Help required: Sloping floor level between rooms

[motomikey]

Hi folks,

I have a situation in my house where I have two openings leading from my dining room into my kitchen (one at either end). At one opening the dining room floor is level with the kitchen floor and at the other there is about a 30mm drop. The opening with the 30mm drop is a new opening and this is how the difference in the floor height has suddenly come to light.

I really don't want a ramp down to the kitchen at one opening, and absolutely don't want a 30mm step (besides the tripping hazard it would really ruin the symmetry I'm trying to achieve).

I don't think screeding it with a self leveller is an option here either, as I'm not confident that it's just the kitchen floor which isn't level. If I get it wrong the screed is going to flow through my whole house - the missus wouldn't be ammused

In an effort to level the floor of the two rooms ready for tiling here is my plan:
- Put 9mm ply over the whole floor of the two rooms
- Graduate the kitchen floor from one end to the other using plywood and stepping it down from 30mm at one end to 9mm at the other in 3mm increments over the 3.5m span between the two openings (a 3mm step every 500mm or so). I know this still leaves me with a 9mm slope in one opening - but that is manageable - I just don't want a 30mm slope
- When tiling the floor - use the tile adhesive to smooth out the 'stepped' gradient.

A not very good diagram of what I'm trying to acheive...

Can someone please advise me if this is likely to work or if there is a much more practical way that I'm just not thinking of?

Would a 3mm drop every 500mm make a noticeable slope or staircase effect across the floor? Would the tile adhesive then be able to smooth out the stepped effect making it a more gentle slope that you don't really see?

So many questions!... Sorry.

Any help and advice much appreciated. Cheers.
Mike

 

[Chri5]

Whats the sub floor under the lower floor ?

If it's joists why not pack them up and then the floor skin goes on level with the other room.

If say you need to drop from 32 to 0 mm over 8 joists then each joist gets packed 4mm.

i.e 1st 32, 2nd 28, 3rd 24, 4th 20mm etc.....

 

[motomikey]

Whats the sub floor under the lower floor ?

If it's joists why not pack them up and then the floor skin goes on level with the other room.

If say you need to drop from 32 to 0 mm over 8 joists then each joist gets packed 4mm.

i.e 1st 32, 2nd 28, 3rd 24, 4th 20mm etc.....

Thanks for the reply - and it makes perfect sense too. However...

removing the floorboards could be an additional problem in itself, as the internal walls have already been framed out, insulated and plasterboarded. I would not be able to remove all of the floorboards.

Can you think of anything else that wouldn't involve removing the floorboards?

Cheers

 

[Chri5]

The floor may have dropped due to joists sitting on lime mortar beds, if it had the normal would be to prop up the joists (car jack) and re pack the mortar with slate.

Too late for that.

Anything you do must be solid and level, so the packing needs to be done in very gentle increments.

Marine ply is available in 4mm thickness and I suggest you use that in variation- so that you sandwich more layers at at the big drop end.

It still means your need a very good tiler to return the floor to absolute level- on the tile adhesive side some material can be laid 10-15mm thick.

That ramps up the cost of adhesive and also means slow, patient (thicker layer requires more drying time) and well skilled tiler required.

 

[kevindgas]

looking at this
my thoughts are why use 9mm ply thoughout?
as for the stepped areas use the strips to step it, but then use a solid piece on the top so you end up with a flat floor
so you start with a 12mm board use 3mm boards to make the steps up to 21mm, then 18, then 15, then overlay with the 9mm board to get your 30 > 24mm thicknesses
then use a 6mm board with 3mm strips to create the 12, 9 and 6 steps
and finally a 3mm strip again overlay with your 9mm board to get 21>9

 

[motomikey]

Thanks for the replies fellas. I'll of course take on board all the advice given.

The reason for the 9mm ply throughout is to help level out the slightly uneven floorboards, fill in numerous small gaps and generally help seal the floor a bit.
It might be viewed as overkill, but I've already done it throughout the rest of the house.

Thanks again