Help! SLC fail - Self levelling compound failed Pro 50

[Chalker]

Hi,
jackonboards spec is to screw down to timber at 300mm intervals, so that's what I do.
I find if I were to glue instead/aswel there is additional cost of time, primer, adhesive, also raised flooring height.
im not saying glueing is wrong, it's just not something that I do.

They say not to stick down, just to screw using the washers. I use adhesive and screws (next day) on insulation boards.
Don't think this is your problem though.

 

[nybor62]

i recently used the same slc , and dont rate it at all ,and has for the adhesive , very little flex in it imo

 

[Qwerty]

I agree that it is unlikely to be the cause but I'm curious as to where you guys have been told not to glue. The fixing instructions I've seen say to glue.... http://www.tile-backer.co.uk/pdfs/2010.08 JACKOBOARD Construction Board Installation - floors.pdf

 

[Chalker]

Just read that. It does say you have to use adhesive and screws. But using Marmox boards you can just use screws. I have always stuck and screwed, it seems better.

 

[Budha7]

I must say, that's not the literature that I have read! But very interesting, and I will adjust accordingly. Thank you.
i believe dukka and marmox are recommended screw only aswel.
learn something new everyday..

 

[Qwerty]

Afraid not guys.... Marmox is almost identical to jackoboard and instruct to glue also.... Broken Link Removed

Sorry, don't mean to hijack the thread! I agree with thermal shock also. Hope the stat tells all!

 

[Budha7]

Marmox instructions there say screw every 300mm, doesn't say anything about adhesive.
But does offer 2 different ways of fixing. Adhesive of screw

 

[Budha7]

*or

 

[lizzardtong]

there you go :

Assembly information

JACKOBOARD Construction board for floor use

Special sealing tape (e.g. JACKOBOARD sealing tape) should be used to reinforce the board
joints in wet areas. In addition, care must be taken to seal any penetrations in the construction
board, e.g. for pipes or screws and anchors, using suitable sealing agents.
We recommend covering the entire construction board surface with an additional layer of
reinforcement weave.
The construction boards must not be reinforced until the thin-bed mortar used to bond the
construction boards to the substrate is completely dry.
Use on wooden substrates
The construction boards can only be installed on substrates that are similar to timber formwork.
Installation on a substrate that is only planked is not recommended.
Suitable adhesives, applied with a notched trowel, are used to glue the entire surface of the
JACKOBOARD construction board (min. thickness: 10 mm) to the wooden substrate. The
entire surface of the JACKOBOARD construction board is bedded firmly in the adhesive by
gently pushing it back and forth. The construction boards should be laid with staggered joints.
Once the adhesive bonding of the construction board to the timber formwork is completely dry,
the construction boards must be additionally fastened using wooden screws and insulation board
discs (e.g. JACKOBOARD stainless steel insulation board discs). At least 5 screws are needed for
each m2 and they must be screwed to a depth of at least 20 mm into the timber structure. The
screws should be spaced at least 30 mm from the edge of the construction board. The screws
must be tightened until the head is flush with the surface. The construction board can be slightly
indented with a hammer before fastening the screws to ensure that the insulation board discs do
not protrude above the surface of the construction board.
All construction board joints must be reinforced with an alkaline-resistant fibre glass weave
(e.g. JACKOBOARD glass fibre tape) with a minimum thickness of 120 mm.
Special sealing tape (e.g. JACKOBOARD sealing tape) should be used to reinforce the board
joints in wet areas. In addition, care must be taken to seal any penetrations in the construction
board, e.g. for pipes or screws and anchors, using suitable sealing agents.
We recommend reinforcing the entire construction board surface with an additional layer of
protective weave when installing on wooden substrates.



The construction boards must not be reinforced until the thin-bed mortar used to bond the

construction boards to the substrate is completely dry

 

[Qwerty]

 

[Budha7]

This is why the forum is so good, so much info.
From now on I will be glueing and screwing..

i hope this stat can give me some much needed info.
it appears from the general consensus that it is thermal shock, I just need to find out how/why/who..

 

[Budha7]

Geoff, I'm not disputing at all.
on the flooring section, marmox says use adhesive steps 1 to 4, I think.
Then it says screw flooring, separately as step 1. Implying that screwing is another form of fixing as oppose to glueing and screwing.

 

[Budha7]

Purely, for gathering info.

 

[lizzardtong]

I always aim for overkill.

 

[thompsonbrown]

Did you position heating probe in correct position also did you use less than 100w psm heating kit.

 

[Budha7]

Hi
Yes probe was installed as per warm up instructions.
I believe the warm up loose wire to be 150w per mtr, but don't quote me on that.

 

[thompsonbrown]

Hi
Yes probe was installed as per warm up instructions.
I believe the warm up loose wire to be 150w per mtr, but don't quote me on that.

Max wattage for a suspended floor (wooden 100w). In my personal opinion this isn't the reason for your failed floor. However Manufactures will differ.

 

[Budha7]

Does using an insulated backer board not dispell the fact that it is on timber (wattage), as the heat is forced up through the tile instead of down into the timber?

 

[Budha7]

I'm not being awkward! Just asking.

 

[Budha7]

Sorry...It's late...

 

[One Day]

Max wattage for a suspended floor (wooden 100w). In my personal opinion this isn't the reason for your failed floor. However Manufactures will differ.

That recommendation though is assuming a direct fix to timber. All manufacturers will ignore the use of insulation boards on timber just to avoid any potential issues, so it's always 100w for timber, 150 for concrete (who the flip fixes ufh to concrete anyway?!)

 

[One Day]

Sorry I'm thinking of floating... It's late...

Floating? Oh Ohhhh!

 

[Budha7]

Ha ha! Sorry, It's a late and a few beers on board, I'm off to bed....
i should of just deleted it!

 

[White Room]

Know your substrates before tiling....

 

[Rich Midge]

Anything resolved yet? Over the last 18 months I couldn't tell you how many fails I've heard about regarding Norcros in N Wales. The latest reason they provided for a failed floor, cheap European timber being used in the construction not quality British wood! This was a new build they'd been out to spec. I've had pro 50 fail twice, looked almost like curdled milk the next day. They told me I hadn't primed the floor correctly! It was only after the main contractor, who was putting alot of money through Norcros, had the pro 50 independently tested that they admitted there was some kind of contamination in the powder before it left the factory. I'll never use Norcros powders again, shocking performance from there products and absolutely no backing from there customer service