Sealing limestone flagstones ... Pictures :)

[Jolsand]

Hi all

This traditional building methods malarky takes AGES!

For an update on previous posts... The channel has been dug, and made breathable with some geocell glass things .. Bottom of walls now limed ... And now we have limestone flags laid!!

They need a clean, and to be grouted and sealed ... but yay!

How do I seal while maintaining breathability? Have seen 'smart seal' having some claims to breathability?

Also clay paint is probably the way we are going on walls ... But have to wait at least 4x weeks for lime plaster to dry....

The end is in sight!

 

[88v8]

Yes, it does take ages, but satisfying, eh?

Plaster needs to dry at least four weeks per quarter inch of thickness. You know of course to thin the first coat of clay paint.

I don't believe in breathable sealant. I think it's snake oil. However, as you haven't grouted yet, that's OK.
Seasl then first, before you grout. That way there will be no sealant on the joints. The floor breathes through the joints, not the flags,.so it's important not to seal the joints. Normally this is fiddly, avoiding getting sealant on the joints, but not in your case.

When the sealant is dry, grout with NHL 3.5 + silver sand, tamping it well into the joints, and clean off the surplus as you go with a hessian sack.
If the joints are very fine, replace the silver sand with stone dust.

Ivor

 

[TheForge]

A genuine question as I often hear the mantra ‘floors breath through the joints’, if floors don’t ‘breathe’ through the stones why will an impermeable sheet taped to a floor so as to be as airtight as possible be wet on the underside when removed?

Also, if evaporation only happens through the joints then the choice of floor covering should be irrelevant, only the width of the joints would matter.

 

[Jolsand]

I don't believe in breathable sealant. I think it's snake oil. However, as you haven't grouted yet, that's OK.
Seasl then first, before you grout. That way there will be no sealant on the joints. The floor breathes through the joints, not the flags,.so it's important not to seal the joints. Normally this is fiddly, avoiding getting sealant on the joints, but not in your case.

So... In theory then you wouldn't have to use a limestone or natural stone tiles ... As long as the joints were lime you could have ceramic ? Too late for me but interesting!

Any recommendation on brands of sealant?

Thanks
Jo

 

[TheForge]

Beeswax or linseed oil. Ecover liquid Floor soap used neat works well to, work it well I to the stone unti the lather has gone. A few coats are needed to build up a finish.

 

[worms]

A genuine question as I often hear the mantra ‘floors breath through the joints’, if floors don’t ‘breathe’ through the stones why will an impermeable sheet taped to a floor so as to be as airtight as possible be wet on the underside when removed?

An impermeable sheet taped to a cold concrete floor will be wet underneath, too! Presumably condensation in the small amount of air between floor and sheet.

 

[MatthewC]

A genuine question as I often hear the mantra ‘floors breath through the joints’, if floors don’t ‘breathe’ through the stones why will an impermeable sheet taped to a floor so as to be as airtight as possible be wet on the underside when removed?

Also, if evaporation only happens through the joints then the choice of floor covering should be irrelevant, only the width of the joints would matter.

I'm with you on this one. I would say that the floor does breathe through both stone and grout (and possibly even preferentially through the grout). Almost 8 years ago, I didn't seal my limestone floor (on limecrete) and the only issue I have ever had is that my wife would like it shiny!

 

[88v8]

It probably depends on the stone. Some stones are more permeable. Just as some stone supports the wicking process we know as 'rising damp' and some doesn't.
We know what happens to walls that are cement pointed, can't breathe. Sometimes the wall becomes so saturated that the face blows off, sometimes not, depends on the brick or stone.

Our concrete sitting room floor was damp around its perimeter. Replaced with limecrete. On that we laid mock-stone concrete slabs, superb antique appearance, but concrete and moreover surfaced with e 3M resin coating so totally impermeable.... but they were laid and pointed in lime.
And around the perimeter, two rows of quarries, with wide joints.
Eight years on, no damp, so it must be 'breathing'. Through its bedding and pointing.

It only takes a thin layer of unsuitable chemical - eg plastic paint - to frustrate breathability.
Seal the joints for the sake of making it shiny?? No thanks.

Ivor

 

[TheForge]

I would agree with you Ivor.

Just another thought on the curing time for plaster, it’s obviously preferable to wait as long as possible before painting, but limewash, the most permeable of all finishes and the most appropriate for lime plaster, can be applied as soon as you wish.

Clay paint is also not the only option for fresh plaster. Traditional distempers (soft, casein or oil bound) are also perfectly suitable and cheaper! Distemper is just chalk or china clay, gelatin and water with the durian of additional natural binders for added durability.

I’m not entirely sure what is in clay paint but there must be dispersal agents to hold the pigment in solution along with biocides.