Hi, Can anyone recommend a grout joint width and colour for my 450mm by 450mm travertine pattern porcelain floor tile. The Bathroom in question is approx, 2400mm by 2400mm. with a tiled area of 1800mm by 2400mm. Thanks

2mm ivory,flexi.

What substrate is the floor?

as Grumpy asks, if floor is likely to be subject to movement, ie under floor heating, wooden sub floor, I personally wouldn't go below 4mm

Personally I would opt for 3mm

If any movement likely at all then mine would be 5mm if not then would probably go for 3mm.

Also would always grout with a flexible grout to counteract the natural movement in natural stone products.

Would always ensure movement minimised by suitable prep of substrate, over boarding etc. Otherwise would not tile floor at all

Thanks for your replies. The floor is ply over flooring chipboard. The floor is quite stiff, hardly any spring.

Originally Posted by Leatherface

Would always ensure movement minimised by suitable prep of substrate, over boarding etc. Otherwise would not tile floor at all

but if you have ufh Nick, you're always gonna get a degree of thermal expansion/contraction

I forgot to add that there is no underfloor heating.

Originally Posted by nickebbrell

Thanks for your replies. The floor is ply over flooring chipboard. The floor is quite stiff, hardly any spring.

Yes, but what thickness ply? Would seem to be a good place for a 5mm joint to me.

I'd go for 4mm then

again I am going against the grain. Have done hundreds of bathroom floor jobs, loads with UFH many diff types of tile, all with 3mm grout width.
NOT ONE CRACKED OR LIFTED TILE EVER !!!!

Its 3/8" ply screwed at 150mm centres over very flat chipboard floor that really is very solid

Your call Nickebbrell, let us know what you decide and post some pics to see how it has gone.

Just to add, all my under floor heating jobs in bathrooms are self levelled prior to tiling with Mapei Fibre Plan

If as you say say there is very little spring this would suggest that there is still (possibly) some slight movement aparent, PLEASE use a flexible adhesive and flexible grout as you will have cracking appear in the future if not.

Originally Posted by Leatherface

again I am going against the grain. Have done hundreds of bathroom floor jobs, loads with UFH many diff types of tile, all with 3mm grout width.
NOT ONE CRACKED OR LIFTED TILE EVER !!!!

I can't remember that far back to when I was in the hundreds lol

Originally Posted by doug boardley

I can't remember that far back to when I was in the hundreds lol

Was a figure of speech !
have never had one fail !

same as leatherface 3mm floors 2mm walls ivory grout (flexi) ivory silicone. im not keen on wide joints.the only time i use wide joints is with ie slate,terracota

3mm and mapei jasmine grout