Butting up....

[kellys_eye]

no, not a gay sexual practice (is it????) but the long and wide tiles I have (600x300) are square edged and I'm considering laying them butt up aginst each other as, joined this way, the seam is nearly invisible.

Any misdemeanours to avoid or any impossibilities in doing this? Does the tile adhesive dry ok when tiles are laid this way?

BTW, got me a £16.99 tile cutter from Aldi. Took it apart and extended the bars to give me a cutter that does tiles up to 800mm long now!

[Colour Republic]

You will need a cement based adhesive for that sized tile. It is too large for ready mixed

You you will need to leave a space for some flexible grout. If the substrate moves at all you will end up with tiles on the floor or worse on someones head. Also don't forget to leave a gap at the internal corners which is then sealed with silicone to create an expansion gap... or again you may find the tiles tenting and pinging off with the natural expansion and contraction of the building.

[kellys_eye]

Ta for that.

The tiles (ceramic) are going on a concrete base (levelled with compound) and up the inside of a large (plastered) fireplace. No flexing is possible I reckon nor would I expect to see expansion (or would I?). Will this still require a concrete based adhesive or would I get away with the 'Unibond, extra strong, conrete floor tiling and grout adhesive' (that it says on the tub)?

Will 'some' spacing be better than none?

[Colour Republic]

You would be surprised at how much concrete and buildings can move. All types of buildings expand and contract with incredible force too. Have you ever seen a crack in a concrete floor?

The minimum for a floor joint is 3mm according to BS, if it was a small area I might be tempted to go smaller, but there are many different types of adhesive that will do very specific things I want it to do. So if I wanted to close the grout joint right down then I would spec the floor different.

I would never and I mean never! Use a ready mixed floor adhesive, that adhesive is cack and know countless people who have had it fail. People assume that because something is sold that it must be up to the job. As for unibond they're a big company right? You have to ask why they suggest to pva before tiling when nearly every other manufacturer of tile adhesive says it's bad practice. So for the rant I just hate the thought of someone using ready mixed floor adhesive.

As for the fireplace, if it is just a few tiles and it's more decorative than functional then I might take the risk of butting them up but keep a few spare just in case

[kellys_eye]

Point(s) taken so thanks for that. Fortunately the Unibond is unused so I'll return it for some 'proper' stuff. Do you have a recommended product in this case?

[Colour Republic]

Mapei, bal, Weber, Larsen's, Granfix... take your pick

If you are shopping in B&Q which I assume that's where you got the Unibond, then look out for 'Buildfix' which is Mapei adhesive made for B&Q.

You don't say what type of tiles they are. Porcs, ceramic, stone??? You'll want a flexible cement based adhesive. If it's stone then there are other considerations like sealing and the colour of the adhesive used. For example a travatine you'll want to use white adhesive, slate you can use grey...

You may also need to prime the floor first depending on which adhesive you use. It's not quite as simple as slapping down some adhesive and chucking the tiles on top... well not if you want it to last anyway

[tictic]

never..ever...Butt tiles up....

very bad practice....walls and floors will have movement in them....

this ..fireplace.. thats plastered, will it be tiled.. will there be heat coming from the fire place??..or is it just for show etc...if there is heat then you need to look into a few things..

the gypsum plaster is no good,the heat will crack it,thus tiles will pop/tent off the wall...what is the spacing around the fire place...

[kellys_eye]

Hmmmm, this is getting interesting ..... and informative

right....

1. ceramic tiles as mentioned above (600mm x 300mm, most cut down to 500mm long though)
2. a working fireplace with woodstove
3. fireplace is 1m wide, 1m high, 0.5m deep, brick built, as mentioned plastered side walls, not mentioned concrete rendered rear wall, solid concrete (150mm thick) base extending to 1m from rear wall.

There is a minimum of 350mm clearance at each side of the stove. The stove 'pipe' exits the rear of the box and runs quite close to the rear wall (they will be about 100mm from it after the tiles are laid).

So..... can I assume plastered walls on either side are ok?
It would follow that concrete rendered rear wall is ok for tiling too?

Based on all the info I've listed are we still 'on' with flexible concrete-based adhesive? Are there any other precautions? particularly with the rear wall tiling and the possibility of relatively high heat - localised?

The 'butting up' idea has now been abandoned based on the advice already given. I'm hoping to get the work done this week so all advice is really, really appreciated

BTW the only DIY place near me is a Homebase

[kellys_eye]

ooops - the tiles are PORCELAIN, not ceramic (if this makes a difference???)