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How to build a bath frame

A person using a hammer to adjust the position of a timber bath frame

Overview

If you're installing a new bath, you'll need to support it with a timber frame. We’ll teach you how to build the frame to size and install it properly in your bathroom. You'll also see how to reinforce the frame and compensate for an uneven floor.

Steps

1Mark a line on the wall for the top of the bath frame

Measure the height of your bath. Add another 80mm or so and mark that level on your wall studs. This is the mark for the top of the frame. The extra 80mm allows for differences in floor height. In this case our bath is 370mm so we've marked our line at 450mm.
A person marking measurements on wall studs using a spirit level

2Install noggins between the wall joists to support the bath frame

Measure the gaps between each of the wall joists at the height of your line. Then use your circular saw to cut a timber noggin to size for each gap. Now nail the noggins into the gaps with your nail gun. The noggins give the bath frame extra support and hold external linings. 
A person using a nail gun to attach a noggin between wall studs

3Measure and cut the sides of the bath frame

Position the bath with one end sitting 70mm out from the wall to allow for the frame. Then measure from the wall to the far end of the bath and add another 70mm. Take this measurement and cut four lengths of timber for the top and bottom sides (plates) of the bath frame. 
A person using a measuring tape to measure the length of a bath

4Mark the positions of the vertical studs for your bath frame

Mark where the vertical studs will go on the top and bottom plates by tracing around an offcut of framing timber with a pencil. Put a stud at each end and space the others evenly along the frame every 600mm. Spacing them like this will make it easier later when you want to cover the frame.

A person marking a line on a piece of framing timber using an offcut

5Assemble the sides of the bath frame

Measure and cut eight vertical studs, all 95mm less than the height you want for your frame. The studs are 95mm shorter than the height of the frame to allow for the thickness of the top and bottom plates. We add 5mm to allow for any variations in the height of the floor. Nail the studs into place between your top and bottom plates to create the two sides of your frame.

A person using a nail gun to join lengths of timber to make a frame

6Install the sides of the bath frame

Put one side of the frame in position against the wall. Then line the other side up so it is parallel. In this case, we've separated the two sides by 850mm, which is the width of the bath, minus 30mm. This gives us a 15mm ledge on each side of the frame for the bath to rest on. Once you're happy with the position of the two sides, nail them into place.
A person using a hammer to adjust the position of a timber bath frame

7Build the ends of the bath frame

Straighten the outside edge of the frame with a spirit level and measure the distance between the two sides. This gives you the width of your end pieces for the frame. Use this measurement to cut top and bottom plates for both ends. Then cut three vertical studs for each end, using the same length you used for the previous studs. To assemble each end, nail three studs between a top and bottom plate.

A person using a nail gun to join lengths of timber to make a frame

8Install the ends of the bath frame

Use your nail gun to secure each end in place. In our case, one of our ends is unsupported by a wall. So as we nail it, we use our spirit level to check that its vertical edges are right. To finish, place the bath inside the frame to make sure it supports all four edges properly.
A finished timber bath frame in the corner of a bathroom with exposed stud walls

9Ready to install your bath?

Check out our video on how to make a mortar bed for a bath.
Health & Safety

Please make sure you use all equipment appropriately and safely when following the advice in these D.I.Y. videos. You need to be familiar with how to use equipment safely and follow the instructions that came with the equipment. If you are unsure, you may feel it is safest to consult an expert, such as the manufacturer or an expert Bunnings Team Member.

Grave health hazards are linked to asbestos, which may be in homes built up to 1990. Health hazards may result from exposure to lead-based paints in older materials and copper chromium arsenic (CCA) treated timber. For information on the dangers of asbestos, lead-based paint and CCA treated timber and tips for dealing with these materials contact your local council's Environmental Health Officer.