Fitting a bathtub: DIY or professional?

Short answer: replacing a rectangular bathtub in the same place is something a handy DIYer can do, as long as the waste and water supply are already in the right place. The bath must be perfectly level, the waste must be fitted and tested before the bath goes in, and the bath is filled before you seal it the next day. If the waste has to be moved, a concealed mixer is planned, or you have doubts about the floor or the pipes, call in a professional or a certified installer. A professional is never unnecessary in a bathroom: a leak under a bath often only shows once the ceiling below gets wet.

Read this article in Dutch as well: Ligbad plaatsen: zelf doen of vakman?.

What is involved in fitting a bathtub?

A bath looks like a simple product: a tub, feet, a waste and a mixer. The real work is in the details. A full bath with a person in it easily weighs more than 250 kilos. The floor has to carry that, the feet have to be set correctly and the edges have to meet a solid wall. Then there is the waste, which you no longer see once the bath is in. If it leaks, you only notice later.

The type of bath you choose also decides how hard the job is:

A Blissa 170x70 rectangular bathtub with a matching 170 cm front panel and side panel is the simplest choice. For a corner solution choose a Kaliope asymmetric corner bath, and if you have space choose a Crea back-to-wall freestanding bathtub. Curious how it will look? Try it first in our blog on the bathroom configurator. More about the brand is in our brand blog on Cersanit.

What can you do yourself?

With some experience you can prepare and carry out a lot yourself:

• remove the old bath, take off old sealant with Fila Zero Sil silicone remover and clean the wall;
• measure with a tape measure with auto-lock and check that the floor is flat and dry;
• set the new bath on its feet and align it with a 60 cm spirit level and a 120 cm spirit level;
• fit the bath waste with click-clack plug or an automatic bath waste and test the waste;
• build a casing or fit a panel, and seal after a day.

Before drilling into a wall, locate pipes and cables with a multifunction wall detector.

Step by step: replacing a rectangular bath

1. Turn off and drain the water. Close the main stopcock and let the pipes drain.
2. Remove the old bath. Cut through the sealant, take off the mixer and the waste and lift the bath out with two people.
3. Check the floor. It must be flat, dry and strong. Do you see damp patches or rotten wood? Stop and have it checked first.
4. Fit the waste first. Fit the bath waste while you can still reach it easily. Tighten the couplings hand-tight plus a quarter turn with water pump pliers set.
5. Position and level. Place the bath and adjust the feet so the rim is level lengthwise and crosswise. The bottom of the bath already slopes towards the waste.
6. Test the waste. Pour a few buckets of water into the bath and use a torch to check everything stays dry.
7. Seal the rim. Apply Aquastop BT sealing tape between the bath rim and the wall before tiling. That keeps it watertight, even if the sealant comes loose later.
8. Casing or panel. Fit the panel or build a casing. Always leave an access hatch at the waste.
9. Fill and seal. Fill the bath with water and leave it overnight. Then seal with sanitary silicone sealant and a sealant gun. That way the joint does not tear when the bath is full later. How to make a neat sealant joint is explained in our blog on resealing a bathroom with new silicone.

Mixer and bath screen

A wall-mounted mixer such as the Cari bath mixer connects to existing wall connections. A flexible connection hose helps with a loose connection. A Mille concealed bath mixer with box has to be built into the wall before tiling. That is a job for an installer. If you want to shower in the bath, fit a Larga bath screen and make sure the bath rim is properly sealed.

When should you choose a professional?

👷 A professional is never unnecessary. Choose a professional or certified installer if the waste has to be moved, if a concealed mixer or a freestanding bath with a floor waste is planned, if the floor is wooden or you doubt its strength, or if pipes have to be bent, soldered or pressed. If in doubt about water or drainage, always use a certified installer. The same goes for a bathroom above a living room: a leak there does extra damage.

A mixed approach often works well: you strip out and prepare, the installer makes the connections, and you finish the job afterwards. More on that choice is in our blog on renovating a bathroom: DIY or professional and our guide to planning a bathroom renovation. If you are also tiling, read our blog on tiling a bathroom.

Working safely

A bath is heavy and awkward. Always lift with two people and keep your back straight. Wear work gloves with nitrile coating against sharp edges of old tiles and broken sealant. Stripping out and drilling call for safety goggles. Working on your knees is more comfortable with knee pads.

⚠️ Always turn off the water before loosening mixers or wastes. If there is an electrical connection nearby, such as underfloor heating or a socket, leave it alone and ask a certified installer.

💡 Take a photo of the pipes and the waste before you close the casing. Then you will know exactly where everything is later.

Frequently asked questions

Can I fit a bathtub myself?

Yes, replacing a rectangular bath in the same place is doable if you are handy. If the waste or the water supply has to be moved, leave that to a professional or certified installer.

Why should the bath be full before you seal it?

A full bath drops a few millimetres. If you seal an empty bath, the joint tears as soon as the bath is filled.

Does the casing need an access hatch?

Yes. Through the hatch you can check the waste and act quickly if there is a leak, without breaking out tiles.

How long does fitting a bath take?

Replacing a bath in the same place usually takes one to two days, including curing time for the sealant. With tiling and a new casing it takes longer.

Where can you find everything for this job?

At Saniso, the online store for DIYers and professionals, you will find tools, materials and personal protective equipment for your job.

• Browse our construction tools and our workwear and safety.
• Create a customer account and order easily.
• Working on a bigger project or want to hand over the job? Request a project quote.
• Book a showroom visit, at least 24 hours in advance.
• Not sure which material suits your job? Get in touch with us.

In doubt about the approach? Feel free to call in a professional.

Saniso – Build your home with Saniso.