minmal grout lines

[Draka]

Hi all.

I am building an extension to my house and one of the major features will be the floor, I want to minimize the grout lines between tiles ( I would butt them if possible) and to have a perfectly flat floor.

The floor will be on 2 different areas the new extension will be 150mm slab then 150mm polystyrene insulation then 80mm screed with UFH then self levelling compound then travertine tile 11mm x 610mm x 610mm, in the existing house it will be on a wooden joisted floor so I will be placing battens then chipboard then insulation then screed with UFH then self levelling compound then tiles, I hope to have a seemless transition between the new and old sections.

Any advice on

A. getting minimal grout lines and whether thier is a minimun due to expansion or the grout getting in to the gap, would Epoxy resin for example be a good choice ?

B. wether this is something I cqan do with time and care, for example I was thinking if I could get some flat wire mesh approximatly 5mm thick and lay this on the floor then blot mastic on the back of the tiles and push them down until they sit on the wire it should make for a perfectly flat floor, or if the floor was perfectly flat maybe use some other sort of glue and lay them like carpet tiles ? are these stupid ideas ? should I stick with the more traditional approach I just dont want to be breaking up some tiles because they sit up slighly after the tiler has laid them as I dont feel confident to go with the tradional approach myself.

Feedback greatfully appeciated

 

[Richard C]

First you’d do better to post the correct forum where you should get a much better response; I know it’s a floor but you need to post the Tiling forum. Several things strike me which need consideration;

• Chip board is not a suitable full stop, it’s crap; only ever use well supported WBP ply as a tile base & 25mm thick in a heavy load/traffic area such as yours.
• Additionally, you cant lay a concrete screed floor over a suspended timber floor as you suggest, it will crack & break up.
• When tiling over 2 different, adjacent substrates (concrete/timber), you will need an uncoupling membrane under the tiles & possibly an expansion joint (depending on floor area & layout) or you will get a crack appearing where the two meet.
• You barking completely up the wrong tree with the wire mesh & mastic, forget it. Floor tiles must be fully supported on a thick, solid bed adhesive of the correct type or they will crack & the grout will fail.
• Minimal grout lines are possible but it depends on the tiles & the manufacturers recommendations; with a large floor area, I would not advise going below 1mm.
• Travertine tiles usually need special consideration/preparation before laying & the correct adhesive/grout or they could be stained & your floor will be ruined.
• They are large tiles; a good professional tiler will be able to give you a flat floor with minimal lippage but it depends on a good flat surface to start off with, the tiles & how you define “perfectly flat”. Depending on your expectations, the tiles may need to be honed & polished after laying; not cheap!
• It’s essential to select good quality materials of the correct type & this alone requires experience in your case.
• What type of UFH are you proposing?

Have a read through the Tiling Forum sticky & the Tiling Forum archive for similar threads (there are many) which will give you a good idea what your up against. Your project is way above your average DIY tile job & I would not advise anyone with little or no experience to even contemplate it. Your going to need the expertise of a good professional tiler but be careful how you select one. Always best to look at their previous work if you can as some have been know to lie about their profficiency & expertise; getting the wrong one in your case could prove catastrophic.

 

[Draka]

thanks richard

have posted in the correct place now, I have budgeted £1000 for grouts adhesives and hiring a tiler, but wanted to explore the idea of doing it myself as there have already been a number of savings I have made by exploring my options.

I was advised by the UFH company that screeding between joists was normal practice, it wouldnt be over the top of the joists and some UFH companies seemed to think the insulation alone would be enough to support it without the chipboard but I wanted to edge on the side of precaution.

I think your idea of an expansion joint between substrates sounds sensible but what would be the best way of doing this ? and how wide would it need to be ?

 

[Richard C]

have posted in the correct place now, I have budgeted £1000 for grouts adhesives and hiring a tiler, but wanted to explore the idea of doing it myself as there have already been a number of savings I have made by exploring my options.

Tiling is well within the capabilities of competent DIY providing you make an effort to understand what you’re doing; correct prep & decent tiling materials correct for the job are so very important, especially in your case where your stepping into what can be a difficult area for DIY. All too often folks rush down to the local DIY shed on Saturday, buy some tiles & totally inappropriate tiling materials, slap em up on a Sunday & wonder why it all goes pear shaped. It isn’t rocket science but you do need to understand what you’re doing & because the prep needed isn’t always immediately obvious to someone who doesn’t have experience with the various materials used. I’m all for folks having a go & that’s the reason this forum exists; both I & several other regular pro contributors on the forum will always help & advise as much as possible but I’ve got to admit that some of your questions & ideas fill me with apprehension. I would certainly advise that you take time out to do a lot more research before you do anything & ask lots more questions on here.

I was advised by the UFH company that screeding between joists was normal practice, it wouldnt be over the top of the joists and some UFH companies seemed to think the insulation alone would be enough to support it without the chipboard but I wanted to edge on the side of precaution.

Your original post seemed to intimate you were going to screed over chipboard over insulation, SLC then tiles;

in the existing house it will be on a wooden joisted floor so I will be placing battens then chipboard then insulation then screed with UFH then self levelling compound then tiles,

You now mention screeding between the joists I’m now a little confused as to what type of floor you actually have; if you can you explain further to clarify, I should be able to give advice.

I think your idea of an expansion joint between substrates sounds sensible but what would be the best way of doing this ? and how wide would it need to be ?

Weather or not you will need one depends on the size of the floor area, the shape & where the two different substrates join; I just raised a flag, you may or may not need one but with info so far, difficult to say.

I'll look up your tiling posts later

 

[Draka]

thanks again for your reply

those Ideas where just things I was throwing out there as I am all for trying new ways of doing things, still not quite sure what I wrong with them but I trust the voice of experience, something as I am sure you can tell when it comes to tiling I have none of.

The existing house is a brick built 1930's semi with a suspended timber floor, I planned to place battens on the inside of the joists to support the chipboard then put insulation on top then screed with UFH approx 80mm to meet the level of the top of the joist then put SLC down to make the floor perfectly level, then the tiling begins.

the overall floorspace to be tiled is approx 70m2 and approx 60/40 old/new although there are only 2 places you will geta crossover of 2.4m and 1.9m the former being in the main living area and very important to get right.