Foam layer under joists...

[Rab78]

Hi there I have started tiling onto chipboard and I'm using dunlop flexible set fast plus with flexable additive for added flexablity. Now I have tested most of the floor for movement and the client has hired a joiner to take care of the major parts with too much movement.

There is an overall problem, the joists have a 10mm layer of foam, perhaps used to sound proof the joists from making noise to the neighbours below. Now the foam give a bit, say 2mm or so when pressed directly from the joist.

The job is 112sqr mtrs of offset tiling, ceramic 50*50 with 4"*4" mosaic offsetting at the corner of each tile.

My main question is, although im flexing everything up material wise, will this suffice for such a large area and 'hard to tell' movement?

Assuming that there is 1mm of movement all of the time after the job, should flexable adhesive and grout be good enough?

The other option is the more expensive one, using 2part flexi/liquid mixture and beleive me it costs more than the tiles, even when discounted.

So, please help if you can because the job is on hold until I have confidence.

Thanks in adv. Rab78

 

[CJ]

I would definately overboard this and still use 2 part sticky..........its a big area to get wrong.

Or to be really on the safe side.........lift chipboard and re-board with 25mm WBP ply.

Some will say use ditra.......as I have never used it, I can't comment on it......but it sounds like the kind of job its made for

 

[Rab78]

The customer wants it done without any need to board over or re-board as its too much work, too much mess and too expensive. I'm sure the chipboard would do if it was secure enough, am I wrong in thinking along this line and should I now after putting say about 16mtrs down should I now just abandon the job?

I say this because I am trying to save money and still achieve a decent result.

There must be someone who has been in this situation before?

 

[GazTech]

Hi there I have started tiling onto chipboard and I'm using dunlop flexible set fast plus with flexable additive for added flexablity. Now I have tested most of the floor for movement and the client has hired a joiner to take care of the major parts with too much movement.

There is an overall problem, the joists have a 10mm layer of foam, perhaps used to sound proof the joists from making noise to the neighbours below. Now the foam give a bit, say 2mm or so when pressed directly from the joist.

The job is 112sqr mtrs of offset tiling, ceramic 50*50 with 4"*4" mosaic offsetting at the corner of each tile.

My main question is, although im flexing everything up material wise, will this suffice for such a large area and 'hard to tell' movement?

Assuming that there is 1mm of movement all of the time after the job, should flexable adhesive and grout be good enough?

The other option is the more expensive one, using 2part flexi/liquid mixture and beleive me it costs more than the tiles, even when discounted.

So, please help if you can because the job is on hold until I have confidence.

Thanks in adv. Rab78

I support the products in the Dunlop range, this product already has flexibility, and shouldn't have any additional put with it, and this is definately not recommended straight onto chipboard. The only guarantee you have with our product is with the 2 part flexi....Gaz
Adhesion Products
2-Part Rapidset Flex
• Sets In 3 Hours
• Highly Flexible
• Water-Resistant
• Fixes Most Tiles
• Fixes To Most Floor Backgrounds
• For Floor Tiling Only
• Easy-To-Use 2-Part Kit

Size: 9.3kg, 11.55kg
Ideal Kit For Most Tile Types And Most Floor Backgrounds

Download Material Safety Data Sheet
(Liquid)
Download Material Safety Data Sheet
(Powder)
Download Technical Data Sheet

 

[Rab78]

Well, im going to bond the chipboard, neat with dunlop bonding agent. Then mixing flexi additive with setfast plus (flexible porcelbond tech sets in 3 hours), I'm also having the joists supported with screwed in wedges to counter for any obvious movement. Also extra support to bridge gaps in the joists.

This seems the only road that i can go down for the customers benefit and I have given a lifetime guarantee so that the onice is really on me. but then I'll learn from this.


If anyone can provide extra support for this issue then please let me know.

Regards, Rab78.

 

[CJ]

I hate punters like these.

Try telling them your a tiler..............not Harry bleedin Potter :mad2:

 

[Rab78]

Yeh I wish I could but its gone too far to put it on someone else now. A lack of experience on my part.

I've tiled onto chipboard on many occasions using bonding/set fast plus/flexi grout and there has been no problems.

I will monitor this job after its done and keep everyone posted, it may work.

 

[GazTech]

Rab, if you continue with this work using the Dunlop set fast plus adhesive, no matter what extra additives or floor primers or floor strengthening measures you put into place, you will still have no guarantee from us. We can't endorse this product for this purpose without a plywood overlay. Failure will be entirely down to yourself. I have a duty as support technician for Dunlop adhesives to advise you to avert disaster, eliminate the risk please just switch product and swallow the cost difference now, ....Gaz

 

[Rab78]

Yeh I want to switch , just finished the 2nd sitting room a bit of an unused room in the house, well not used frequently, I can always switch to two part flexi rapid for main areas like the hallway, kitchen and main sitting area.

Thanks for the concern and I will keep you up to date on any adverse effects. Like I say I will monitor this even when the job is complete.

 

[wayne]

you could try using ardex 7001 timber system. not as expensive as 2 part but brilliant gear. may have to use some myself as customer has overlaid chipboard with 6mm ply and wont change it.