limestone floor sealer

[Diane Jameson]

I have put down a limecrete floor on glapor and finished it with large new limestone flags on a lime mortar. I was going to leave unsealed but they are very porous so I was wondering if anyone had any ideas of what to use to keep it porous but not so much that whatever might be spilled soaks into the surface? 48 sq metres

 

[Kearn]

You’re asking the impossible. Porous but waterproof!

The reality is, no moisture will be evaporating through your tiles, so sealing isn’t an issue if you have aesthetic concerns.
The RFG layer is the capillary break, what goes on top is largely irrelevant from a moisture management perspective. At best, less than 1% of trapped moisture might evaporate up as vapour and try to be released through the slab.

We have similar slabs in our kitchen, I opted to seal as red wine / ribena stains aren’t appealing… elsewhere in the house I haven’t bothered as life happens.

Thankfully, I sealed these on a Friday. When I came back to site Monday, there was an enormous splatter of purple bird on them (building wasn’t secure, so something had flown in and perched on the joists above). Very glad I had sealed…!

I used
ROCATEX NATURAL FINISH SEALANT 1LITRE (RX/0931)

other options also available…

 

[IHateDamp]

You’re asking the impossible. Porous but waterproof!

The reality is, no moisture will be evaporating through your tiles, so sealing isn’t an issue if you have aesthetic concerns.
The RFG layer is the capillary break, what goes on top is largely irrelevant from a moisture management perspective. At best, less than 1% of trapped moisture might evaporate up as vapour and try to be released through the slab.

Curious and slightly confused. Does that mean with the RFG layer, limecrete as a breathable layer is not necessary and could have used concrete?
Or that laying a vinyl sheet floor will not be problematic in this case?

Is an RFG layer better in some way than a damp proof membrane?

Sorry for so many questions but trying to understand.

 

[Diane Jameson]

You’re asking the impossible. Porous but waterproof!

The reality is, no moisture will be evaporating through your tiles, so sealing isn’t an issue if you have aesthetic concerns.
The RFG layer is the capillary break, what goes on top is largely irrelevant from a moisture management perspective. At best, less than 1% of trapped moisture might evaporate up as vapour and try to be released through the slab.

We have similar slabs in our kitchen, I opted to seal as red wine / ribena stains aren’t appealing… elsewhere in the house I haven’t bothered as life happens.

Thankfully, I sealed these on a Friday. When I came back to site Monday, there was an enormous splatter of purple bird on them (building wasn’t secure, so something had flown in and perched on the joists above). Very glad I had sealed…!

I used
ROCATEX NATURAL FINISH SEALANT 1LITRE (RX/0931)

other options also available…

View attachment 17943

Thanks for the info and pictures of your floor. I know it's impossible to have sealed floor and porosity. We we following Mike wye flooring for Old houses and put French drains outside and inside to drain any moisture away to the outside as well. It now seems we didn't need to use limecrete but it's there now so we were trying to keep the breathability. I may seal with something but still not sure. Ty mawr sell a sealer that claims some breathability I might contact them for clarity. Thanks for your input.

 

[stuart45]

Curious and slightly confused. Does that mean with the RFG layer, limecrete as a breathable layer is not necessary and could have used concrete?
Or that laying a vinyl sheet floor will not be problematic in this case?

Is an RFG layer better in some way than a damp proof membrane?

Sorry for so many questions but trying to understand.

It's a lot more expensive, so I'd guess that most people using it would go all the way and lay a limecrete slab.
However it's a good point. Concrete isn't totally imperious. Depending on the strength and type of aggregate used, it can allow a fair bit of moisture through. No fines concrete for example can be used in car parks to allow surface water to pass straight through it..

 

[Kearn]

Curious and slightly confused. Does that mean with the RFG layer, limecrete as a breathable layer is not necessary and could have used concrete?
Or that laying a vinyl sheet floor will not be problematic in this case?

Is an RFG layer better in some way than a damp proof membrane?

Sorry for so many questions but trying to understand.

Yes, pretty much.

A minute amount of vapour may evaporate through the slab, but effectively all moisture is managed down by the RFG.

Europeans, where RFG is much more a thing and originates form, use it with a DPM and concrete slab over.

Limecrete has other benefits, many like the carbon footprint, its can also be tiled on sooner, which helped me in a fix, but moisture management properties aren’t relevant in this situation. On the down side, it’s more costly, and way slower and labour intensive to lay…

 

[eezageeza]

For what its worth, we recently laid a limestone floor and used Lithofin (both cleaner and sealer) to finish it. Breathability wasn't a concern for us as it was going onto a concrete base.

It seems to work very well - we haven't managed to make any stains stick yet anyway - but be aware that it does darken the stone colour a little.

 

[IHateDamp]

Yes, pretty much.

A minute amount of vapour may evaporate through the slab, but effectively all moisture is managed down by the RFG.

Europeans, where RFG is much more a thing and originates form, use it with a DPM and concrete slab over.

Limecrete has other benefits, many like the carbon footprint, its can also be tiled on sooner, which helped me in a fix, but moisture management properties aren’t relevant in this situation. On the down side, it’s more costly, and way slower and labour intensive to lay…

I found your comment I pasted below from a few years ago and nobody hurled any apples ! So why is there a hoo-ha about concrete floor laid in old buildings pushing water into walls?

Well, just to play devils advocate here on the topic in general, and prefaced with the fact that I invested a ton of energy, money and swearing while laying a RFG and limectete floor some years ago…and will soon have a new project with at least one floor to be’investigated’ and then relaid.

I’m planning to consider a concrete slab…
Don’t hurl your apples just yet!

But with all the recent understanding about NHLs which are finally showing their true properties after being used in situ for some time (too hard and not really that breathable), and the trend towards hot lime instead where it matters.

It seems to be that the real benefit in a limecrete floor, is actually the RFG moisture management layer and physical buffer between actual ground and internal ground level.

There is a lot of evidence coming to light that shows an NHL floor really doesn’t breathe, but when laid on the correct sub floor, it doesn’t actually need to, hence why SPAB and the like are considering and recommending concrete slabs on top of the right base.

food for thought…

 

[IHateDamp]

We we following Mike wye flooring for Old houses and put French drains outside and inside to drain any moisture away to the outside as well. It now seems we didn't need to use limecrete but it's there now so we were trying to keep the breathability. I may seal with something but still not sure. Ty mawr sell a sealer that claims some breathability I might contact them for clarity. Thanks for your input.

Hi Diane I'm wondering was your site particularly wet seeing as you did the french drains ? In that position I think I would want a belt and braces approach; i.e. do everything to ensure no damp would be trapped anywhere.

 

[Diane Jameson]

Hi Diane I'm wondering was your site particularly wet seeing as you did the french drains ? In that position I think I would want a belt and braces approach; i.e. do everything to ensure no damp would be trapped anywhere.

The walls were wet so the concrete was taken off halfway up and replaced with lime. Some of the outside ground levels were too high, this room adjoins another outside room which is at a higher level so all outside levels were taken down to as far as we could get them and french drains put around the perimeter, still not sure if we are going to win, but so far it seems to be fine. There was one corner wall that seemed to get really wet so we opted for the interior drains below the RFG. I wish we had know all this 35 years ago when we started and now wouldn't be in this position. Builders still have no clue here and want to inject the walls with damp proofing and cover all in cement.

 

[Diane Jameson]

Yes, pretty much.

A minute amount of vapour may evaporate through the slab, but effectively all moisture is managed down by the RFG.

Europeans, where RFG is much more a thing and originates form, use it with a DPM and concrete slab over.

Limecrete has other benefits, many like the carbon footprint, its can also be tiled on sooner, which helped me in a fix, but moisture management properties aren’t relevant in this situation. On the down side, it’s more costly, and way slower and labour intensive to lay…

curious to know where does the moisture go if there is an impervious layer put on a RFG base?

 

[Kearn]

Red

I found your comment I pasted below from a few years ago and nobody hurled any apples ! So why is there a hoo-ha about concrete floor laid in old buildings pushing water into walls?

its not the concrete that does the damage, it’s the lack of buffering for ground moisture beneath it and the fact it’s on plastic sheeting directly onto wet ground.

RFG is a capillary break, it buffers ground moisture and prevents it from reaching the slab above.
Therefore the slab is largely irrelevant, there may a tiny amount of vapour that reaches it, but negligible.

 

[Kearn]

curious to know where does the moisture go if there is an impervious layer put on a RFG base?

Back to whence it came… liquid doesn’t go up, vapour does, but that is negligible here. The RFG is a capillary break, the wetness comes and recedes. Assuming you spec enough depth and the ground conditions aren’t a lake.

 

[skybloo1]

We did the same back in 2020 - Glapor, Limecrete, flagstones pointed with lime mortar throughout the whole house. As I understood it any residual moisture vapour would escape via the pointing. We sealed the flagstones using Fila Xtreme (just the flagstones, not the joints). No problems at all with damp or stains

 

[Diane Jameson]

Thanks, that's good to know.