Expansion joints - Advice on tiling a large area

Looking for a bit of advice guys
Just completing a renovation to my house and have approx 100 sq metres of a 3 size mix of porcelain tile to lay. I plan to tile all of the corridors, hall, kitchen, utility etc with the one tile and would really like to run the pattern through the entire area. Tiles vary in size from 26.5cm sq to 53cm sq so the pattern won't give me a straight joint line for any real distance.
On an area of this size, do you experts out there reckon that I'll get away with expansion joints under each door, without the need to break up individual rooms by fitting expansion joints up the middle of rooms. The biggest room by far is the kitchen / dinette which is 21ft by 15.5ft, with a dinette running off it at 90 degrees and measuring 11ft by 13ft. (It looks like an 'L' shaped room)
About a third of the area to be tiled is the original part of the house. I removed the floor back to sub floor level in all of it, installed underfloor heating (fed off the oil boiler) and the finished concrete floors have been drying out since early July - so are well dried out now, although I haven't run the underfloor yet.(plan to run it for 2 or 3 days before I tile, then turn it off for a few days). There are a few drying cracks in the finished floor where the builder weakened the floor at certain points, mainly doorways in order to control any cracking in as straight a line as possible. There are a couple of hairline cracks in the big kitchen/dinette area (1mm wide approx). Would it be OK to tile over these without expansion joints. One 2mm crack in a straight line at an angle/bend in the hallway.
The underfloor heating installer mentioned Ditra matting to me, but my understanding of Ditra is that its more for floors with possible 'vertical' movement. I will be using flexible adhesive & grout.
Any advice on how to proceed?

[guy1976]

ditra is used for horizontal movement if you laid the full floor in that you wouldnt need expansion joints

Thanks for your reply.
Do you think if I used ditra matting I'd get away with being able to tile straight through doorways and all. There could possibly be different floor temperatures in different rooms with the underfloor thermostats. Could that be a problem?

[sc24]

i would use ditra, as regards to the doorway expansions i would ring the schluter tech helpline and go with their advice, you should put expansions in doorways or at least a break in the tiling but i would get their advice

Many thanks for the replies guys. Will run with the ditra and so it right. Hopefully with expansion joints at the doors It'll be a lasting job.

[guy1976]

Originally Posted by MASSEY

Many thanks for the replies guys. Will run with the ditra and so it right. Hopefully with expansion joints at the doors It'll be a lasting job.

and a expensive 1 if your using 100m2 of ditra

[sc24]

worth it though in the long run

Expensive indeed- probably about £700 going by quotes I've been getting, but doesn't sound like theres much other choice.(unless anyone has any other ideas)

[sc24]

100m2 of ditra? £700, go with it, good price

[pjc]

pci do a separation membrane which is 1mm thick may help

Having worked for Schluter in the past I think you'll find that they wont say DITRA is an alternative to expansion joints. In theory due to the fact your removing the bond between the tiles and the floor you shouldn't need expansion joints but Schluter will not recommend this as it goes against whats in the Bristish Standards.
With regards to the joints you are looking at putting them somewhere between every 6 - 10m so providing no room is bigger than this then you would only need to have perimeter expansion joints. (a gap under a skirting will do).
With regards to the cracks in the floor, the DITRA will bridge cracks up to three mm so it will be fine without the need for a joint over them.
You should still use joints in doorways.
Schluters tel number is 01530 813396 and ask to speak to Glynn as he's probably the best to speak to.

put your expansion joint around the perimeter of the rooms, you can hide it with timber skirting or tiled skirting, used this method on 4 barn conversions a few years back, it was in the architects spec and although it was the first time i did it i believe it worked fine, trimline do all these expansion joints