B
ben2579
Chipboard is just bad in bathrooms full stop. It swells waaaaay too much when it gets even the slightest bit of damp on it.
18mm marine ply minimum. But as it's a bathroom I'd go with the cement boards as suggested.
It wouldn't have been too much of a maul if it's such a small area to simply cut out the chipboard and replace with ply, then overboard.
The heating mat is fine to be used in bathrooms though providing the thermostat is the right one for bathrooms, or is placed outside the bathroom.
thanks for everyones help!! I am meeting with tiler tomorrow to discuss way forward - he did for what it is worth offer through his company a guarantee on any work (although i am well aware of the value of guarantees in this economic climate). I also have an independent coming to look at the work tomorrow for a 2nd opinion. But anyway excellent forum and I will use again in the future!!!