A bathroom sink displayed on a store shelf. Some shoppers and a salesman are in the background.

Price Guide: How Much to Build a Downstairs Toilet Extension?

It’s time to add a new toilet to the downstairs floor of your home. You’re tired of waiting to use the bathroom suite upstairs so the planning for the extension begins. But, where to start? And, how much will the extension set you back in terms of costs? The great news is that planning to build and set aside a budget for a downstairs toilet extension isn’t all that complicated. With some careful consideration and choosing the products ahead of time, you can ensure that the cost of an extension toilet is going to be more than manageable.

Below, you’ll find all the guidance you need for the building costs of a toilet extension. From looking at the construction cost to the building work that’s going to be involved, proper planning is certainly key as you will come to see. Allow us to help you plan the extension cost of your new downstairs toilet…

Basic Cost of an Extension

When calculating the new cost of a downstairs toilet, you’re going to have to factor a few things in. The overall total costs amount to the labour cost and materials that are going to be used. A new bathroom can cost you in excess of £6,000 depending on how luxurious your new fixtures and fittings are. On the contrary, a smaller and more basic downstairs toilet can be built for well under £1,000.

When you plan the extension cost, it’s a good idea to start with a basic amount you are comfortable spending. In addition to this, you should also set aside more cash in case you run into any complications. This could be for planning permission issues or waste disposal that crops up. Always budget more than you need as this can save your back when it comes to building a new bathroom in your home.

Why Invest in Bathroom Extensions?

A bathroom extension can add immense value to your property, making it more appealing to buyers. Even if you are not looking to resell your home, a downstairs toilet can also bring about practicality as in larger families there should always be more than one bathroom available.

If you don’t have somewhere to carry out laundry tasks, a bathroom extension can also double up as a utility room, providing you with a dedicated area to wash and dry clothes. Bathroom extensions are always a great investment where they can be afforded due to their overall appeal. They ensure that everyone in the family has a place to go when needed and work as an ideal starting point for increasing your home’s sale price.

Considerations for Calculating the Cost for Extension

As mentioned above, there are a number of considerations to think about when calculating the cost of your new bathroom. Depending on the size of the extension and whether you want it to be a toilet room or fully kitted bathroom, you will need to take measurements to create a clear job description.

Of course, the difference in price will also come with choosing the fixtures and fittings to be installed. If you want to create a wet room for after gym activities, for example, that will cost far less than a freestanding tub in an en-suite. No matter your budget, it is possible to predict the price of the cost of bathroom extensions, here’s some handy information to help you complete the job:

A 2×2 extension

Budget – removal £200, suite £500, tiling £300, extra elements £100, labour £900 = total cost of £1,900

A 3×3 extension

Standard – removal £400, suite £,1000, tiling £600, extras £300, labour £1,500 = total cost of £3,800

A 4×4 extension

Luxury – removal £600, suite £2,000, tiling £1,000, extras £800, labour £3000 = total cost of £7,400

As you can see from the calculation guidance above, a bathroom extension can cost homeowners anywhere between £1,900 and £8,000. Of course, there are means and ways to reduce the costs, but this would likely mean compromising on one of the areas outlined above.

Cost Calculators

If you require a more specific outlining of the cost of your planned extension, there are a range of calculator tools that can be used online. This is an easy way to work out the exact measurements of the area vs the work needed to complete the job.


If you choose to go with a budget bathroom you will certainly save money but the quality of your overall bathroom may be lacking. When it comes to your budget, you really do get what you pay for and this is especially true for an interior design job.

From large fixtures such as showers to the plumbing and lighting fittings, there are lots of things to tick off the list. Choose to spend less and the overall quality of the labour could also slack, this can be found in many builder companies which use poor materials to finish aspects such as the tiling work.

Materials Used

The materials used will impact what you can expect to pay for your bathroom extension. The cost of extension materials can greatly vary depending on whether you have a low, average, or high budget. You’ll also need to factor in work such as plumbing which may require more technical materials and the costs for extending your home.

There are obvious means by which you can save when it comes to your bathroom extension work. By choosing lower-priced materials such as tiles, you can allocate more of your budget to the work required.

The bottom line is if you’re building your new bathroom on a budget, you won’t be able to work with fancier materials such as marble. Stick to the basics and you’ll definitely save on the costs of the overall job.


The size of your new extension is going to determine how much you’ll need to spend overall. If you’re only adding a smaller sized room to the house, of course, you will be paying less. On the contrary, if you want the full works, bathtub and all, overall costs are going to be much higher.

Our advice is to always take precise measurements of the area you wish to add to the property before settling on a price for the overall costs. Many people simply underestimate the labour work required by tradespeople and don’t take into account proper sizing.


What you will be installing in your new bathroom really matters when it comes to thinking ahead about costs. As shown above, an extension can cost anything between £2,000 and £8,000. A large chunk of the price comes down to the fixtures and fittings you are choosing to have installed. If you want to create a simple toilet room, you won’t have to worry too much. Toilets can be bought at a fairly low price and you’ll definitely stick well within your budget.

However, if you would like a fully fitted bathroom extension featuring a bath, shower, basin, and extractor fan, you can expect to pay more. Think about exactly what you are installing and work from there. If you want a luxurious roll-top bath, for example, don’t forget to account for plumbing works as part of your cost.

Tiling can also be an expensive aspect of a bathroom extension. Depending on the styles and material of tiles you choose, this job not only requires labour but a decent chunk of cash.

Furniture We Recommend

If you need a helping hand with bathroom furniture ideas, Bella Bathrooms has you covered. Take a look at our top picks for a beautiful extension no matter what sized space you are working with.

1. Richmond Wall Hung Cloakroom Suite

If your new extension is on the smaller side, this wall hung suite could be ideal for your bathroom space. Fitting perfectly into a cloakroom, the price and quality of this particular suite provides excellent value for money. With an elegant traditional layout, the matching toilet and sink set is sure to complete your new bathroom area. The detailing throughout makes this set truly authentic with its high gloss white finish and chrome lever flush handle on the toilet.

Included in this stunning suite set, you will get a close-coupled toilet and basin. The basin tap will need to be bought separately as it is not included in the cost.

2. Cassellie Daisy Lou Cloakroom Bathroom Suite

For a smaller extension, this bathroom suite is sure to delight with its modern fittings inclusive of a toilet and basin. The clean-cut lines of the bathroom components are minimalistic and offer a versatile route for anybody who is a fan of a simple aesthetic. The geometric look to each of the elements is truly on-trend, while the small sizes ensure that your layout is accessible and fluid, even in compact cloakroom settings.

You can choose between a standard and comfort height for the toilet. Customers are to buy the tap for the basin separately.

3. Nuie Merit Gloss Cloakroom Pack

Looking to create a clean and sophisticated finish in your new bathroom downstairs? If so, the Nuie Merit Cloakroom Pack is ideal for a more compact space. The high-gloss finish across the coupled toilet and matching basin reflect light in the space, giving the illusion of a larger environment. Designed with clean lines and using quality materials, everything about this duo works together in a simple and contemporary way.

The integrated basin negates the need for a separate sink while the toilet comes with a quiet close lid. Note that the tap is not included with this downstairs toilet cost and will need to be bought separately.

4. RAK Series 600 Back To Wall Toilet And Vanity Unit

Another option for lovers of contemporary bathrooms, this minimalist suite set comes at a great value for money and is the perfect starter pack for an en-suite. With this RAK series toilet and basin combo fitted, all that’s needed is a shower to make a complete bathroom for everyone to use in the family. Using a space-saving design, there are fewer toilets that fit so snuggly into a smaller space. With a quiet close lid and a 25 years manufacturers guarantee, this set will look perfect in your own house.

Make sure to buy the tap separately for the sink as it does not come included with this toilet and vanity set.

5. Hudson Reed Luna Toilet And Basin Set

This bathroom set is designed as the ultimate space-saver with a modern style throughout. Clean lines and glossy white surfaces will give any bathroom extension a sleek and refined finish. The addition of a soft close toilet lid is another aspect that can be appreciated by the user, adding further convenience.

Ideal for a smaller bathroom, you can keep the extension cost at a budget level for sure with this suite. With this neutral suite, you can choose to accessorise the space to complete the overall design. A great choice for easy installation in your house, in just a few simple steps your brand new suite will be ready.

Note that the sink tap does not come included and must be bought separately. Make sure to buy a chrome tap to complete your new bathroom extension.


Do you still have some questions regarding your downstairs bathroom extension? We’ve endeavoured to answer the most common questions surrounding this topic below.

How much value does a downstairs toilet add?

You can add an extra 5% to your home value by adding a downstairs toilet extension. Even a cloakroom sized toilet in your home on the downstairs level will certainly make your home more appealing to buyers and add extra value when it comes to selling.

If you haven’t already considered adding an additional bathroom or toilet room to your house, perhaps it’s time to. With a little bit of upfront investment, you can benefit from extra practicality and added value overall.

How much does a bathroom extension cost UK 2021?

The costs of a bathroom extension in 2021 are variable as outlined above in this article. From the plumbing to the actual building work required to extend your house (if applicable), there are plenty of expenses to consider. You should make sure to carefully calculate the costs of your extension prior to seeking quotes from a builder company to carry out the work.

There are many online calculator tools that will enable you to do this easily and compare prices of local tradesmen in your area. You should be sure to detail everything that you will require for the job to get an accurate idea of the overall price for the job.

Does a downstairs toilet need building regulations?

When it comes to planning permission for your new downstairs toilet, you will need to seek advice. In general, you won’t need to seek approval from the building regulations, however, in the case of a larger extension it may be applicable to do so.

Depending on where you live and whether your home is located in a conservation area, you may need the approval to add an extension to your home. This is something that is variable though with different rules applying depending on the council where you are located.

How much space do you need for a downstairs toilet?

The minimum space required for a downstairs toilet extension is 70cm wide and 130cm long. This amount of space will fit in both a toilet and sink while still allowing full accessibility to the area. Depending on the space that you have available in your house, you could also consider a planning application to extend the space into your garden area. While the measurements provided here are the minimum requirements, remember that for wheelchair users or elderly people, this space may prove simply too restrictive and not safe.

How to maximise space in a small cloakroom toilet?

If you’ve built your new cloakroom extension but you’re looking for ways to maximise the space available, there are ways you can do this easily. We recommend hanging a mirror up which will give the illusion of more space all around, in addition to this, choosing glossy finishes rather than matte can help too.

In the case of shower enclosures, the use of glass can really aid in maximising space as the material allows light to travel freely. Without further obstructions in the space, the bathroom will seem more open and free to move around in. For colour schemes, stick to neutral or pastel tones and choose simple tiles free from patterns to keep the area as simple and clean-looking as possible.