Hello,

I am installing a new bathroom in the first floor box room at the back of my victorian terrace (existing bathroom in the room beneath) with separate bath and shower enclosure.

Having emptied the room and pulled up the carpet, hardboard and floorboards for first fix plumbing, joist strengthening etc. I have noted that the boards are in pretty poor condition and have evidence of woodworm at some point in the past. As a result, I have decided to get rid of the floorboards and lay new board straight on to the joists.

I have had so many different opinions on what to use at this point that I don't know where to go from here...

Some say floor grade chipboard, some say 18mm WBP, and my plumber has recommended "Dukkaboard", though this seems pretty expensive.

We're not on a huge budget, so the tiles we go with (haven't decided yet) will be at the cheaper end of the spectrum, but safe to say they will be porcelain and on the large side (600 x 400/500/600)

Can anyone advise the best way to go with this? Ideally I do not want to raise the level of the floor too much, and would like to keep costs down.

Many thanks,

Will

You could use 21-24mm wpb fix some noggins between the joists for extra strenght

and then uncouple it..

Or 18mm ply with extra noggins and overboard with Tile Backer boards.

The choice is yours.

But do not tile straight on top of any preparation that is fixed direct to the joists.

Okay, so the key is to "uncouple" whatever I fix to the joists with a separate layer of something?

Can anyone see any problems with:

18 or 22mm P5 2400 x 600 Flooring T&G MR Chipboard screwed to joists (with added noggins?) followed by 6mm Dukkaboard, screwed and taped?

I would use 18mm wbp ply then stick ducker board with opf and screw imo it is worth paying a little more for ply should be able to get for no more than £30 for 8ft by 4ft sheet

I havnt use Dukkaboard but I would go with BWP ply 18mm min then over board with a cement backer board. The cement boards will need to be glued and screwed down, the glue will fill any voids under the boards. Adding extra noggins is also a good idea.

Even if you go for the cheapest tiles on the market, it will be a total waste of money if you dont prep the floor properly, I think this will give you a good substrate to tile onto.