Tiling EXPERTS - your thoughts please...
Discussion
Substrate: Concrete (ground floor). Properly dry (poured some months ago, and has had the benefit from central heating for nearly a month). Prepared in line with the instructions on the adhesive pack.
Adhesive:

Tiles: Porcelain 30cm x 30cm, about 10mm thick
Grout: TBC (But I’ll choose something suitable)
Tiler: Me (although I'm not a pro, I’ve done a fair bit of tiling before – about 10 bathrooms, 5 kitchens etc)
Can anyone suggest a good reason why I shouldn’t use 1mm spacers?
Adhesive:

Tiles: Porcelain 30cm x 30cm, about 10mm thick
Grout: TBC (But I’ll choose something suitable)
Tiler: Me (although I'm not a pro, I’ve done a fair bit of tiling before – about 10 bathrooms, 5 kitchens etc)
Can anyone suggest a good reason why I shouldn’t use 1mm spacers?
monthefish said:
Substrate: Concrete (ground floor). Properly dry (poured some months ago, and has had the benefit from central heating for nearly a month). Prepared in line with the instructions on the adhesive pack.
Adhesive:

Tiles: Porcelain 30cm x 30cm, about 10mm thick
Grout: TBC (But I’ll choose something suitable)
Tiler: Me (although I'm not a pro, I’ve done a fair bit of tiling before – about 10 bathrooms, 5 kitchens etc)
Can anyone suggest a good reason why I shouldn’t use 1mm spacers?
1 Is the floor a normal concrete base or Anhydrate screed (Pumped in usually)? If yes then needs more prepAdhesive:

Tiles: Porcelain 30cm x 30cm, about 10mm thick
Grout: TBC (But I’ll choose something suitable)
Tiler: Me (although I'm not a pro, I’ve done a fair bit of tiling before – about 10 bathrooms, 5 kitchens etc)
Can anyone suggest a good reason why I shouldn’t use 1mm spacers?
2 I personally wouldn't use that adhesive, I prefer powder, but also with porcelain you need a flexible adhesive or porcelain specific one
3 are the tiles polished porcelain? if so then be aware coarse grout may scratch the surface when applied
4 If the tiles are good quality rectified edge then you will probably be ok with 1mm but gives you little Le-way for any size discrepancy, 2 or 3mm will give you a bit more to play with
5 as for laying, preparation is the key, dry lay it first, and check the lines for square

I agree with the last poster, and I also would use a powder tile adhesive, possible Evostick fast set powder adhesive for concrete floors. The adhesive comes in 20 kg. packs, mixing 5 kg atime, which at 1mm thick will do aprox 2m sq.
Do the floor in sections, allowing 24 hours in between, then 3 hours in between grouting. Use Evostic grouting, how do I know all this, I used the above 7 years ago on a wet room floor, and you know what...it still looks perfect.
Do the floor in sections, allowing 24 hours in between, then 3 hours in between grouting. Use Evostic grouting, how do I know all this, I used the above 7 years ago on a wet room floor, and you know what...it still looks perfect.
Thanks for your thoughts.
Agree, re doing a bit at a time (this is the way I always work, and I think I suggested this to someone else on here that was tiling for the first time! (I think it’s probably the most important tiling tip there is!)). It’s quite a big area, and so being square is going to be very important. It will obviously look better with smaller grout channels, however, like you say, 1mm doesn’t leave much tolerance! I think I’ve chickened out of the 1mm just talking about it….
Grout – Thanks for tip. I’ve used the same tiles previously and grouted with no probs.
Out of interest, why would a 10mm thick porcelain tile require a flexible adhesive? The reason I was going with the Unibond product is that I’ve used it a few times before (and have used it with porcelain tiles) with no problems, and all the jobs have stood the test of time.
Agree, re doing a bit at a time (this is the way I always work, and I think I suggested this to someone else on here that was tiling for the first time! (I think it’s probably the most important tiling tip there is!)). It’s quite a big area, and so being square is going to be very important. It will obviously look better with smaller grout channels, however, like you say, 1mm doesn’t leave much tolerance! I think I’ve chickened out of the 1mm just talking about it….

Grout – Thanks for tip. I’ve used the same tiles previously and grouted with no probs.
Out of interest, why would a 10mm thick porcelain tile require a flexible adhesive? The reason I was going with the Unibond product is that I’ve used it a few times before (and have used it with porcelain tiles) with no problems, and all the jobs have stood the test of time.
Porcelain is usually non porous, unless its cheap tat, and as a result it doesn't adhere well to normal adhesive, Polymer modified adhesive (Flexible) will get a real good grip (think micro-pourus). I will use an SP flex for most floors any way for peace of mind.
Your right about doing small areas at a time. The best advise I could give is you cant over plan, if you work off the centre of the room, and make sure all cuts are equal and not to small and fiddly you should be right. If the floor isn't level work from the highest point to get your level.
Also the powder adhesive is rapid set usually, so only mix small amounts as you have a 20-30 min work time, and 2hr set time.
Your right about doing small areas at a time. The best advise I could give is you cant over plan, if you work off the centre of the room, and make sure all cuts are equal and not to small and fiddly you should be right. If the floor isn't level work from the highest point to get your level.
Also the powder adhesive is rapid set usually, so only mix small amounts as you have a 20-30 min work time, and 2hr set time.
Edited by Chris77 on Thursday 21st January 11:42
I'm not an expert, I've done three rooms in my whole life
The last one I did was 25' x 26' using 17" tiles with 1/4" space.
It looks really good, but I know there is one place in that room where I made a small correction. Had I been using 1mm space between tiles, that correction may not have been possible without it being very visable.
So unless you are very good and the room is not too large, I would give it some thought with regard to abilty. I don't know your level of competence, so don't take offence
Asthetically, I like the narrow spacing in large tiles (20" x 20" and above) like the copper strips in marble.

The last one I did was 25' x 26' using 17" tiles with 1/4" space.
It looks really good, but I know there is one place in that room where I made a small correction. Had I been using 1mm space between tiles, that correction may not have been possible without it being very visable.
So unless you are very good and the room is not too large, I would give it some thought with regard to abilty. I don't know your level of competence, so don't take offence

Asthetically, I like the narrow spacing in large tiles (20" x 20" and above) like the copper strips in marble.
Chris77 said:
Porcelain is usually non porous, unless its cheap tat, and as a result it doesn't adhere well to normal adhesive, Polymer modified adhesive (Flexible) will get a real good grip (think micro-pourus). I will use an SP flex for most floors any way for peace of mind.
Your right about doing small areas at a time. The best advise I could give is you cant over plan, if you work off the centre of the room, and make sure all cuts are equal and not to small and fiddly you should be right. If the floor isn't level work from the highest point to get your level.
Also the powder adhesive is rapid set usually, so only mix small amounts as you have a 20-30 min work time, and 2hr set time.
Absolutely agree, I also always lay the tiles on the floor, and move the line of the tiles to either reduce/remove fiddly cuts, but ensuring the “run”, look of the tiles is good on the eye.Your right about doing small areas at a time. The best advise I could give is you cant over plan, if you work off the centre of the room, and make sure all cuts are equal and not to small and fiddly you should be right. If the floor isn't level work from the highest point to get your level.
Also the powder adhesive is rapid set usually, so only mix small amounts as you have a 20-30 min work time, and 2hr set time.
Edited by Chris77 on Thursday 21st January 11:42
jeff m said:
I'm not an expert, I've done three rooms in my whole life
The last one I did was 25' x 26' using 17" tiles with 1/4" space.
It looks really good, but I know there is one place in that room where I made a small correction. Had I been using 1mm space between tiles, that correction may not have been possible without it being very visable.
So unless you are very good and the room is not too large, I would give it some thought with regard to abilty. I don't know your level of competence, so don't take offence
No offence taken. 
The last one I did was 25' x 26' using 17" tiles with 1/4" space.
It looks really good, but I know there is one place in that room where I made a small correction. Had I been using 1mm space between tiles, that correction may not have been possible without it being very visable.
So unless you are very good and the room is not too large, I would give it some thought with regard to abilty. I don't know your level of competence, so don't take offence


I would suggest that I am pretty good (as good as an average professional), but the room is quite large, and therefore your comment "but I know there is one place in that room where I made a small correction. Had I been using 1mm space between tiles, that correction may not have been possible without it being very visable." is exactly what I was concerned about. Nail. Head.
I've decided I'm going for 2mm, mainly due to the fact that I don't think the floor finish is perfect enough to carry off 1mm. I'll maybe post pics when I'm done, although the level of close-up of the photo will be proportional to the level of success - if the photo is taken from the back garden, you'll know it didn't go too well.

Spudler said:
I'd suggest randomly measuring tiles to be sure they're mm perfect. Unless your paying big bucks for the tiles its very unlikely they are.
Or just lay them out on a flat surface, edges touching, and see the accuracy that way. I used travertine in a bathroom and the tolerance was excellent, far less than 1mm.Simpo Two said:
Spudler said:
I'd suggest randomly measuring tiles to be sure they're mm perfect. Unless your paying big bucks for the tiles its very unlikely they are.
Or just lay them out on a flat surface, edges touching, and see the accuracy that way. I used travertine in a bathroom and the tolerance was excellent, far less than 1mm.
monthefish said:
jeff m said:
I'm not an expert, I've done three rooms in my whole life
The last one I did was 25' x 26' using 17" tiles with 1/4" space.
It looks really good, but I know there is one place in that room where I made a small correction. Had I been using 1mm space between tiles, that correction may not have been possible without it being very visable.
So unless you are very good and the room is not too large, I would give it some thought with regard to abilty. I don't know your level of competence, so don't take offence
No offence taken. 
The last one I did was 25' x 26' using 17" tiles with 1/4" space.
It looks really good, but I know there is one place in that room where I made a small correction. Had I been using 1mm space between tiles, that correction may not have been possible without it being very visable.
So unless you are very good and the room is not too large, I would give it some thought with regard to abilty. I don't know your level of competence, so don't take offence


I would suggest that I am pretty good (as good as an average professional), but the room is quite large, and therefore your comment "but I know there is one place in that room where I made a small correction. Had I been using 1mm space between tiles, that correction may not have been possible without it being very visable." is exactly what I was concerned about. Nail. Head.
I've decided I'm going for 2mm, mainly due to the fact that I don't think the floor finish is perfect enough to carry off 1mm. I'll maybe post pics when I'm done, although the level of close-up of the photo will be proportional to the level of success - if the photo is taken from the back garden, you'll know it didn't go too well.


Good luck.
Spudler said:
Simpo Two said:
Or just lay them out on a flat surface, edges touching, and see the accuracy that way. I used travertine in a bathroom and the tolerance was excellent, far less than 1mm.

Lining them up in a square (and thereby multiplying any size errors until they are detectable) is not only more accurate than measuring individual tiles, but you don't even need a tape measure. Use the force, silly.
Simpo Two said:
Spudler said:
Simpo Two said:
Or just lay them out on a flat surface, edges touching, and see the accuracy that way. I used travertine in a bathroom and the tolerance was excellent, far less than 1mm.

Lining them up in a square (and thereby multiplying any size errors until they are detectable) is not only more accurate than measuring individual tiles, but you don't even need a tape measure. Use the force, silly.
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