Good Water resistant thick bed floor adhesive - Tile Advice

But with moisture being able to breathe and make its way through grout joints this is unlikely to happen, like you say not impossible though.

Salts will accumulate where moisture is evaporating e.g. They come out of solution and crystallise, on or near the evaporating surface.

Tape some plastic to the floor for a few days and see how moist it gets.

Why not just use a liquid dpm, ardex I think

Yes Ardex technical advised that salts could cause essofflerecent as like you say they will accumulate when they make there way through the grout joints,however the chances are highly unlikely unless we live near a lot of waste land where salts in the ground will be high.

My view was to use a epoxy DPM however both Ardex & Mapei said not to waste the money as like I've said before they said it's not necessary if tiling the floor.

I know going to get into Dpm or not but salts are in the ground pretty much everywhere that is why you have to replaster when putting in a new silicone dpc because when your wall got wet with rising damp salts will have migrated with the damp into your plaster . Then after having your dpc replaced you would still get damp readings in your wall if you didn't replace plaster as salts would attract moisture in the air much in the same way your salt cellar nozzle gets blocked. So long and short is you will get salts .

liquid DPMs are only designed to deal with residual moisture not rising damp where the relative hydrostatic pressure can cause osmotic swelling under the DPM and ultimately failure. some sort of breathable or moisture stabilising membrane woudlbe better such as some of the drainage membranes from John Newton Ltd and such likes. Perhaps Ditra.

Obviously the correct way to proceed would be to take up the existing floor and install a suitable DPM but this relies on the DPM being integrated with and DPM in the walls which is not present will force the moisture into the walls. I've done my fare share of Victorian house renovations in the past and found that if you cannot live with what is already there i.e. the quarry tiles...then removing the existing and replacing with modern materials is the easiest way but obviously not the cheapest way.

I don't like the way we as a society have to destroy the character of some of these old places in a bid to "modernise them" with inappropriate modern materials and methods. I would try and put quarry tiles back down or even clean up and save the ones that are already there but that is of course a purely personal view.

If the renovation is subject to building regulations control you may find not putting in a DPM puts you in breach of part C so be wary.

Sam2494 said:

Yes Ardex technical advised that salts could cause essofflerecent as like you say they will accumulate when they make there way through the grout joints,however the chances are highly unlikely unless we live near a lot of waste land where salts in the ground will be high.*


My view was to use a epoxy DPM however both Ardex & Mapei said not to waste the money as like I've said before they said it's not necessary if tiling the floor.**

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*what does this actually mean... what has waste land got to do with it... soluble salts are in the water in the entire water table throughout the UK, off into the sea and over into the rest of the world... the efflorescence is not caused by salts in the ground water its caused by evaporation of moisture from the surface of the grout which leaves behind calcium, magnesium and sodium carbonate (depending on the makeup of the background materials) on the surface of the floor. This appears as white chrystals. It is nowt to do with ground borne moisture... if it was how do you think efflorescence appears on brickwork at the forth story of a new house...

** A systm of control of moisture in buildings is a requirement of part C of the building regulations. It is usually achieved in ground borne floor slabs by means of a polythene DPM. Tiling or no tiling is completely irrelevant.

Sam2494 said:

Yes Ardex technical advised that salts could cause essofflerecent as like you say they will accumulate when they make there way through the grout joints,however the chances are highly unlikely unless we live near a lot of waste land where salts in the ground will be high.

My view was to use a epoxy DPM however both Ardex & Mapei said not to waste the money as like I've said before they said it's not necessary if tiling the floor.

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In instances where you have damp rising through a ground supported floor slab, the most harmful salts are the ones derived from organic matter, Chloride and Nitrate ions these type of salts can absorb water from the atmosphere and cause a secondary for of dampness therefore the salts that crystalise at the surface are not the most harmful in instances of rising damp.

Bond said:

In instances where you have damp rising through a ground supported floor slab, the most harmful salts are the ones derived from organic matter, Chloride and Nitrate ions these type of salts can absorb water from the atmosphere and cause a secondary for of dampness therefore the salts that crystalise at the surface are not the most harmful in instances of rising damp.

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Sulphate salts in ground borne moisture are none too pleasant either. IN the right circumstances they can cause a thaumesite reaction which turns solid concrete into very smelly jelly.

Ajax123 said:

*what does this actually mean... what has waste land got to do with it... soluble salts are in the water in the entire water table throughout the UK, off into the sea and over into the rest of the world... the efflorescence is not caused by salts in the ground water its caused by evaporation of moisture from the surface of the grout which leaves behind calcium, magnesium and sodium carbonate (depending on the makeup of the background materials) on the surface of the floor. This appears as white chrystals. It is nowt to do with ground borne moisture... if it was how do you think efflorescence appears on brickwork at the forth story of a new house...

** A systm of control of moisture in buildings is a requirement of part C of the building regulations. It is usually achieved in ground borne floor slabs by means of a polythene DPM. Tiling or no tiling is completely irrelevant.

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I meant to say "Marshland" sorry, if the property is in an area surrounded by a lot of marshland then naturally there is going to excessive amount of moisture in the ground. Which then would lead to more than usual moisture coming up through the floor slab, making its way through grout joints and then there would be large amounts of moisture to evaporate which would lead to essofflerecent.

I understand that essofflerecent isn't caused by ground moisture as like you say take brickwork for instance, that's caused from any water on the Surface evaporating and reacting to cause essofflerecent.

Yes I know that an integral polythene DPM is what stops rising damp entering a floor slab, an epoxy just creates a barrier to stop it coming through onto the surface of the slab.