Self Levelling hairline fractures - What to do?

g1ose

Hi All,

I decided to have a go at my new bathroom floor recently. Long story short:
Removed old floorboards
Marine ply 18mm on top of joists
a good few hundred screws to ensure it doesn't move
Filled all gaps with flexible caulk and masking taped all edges/gaps
primer (water/pva mix)
underfloor heating (electric loose cable)
Self levelling compound (instructions followed strictly)

After 2 days of the self leveller I can see many hairline fractures. No hollow areas but the floor is cracking and popping when you walk on it and when the pipes that run under it heat up.

Now my question is what can I do now. I'm planning on laying LVT ontop of the new floor but I'm worried if I lay it it may break up further underneath.
But trying to get it up now would mean a lot of work and almost certainly a dead underfloor heating system.

Do I
a) put down some adhesive and LVT and hope for the best
b) fill in the small fractures with something before doing a?
c) put another layer of SLC down or even a underlay of some description and then do a?
d) break it all up, give up on self levelling and UFH and just stick the flooring ontop of the ply?
e) something else?

Any help would be greatly appreciated.

Thanks

jk0

I don't think you are meant to put self leveling compound over heating wire, are you?

I used the Wickes system a few years ago, and the height of the cables was lost in extra tile adhesive. (Powder type mixed with water.)

andyhop

18mm isn't sufficient

22mm or 25mm would be ideal

All edges should have been supported, joints staggered

Primer should have been used on rear and edges only

Mat down then screed, UFH must not be switched on until tiled, then slowly over weeks bring the temp up to max set point

Fibre reinforced screed is superior to normal water/latex based. ,Mapei fibreplan , weber floor flex are ideal, 6mm cover needed and allow to dry naturally

g1ose

Thanks for the replies.

jk0 - It says suitable for UFH so shouldnt be a problem, besides it hasnt been turned on yet so not the cause.

andyhop - thanks for the advise. what are your thoughts on the next step going forward?