Floor Tiles

[elizabeth]

Hello All,
I wonder if anyone could advise me please as to to the right lime mortar mix needed to bed in terracotta tiles on a limecrete floor.

 

[plasticpigeon]

I was recommended 1:3 with NHL5 on a limecrete floor if I remember correctly. They're still stuck down 3 years later. Ty Mawr will be able to tell you for sure.

 

[elizabeth]

Thank you Plasticpigeon, I am glad for your advice, vey helpful, I will purchase the lime now.

 

[Flyfisher]

Would NHL5 be a bit on the hard side, as well as reducing the breathability of the limecrete?

Norfolk pamments suggest a 4:1 mix, but don't specify the NHL grade: http://www.pamments.co.uk/laying.html

I can't see that this application requires a great deal of strength so I'd go with a weak NHL2 mix for maximum breathability.

 

[plasticpigeon]

The limecrete slab is made with NHL5 so I can't see why the screed to lay tiles on top would make any difference to the breathability, and for a floor it needs to be solid, and the last thing anyone wants is the floor tiles coming loose, but also it is what Ty Mawr recommended when I laid my floor and tiled over with 9" quarry tiles.

 

[Flyfisher]

If the slab itself is NHL5 then I'd agree with using the same to bed the tiles - little point using anything less, though it should do no harm. I wonder what type of limecrete Elizabeth's floor is constructed from?

As for the tiles coming loose, I'd be surprised if this was a problem with any grade of lime mortar because in normal usage there really shouldn't be any lifting force at all. The key things are for them to be firmly and evenly bedded onto the substrate below (whatever it is) to resist any downward force and adequately grouted to resist any lateral force. After that there really is nowhere for them to move.

We have pamments laid directly on earth and while they might not be as uniformly level as they would be on a limecrete (or concrete :shock: ) floor, they show no signs of lifting. Block paving is much the same - bedded on sand and grouted with sand. Simply no need to 'stick' them down when gravity handles that side of things.

 

[plasticpigeon]

You have to make the choice that you are happiest with. I am more happy with the tiles stuck down on a solid surface, if for no other reason than they don't come unstuck when walked on before grouting. There may not be a lifting force but if there are any raised corners or edges, any weight on these puts a force on the tile that can raise the opposite side. I don't think anyone supplies a limecrete floor that isn't NHL5, certainly not when I was looking for suppliers about 3 years ago!

 

[Flyfisher]

You have to make the choice that you are happiest with.

I know what you mean, though some people are happiest with uPVC windows and cement render :wink:

I am more happy with the tiles stuck down on a solid surface, if for no other reason than they don't come unstuck when walked on before grouting. There may not be a lifting force but if there are any raised corners or edges, any weight on these puts a force on the tile that can raise the opposite side. I don't think anyone supplies a limecrete floor that isn't NHL5, certainly not when I was looking for suppliers about 3 years ago!

Interesting point about commercial limecrete floors - I wasn't aware of that. Perhaps I made a mistake when laying my own limecrete slab in a large inglenook fireplace using an NHL2/Leca mix, though it seems solid enough.

As for uneven tiles with raised edges etc, I presume that sort of thing would not be a problem when laid on earth or sand, or any other sort of pliable base, as traffic would gradually settle the tiles into an appropriate position to preclude further movement, leading to a rock-solid floor. This might take a little time of course, which is perhaps why we tend to favour a slab-type floor these days? But I sometimes wonder about the advantages of a limecrete floor covered with pamments or similar compared to those same pamments laid directly on earth, when both methods would provide a solid, breathable floor easily capable of bearing any domestic loads and would look identical. Perhaps our rush to embrace lime over cement (a generally good thing of course) causes us to forget to question the need for a solid floor slab in the first place?

 

[88v8]

I think over any significant span, NHL5 is used to obtain the necessary beam strength.

Our quarry tiles were laid by a so-called conservation builder, bedded in scalpings on the earth, and sat on blobs of cement/hydrated lime.
Unsurprisingly a large number are now rocking or downright loose.
I saw in the local news that he apparently topped himself recently, so my plasticene men/hatpins seems to have worked :evil:

On our limecrete floor, the quarries were bedded and pointed in an NHL5 mix, and four years later we have no visible breathability problems.

Ivor

 

[MatthewC]

On reading the above, I was quite sure that I had used NHL3.5 on my limecrete floor (both the slab and the bed for flags), but I just found the receipts from 2011 and it was NHL5! The exact materials were on the advice of Mike Wye & Co. The floor has been excellent with no problems whatsoever (except in getting the flags perfect!!).

 

[plasticpigeon]

Our quarry tiles were laid by a so-called conservation builder, bedded in scalpings on the earth, and sat on blobs of cement/hydrated lime.
Unsurprisingly a large number are now rocking or downright loose.
I saw in the local news that he apparently topped himself recently, so my plasticene men/hatpins seems to have worked :evil:

Ivor

Can I send you some names and photos of people on my list?!