Questions about old quarry tiles

[somersethouse]

About a year ago we lifted the old carpets and underlays in the living and dining room of our house (we suspect the house to be early Victorian but don't know the exact date). The floor underneath is of old quarry tiles (red and black chequered) and was in okay-ish condition but there were a number of missing quarry tiles (which we have replaced - laying them directly onto the sand like the others that were already in place). There was also a fair bit of crusty, white, hard build up in places (which we have scraped and cleaned off). The overall appearance of the floors is pretty good but we have had a few problems (particularly in one of the rooms - the dining room) :-

Initially, we had a very fine whitish powdery substance coming up through the tiles in one area of the dining room. It would appear daily (usually overnight, particularly if it was very cold during the night). It only came through the red tiles. I started by just sweeping it up every day but it was beginning to drive me round the bend so I experimented by coating the floor with linseed oil - this immediately solved the problem and a few months on, we have not had any sign of this white powdery stuff (phew!).

The problem that we have now is that we are getting a different kind of whitish substance forming on the top of some of the red tiles (in general it affects the tiles that run along the external walls of the room and can effect tiles up to about three or four rows from the edge. From doing as much reading up as I can, it would seem that this is caused by salts being carried through the tiles by water (which evaporates leaving the salts behind on the surface of the tiles). The coating of linseed oil has had no effect on this phenomenon. Certain tiles are badly affected and it is very unsightly (I don't mind a roughish looking floor that shows it age at all but this whitish stuff just looks very odd).

I understand that it is good for a floor like this to 'breathe' and allow water to pass up though it and evaporate but don't know how best to tackle these white marks. Is it likely to be the result of 'too much' ground moisture under the floor? The external ground level is high on the one side of the room and there is a French drain running along it (this was the only solution as it is in my neighbours garden unfortunately and as their whole garden is above the level of our house, there isn't much chance to do anything to remedy the ground level situation at the current time). The other side of the room (also currently affected by the white marks) does not have a high external ground problem (although a leaking gutter was replaced along that wall back in December and the lower half of the wall has just recently been re-pointed with lime).

I can't see much else that I can do externally to try and reduce the amount of moisture under the floor and wondered what my options are internally...? The phenomenon only affects red tiles (are black tiles less permeable\breathable?) so I wondered if replacing the affected tiles with black tiles might resolve (or mask) the problem? I could paint them with red tile paint so as to keep the pattern. I know that masking problems is not a great way to go but don't see what other options I have. Does anyone have any bright ideas or suggestions? What are peoples thoughts on laying a sheet of plastic under the affected areas? I again know that this is not ideal as it is not the way these floors were intended to function but I am clutching at straws!! A vast majority of the floor seems to be unaffected so I am wondering if I could try something in just the affected areas.

I'd really appreciate peoples thoughts and any advice.

 

[MdB]

It sounds to me that you have a good understanding of the problem with the best solution being to reduce the ground water levels under the floor. To this end, I would consider checking your french drain to ensure that the moisture it collects has some where to drain to and that the pipe in it isn't blocked.

Changing to less breathable tiles will cure the problem you are seeing but equally it will increase the moisture level under the floor which may cause issues elsewhere such as in your walls. Not an easy one to suggest a good solution I am afraid.

 

[JoceAndChris]

Oh, poor you, I know this problem too too well. My old tiles have so much efflorescence on them that it feels like walking on sand. I've never found a solution - like you we're below ground where they are. The dehumidifier makes them worse. If it makes you feel any better it seems to be far worse in summer, when friends comment " why has your floor turned white?" and in the autumn/ winter they go red again.
If you really hate it, could you put a rug or mat over the top? I'm thinking of laying down the kind of rush matting stuff you see in NT houses.

 

[Lime]

In my recently laid floor in my kitchen a few years ago the old but thoroughly cleaned tiles were relaid upon a lime mix over earth.
The floor has been uncovered all the time since then and was initially completely free of any white marks of any sort.
However this year a few random tiles have sprouted a fluffy white material.
My feeling is that the tiles themselves are hygroscopic and attract moisture from damp air from time to time.
When the air is less damp evaporation takes place leaving behind this white substance.
There was much discussion about this several years ago.
Although I haven't looked at the following link for some while, i believe the efflorescence is considered to be animal in origin.
i.e. the tiles or bricks have at some time been urinated or defecated upon.


http://www.konrad-fischer-info.de/english.htm

 

[somersethouse]

Hi All,

Many thanks for your replies which confirm some of my suspicions about the causes of the problems. I am going to re-inspect the French drain and see if any maintenance \ improvements are needed and I am hoping that the new guttering and pointing on the other wall will have an impact on that side of the room (there was originally a lot of moss growing on the outside of that wall but it has pretty much died off now which seems to be a positive sign). The property next to ours was very much a working farm in it's day (probably until fairly recently) which could indicate that some of the salts are animal in origin as suggested by Lime (and of course domestic pets kept in our own house - a village 'Town House' - could also have contributed over the years. There are scratch marks on the living room door which are definitely caused by a dog that was confined to that area of the house in the past.

Joce, it is reassuring to know that the problem is less visible in the autumn\winter (and also that we are not alone in our predicament).

Anyway, thanks again and hope you all have a good weekend.

I'll try to post some pics of our house at some point...