# Forum Home Renovation Bathrooms  Replace a timber floor with a concrete slab

## RNY

Hi there.....i'm currently researching a new bathroom i want to create in a part of the house never previously a wet area.
Aside from the requisite damp coursing and tanking of the room it has an original tongue n groove suspended timber floor.
The house is circa 1930-35 and im hoping after the plumbing is established underfloor level i can install a concrete slab on to which tiling is normally attached....
I have read that placing slab floors inside the perimeter foundations of old houses causes diversion and escalation of rising damp to the walls. Is this true/likely/plausible?
Either way i dont want to sheet and tile the timber floor if i can as i have had previous bad experience with tiles loosening and leaking through movement.
I have remove the timber floor anyway to install the plumbing and services beforehand as well so i'm literally starting from scratch.
Can anyone help with ideas please?
Regards Michael
I have read that placing slab floors inside the perimeter foundations of old houses causes diversion and escalation of rising damp to the walls. Is this true/likely/plausible?
Either way i dont want to sheet and tile the timber floor if i can as i have had previous bad experience with tiles loosening and leaking through movement.
I have remove the timber floor anyway to install the plumbing and services beforehand as well so i'm literally starting from scratch.
Can anyone help with ideas please?
Regards Michael

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## goldie1

Why a concrete slab. Use scyon flooring and villaboard wall sheet properly waterproofed    Scyon - Scyon Secura Interior Flooring

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## Oldsaltoz

+ 1   :Wtg:

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## RNY

I am of the opinion that concrete is more stable for wet areas than effectively tiling over a moveable substrate.
I have had tiling problems in the past.
The walls are brick and plaster. This is an old house. 
The big question is whether a slab will cause big problems down the track?
Mind you its not big. The space is only about 7 feet x 10 feet.

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## mudbrick

How high is you floor off the ground?  What type of floor did you have trouble with in the past, it could  be that it was not done right in the first place.
There should be no problem tiling over scyon or FC sheet whatsoever provided the joists are adequate to begin with. If you are concerned about flex or movement in a fibre cement floor you could get a carpenter in to add extra joists to give extra strength to the sub floor.
In terms of adhesion there should be no difference between sheet products and a slab as both will Be waterproofed before tiling.
You can even use one of the thicker sheets if you really want to stiffen up the floor but this adds weight and gives you a higher step at the doorway.

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## seriph1

I don't feel this is a practical solution. First, won't it have to be a suspended concrete slab? Even if only 300mm off the ground, you're up for a bunch of concrete. Rising damp shouldn't be an issue provided all the mitigation systems are employed, but they add cost as well. Provided the stumps are sound and the floor is prepared in the correct way, you should enjoy many years of trouble free service from a tile-over-timber floor. That said, if the prep work is not done correctly and the structure is inherently unsound then yes, there will be issues.  
But I am no expert and don't know the conditions in your room.

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## goldie1

[QUOTE=seriph1;966513] Provided the stumps are sound and the floor is prepared in the correct way, you should enjoy many years of trouble free service from a tile-over-timber floor. 
[/QUOTE 
I hope you mean timber frame and not timber floorboards. I wouldn't think of doing a bathroom with 
timber floorboards

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## Marc

If you have removed the timber floor already make sure your bearers and joist are sound. Get someone to check and if necessary beef them up. Then compressed fibro (19mm) or the more modern Scyon on top and you can treat it as a concrete slab. 
You can of course do the old fashion way and make a suspended concrete slab but you will be making a rod for your own back because you have to remove all bearers and joist and that in itself will need to be done properly. Then you need to build brick pears all around, form-work pouring the concrete ... I get the shivers just thinking about all this unnecessary work.

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## Gaza

Hebel power floor perfect for this solution   
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## seriph1

Goldie1 no I mean floorboards. I've owned or worked on homes with tiled floors over boards for many years. Provided the right prep is done - which of course includes AC sheet or equivalent over the boards - there are few problems unless there is soil movement. Caveat: most of my personal and professional experience is with period homes therefore tiles of far smaller size than are popular now. That said, I've been state manager of a very large tiling firm since 2013 and even the larger tiles can be laid over boards in the right conditions.  
Just my opinion of course.

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## goldie1

> Goldie1 no I mean floorboards. I've owned or worked on homes with tiled floors over boards for many years. Provided the right prep is done - which of course includes AC sheet or equivalent over the boards - there are few problems unless there is soil movement. Caveat: most of my personal and professional experience is with period homes therefore tiles of far smaller size than are popular now. That said, I've been state manager of a very large tiling firm since 2013 and even the larger tiles can be laid over boards in the right conditions.  
> Just my opinion of course.

  Sure I have done bathrooms with FC tile underlay over floorboards because compressed sheet  
flooring was such a PITA  but not since Scyon and Durafloor have come on the market  
I do refurb work so by the time you rip up some of the floor boards for the plumber its just as  
easy to take up the lot

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## Marc

:Iagree:

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## RNY

Hi all, 
I removed the wooden floor over the weekend and cleaned up the bearers and joists. I have decided to go the 'scyon' floor path over doubled up quantity of joists. 
i have two questions now. 
1) the bearers the joist were nailed to are merely 3/4" thick jarrah battens that were loose positioned on the foundation. effectively the whole foor appeared to be a 'floating' foor. I dont want this for a tiling application so I want to secure the batten/bearers to the foundation and then refit the joists in the original fashion.  
Can anyone recommend a solution to tying the floor down to the foundation? Drilling and dyna-bolting was a thought but the foundation concrete looks so coarse with gravel metal I fear it might fracture with drilling and installing bolting mechanisms. 
2) there is evidence of some salt crystals on one section of the concrete foundation opposite the ventilation openings. The actual concrete looks sound enough though. Can I treat this with any chemical or process to increase the resistance to ongoing attack? 
people's feedback and constructive comments will be appreciated. 
Regards, Michael in Adelaide.

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## RNY

> Hi all, 
> I removed the wooden floor over the weekend and cleaned up the bearers and joists. I have decided to go the 'scyon' floor path over doubled up quantity of joists. 
> i have two questions now. 
> 1) the bearers the joist were nailed to are merely 3/4" thick jarrah battens that were loose positioned on the foundation. effectively the whole foor appeared to be a 'floating' foor. I dont want this for a tiling application so I want to secure the batten/bearers to the foundation and then refit the joists in the original fashion.  
> Can anyone recommend a solution to tying the floor down to the foundation? Drilling and dyna-bolting was a thought but the foundation concrete looks so coarse with gravel metal I fear it might fracture with drilling and installing bolting mechanisms. 
> 2) there is evidence of some salt crystals on one section of the concrete foundation opposite the ventilation openings. The actual concrete looks sound enough though. Can I treat this with any chemical or process to increase the resistance to ongoing attack? 
> people's feedback and constructive comments will be appreciated. 
> Regards, Michael in Adelaide.

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## Pulse

Just put the joists back on the jarrah sill, looks pretty dry and solid. A few dynabolts would be ok but it is not going anywhere. You could always use some sikaflex to stick it down.  
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## goldie1

It all looks pretty dry if its been there since the 30s but you could use some alcore under it and fix with 
threaded rod and chemset Ramset Australia - Chemical Anchoring

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