Solid kitchen floor - quarries or sandstone flags? How to lay? Breathable?

[sarah.in.liverpool]

Kitchen floor options

We are laying a new breathable floor in our kitchen, after following lots of advice from this forum. We have some questions about this process. Pictures currently of what the floor looks like at the moment.

Laying stand stone flags on kitchen floor OR laying un-glazed quarry tiles, with breathable jute rugs around kitchen, with a breathable grout.

1A: Are sandstone flags appropriate? Is this an appropriate material? Will they allow the ground to breathe through them? OR
Are there any decent modern quarry unglazed quarry tiles available? Or shall we look for reclaimed Victorian quarry tiles exclusively?

1B: What kind of grout do we use? What do we lay the flags on? Directly on the dirt or do we use a lime ‘screed’ or sand or? Can someone point us into the right direction?

1C: Shall we leave a 30cm perimeter where there is only grout / screed or smaller tiles in this perimeter to allow the floor to breathe more at the edges?

Property Details

3 Bed Victorian mid-terraced house. Solid build (no cavity). Built approx. late 1890s.

Solid Floor in kitchen – previously original Ruabon quarry tiles laid on dirt.
Ruabon quarry tiles as a concrete screed had been laid over them – sending damp into the edges, into the skirting board and walls.
Now removing concrete and original tiles and re-laying a new floor back onto dirt. We will ensure good ventilation in this area too.

Kitchen Area: 18.6 Sq M (approx)

N.B. I know that a limecrete floor, dug to around 25cm with a glass aggregate underneath is a warmer and more breathable option, but the cost of around £200-£250 per square meter (total around £4000) is slightly too prohibitive for us.

In the future this may be an option and then we may re-lay the sandstone flags / quarry tiles back over the limecrete. I read somewhere on another forum post that "The gold standard for breathability is to remove the tiles, backfill with limecrete and fit sandstone." I just cannot afford the limecrete at the moment so was thinking just the sandstone flags.

 

[aockenden]

Have you thoroughly considered your position that you can’t just insulate under the floor now? Relaying a floor is a big, dirty, disruptive job. Personally I couldn’t stand to lay it knowing that I planned to just dig it all up again to insulate when I had the cash. You sure it’s not worth just waiting until you can afford to go all the way and have this 100% done the first time?

As for bedding and grouting, the way I’ve seen it done is usually with some type of NHL based lime mortar.

 

[sarah.in.liverpool]

Have you thoroughly considered your position that you can’t just insulate under the floor now? Relaying a floor is a big, dirty, disruptive job. Personally I couldn’t stand to lay it knowing that I planned to just dig it all up again to insulate when I had the cash. You sure it’s not worth just waiting until you can afford to go all the way and have this 100% done the first time?

As for bedding and grouting, the way I’ve seen it done is usually with some type of NHL based lime mortar.

Thanks for your response.

If the main advantage of the limecrete is the warmth, then I'm not sure we will go for it. We just want breathability to stop damp from going into the walls / skirting board. So sandstone flags on a NHL based lime mortar for the bedding of the flags would be best?

 

[aockenden]

Thanks for your response.

If the main advantage of the limecrete is the warmth, then I'm not sure we will go for it. We just want breathability to stop damp from going into the walls / skirting board. So sandstone flags on a NHL based lime mortar for the bedding of the flags would be best?

Insulation under the floor should also help to keep the floor dry, as it will raise the surface temp of the floor thereby reducing the amount of internal condensation that forms on the surface of the floor.

That should work, but there are alternatives to the sandstone for sure if you want. Limestone, slate, terracota and brick are other popular choices. Most of the vapor transfer probably occurs through the lime-grouted joints anyways so I believe the breathability of the stones themselves is only secondarily important.

The other thing to think about is if your going to “seal” the stones / tiles to prevent them getting stained, then their breathability will likely take a hit anyways. You hear stories / sales pitches about various sealants / oils that maintain vapour permeability of the masonry that they are applied to… not sure what to believe on those. I think when we do ours in our house we’ll probably just seal the stones themselves but leave the NHL grouting totally unsealed and just accept that the joints might need to be raked out and regrouted every 5-10 years or whatever as general maintenance if they’re getting too grubby looking…

 

[sarah.in.liverpool]

Insulation under the floor should also help to keep the floor dry, as it will raise the surface temp of the floor thereby reducing the amount of internal condensation that forms on the surface of the floor.

That should work, but there are alternatives to the sandstone for sure if you want. Limestone, slate, terracota and brick are other popular choices. Most of the vapor transfer probably occurs through the lime-grouted joints anyways so I believe the breathability of the stones themselves is only secondarily important.

The other thing to think about is if your going to “seal” the stones / tiles to prevent them getting stained, then their breathability will likely take a hit anyways. You hear stories / sales pitches about various sealants / oils that maintain vapour permeability of the masonry that they are applied to… not sure what to believe on those. I think when we do ours in our house we’ll probably just seal the stones themselves but leave the NHL grouting totally unsealed and just accept that the joints might need to be raked out and regrouted every 5-10 years or whatever as general maintenance if they’re getting too grubby looking…

Thank you Aockenden, understood re: sealing the tiles, I don't think I'll be doing that.

And will leave the NHL grouting unsealed. I will put breathable Matt's around the kitchen too to help with it all.