fitting a new bath - wood underneath?

har0ld

I've been in the bathroom industry for many years.
The bath will definitely be prepared to have screws (as supplied) screwed into the base to fix the legs, the chipboard that was visible on your old bath was the old/cheaper away to strengthen the bath, your new one will more than likely have an encapsulated base board that may be wood or could be some other composite.
The wood, referred to, is as a previous post implied.
You are endeavoring to spread the weight of the bath across as many of your home's joists as possible, assuming you are fixing on to a wooden floor.
Personally I often try to remove chipboard from any area in a bathroom where water might get - especially under the bath. I always try to ideally replace existing chip flooring with marine ply or at very least add a good thickness of ply on to existing chipboard surface. This needs to be screwed down at regular intervals ideally into the joists (this is why replacing is better than strengthening as you then know that you aren't screwing into concealed pipes or cables). adding a wooden batten to the walls where the bath is fixed, if properly fixed, adds loads of extra strength and is well worth the effort.
Last tip, when you come to running a silicone bead around the bath where the tiles meet the edge - fill the bath to the brim with cold water first and leave it there for ideally 24 hours whilst the silicone sealant cures. (this means that the silicone will for ever more be under compression rather than tension and is extremely unlikely to fail)
Remember - all wood moves, bathrooms are wet places and chipboard is like a sponge!

littlejaffa

i bit the bullet and assumed there was wood under the fibre glass on the outside of the bath - drilled down and looo there was wood shavings!

Thanks for your help - re the family member who knows about these things - i'm it! it's not often a person fits a bath and we alll have to learn the first time - now onto the easy bit of plumbing, plastering and tilling! That i can do!

thanks again folks