Quarry Tiles Over Existing Quarry Tiles do They Stay Brerathable?
Advice and information on tiling and fixing tiles to a variety of surfaces

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Quarry Tiles Over Existing Quarry Tiles do They Stay Brerathable?

by Colink » Mon Jul 08, 2019 11:34 pm

100 year old terrace house. Front room appears to have original (or very old) quarry tiles on top of a thin base (not sure what), back room seems to be some form of concrete floor, age unknown.

Area has a high water table and damp floors and damp solid walls are the norm in this area.

We will be applying a chemical or liquid DPC to the walls but do not want to uplift the existing floor, but can increase floor height by around 30mm.

Many posts in various forums discuss liquid DPM to be applied to floors or seal with plastic membrane, but some replies give warning about the need to keep the floor breathable.

This seems like a sensible way to proceed.

My proposed solution:
Lay new or reclaimed Quarry Tiles over the existing floor using some form of breathable mortar eg Hourdex.

We will also fit some form of re-circulating air system to extract dampness from the air.

I would appreciate comments on this or alternative solutions.

Any possible issues I have not considered.

Assuming we will be removing some plaster at bottom of all walls to apply chemical DPC, is there any specific thing we should do when tiling up to the wall - before or after we replaster and add skirting board?

Tile sealer?
Obviously we do not want to completely seal the tiles. What should we apply to the tiles to minimize effects of liquid spills and to help maintain the surface.

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Re: Quarry Tiles Over Existing Quarry Tiles do They Stay Brerathable?

by thedoctor » Mon Jul 22, 2019 5:00 pm

In this situation you cannot have a completely waterproof area that is still breathable. You can have one or the other and allowing the damp to still breathe through the floor will continue to give you big problems, not least of all the health implications of having damp everywhere which always leads to mould. If the mould cannot be seen it cannot be treated and can become harmful.

Walls should be stripped of plaster to 1200mm high. The floor should be swept clean and then tanked also.

Floor tanking should always overlap wall tanking as the joint between the two is usually the most vulnerable place.

Rising damp in walls is capable of rising to a maximum height of 1.2m so all plaster should be stripped back to that height. After tanking the walls can be replasered by

See our project on DIY Tanking and other waterproofing methods at https://www.diydoctor.org.uk/page/3/?s=tanking

Also see the following videos to help with DIY Liquid DPM and DIY Tanking



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