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How to repair concrete slab and wall after removing inserted bathtub?

blb48
Budding Contributor

How to repair concrete slab and wall after removing inserted bathtub?

I've removed an old bathtub that had been bedded into a mound of concrete. I've ground down the concrete mound and want to repair the concrete floor and old walls. Questions: Do I need to grind the concrete down completely to the level of the surrounding floor?   Can I lay new concrete directly over the old concrete?   If so, does there need to be some sort of reinforcement?

 

Can I move the bathtub waste and the taps to the other end of the space? Would that be difficult?

 

The old bathtub waste, which joins shower waste.The old bathtub waste, which joins shower waste.The lumpy slab and old tiles.The lumpy slab and old tiles.The lumpy slab and old tiles. Slab 2-4 cm below tiled floor.cm.The lumpy slab and old tiles. Slab 2-4 cm below tiled floor.cm.The rim of the bath was inserted into the wall.The rim of the bath was inserted into the wall.

MitchellMc
Bunnings Team Member
Bunnings Team Member

Re: How to repair concrete slab and wall after removing inserted bathtub.

Hi @blb48,

 

It would be helpful for our members if you could let them know some more details about your project. What are you planning on having in this area? Are you installing a new bath or perhaps converting it to a shower? Maybe you are just tiling this area?

 

Presuming that you want a floor that is level and at the same height as the rest of the area, you'll need to remove the concrete to a depth that will allow you to use self-levelling cement over it. If you remove the concrete to between 1- 25mm below your desired finish height, you can then use Dunlop 15kg Multi Purpose Floor Leveller over the area.

 

You don't need re-enforcement, but the concrete needs to be clean, sound and free from all contaminating materials. Vacuuming with a suitable bucket-style vac to remove any dust is essential. You'll then be able to use the Dunlop 1L Primer And Additive before pouring the self-leveller.

 

For the walls, re-sheeting with James Hardie 2400 x 1200 x 6mm 2.88m² Villaboard Lining will probably be the easiest solution.

 

Moving the waste is an option, but the ease at which you could do so will largely depend on your skills and how difficult the concrete is to cut the channel into.

 

Please let us know if you have any questions.

 

Mitchell

 

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blb48
Budding Contributor

Re: How to repair concrete slab and wall after removing inserted bathtub.

Thank you, Mitchell

The solution you have suggested had been bubbling around in my head (among others), but you've given me the confidence to pursue it. I hadn't thought of re-sheeting, but that would be an easy solution for the damaged walls.

 

Can I just run this sequence of activity past you?

1  Grind down any points that are higher than the floor.

2  Clean the area.

3  Prime the area.

4  Apply the floor leveller. I'm assuming that the floor leveller will fill in any 'potholes'.

5  Tile.

One more question.     Does the floor have to be dry to apply the primer and leveller? 

 

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EricL
Bunnings Team Member
Bunnings Team Member

Re: How to repair concrete slab and wall after removing inserted bathtub.

Hello @blb48,

 

It's great that you've received excellent advice from @MitchellMc. As to the steps you've mentioned yes they are correct. Yes, the floor needs to be dry before you put the primer on. On that note are you turning this spot into a wet shower area? If you are, waterproofing the area will be necessary to avoid water leaks and moisture condensation.

 

I suggest this step-by-step guide: How To Waterproof A Shower - DIY At Bunnings.

 

Moving the current plumbing fittings is possible. However, I suggest getting the services of a registered plumber. By using the plumber's services, the plumbing works can be officially signed off. This will provide you with a measure of security should there be any issues. 

 

Please keep us updated, we look forward to seeing more of your progress. 

 

Eric

 

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blb48
Budding Contributor

Re: How to repair concrete slab and wall after removing inserted bathtub.

Hello again.

If I wanted to raise the concrete so that I have a platform 6-12cm high, could I just box it and use quickset concrete, or any concrete at all, to make a new pad raised above the current floor level?  I thought I might raise this pad, build a wall to waterproof and tile, and then also include a bench to sit on next to the taps I'm not going to move, but to add a shower.

 

Sort of like this.

planplangoal (tee hee)goal (tee hee)

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EricL
Bunnings Team Member
Bunnings Team Member

Re: How to repair concrete slab and wall after removing inserted bathtub.

Hello @blb48

 

Thank you for sharing your query about making a concrete platform.

 

Using quick-set concrete is very time-sensitive as the name implies. You have a small window in which to remove air pockets in the cement and put a flat finish on it. I suggest using Bastion 20kg Concrete Mix instead to allow you the time to properly form and set the concrete and remove air pockets that might get trapped. 

 

Please make sure to provide enough drying time for the concrete to set. If the concrete is tiled too soon, moisture from inside will push the tile adhesive off and your tiles will fall.       

 

If you need more information please let us know.

 

Eric

 

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