Laying floor tiles/pamments inside

[sevenleaf]

I am looking for some advice with regard to (re)laying a number of original and reclaimed clay floor tiles/bricks/pamments in our ~300yr old timber framed cottage.

We have had the downstairs floor dug out in two rooms, a breathable insulation added (an incredibly lightweight black 'coal' substance with a weed membrane layed either side) and a limecrete layer poured on top. We are now looking to have the reclaimed clay tiles laid on top.

The whole philosophy of the revovation has revolved around breathability - only lime has been used, and I would like any advice with the following:

1. The ''bed' upon which the 9"x4.5" tiles should be laid
2. What can be put in the gap inbetween (silica sand has been suggested)
3. Any substance that can bring out the (incredible) colour and detail of the tiles without affecting the breathability
4. Minimalisation of efflorescence (if this is even a thing when using lime? I have had to clean/remove a lot of 'gunk' from around the edges of our existing tiles.

Any advice or experience would be much appreciated. I have some further questions that I will be posting in due course!

 

[Helen Foster]

Hiya,

We used the same recycled foamed glass insulation in 2 rooms with limecrete on top and bedded our York flags with NHL lime.

1. Bedding; Some suppliers suggest NHL5 for strength (but it is also the least breathable of the NHLs) so NHL3.5 (mixed with sharp sand) is maybe better as long as you follow the rules about not walking on the surface for the suggested length of time (depends on thickness of bedding and temperatures etc but I'd wait at least a week). I'd then point the gaps with the same mix - With sand you'll find you're always vacuuming it out and it'll need replacing over time. You could brush in a mix of kiln dried sand and lime and water it down if the gaps between tiles are very fine, but pointing will give you the best finish in my experience.

2. I'd then point the gaps with the same mix, preferably NHL3.5 - sand is OK but you'll find you always vacuum it out and it'll need replacing over time. Make sure to keep it well damped as usual with lime and once brushed off this will look lovely, bringing out the aggregate in the mix.

3. I sealed our stone flags with boiled linseed oil - test a tile(s) first before laying to check you like the finish. It brings out the colour and gives a natural, breathable seal. use VERY sparingly - too generous and they'll be sticky. Better 2-3 very thin coats than one thick one. Spirit shouldn't be mixed with it if you ensure you used it thinly.

4. Minimise staining by ensuring not to get lime mix on the surface of the tiles.

Hope that helps a little bit.
Helen

 

[plasticpigeon]

I've done this job, and laid the tiles on a very similar limecrete floor. Now I am no authority, but so far everything has worked fine, 4 years later the floor is doing well. I laid the quarries 9 x 9 in my case on a screed of nhl and sharp sand. As my quarries were of different thicknesses I had to lay each one individually in its own bed which was very time consuming. If yours are all the same thickness it will make the job easier as you can do it in sections. I think it is most important to lay the tiles edge to edge with no gap at all. The irregularity of the tiles will dictate that there are small gaps in places, but if you try for no gaps it will look best. You then have to grout with something very runny. I know that from Victorian times pure cement slurry was used but I used a very very fine grout that I got from Ty mawr. It looks like talc but I think is lime and stone dust or some other fine aggregate (I talc is very fine stone dust!). The problem is that it is white, so I dyed mine black with cement dye, but I'm sure white will look good too. The most important thing to me is to lay edge to edge, any gaps look modern and horrible. I cleaned up as much as poss with water and then brick acid to clean the lime stains. I'm not sure any surface treatment is needed. After a while the natural wear brings out the colour and shine. Linseed oil thinned with turps can be used, and is traditional but I'm not sure it is needed. It's also not very breathable, but Ty Mawr explained that the floor acts as much as a moisture sink than anything else as there is no capillary action due to the closed cell nature of the foamed glass (stuff that looks like coal), so the only water going into the slab is due to evaporation from the ground, and the slab is large enough to act as a buffer so evaporation from the surface is minimal. Who knows if this is correct but it is what the inventors of the floor said to me!

 

[88v8]

The builders who laid our reclaimed quarries did a poor job, one of their sins was to point them with what is known in the botcher's trade as drypack, a mix of lime & sand brushed dry into the joints in the vague hope that the floor will be damp enough to make it set.

When most of it went into holes I vacuumed it out and pointed with NHL3.5 or perhaps NHL2, and sharp sand. Where the joints were thin I used silver sand (garden centre) which is very fine and will get into narrow gaps. Lime & stone dust would also do that job.
For the lime to set, the joints must be damp. Not wet, but damp. A hand mister (also garden centre) is OK.
Consolidate the pointing by bashing it with a churn brush as you go along, and finish with various diameters of dowel to suit the gaps.

Whilst pointing, I was wiping off the edges quite aggressively with a piece of old sacking and a toothbrush. As you say, hard to remove once dried.

Proper pointing is a long a tedious job, which is why builders don't want to do it.

Ivor

 

[Flyfisher]

Good post Ivor, which exactly matches my experience - especially the final sentence.

I had to insist that our builder hand pointed the pamments laid for our new kitchen floor. It took a bit longer, and therefore cost a bit more, but it resulted in a better job than brushing lime grouting all over the new tiles. Even so, it was necessary to clean the edges of the tiles (with spirits of salts, aka hydrochloric acid) to remove traces of lime, though nowhere near the difficulty of doing this for the entire surface of every tile (c.2000 9-inch pamments!).

Regarding the use of fine sand (Not sure what 'silica sand' is - isn't all sand basically silica? Perhaps it means kiln-dried sand?) I would not recommend this for indoor use because I have done precisely this for a 4m2 area of pamments laid directly on earth underneath a staircase. My assumption was that the residual ground damp would consolidate the sand to form a solid joint. Unfortunately - or fortunately I suppose - the breathability of the floor is so good that there is no residual damp and therefore the sand remains so dry that on the rare occasion that the floor is vacuumed it removes a lot of the sand!

I agree with Ivor that when pointing the trick is to firmly pack the lime mixture between the tiles, though I personally avoid using a brush because of the mess it makes of the tiles. I prefer to use a 'tuck pointer' (google for details) of an appropriate width. For very tight joints I grind down the narrowest tuck pointer I can find. I still manage to get some lime on the tile edges but not too much and, as Ivor says, it can be mostly removed as you go along. I then do a final clean up with spirits of salts at the end of the job (or end of the day for a large job). I generally use NHL2 and sharp sand at between 1:2 - 1:3 depending on the colour I want.

Frankly, these sorts of jobs are mostly a matter of confidence. A really skilled pointer will certainly work faster than a novice but even a novice can achieve pretty much the same results given enough time and care.

 

[sevenleaf]

Thanks to all for sharing your experiences in such detail.

Being custodian of a period property can such be a daunting respomsibility at times, and it was for exactly this reason that I joined this forum. I hope to be able to post before and after pictures in due course!