Subfloor preparation old house

[Edwin Tintoe]

Hi, first post here. I've been lurking this forum for advice for a while, thank you all who share your knowledge.

I'm to tile a kitchen of an old (old old) house, farmers concrete with NO DPM, house has no dpc, stone walls. Area 17 sqm, waves up to 12 mm difference, to be finished with porcelain tile. This house has been diy'd by different individuals for over 60 years, such is the nature of the place I'm afraid. We lifted lino with rotten chipboard and a sheet of plastic (DPM) underneath. Concrete was fairly wet, now dried, at least on surface. The concrete is topped with a red pigmented screed around 10mm in thickness (picture where removed as it sounded hollow). Replacing slab is the last last option,as this is a diy and budget sensitive project.

Question: is it wise to remove the screed? How should I then proceed in preparing the subfloor for tiling? I've been through a multitude of options, these two stand out:

1. Keep the screed, Sbr slurry, level with SLC,tile with ditra, tile

2. Remove screed, install insulating waterproof backerboard like wedi or marmox on a bed of adhesive, tile.

There will be some moisture in the floor as it's just slab on ground (probably added by another diyer when I was not walking this earth yet. I'm worried that overt dampproofing will push moisture up the walls. And that a lack thereof will result in the tile setup fail.Can anyone advise please whether my suggested options are ok, or if there's an approach that I've missed and could deal with this better?

Thank you! Whenever you're reading this -have a good day

 

[judge]

Your right about the moisture being pushed into the walls if you totally tank or waterproof the floor.Personally I would contact a tile manufacturer and ask they're opinion.i know that bal's flexbone membrane allows for moisture release but not sure if it would be suitable for this purpose

 

[Edwin Tintoe]

Your right about the moisture being pushed into the walls if you totally tank or waterproof the floor.Personally I would contact a tile manufacturer and ask they're opinion.i know that bal's flexbone membrane allows for moisture release but not sure if it would be suitable for this purpose

Thank you kindly. Believe there are several manu of these membranes, I'll investigate. Suppose a leveller and adhesive would have to be somewhat permeable too?

 

[judge]

Thank you kindly. Believe there are several manu of these membranes, I'll investigate. Suppose a leveller and adhesive would have to be somewhat permeable too?

Yes ,you can get hold of both these days

 

[Kevbos]

Hi, first post here. I've been lurking this forum for advice for a while, thank you all who share your knowledge.

I'm to tile a kitchen of an old (old old) house, farmers concrete with NO DPM, house has no dpc, stone walls. Area 17 sqm, waves up to 12 mm difference, to be finished with porcelain tile. This house has been diy'd by different individuals for over 60 years, such is the nature of the place I'm afraid. We lifted lino with rotten chipboard and a sheet of plastic (DPM) underneath. Concrete was fairly wet, now dried, at least on surface. The concrete is topped with a red pigmented screed around 10mm in thickness (picture where removed as it sounded hollow). Replacing slab is the last last option,as this is a diy and budget sensitive project.

Question: is it wise to remove the screed? How should I then proceed in preparing the subfloor for tiling? I've been through a multitude of options, these two stand out:

1. Keep the screed, Sbr slurry, level with SLC,tile with ditra, tile

2. Remove screed, install insulating waterproof backerboard like wedi or marmox on a bed of adhesive, tile.

There will be some moisture in the floor as it's just slab on ground (probably added by another diyer when I was not walking this earth yet. I'm worried that overt dampproofing will push moisture up the walls. And that a lack thereof will result in the tile setup fail.Can anyone advise please whether my suggested options are ok, or if there's an approach that I've missed and could deal with this better?

Thank you! Whenever you're reading this -have a good day

View attachment 123887

Nothing lasts forever !! It is an old house that sounds like it needs some attention , you know what you should be doing ,but for some extra advice , concrete or screeds or brickwork etc that are at mercy of water for years , lose there strength as the cement and lime gets washed out , if the floor sounds bad then fix it

 

[Bod2021]

The best option which will last and not push damp into the walls is to remove as much old concrete / screed from the existing floor as possible and then to lay a new Limecrete floor, which will be vapour permeable, but should be topped with, for example, a breathable stone material, not porcelain

Another option is to remove at least 75mm of existing floor and add a DPM, topped with new, levelled and floated concrete or a compacted cement screed. Then you will need to address the walls by drilling along the bottom and injecting with a water-repellent. The floor can then be topped with any tiles, including porcelain, but the injected walls may need retreating after several years.

 

[Edwin Tintoe]

The best option which will last and not push damp into the walls is to remove as much old concrete / screed from the existing floor as possible and then to lay a new Limecrete floor, which will be vapour permeable, but should be topped with, for example, a breathable stone material, not porcelain

Another option is to remove at least 75mm of existing floor and add a DPM, topped with new, levelled and floated concrete or a compacted cement screed. Then you will need to address the walls by drilling along the bottom and injecting with a water-repellent. The floor can then be topped with any tiles, including porcelain, but the injected walls may need retreating after several years.

Thank you!