cracking screeds/tiles and underfloor heating

[JOHNNYCLARKE]

THIS SEEMS TO BE A RECURRING PROBLEM.

ANYONE GOT ANY VIEWS ON BEST PRECAUTIONS TO TAKE OR WHICH PRODUCTS TO USE.

90 % OF SCREEDS I LAY LIMESTONE ON HAVE WATER FED UNDERFLOOR HEATING.
EVEN WITH THE FIBROUS SCREEDS THAT ARE OFTEN USED THE SCREED STILL CRACKS AT WEAK POINTS IN DOORWAYS.

BUILDERS ON DOMESTIC JOBS ALMOST NEVER PUT EXPANSION JOINTS IN SCREED AS THEY SHOULD EVEN THOUGH I ADVISE.( SO I AM COVERED)

I ALWAYS TRY TO GET CLIENT TO HAVE DITRA MATTING BUT ON FLOOR AREAS ON AVERAGE BETWEEN 30 - 80 SQ MTS FOR A KITCHEN /BREAKFAST AREA PLUS OTHER AREAS THIS ADDS UP TO A LOT OF EXTRA MONEY.

IN LAST YEAR, TO SAVE MONEY ON PUTTING DITRA OVER WHOLE AREA I HAVE STARTED JUST PUTTING DITRA UNDER TILES THAT GO THROUGH DOORWAYS OR WHERE I CAN SEE SCREED HAS CRACKED AFTER ABOUT A MONTH BEING DOWN.
THIS MEANS OF COURSE THAT I HAVE TO CHANGE ADHESIVE BED HEIGHT IN THESE AREAS TO ACCOMODATE 4MM DITRA WHICH CAN BE AWKWARD OR GRIND 4MM OFF THE BACK OF STONE.

HAS ANYONE EVER DONE THIS AS WELL??
HAD ANY PROBLEMS?
SCLUTER SYSTEMS WILL NOT GUARANTEE DITRA DONE IN ISOLATED SPOTS LIKE THIS .

i HAVE NOW FOUND A PRODUCT CALLED PECILASTIC MADE BY PCI. THIS IS ONLY 0.8MM THICK AND MEANS I DONT HAVE TO GRIND BACK OFF TILES.

HAS ANYONE USED THIS EXTENSIVELY AND HAD NO COME BACK PROBLEMS?

IT SEEMS THE IDEAL SOLUTION COZ IT WAS CHEAPER THAN DITRA OR BLANKE UNI MATT.

DITRA HAS COME DOWN IN PRICE ALOT OVER LAST 4 MONTHS AND IVE FOUND A PLACE THAT SELLS IT FOR ABOUT £ 5.00 PER SQ MT IF YOU GET TWO ROLLS OR MORE.

ANY INPUT ON THIS WOULD BE HELPFUL.

THANKS JOHNNY

[Raja]

bought a roll from ctd £241 for 30 metres am going to use it for first time when i tile my garage floor which is concrete

water based underfloor heating systems expand and contract a lot more than the electric equivilent.
are the screeds cured properly,
is the underfloor heating system taken up to and down from full temp before the tiling install begins?
does the waterpipe pass through the doorways?.....if not these areas will take longer to cure than the rest of the floor!

p.s when i fix to these water based systems i always use keraquick white/grey and latex plus additive taking the product to s2 standard........(much more flexi)
hope this helps

[JOHNNYCLARKE]

Don

pci sounds the business but doesnt it worry you that it is only 0.8mm thick.
with ditra you feel the stone is sitting on 4mm ribbing with plenty of air /room underneath to accomodate a few small cracks.
How are are you going to stick this thin mat down with thin bed adhesive on to a rough concrete base .
Im all for these decoupling systems. It is a real pain to go back and dig up stone tiles cut round doorways and under skirtings at a later date.
Dont get me wrong there is never any argument that i will be paid for this reparation because I give the client the three options at beginning before i start and its in writing.
ie.

OPTION 1.
Just tile floor with flexible adhesive
But no floor is guaranteed against cracks unless expansion joints are put in screed as ber bs standards and same for tiles above this joint.

OPTION 2.
flexible adhesive and use ditra over cracks in screed that may have appeared .
But no guarantee here either coz schluter say they dont gauarantee this method.
Builder has not put expansion joints in screed either so waste of time putting expansion in tiles .
Incidentally it does seem to work so far.

OPTION 3.
Expansion joints put in screed by builder and tiles by me
ditra or similar over whole area.
Schluter still dont guarantee this if adhesive bed over 5mm thick!!!
90% of stone fixing jobs have an average of 5mm thicknes or more of solid bed adhesive to level/ make floor dead flat no lips.
SO YOU CANT WIN!!!

BUT ITS GOT TO A POINT WHERE I HAVE LOST DOMESTIC JOBS 100-300 SQ MTS JUST BECAUSE I POINT OUT THE PITFALLS .
THERE SEEM TO BE MANY TILERS WHO SAY THEIR TILES WILL BE OK WITH JUST FLEX ADHESIVE AND CLIENTS BELIEVE THEM.

[Raja]

sorry johnny my fault sud of said ditra wil b my first time using it in my garage floor will read up on the other product u mention.

[grumpygrouter]

You might want to send a PM to PJC, he uses the stuff all the time and pushes its virtues all the time in the forums. he will give you the low down........tell him grumpy sent you........

Grumpy

[Holohana]

I've used PECILASTIC on a job at Heathrow's new Terminal 5 under conglomorate tiles and also granite slabs.

Laid a bed of adhesive with a 6mm trowel then secured PECILASTIC with a large float.

I did wonder how it provided the same option as Ditra but thats what was speced and as that was one of the biggest projects in Europe i guess they know what they were doing!

[grumpygrouter]

DITRA HAS COME DOWN IN PRICE ALOT OVER LAST 4 MONTHS AND IVE FOUND A PLACE THAT SELLS IT FOR ABOUT £ 5.00 PER SQ MT IF YOU GET TWO ROLLS OR MORE.

Where can you get Ditra for that price Johnny?

Grumpy

[JOHNNYCLARKE]

holohana

let me know if you have to go back ??
this is as good a test as anywhere, eh.

Johnny
----
thanks GRUMPY

will get in touch with PJC re pecilastic.

Boydons of Croydon Surrey 0208 683 6000. do ditra very cheap.
Dont know how carriage will be though to Nairn!!!

Try suppliers up your way as theres definitely something going on here with the ditra.
Theyre finally getting some serious competition I think and prices are falling.

Were talking deals on a 30 metre roll or multiple rolls though.

Dont know if you use electric heating much but Ive been buying from underfloor heating ltd in Basingstoke for last year and great value.
same 10 year guarantees etcc.
theyre all very much the same these mats tech wise but my tiler who fits these every other week reckons the sticky tape on them is good and easy to cut for returns /single runs.
And believe me Ive rteied most of them.

Johnny

THIS FORUM IS ADDICTIVE. ONLY BEEN A MEMBER SINCE FRIDAY NIGHT
AND SPENDING MORE TIME ON THIS THAN TRYING TO RECOUP MY MONEY FOR THE CHANDELIER FIASCO.
STILL IT IS GOOD TO SHARE KNOWLEDGE AND I CAN ALREADY SEE THERE ARE MANY TILERS OUT THERE WHO KNOW THEIR STUFF.

WISH THIS FORUM WAS AROUND WHEN I WAS STARTING OUT 25 YEARS AGO. MY ONLY COMPANION WAS A TWO PAGE SECTION IN A COLLINS DIY BOOK FROM SMITHS!!

[Pawelzik]

Originally Posted by JOHNNYCLARKE

IN LAST YEAR, TO SAVE MONEY ON PUTTING DITRA OVER WHOLE AREA I HAVE STARTED JUST PUTTING DITRA UNDER TILES THAT GO THROUGH DOORWAYS OR WHERE I CAN SEE SCREED HAS CRACKED AFTER ABOUT A MONTH BEING DOWN.
THIS MEANS OF COURSE THAT I HAVE TO CHANGE ADHESIVE BED HEIGHT IN THESE AREAS TO ACCOMODATE 4MM DITRA WHICH CAN BE AWKWARD OR GRIND 4MM OFF THE BACK OF STONE.

ANY INPUT ON THIS WOULD BE HELPFUL.

THANKS JOHNNY

To give you an idea for a more flat decoupling matting you may contact the German company Oxiegen GmbH, check www.oxiegen.de . English mails are answered, ask Mr. Heinfried Watermann for the technical profile of his decoupling matting PANTHER QE 10, thicKness 1,3 mm. Take relation on me, Martin