How to install limestone flagstones?

[JoceAndChris]

Out of interest, how would you go about installing flags like these?

http://www.antique-french-stone-flooring.com/

These are very similar to what we have in our hall and kitchen and I think originally they were throughout the whole downstairs basement kitchen and work areas. We've never lifted them but I imagine they're laid on soil and rubble if what's under the floorboards is anything to go by. The hall sits above a vaulted tunnel. I wonder how they did it.

I was thinking how nice it would be to have these in our new bathroom but that floor is timber suspended a foot above the earth. I doubt you'd be able to suspend flagstones like this?

But then, the slate tiles that have just arrived from Fired Earth are so heavy I also wonder if they're suitable to lay on a timber floor that sits a foot above ground level?

 

[Pennyviz]

They are lovely flagstones! Theoretically, you can lay tiles or stone on top of floorboards but you have to make sure you have a really good layer of plyboard, cement backer board or insulating board screwed down tight to stop movement and the tiles cracking.

Penny

 

[JoceAndChris]

Thanks Penny!

I wonder how you get round one slab having a depth of 4 inches and one having a depth of 2.5??

 

[TheForge]

Flagstones are immensely heavy. I'm reasonably strong but struggle to lift even relatively small ones. I've laid larger slabs with straps underneath between two people and that was a struggle!

They also tend to be very uneven on the underside.

I can't imagine laying them over a wooden floor would be easy (if even possible as you'd need to set them in a thick mortar or sand bed) and would put a huge load on the joists.

 

[JoceAndChris]

I see. All very interesting. I suppose our flagstone hallway does not sink into our undercroft because the tunnel under it is an arch, which is strong, and there will be tons of earth/sand/rubble between the flagstones and that tunnel ceiling.

In that case it's a no go for the bathroom, but I reckon we could use flagstones in our basement if we have the energy to dig out all the concrete that's been poured down there.

 

[Me!]

You probably could do it, depending on the span of the floor joists and how good the foundations are at the edges (or how good you could make them). You could then replace your existing floor with a beam and block floor and then put your stone flooring on top of that.
Not a very period construction method I know, but I suppose it depends if your existing floor is worth keeping?

 

[MikeG]

Sorry to pour cold water on this, but I think any attempt to lay traditional stone flags on a wooden floor is pretty close to nuts. It is doomed to failure, has every chance of overloading the joists, and you or your successor in the house will be back on here in a few years time asking about removing them. If you insist on flags (and they're beautiful & practical), then you should take the floor structure up and replace it with a suspended concrete floor (there are various options), and set the flags on a bed of screed/ mortar to equalise the varying depths and aid leveling.

 

[MatthewC]

Sorry to pour cold water on this......

...which is literally what you would be doing, as (apart from Mike's points) a wooden floor would move gently and water in the bathroom would penetrate the joints of the flags.

 

[Flyfisher]

I wouldn't say laying flags on a suspended wooden floor is impossible per se, but it must certainly be looked at from a structural perspective and the fact is that a wooden floor intended and built for 'normal' household loads (ie people and furniture) is pretty much guaranteed not to be strong enough for a layer of stone on top.

We're probably all aware of the loading issues associated with large bathtubs, which can often require the floor to be strengthened to support the combined mass of a heavy bathtub and a large volume of water, so I would think of flags being in the same category - in a structural sense. And while it might be technically possible to strengthen the existing floor, it's likely to be a major undertaking . . . which I supposed could be summarised as 'nuts' :wink:

 

[Pennyviz]

Could try talking to these people:

http://www.flagstonesdirect.co.uk/

I know a lot of the original flagstones found in old places are of varying thicknesses and can be huge, and wouldn't work on a suspended timber floor, but not sure of the dimensions of those ones you linked to. The ones from the link above they say can be put on timber with the right support apparently.

Penny

 

[JoceAndChris]

Interesting posts from all!

I think we have decided not to - anyway, the new bath is in, so if we were going to have an entirely new floor construction the time to have done it would have been before fitting in the new bath. That's now set in a wooden construction and sealed in.

I posted the question partly from wondering how they would have fitted in the bathroom, and partly wondering how I'd fit them downstairs in our basement kitchen. Thanks very much for all the helpful ideas!

I'm now really quite worried about the Fired Earth slate tiles. They weigh a ton. I'm worried about them going on the walls and I'm worried about the going on the floor. It seems an unfeasible weight for either. I'll let you know what happens!

As for water going down into the floor - I'd imagine that were it constructed correctly (limecrete above earth?) it wouldn't matter very much? If you have stone walls - which I do - with lime plaster on both the outside and inside - which I do - and limewash - also, yes, then surely a ground floor bathroom could have flagstones laid on earth without worry? You wouldn't tip buckets of water down ( I don't, anywhere) but you wouldn't worry about getting out of the bath and dripping all over the floor?

 

[Flyfisher]

I agree that water spillage shouldn't be a problem with flags laid on a ground floor, whether plain earth or on a limecrete base. Indeed, I'd bet that such floors would have been regularly washed and scrubbed with fairly copious amounts of water in the good old days. As you suggest, any seepage between the flags should simply soak harmlessly into the substrate. I certainly wouldn't worry about such floors getting wet.

 

[GPHouse]

Has anyone got any good advice / found any good resources on restoring flags in situ?

It;s one of my next jobs and I;ve just had a couple of quotes at £80/sqm and I have a lot of space.... I dont mind the work.

Mine look like blue liad, have had some edges congretet which is flaking and there is some delamination.

Damp has been resolved and they are lovely stones.... I just want to get them cleaned, sealed (breathable), and pointed.

G

 

[Maddie-Rose]

My kitchen had a wooden suspended floor, & we wanted to lay huge rustic slate tiles, but wouldn't of dreamt of laying this ontop of. Firstly with all the mortar too, the height of the floor may then be too high?

Secondly, what if the underneath boards rot or fracture in the future?

We removed our suspended floor, then laid our slate flags onto a mortar bed

 

[JoceAndChris]

Thanks Maddie Rose - I'll aim to do the same in the future when it comes to the kitchen!

Thanks FF - I also think a bit of water if installation is correct is OK.

Has anyone got any good advice / found any good resources on restoring flags in situ?

It;s one of my next jobs and I;ve just had a couple of quotes at £80/sqm and I have a lot of space.... I dont mind the work.

Mine look like blue liad, have had some edges congretet which is flaking and there is some delamination.

Damp has been resolved and they are lovely stones.... I just want to get them cleaned, sealed (breathable), and pointed.


G

Hi there I really recommend the Liberon products on stone - they really bring them up a treat. There's a cleaner, and an oil based sealer. They have a nice smell and go into the stone a treat. As for pointing, I havent done it, it looks a nightmare! I posted about it here and got excellent advice on how to make the lime pointing but I've never summoned up the courage to do it as if it's wrong it will be so much worse than how it looks currently!