How to install a new bath

Their are two main ways to install a new bath and it doesn’t really matter which one you use as long as you support the bath property. As you know baths come in many shapes and sizes from the very small, which is only good children under 3 and hamsters, to the deep spa bath which make you upgrade your hot water system just to fill it. The one thing that they all need is to be installed correctly.

Bath installation  – sand, cement and timber.

If you are installing a bath against a wall then you may have the lip of the bath notched into the timber wall studs. This means the wall sheets will come down just over the lip so that any water that is splashed up while practising your Olympic swimming will run back into the bath and not into the wall.

Step one: Measure how deep your bath is

Measure how deep your bath is and add 3 inches for the sand and cement mix. Notch out your wall studs so that the bath will sit in and level. Note that the whole lip of the bath that is against the walls should be ‘let in’ to the stud so the wall sheet can be install over the lip.

Step two: Make a timber frame

Any part of the bath lip that does not have support will need a timber frame under it. I always use treated pine for this because it will last and is inexpensive. Your frame should look like a ladder that has been laid down on it’s side. The top timber rail should be hard up under the lip of the bath and the bottom rail should sit on the floor with short timber studs in between. I use 35mm x 70mm or 1.4 inches x 2.75 inches treated pine to make the bath with 400mm or 16 inches spacing between the studs. If you have a very large spa use 45mm x 90mm or 1.8 inches x 3.5 inches treated pine.

Step three: Make sure you level room for the tiles on the front of the bath

Most people tile from the bath lip down to the floor. However when you install your timber bath frame you will need it to be in deep enough to allow for the cement based sheeting, tile glue, and the tiles. This will normally be around about 20mm or  .79 inch depending on the thickness of your tiles.

For example:

• 6mm or .236 inches Cement based cementing
• 4mm  or .157 inches Tile glue
• 10mm  or .394 inches tiles

Step four: Connect your plumbing

The bath should be installed and siting on the timber frame without the cement based sheeting. Now is the time to connect the bath waste pipe to the bath. You should make sure the bath and the waste pipe will line up before you start to build your frame. I always test the pipe by pouring a clean bucket of water into the bath and then looking for any leaks. So before you think ‘Hey how hard can it be?’ Take the time to get it right because you don’t want water flowing into house.

Step Five: Cement the bath in place

Using standard sand and cement (not mortar mix) out of a bag I then mix the it up one bag at a time. Use a large bucket and mix the sand and cement to a dry mix so it is just damp (i use a drill and mixer for this). Then pack it under all part of the bottom of the house. Make sure you pack it tightly for the best results. It is important not to have the cement mix to wet as it can shrink and then the installation will not support and bath. This means when auntie Marther comes over and needs to use your bath after a very large meal it may crack and ruin the bath.

Step Six: Install the cement backing board

Install the cement based backing board around the side and/or front of the bath. You should be ready to tile and the tiles should be flush with the lip or edge of the bath. Don’t forget to use silicon around the bath between the bath and the tiles. Do not use grout between the bath and tiles as it will crack.

Concrete

If you want to use concrete or bricks to build up under the bath I suggest use Hebel bricks  (aerated concrete block) because they are light and strong and easily cut with a hand saw. They simply glue together using cement based thin bed tile glue or you can use the Hebel glue which is the same thing at twice the price.

Install your bath by notching it into the wall and then using a level brick around the bath and bring it right up under the lip. Make sure you set the bricks back from the lip to allow for the tile and tile glue. This method is fairly quick but is not as quick has the timber frame method.

Bath installation tips

• Always use good quality materials
• Do not use expanding foam under the bath as it breaks down and will void the warranty on most baths.
• Be careful when nailing the cement backer board on not to chip or damage the bath.
• Always measure and then make your timber frame away from the bath so you don’t nail the bath.
• Silicon under the frame and sit the bath on to the silicon.

Bath installation Variations

Some spa bath come with there own metal frame with adjusting feet. Just put the spa where you want it (you may nave to notch the wall) and then adjust the bath level. Connect all the plumbing to the bath and test it by running water into the bath and checking for leaks. Once this is done just install your cement based backing board or sheet onto the bath frame with stainless steel or galvanised screws making sure to allow for the tile and tile glue. You may have to pack the backing board out using a timber spacer to get it in the right position.

Bath installation drop in

This type of installation can be against a wall or in the center of the room. It is the same as the installation above with no notching of the wall. So you make a frame larger than the bath and install cement based backing board on top with a cut out for the bath. You simply drop in the bath and the bath lip should be holding your bath in place. Then cement under the bath for strength and connect the plumbing. You will have to tile right around the bath top lip. For this method is simply a large box that the bath will sit in.

Installing a bath can be straightforward however it is important to be accurate when you measure to get it right. It is also much easier to tile around a bath that has been installed correctly in the first place. If in doubt call a tradesmen to help you. A bath install correctly should last the lifetime of the bathroom.

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