Tiling on concrete floor
Discussion
monthefish said:
stanwan said:
Consider using an insulated tile backer board and then laying some UFH matting on top -It'll improve response and heat retention.
False economy not to insulate first (if you've got the space/depth - The insul boards are about 20mm thick from memory)
voicey said:
I stuck down 10mm XPS insulation onto our slab with a cement based tile adhesive. Once that had gone off I then stuck the tiles down to the XPS with the same adhesive. Dead easy and the tiles are lovely to walk on.
Is that straight onto something like this? http://www.ebay.co.uk/itm/10mm-UNDERFLOOR-UNDER-FL...Is there not a little movement in it? Why are there purpose made 'tile backer boards (XPS)' if this normal XPS is ok?
Esseesse said:
voicey said:
I stuck down 10mm XPS insulation onto our slab with a cement based tile adhesive. Once that had gone off I then stuck the tiles down to the XPS with the same adhesive. Dead easy and the tiles are lovely to walk on.
Is that straight onto something like this? http://www.ebay.co.uk/itm/10mm-UNDERFLOOR-UNDER-FL...Is there not a little movement in it? Why are there purpose made 'tile backer boards (XPS)' if this normal XPS is ok?
m4ckg said:
Google primer for concrete floors and you'll get the correct answer. Under no circumstances use pva to prime the floor
Can someone confirm that this stuff that Wickes sell is appropriate? It's the last thing I have to buy, I have a load of Keraflex being delivered on Friday and all the tiles, tile sealer, and backed XPS are waiting in the garage. 
http://www.wickes.co.uk/Wickes-High-Performance-Fl...
Esseesse said:
Is that straight onto something like this? http://www.ebay.co.uk/itm/10mm-UNDERFLOOR-UNDER-FL...
Is there not a little movement in it? Why are there purpose made 'tile backer boards (XPS)' if this normal XPS is ok?
XPS foam core boards have a little give and aren't recommended for extreme point loads (nor are tiles advisable in these cases).Insualted Tile backer boards are usually XPS core with fibre reinforcement and a concrete facing. The core is waterproof and insulating and the surface gives an excellent adhesion to tile adhesive. XPS foam doesn't bond well to tile adhesive...Is there not a little movement in it? Why are there purpose made 'tile backer boards (XPS)' if this normal XPS is ok?
You want to achieve 100% coverage with underfloor heating to provide the best heat transfer. I've tried using single part flex but it's hard to compress fully and level the tiles. May I suggest using stone and tile PTB - it is thinner compresses easily and will give proper coverage. Mix up 5 kg batches as it is a rapid set..
stanwan said:
Esseesse said:
Is that straight onto something like this? http://www.ebay.co.uk/itm/10mm-UNDERFLOOR-UNDER-FL...
Is there not a little movement in it? Why are there purpose made 'tile backer boards (XPS)' if this normal XPS is ok?
XPS foam core boards have a little give and aren't recommended for extreme point loads (nor are tiles advisable in these cases).Insualted Tile backer boards are usually XPS core with fibre reinforcement and a concrete facing. The core is waterproof and insulating and the surface gives an excellent adhesion to tile adhesive. XPS foam doesn't bond well to tile adhesive...Is there not a little movement in it? Why are there purpose made 'tile backer boards (XPS)' if this normal XPS is ok?
You want to achieve 100% coverage with underfloor heating to provide the best heat transfer. I've tried using single part flex but it's hard to compress fully and level the tiles. May I suggest using stone and tile PTB - it is thinner compresses easily and will give proper coverage. Mix up 5 kg batches as it is a rapid set..
I understand that this is suitable to stick to a concrete slab, and then tile straight on top of. Is that right?
Esseesse said:
stanwan said:
Esseesse said:
Is that straight onto something like this? http://www.ebay.co.uk/itm/10mm-UNDERFLOOR-UNDER-FL...
Is there not a little movement in it? Why are there purpose made 'tile backer boards (XPS)' if this normal XPS is ok?
XPS foam core boards have a little give and aren't recommended for extreme point loads (nor are tiles advisable in these cases).Insualted Tile backer boards are usually XPS core with fibre reinforcement and a concrete facing. The core is waterproof and insulating and the surface gives an excellent adhesion to tile adhesive. XPS foam doesn't bond well to tile adhesive...Is there not a little movement in it? Why are there purpose made 'tile backer boards (XPS)' if this normal XPS is ok?
You want to achieve 100% coverage with underfloor heating to provide the best heat transfer. I've tried using single part flex but it's hard to compress fully and level the tiles. May I suggest using stone and tile PTB - it is thinner compresses easily and will give proper coverage. Mix up 5 kg batches as it is a rapid set..
That board looks fine. You will want to prime the concrete - it'll suck the moisture out of the adhesive too quickly otherwise. Make sure you leave an expansion gap at the edge and make absolutely sure you have boards bedded well into adhesive - unsupported areas will flex and crack tiles.
How flat is your concrete floor? Does it need to be self levelled first? If you are laying large tiles you want it to be nigh on perfect....
I understand that this is suitable to stick to a concrete slab, and then tile straight on top of. Is that right?
stanwan said:
That board looks fine. You will want to prime the concrete - it'll suck the moisture out of the adhesive too quickly otherwise.
Is that Acrylic Primer I linked to a few posts above the right kind of thing?stanwan said:
How flat is your concrete floor? Does it need to be self levelled first? If you are laying large tiles you want it to be nigh on perfect....
Pretty flat I think, but I will make sure before I do anything. There might be a slight kink somewhere that I only noticed the other day when I slid a large full sized and heavy server case across the room. The tiles are 300mm square.Esseesse said:
Pretty flat I think, but I will make sure before I do anything. There might be a slight kink somewhere that I only noticed the other day when I slid a large full sized and heavy server case across the room. The tiles are 300mm square.
.Acrylic primer will be fine - follow dilution instructions for the substrate. 300 is easy peasy. Get some levelling wedges from Topps if you are a newbie - it'll make life a lot easier
Esseesse said:
Thanks, I'm not doing underfloor heating, just insulating the slab. The stuff I've bought looks like this...
I understand that this is suitable to stick to a concrete slab, and then tile straight on top of. Is that right?
That'll work fine, although so would the cheaper standard XPS insulation as well.I understand that this is suitable to stick to a concrete slab, and then tile straight on top of. Is that right?
I was advised by local tile store that modern adhesives don't really need primer unless particularly troublesome. I went straight onto bitumen paint, tile adhesive to the XPS, then UFH, self level and tile adhesive/tile above.
Working fine still 9 months later.
Yep if I had just replied on the little spacer thingys whilst tiling my bathroom (ceramic tiles) the tiles would be all over the place. Guess it's down to slightly different temperatures in the kiln when they're fired. Have to continually check down the joint line to make sure they're all in line, which is further compounded by the "brick wall" pattern I've used. Look forward to seeing your floor done, I want to do our kitchen and hallway in slate (or slate effect) tiles in the future.
Yes, you have to use your judgement on where to place the spacers. In reality due to convex/concave sides, joints vary from about 2-3.3mm ish (The tiles have a 1.5mm lip on the edge so grout lines will be about 5mm-6.5mm). Also my tiles vary in size from about 295mm to 300mm, and in height by 0.5mm, maybe occasionally 1mm. I ended up quite soon after beginning sorting tiles into groups of smaller, medium and large, and selecting ones that best fit with it's neighbours.
I brushed some stray adhesive dust (off white) into the groove where the grout will go at one of the edges/interfaces that I think is the poorest and strangely it seemed to minimise any imperfection. I had expected the contrast to highlight any flaws. The grout I have is very light grey, I was considering getting something else darker or closer to the tile colour to minimise flaws but I don't think it'll be necessary. I think I'll go round a few bits with some flour before I grout just to be double sure though.
Edit: With porcelain, you could nearly rely on the spacers. Of course you couldn't 100%, but generally any differences were between the spacer being a tight or a slightly loose fit.
I brushed some stray adhesive dust (off white) into the groove where the grout will go at one of the edges/interfaces that I think is the poorest and strangely it seemed to minimise any imperfection. I had expected the contrast to highlight any flaws. The grout I have is very light grey, I was considering getting something else darker or closer to the tile colour to minimise flaws but I don't think it'll be necessary. I think I'll go round a few bits with some flour before I grout just to be double sure though.
Edit: With porcelain, you could nearly rely on the spacers. Of course you couldn't 100%, but generally any differences were between the spacer being a tight or a slightly loose fit.
Edited by Esseesse on Wednesday 3rd June 13:03
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