Plasterboard under chipboard flooring

I am repairing a bathroom floor which has crumbling chipboard.


I've discovered that under the 22mm chipboard is some kind of plasterboard (18mm) with a small amount of fibreglass wool under that and then more chipboard underneath that (which is solid).

My initial plan was to cut back the crumbling chipboard to the middle of a joist and then to secure new chipboard to that with battens for support as necessary. However...now that I've found the second layer of chipboard underneath, I'm wondering if I can just fit new chipboard over the top without securing to anything. Would the plasterboard be strong enough to just lay new chipboard on top?

Also, the plasterboard is cracking in places. What would be suitable for repairing that? Self-levelling compound? Something else?

I'd appreciate any input and advice you might be able to offer.

Thanks!

Is this property a conversion?

Andy

It's a second storey flat, about 30 years old. Possibly timber framed...

Keep going down until you find sound material/background, clear everything to that level/grade and then build back up to sub floor level using battens and "wbp ply" leaving enough height/gap for your desired floor covering. WBP ply in a washroom is better than chipboard.

I have worked on conversions in the early 90's where we had plaster board on the floor then chipboard on top to comply with noise and fire regulations.

Andy

HERTSDRAINAGE2010 said:

I have worked on conversions in the early 90's where we had plaster board on the floor then chipboard on top to comply with noise and fire regulations.

Andy

Click to expand...

Yeah. Makes sense. Better soundproofing can be done now and will need to be if current flooring has failed.

Thanks for your replies.

The bottom layer of chipboard is solid so I was thinking to leave that and not try to attach anything to the joists beneath. So are you suggesting to get rid of the faulty/failing plasterboard? What would be a suitable replacement for fire/acoustic insulation?

And where would I put the battens?