costs down when installing a downstairs toilet is to keep things simple, but you will need at least a small wash basin plus some sort of ventilation and a light source. The cost of having a toilet installed under your stairs can vary greatly depending on how much work is required. However small your new toilet may be, you still need to comply with all building regulations although planning permission may not be required unless you live in a listed building.

The main building regulation requirements concern having proper drainage and the safe installation of any new electrical fittings and circuits, but you will also need an electric fan if you do not have an exterior window. As a minimum, this job will entail new plumbing and drainage along with new electrical circuits, with a light fitting and perhaps an extractor fan. There will also be a need for a stud wall to a section of the bathroom plus of course a door to be fitted.

Utilising an existing space as a new toilet you may want to consider other related jobs at the same time. For example, once you have partitioned off the new room to be used as a toilet with a stud wall and door, you may find it necessary to redecorate as this brand new wall and a freshly painted door will make the surrounding decor look tired and grumpy. If you are adding a radiator then you need to check that the existing boiler can cope with this additional demand. If not, you could perhaps consider electric underfloor heating or simply installing an electric radiator.

It is possible to install a downstairs loo as a DIY project as long as you have some decent carpentry and plumbing skills, but you will need the services of an electrician to add a lighting circuit and an extractor fan if required. If doing this job DIY, you need to be very careful about planning and building regulations. Experienced contractors will be well aware of the regulations and know exactly what they should be doing, but the average DIY enthusiast will need a lot of guidance. If the available space is very small, even though it may be potentially possible to add a toilet, it could be worth considering adding an extension to make a decent sized bathroom downstairs, especially if the toilet is to be sued by a wheelchair user or someone with mobility problems.

This is a fairly straightforward job, though it can be labour intensive. Most of the problems which end up increasing the cost of the job are due to poor planning and failure to comply with building regulations in terms of drainage, space, ventilation or lighting. As with any project, time spent planning is rarely wasted, as the saying goes, measure twice and cut once!

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The Cost of Installing a Downstairs Toilet

The average material cost to install a toilet downstairs will depend on the cost of the toilet and basin you choose and any extra piping work required as well as additional features such as towel rails, shelving and hooks. A toilet and basin alone will cost between £200-£500 depending on quality.

The average plumber will usually charge around £100-£150 per day. To fit a downstairs toilet and basin, a plumber will often work on their own to complete the work and will take anywhere between 2-4 days. You might have to hire additional tradesmen to finish the job, such as flooring specialists, plasterers and decorators. The overall labour price will depend on your location and the duration the trade is working on the project.

Below are some estimated costs of hiring a plumber to fit a downstairs toilet:

Job Description Avg. Cost Duration
Small bathroom with toilet & basin £1500-£2000 7-10 days
Stud walls £150-£200 4-6 hours
Suppy & fit toilet & basin £400-£700 1-2 days
Fit a privacy window £150-£200 2-4 hours
Fit a bathroom extractor fan £150-£200 2-4 hours
Flooring £200-£300 4-6 hours
Plastering & decorating £300-£400 2-3 days

Cost Breakdown

Individual costs to Fit a Downstairs Toilet- Total Cost: £2,000






Waste Removal


You can increase the value of your home, avoid any queues for the toilet and they are also great for elderly or less mobile people as they will no longer have to go up and down stairs every time they need the loo.
Nowadays many councils will insist that any toilet installed downstairs will be fully accessible for wheelchair users. So the door-frame has to be wide enough for a wheelchair and there needs to be enough space to manoeuvre a wheelchair around. But always check directly with your local authority before making any plans!
You don't have to, but many do! But without a window, you will need an extractor fan plus of course lighting.
Typically this type of job will cost around '2,000 to '4,000 depending on the materials and fittings plus of course the labour. On average adding a new downstairs toilet will take about 10 days to complete.
Adding a downstairs toilet can make a home much better to live in and increase not just the value, but also the appeal and saleability of your house! As a general rule of thumb, expect a downstairs toilet professionally plumbed and installed to add around 5% to the property value.
When installing a conventional toilet it is necessary to lift floors and install plumbing to your current main drainpipe. However, Saniflo type macerating toilet systems are much easier to install compared to traditional toilet systems as when waste is flushed it is completely pulverized then pumped up to 150 feet away.
It is possible though not ideal. You would need to locate the underground foul drains and identify a suitable location for connection, or possibly connect new pipework internally. You could also choose to install a macerator which allows for smaller bore pipework so the waste can be pumped to a suitable connection.