How to install a heavy bath?

[RichardA36]

We are doing a remodelling of our bathroom in Brunswick, Victoria to change the tiles on the bath, remove the current lip on the outside of the bath and also insert some false walls to cover the ledge - or in other words box the bath in.

It will be straight forward for the plumbing to come forward on the new wall at the head of the bath.  This is an old timber house but renovations some 20 years ago put in concrete stumps, modern wiring and modern plumbing.

But I have seven questions before I proceed too much further.

Question 1.  The bath is a steel bath and you can just see the cradle of concrete it is sitting on.  The current bath 90 x 45 frame does not support the bath at all - it only provides the framework for the vertical and horizontal panels that the files were adhered to.  I have removed part of the frame from the front and you can just see that the bath lip is above the supports.  The only parts contacting the lip of the bath were the horizontal tiles that slid under the lip of- so they would not have taken weight other than through the silicone seal.

Is this the correct way to install this heavy bath?  

Question 2.  I have to put in another framework at the front so that the tiles start under the lip of the bath.  I cannot do this until the issue of supporting the bath is resolved so all input gladly received.

Does the frame have to be anything else than MPG 10?

Question 3.  Does it need a water proof rating?  The existing timber appears to untreated MGP 10 pine.

Question 4.  The false walls will enable the new tiles to sit on the lip of the bath.  As they are not a load carrying wall I have been told that 70 x 45 framing will suffice.  The sole plate will sit on the ledge and the top plate will sit roughly 1.5 metres above it.  The wall panel will be wet area cement sheet or wet area plasterboard - yet to be decided:

Is there any reason to have heavier timber than 70 x 45?

Question 5.  Does this framing need to be other than MGP 10?

Question 6. The sole plate will sit on the ledge.

However should I ensure that the weight is transferred to the floor - probably by ensuring the ledge is supported from the floor?

Question 7.  Should the old tiles be removed to reduce the load on the building??

[EricL]

Hello @RichardA36 

Thank you for sharing your question about your bathroom renovation. 

• Having seen a fair bit of bathroom installations the timber bath frame often supports the bath itself. Generally speaking, the frame is first built and then the bath is test fitted before the placing the concrete footing at the bottom. The lip of the bath sits on the timber frame.
   
• I propose using 70 x 45mm Outdoor Framing H3 Treated Pine - 3m or similar. H3 pine structural timber is treated for borers, termites and is able to be subjected to moderate wetting in a well-ventilated area for up to 20 years.
   
• MGP10 is a grade of structural pine that indicates it has been machine stress graded to withstand a minimum of 10 megapascals (MPa) of pressure, making it suitable for load-bearing applications like wall frames, roof trusses, and floor joists in construction. The "MGP" stands for Machine Graded Pine, a system that ensures consistent strength, stiffness, and durability in every piece of timber. If you see this on its description, then you know that it has been rated for load bearing applications.
   
• H3 treated pine can withstand moderate wetting so its safe to use in your bathroom set up. 
   
• I would advise using similarly sized timber in regards to your bath framing so that you'll have a uniform finish. Thicker timber of course will provide more support.
   
• Does this framing need to be other than MGP 10? No, it does not. 
   
• It's best practice to ensure that the weight is transferred to the floor so that no section is left floating with no support underneath.
   
• If you are planning on putting new tiles on the wall, I recommend removing the old tiles so that there is no extra weight added to the wall.

Let me call on our experienced members @Dave-1, @AlanM52 and @Noyade for their recommendations.

Here is a handy step-by-step guide: How To Build A Bath Frame 

If you need further assistance, please let us know.

Eric

[Dave-1]

Good Evening @RichardA36 

Thats a bunch of questions and luckily @EricL has stepped through them very nicely I wouldnt be changing any of his recomendations. 

I would be making sure that the weight of the bath is carried by the frame and the concrete foot underneath. That includes the concrete sheeting/waterproofing and tiles. Im not sure how you will extend the wall waterproofing to the bath tile waterproofing as far as I know plumbers do not sign off on a patch styled job. I would hit up a plumber first as it will quiet probarlly effect your insurance for the house.

The waterproofing into the floor comes into play as well.

Is the current bath stuck into that concrete foot solidly? I would normally think teh bathtub would be taken out and then prepwork done all over first (framing/waterproofing/tiles) and then put into place with a fresh concrete foot so the bath rests on that plus the frame nicely.

Dave