Anyone got limestone flooring

[dogman]

Can anyone help the wife pick her flooring

She wants limestone and we have a local shop selling it at £30 meter at present. Its an opus pattern tumbled finish and need to get now as it is on offer.

 

She is up and down as to buy it. It will run through the whole groundfloor.

Worried about it cracking as we will have UFH (low temp) Do we decouple?

Will it stain even after sealing?

what is it like to live with?

[Jeremy Harris]

Your UFH will run a great deal cooler than any bit of floor exposed to the sun in summer, so there's near-zero risk of it cracking.  We have around two thirds of our ground floor in 12mm thick travertine, which is very similar to limestone in composition.  Our UFH runs the floor at an absolute maximum of around 23 deg, if that; most of the time it sits at 22 deg C or less.

[dogman]

@JSHarris did you use a decoupling membrane?

 

[Jeremy Harris]

No, there's no need to at all, as the UFH will always be just a degree or two above room temperature.  Standing on the floor in bare feet makes that bit a lot warmer than the UFH!

 

We used a flexible adhesive, standard set, I can't recall the brand but think it was one Nick had mentioned as being pretty good.

[pudding]

I've got limestone downstairs, with UFH on flexible adhesive and it's fine. It's sealed, and a whole glass of red wine didnt leave a mark.

Edited March 4, 2017 by pudding

[Nickfromwales]

The only thing that marked my travertine, in the bathroom, was my daughter throwing up on it . It doesn't like acidic 'solutions'  that's for sure ! A good bit of elbow grease and some clever cleaning of the floor with various cleaners and it's now barely visible, but was a pita compared to the porcelain outside the bathrooms which just wipes clean in milliseconds, regardless of who's done what to them. 

Is your slab screed, or concrete with Re-bar? 

[dogman]

@Nickfromwales MBC slab so concrete with Re-bar

[Nickfromwales]

A good solid unified slab then, so I'd second the motion for no decoupling . 

The only thing I'd do is a couple of expansion gaps at the door thresholds where there could be some movement. 

Its very hard to just promise someone that it'll be fine, so some caution is always extended, but the absolute truth is that you should get the tilers input also ASAP as it'll be their head on the block not ours. 

Afaic, if primed and laid with a good quality flexible tile adhesive, you should have no issues. I'd only be worried if you intended to have zones and only heat certain rooms at certain times, but that has been well discussed as an unwise way to use the system. Will you just run at one temp so the slab heats and cools 'as one'?

[Temp]

+1

 

If it's too late to add expansion slots then I would decouple. Otherwise not.

 

We have opus pattern stone over UFH. The screed in each room shrank towards it's own centre and it cracked where they met at a doorway (we didn't put an expansion gap). The crack is not straight but curved more in one room than the other. Needless to say this propagated to the stone and the crack runs across three bits. This despite us allowing plenty of time for the screed to dry and warmed up the UFH slowly. No other cracks anywhere else.
 

Think about grout colour. The main downside is that the grout gets dirty, especially in our kitchen. Seal it with several coats of stone sealer as soon as you can. For cleaning dirty grout I recommend you go on-line and look for special Alkaline stone cleaners available in 5L containers. One of these brushes saves the back..

 

 

 

 

Edited March 4, 2017 by Temp

[Nickfromwales]

Sorry @Temp / both, I should have been clearer.

Assuming the slab is laid, I was referring to cuts in the tiles at the door thresholds and putting a coloured silicone / caulk in to allow some separation / movement between tiled 'areas'. 

[Jeremy Harris]

I think there's a great deal of over-thinking going on here!  A heated slab like this in a highly energy efficient house simply will never get "hot" as such, it will get very, very slightly warmer than the room.  We have travertine over a lot of our ground floor, through doorways etc as a continuous run.  There is not even the slightest possibility that it will crack when laid on a steel reinforced slab like this, both because there's no significant temperature changes between the two elements and because the steel fabric in the concrete means that the structural slab can't crack (if it did it would cause problems, as it's load-bearing and supports the whole house).

 

To illustrate this, this is a rough cut from some data collected over the last couple of weeks for the coldest four days we had.  The slab surface temperature rearely gets more than 1 deg C above the room temperature, and most of the time stays well below that:

 

 

The data above is a bit rough, I'm still tidying up the plot, but the horizontal scale is hours, starting at midnight 21/2/17 on the left and ending at midnight 26/2/17 on the right.  The red line in the floor surface temperature (travertine) and the green line is the room air temperature.  You can see when the UFH has come on for an hour or two from the small peaks; most of the time the UFH is off.  We didn't get any really cold weather when I was doing this lot of monitoring, which is a nuisance, as I was hoping to get more data on the relationship between heat input and outside temperature.

 

Anyway, you can see from this that the floor isn't going to get at all hot from the UFH, it will get far hotter from the sun shining on it in summer.

Edited March 4, 2017 by JSHarris

[dogman]

Just to help. The slab is not yet down and will be the normal MBC slab.

I will be following the sensible advice on this forum to treat the the whole ground floor as one zone running at 20-23 deg. The Flooring will run across the whole ground floor which is three large rooms and one small room including the kitchen. I don't really want to use a decoupling membrane as it will add a good chunk to the cost. The tiler did mention that it would be better to try and put a joint at the door thresholds to act as an expansion joint if possible.

I have yet to plan how to lay the tile as Opus can be a bit of a challenge especially as the largest tile will be 900 x 600 and smallest 300x300.

@Nickfromwales What adhesive did you recommend?

 

I think the wife has decided to go for limestone and we can reserve the stone for a 50% deposit on credit card and the will hold it until we need it for a couple of months.

 

However just had the whole plan thrown into chaos as our ground worker has come back from holiday and told me this morning he can no longer do the job. Our reserve is saying that he cannot start for at least 5 weeks and MBC want to start asap

 

 

[Jeremy Harris]

Our travertine is all 600 x 400 IIRC, laid on standard set Mapei white, flexible, adhesive, with cream grout.  The whole lot was sealed with some silicone sealer that was applied once before grouting, then again after grouting, and seems to do a reasonable job.  I think they recommend re-sealing the floor every year or two, which isn't much of a chore as the sealant is very thin and is quick and easy to apply. 

 

It's been down for a couple of years, and goes through four doorways on the ground floor, with no thresholds, just tiled straight through.  The coefficient of linear thermal expansion of limestone/travertine flooring is nearly identical to that of structural concrete, so they won't move differentially at all over a small temperature range.  Problems only really arise when laying something that has a coefficient of linear thermal expansion that is significantly different to the base it's laid on, like hard fired porcelain, that has about half the coefficient of linear thermal expansion of structural concrete.

[dogman]

Thanks JSH .

Mapei is our normal go to adhesive and grout.