140sqm floor 600 by 600 ceramics, expansion joint query!

[NKtile]

Hi fellas..

Can anyone advise.. Just starting a 140sqm commercial job.

Its using 600 by 600 ceramics, brand new floor, perfectly smooth. 3 mm gaps. its 17m by 8m , long rectangular, pretty much no interruptions or obstacles... will be leaving gaps around edges as box skirting is going on afterwards.. Just looking for advise on expansion joint as is not something am too familiar with using...What do we think of one joint inserted halfway up the length.. i.e. at 9 metres point? and any particular type of expansion joint?

Any advise would be much appreciated....

[Sir Ramic]

I would personally put a joint through the centre lengthways and then 3 across the width at about 4m apart.
As for type you could do it yourself or use preformed joints from Schluter-Systems UK Homepage +44 (0) 1530 813396 - Schlüter-Systems

[NKtile]

Cheers SirRamic,

When i have used before have used preformed.. What way you tend to work it when you do it yourself? (as against preformed)?

[whitebeam]

Is there no spec given for the floor by the powers to be

[davy_G]

What are you tiling onto and are there any joins in it? ie different screeds or substraits?

[NKtile]

Hi,

Floor is smooth all laid perfectly concrete floor screed.

And no, no specs laid down by those who pay!

Cheers!

[Leatherface]

On a floor area that size there should already be expansion joints in the sub floor, the expansion joints should run along on top of these. Speak to the contractor for position of joints if you are not sure.
MOVEMENT JOINTS FOR TILE INSTALLATIONS
Expansion and control joints are required in both floors and walls. Expansion joints must extend through both the tile and the substrate on which the tile is applied and are designed to accommodate continuing movement in the structure throughout the life of the building caused by expansion and/or contraction due to thermal or other effects. The installation of control joints in the openings left by the tile contractor are covered in the “Caulking and Sealants” section of the specification.
Control joints are:
• A joint cut or tooled into the concrete surface to control the location of cracks. A control joint in the tile to be located above the control joint in the substrate or above any construction cold joints. Saw cuts to be applied within the first twelve hours of concrete placement.
• A joint in the ceramic tile, extending through the setting materials which is intended to minimize stresses in the bond layer due to differential movement of ceramic tile relative to the substrate, caused by thermal expansion and contraction.
• Saw cuts to penetrate a minimum of 1/3 of the thickness of the slab. Saw cutting of the slab is not the responsibility of the tile contractor.
Control joints to be provided around the perimeter of floors, around columns, where tile abuts other hard materials, at the junction between horizontal and vertical surfaces and at transitions that include corridors and changes in direction, for example T’s, L’s and diagonals.
The location of expansion joints and control joints is the responsibility of the consultant. Exterior expansion or control joints to be caulked with suitable sealants. For interior expansion or control joints, prefabricated expansion joints or double metal or plastic terrazzo strips may be used with a suitable sealant. Some prefabricated expansion joints may be recommended by the manufacturer for exterior use. Cold Joint – Cold joints are formed primarily between slab pours. A control joint to be installed over all cold joints in the slab. Where conditions do not allow one to install a control joint, the use of a crack isolation membrane may be considered, along with a control joint in the tile surface as close as possible to the cold joint in the substrate.
Construction Joint – The plane where two successive placements of concrete meet but do not bond cementitiously. Sometimes dowels or reinforcing steel are used to hold the concrete on both sides together. A control joint to be placed over this joint in the tile.
Isolation Joint – A separation between adjoining similar or dissimilar elements of a concrete structure, usually a vertical plane. Its purpose is to prevent movements of the individual parts from causing cracks in the concrete. Also, sometimes called an expansion joint.
Structural Joint – An isolation joint intended to allow independent movement between adjoining sections of the building.
Recommended spacings and sizes for expansion joints and control joints are as follows:
• Interior tile - control joints 4878 mm to 6098 mm in each direction - minimum 6 mm width. Areas exposed to moisture or direct sunlight - 3659 mm to 4878 mm in each direction- minimum 6 mm width.
Exterior tile - Due to high temperature fluctuations, use minimum 10 mm wide control joints from 2439 mm to 3659 mm in each direction. In areas of extreme temperature variations (over 40ºC) between summer highs and winter lows joint width shall be a minimum 13 mm. The consultant shall specify the required joint width and required distance between joints.

If the sub floor has either NO or INSUFFICIENT movement joints, then I would advise you to think very carefully about tiling the floor at all . You as the tiling contractor are more than likely going to be held responsible for damages to the tiles and rectification works, should the tiles crack.

[Leatherface]

I would personally put a joint through the centre lengthways and then 3 across the width at about 4m apart.
As for type you could do it yourself or use preformed joints from Schluter-Systems UK Homepage +44 (0) 1530 813396 - Schlüter-Systems

You cannot just decide to position expansion joints wherever to think they ought to go. The position of these is dictated by the position of the existing movement joints in the sub - floor. A floor with either NO or Insufficient movement joints may be liable to crack at ANY point, regardless of where your tile expansion joints are positioned, resulting in cracked tiles following the cracks in the sub floor below.

[Leatherface]

When I was working at the Westfield Shopping Centre, we put in some real heavy duty expansion joints in one of the floors. They were metal. box section and had to be bolted together. Dimensions assembled were about 8" x 8" box section. They were fixed into a pre cut trench in the concrete, then screeded into position. Designed to combat some really serious movement.
Found a photo of a "similar type", but these were a different design and specification.

[Sir Ramic]

Then if there are no movement joints already in the concrete slab a decoupling membrane would have to be used.

[Leatherface]

Then if there are no movement joints already in the concrete slab a decoupling membrane would have to be used.

Sorry, misunderstood your prev post.

However can I just add, was probably being overt cautious. did not want to "assume" that a de coupling membrane had been used, as it appeared that the contractor did not indicate this. NK Tile could do with getting confirmation that this is the case. You never know, sure there must be occasions where this has not been done in the past. Just wanted to make sure he covered himself.

[NKtile]

Many many thanks for you help lads,

In a nutshell then what would I want to be asking the contractoe precisely? As you say just want to make sure I am covered, as they just want me to tile whole area 600 by 600 ceramics , leaving plenty of space around the perimiters of the tiled area, ( as I said big box skirting over that) and they wanted a silicon 'gap' midway throught tiled area....

[Leatherface]

Hi mate, basically you need to ask for something in writing to confirm the exact floor specification and provision allowed for movement. Once received sure we can help. If the contractor does not want to give you this I personally would steer clear. Most reputable contractors would be happy to give you a full 'job spec' in writing, to allow you to make provisions for doing the job to the required standard.

[Sir Ramic]

Read the info given on this thread. If there is no expansion already cut through the slab then you are losing the battle already. If they insisted on no expansion through the slab then using a uncoupling membrane such as Ditra.
I have to say though most architects etc i have come across dont give a toss. Even if there is an expansion in the floor they insist on the visible joint being to the nearest tile. Ditra state taht it should be directly above joint running througgh the slab but who ever told the slab it must move or crack where that joint is ????

If the slab is suspect i would go with the uncoupling membrane route given a choice.

If in doubt get it writing, a contract of that size would surely have all the specs laid out anyway....keep a copy!

[Dave]

Then if there are no movement joints already in the concrete slab a decoupling membrane would have to be used.

With you on this one neale......and you can still incorporate movement joints in the main tiling field at recommended distances as per spec for the substrate....along with perimeter joints it will be fine..

Its the substrate that puts stress on the tiling installation and if the installation has sufficent movement joints then delamination/tenting is at a minimum then...un-coupling membranes are better to used...Seen as overkill by some but do serve there purpose....




p.s...nice copy and paste post nick.....

[Leatherface]

OK good to hear more advice, yes was copy and paste, thought easier as it seemed to have all the bases covered. Did not assume that Ditra would have been an option. As the cost would be an important factor to the contractor ££££ & surely would have been mentioned prior if they had intended to go down that route.
Just out of interest, please will you give me your input on why I have seen a couple of floors ( large areas ) which had a few long hairline cracks in the tiles, despite the use of expansion joints Guess no de-coupling membrane used ? But opinions here seem to say that is overkill ?
This area is obviously a minefield.
Cheers

[Sir Ramic]

OK good to hear more advice, yes was copy and paste, thought easier as it seemed to have all the bases covered. Did not assume that Ditra would have been an option. As the cost would be an important factor to the contractor ££££ & surely would have been mentioned prior if they had intended to go down that route.
Just out of interest, please will you give me your input on why I have seen a couple of floors ( large areas ) which had a few long hairline cracks in the tiles, despite the use of expansion joints Guess no de-coupling membrane used ? But opinions here seem to say that is overkill ?
This area is obviously a minefield.
Cheers

And that young Nicholas is why i would opt for the ditra mat....all area covered !


Cracks can and will appear anywhere.

[Leatherface]

OK, understood, should have mentioned Ditra in first place, would have made my post more relevant with second option. But would you still tile it if they did not want to pay for Ditra and there were no visible expansion joints ?
I wouldn't !

[Dave]

For those that don't really understand the movement factors related to large area's then read this...

http://www.tilersforums.co.uk/tiling...ing-shift.html

[smurf21]

You need to work to customers spec, if there isnt one fit preformed expansion strips above existing joints in sub floor, if there arnt any joints as sir ramic says use de coupling membrane,if customer wont accept this just put pre formed strips both ways at 4metre intervals and get a disclaimer signed. good luck.

[wetdec]

Not so technical for you ......

If the sub floor has no visible expansion joint then an uncoupling membrane should be used to accommodate any future shift.

Because you isolate the finished surface from the sub floor it will require an expansion joint as it becomes a floor in its own right these should be at approx 4m intervals.

If as Nick has said the sub floor has expansion joints incorporated it would be wise to mirror this in the finished surface. (providing distances are acceptable)


..

[top tiler]

you only need one joint in the floor as it is not over 10 m wide if it does not have a joint in the middle of the lenght, cut one in when you set the floor out and put an expansion joint over the cut joint keep your expansion around the perimetre problem solved

[NKtile]

Just wanted to say thanks lads for all the help and advise. Cheers!