Sorting out an uneven floor

[mikeyf]

This may not be the first time that someone has asked this, and I apologise if I'm repeating someone else's question. I had a look through the forum and didn't find all the answers that I was looking for.

I've just bought a bungalow on a hill which has concrete subfloor for part of the ground floor and a suspended wooden floor for the rest of the house.

The hallway floor and the living/dining room floor are both chipboard over wooden joists. The hallway is between the two spine walls of the house and the living room is between one spine wall and the exterior wall on the downhill side.
The space between the living room goes from about 2ft at the top of the slope to about 5ft at the bottom of the hill and is held up by a number of pillars of blockwork at various places.

Overall the floor is mostly level but there are a few joists that have sagged by a few millimetres in places and with the current carpet floor covering you can feel the unevenness in the floor as you walk over it. There is also a joist which I suspect has been added as a repair job which is wedged into position with wooden wedges and which might have been positioned slightly too high.

I'd like to replace the carpet with engineered wood or laminate and am not sure the best approach to levelling it off. Do I:
Pull up all the chipboard floorboard and replace with structural ply?
Lay ply/hardwood or something else over the chipboard?
Use lots and lots of levelling compound?
Try and even out the joists?
Something else?

And if I do have to try and even out the joists should I be replace them, packing out the unevenness or sistering them?

Any suggestions gratefully received.
Thanks

 

[Chri5]

Take up the floor and start with the basics of getting the joists even level and firmly set.

A builder mate of mine showed me a clever trick with a car jack, and board.

Take chipboard off, test levels, where level is wrong sit board on sub floor structure, then the car jack, adjust car jack to level joist.

Wedge joist to correct position, point in, use bits of slate tile or however you feel the joist should be fixed.

Once that's done you can then insulated between the joists with Kingspan or celotex, and fit a floor.

22mm can be used direct to joists if the flooring lengths allow. Otherwise it's a marine ply and then the hardwood flooring system on the ply.

 

[mikeyf]

By 22mm do you mean put down 22mm ply on the joists?

For the joist that may be too high, is it OK to plane off a few mm or am I better taking it up and reseating it?

Thanks

 

[catlad]

If you take all the flooring off the joists, then you can either get a long straight bit of wood to aid levelling the joists or a string line. Yes you can plain a bit off the joists if you want, but they were probably level at one time and may just need re positioning.