Please help re tiling prep

HI would really appreciate any help.

Situation- Victorian house, installation of tiled bathroom( floors and walls). Currently a mixture of old and new floorboards. The floor is not level.

Have been advised to use shuns to level under shower and alter the legs for the bath.

Also ben advised to tile on the floor directly onto 18mm ply! However i am worried fixing ply onto floorboards and then a tiling on top will create a large step up from the adjoining carpeted hall.

Is this the best option???

I have done some research and found out that maybe removing the floorboards, using 18mm pl directly on to joists then hardi backer on top might give a stonger base and eliminate this step up? Whats are your suggestions. Any help greatlyappreciated.

O I als forgot to mention i wish to use underfloor heating

Or I gues as its only a 2 bed I could ply the whole of the upstairs?

the height is the issue
transition strip to doorway may help or you may be able to shave some depth of the joists (make sure that it is engineered so this can be done) or ply it all as you suggested

It is not a good idea to reduce the joists!! They would already be under size by todays standards. (Victorian house) Can you take up all existing floorboards and re-do with 25mm ply?

Old floor is probably 20mm ?? so only raised by 5mm, then add hardi or whatever you want to use. Depending on what UFH it is you may want to use the special insulation boards instead of the Hardi

Hope it helps

Richard.

There is another way of stengthening the floor: glue 18mm ply BETWEEN joists fitted to 25 x 50 battens glued and screwed to the side of the joists, then only 18mm on top.
(this would still be ripping the old up)

Put hardi on top and away you go

Thanks for the help!

23mm is the thickness of the existing floorboards. Would replacing with 25mm poly and the insulated board of 6mm or 10mm not be defeating the purpose of the step up??With another 10mm for tiles that would be a transistion of 22mm from hall to bathrooom would i get away with that considering the hall will have carpet and underlay?

I've just recently had my bedroom carpeted with a 10mm thick underlay and at least 10mm thickness of carpet and I actually now step down into my en-suite bathroom from the bedroom. When we tiled the en-suite floor we layed hardibacker boards over the existing floorboards and used 10mm thick tiles plus addy. So all in all, once the carpet starts to settle down, everything should be the same level through the two rooms. Just a bit of experience that is worth bearing in mind in these situations

What about 6mm hardie backer board, screwed and glued.

Obviously, without being able to see the room etc. this advise is based on my assumptions.

I would remove the existing floorboards and add some extra noggins between all the joists to help eliminate deflection. Overboard with 18mm wbp plywood, cover that with 6mm cement lined insulation board such as Wedi or Marmox (glued & screwed). Fix UFH and cover with a latex floor smoothing compound, then tile.

By my reckoning the floor height will be:

ply - 18mm
insulation board - 6mm
UFH + SLC - 4mm
tiles & addy - 12mm

Total = 40mm
When you take into account the existing 22mm floorboards and carpet? height of the adjoining room, that will give you a step of no more than 8mm (hardly noticeable ).

Good luck,

Daz

where would you get the cement board from? Thanks for the great advise!

Look down the list of sponsors on the left hand side and click on U-Heat. You'l find what you need there.

BTW, you will struggle to beat their UFH prices too!