Uneven Floor

[Monkey Wrench]

I'm a Plumber by trade but will often do a bit of tiling as part of a bathroom install when required. I'm currently working on a job in a 2m x 2.25m bathroom which requires me to install an 800 x 1700 floor mounted shower tray and tile approximately the remaining floor (just over 3 metres) with 500 x 300 porcelain tiles. I've tiled a number of floors before without a problem but this particular one is another matter.

The building is a converted barn that was totally gutted and converted into a house about 12 years ago and the flooring material is T&G chipboard flooring. The problem is that the floor drops about 23mm along the 2 metre length which is also the same length along which the floor mounted shower tray is to be mounted. The floor is also uneven along the 2.25 metre length but not nearly so extreme. Levelling the shower tray in itself is going to be a major problem but then, once its level, there's the problem of tiling. If I level the tray but follow the fall when tiling, the shower tray will appear higher one side than the other (along the length). Additionally, trying to tile such an uneven floor with such large tiles seems like a recipe for disaster. Is the only real solution to rip up the floor and start again or can anyone please recommend another solution ?

Thank you in advance for any helpful advice.

 

[Bubblecraft]

My advice would be to lift your P4/P5 boards & level out your joists then put back your P4/P5 & over sheet with Hardibacker 250. That would be my recommendation. If height is going to be an issue, you could replace your P4/P5 with 18mm WBP ply being sure to prime the underside & edges & fit additional noggins/dwangs. I'd go with option one first though

 

[Monkey Wrench]

Thank you very much for the advice Bubblecraft.

Is levelling joists just a matter of fixing appropriate size wood shims along the top ? The other problem is the door threshold is on the "low" side of the 2 metre length so any levelling will automatically raise the door threshold accordingly (probably 23mm in this case plus the Hardiebacker and tile/adhesive).

Thanks again.

 

[Bubblecraft]

Thank you very much for the advice Bubblecraft.

Is levelling joists just a matter of fixing appropriate size wood shims along the top ? The other problem is the door threshold is on the "low" side of the 2 metre length so any levelling will automatically raise the door threshold accordingly (probably 23mm in this case plus the Hardiebacker and tile/adhesive).

Thanks again.

The easiest way is to lay timber shims on top to the desired thickness to bring the floor level. I would space these every 600mm & put a timber noggin no less than 47mm x 125mm (5" x 2") up to the level of your shims.

Unfortunately in some cases, a step into the bathroom cannot be avoided. Finish off with a floor trim with a vertical tile up to it.

 

[Monkey Wrench]

The easiest way is to lay timber shims on top to the desired thickness to bring the floor level. I would space these every 600mm & put a timber noggin no less than 47mm x 125mm (5" x 2") up to the level of your shims.

Unfortunately in some cases, a step into the bathroom cannot be avoided. Finish off with a floor trim with a vertical tile up to it.

Thanks again Bubblecraft.

The joists are running across the fall and not along it, does that make a difference ?

 

[Bubblecraft]

Thanks again Bubblecraft.

The joists are running across the fall and not along it, does that make a difference ?

Yes. That should make it a little easier. Just run them along the top of your joists to the height required. Just make sure your shims are no ness than 2" wide. You'll still need to fit your noggins every 600mm to the height of your shims.

 

[Monkey Wrench]

The other problem is that two of the walls have just been replastered and the board is tucked very snuggly underneath !

 

[Bubblecraft]

If you find it difficult to remove the boards without damage to the walls, use a reciprocator to cut them out. This way you can cut them tight to the wall. Depending where your joist hits, you may have to add an additional joist there too to give you a fixing again. If a lip of flooring is not going to be an issue say you will be boxing in a pipe chase, use a circular saw to cut them out. The flooring that is left will be the width of your guard. This is a far quicker method. Mind & set your guard to the thickness of your flooring so you don't hit any pipes or cabling.

 

[charlie1]

Thank you very much for the advice Bubblecraft.

Is levelling joists just a matter of fixing appropriate size wood shims along the top ? The other problem is the door threshold is on the "low" side of the 2 metre length so any levelling will automatically raise the door threshold accordingly (probably 23mm in this case plus the Hardiebacker and tile/adhesive).

Thanks again.

another way of constructing the raised area would be to rip some 18 mm ply in to strips equal to joists ( about 8 inch ) , screw them each side of the joist to the new height and then insert smaller packers between the ply on top of joists. Hire a laser level or if you have large normal level then this will do.
note: get your ply wood from bnq and get them to rip it down, they also have local price match policy and will beat rivals by 10%.
also, use plenty of screws!

 

[Monkey Wrench]

If you find it difficult to remove the boards without damage to the walls, use a reciprocator to cut them out. This way you can cut them tight to the wall. Depending where your joist hits, you may have to add an additional joist there too to give you a fixing again. If a lip of flooring is not going to be an issue say you will be boxing in a pipe chase, use a circular saw to cut them out. The flooring that is left will be the width of your guard. This is a far quicker method. Mind & set your guard to the thickness of your flooring so you don't hit any pipes or cabling.

Thanks again for the excellent advice Bubblecraft.

I guess there's little point in trying to pull the boards completely out from the walls anyway as, after the leveling, the edges would have to be trimmed flush to the wall as they certainly wouldn't tuck back into where they originally came from ! If I leave a lip of flooring (probably a couple of inches), I guess I'll have to try and fill it with some shims before laying the Hardiebacker and then tiling !