Levelling a floor

[stuartcotterell]

I've just moved into an old flat that has been subject to some movement in the past. As a result, there is a fairly significant slope in one of the rooms. I've not properly measured the slope, but it equates to a height drop of a couple of inches over a metre or so.

I'm evaluating a couple of ways of fixing this. The most "pure" one strikes me as being lifting the boards, packing the joists until level, and then relaying boards.

Alternatively, someone has mentioned building a "false" floor on top of the existing boards. Basically, adding new joists to above the boards, then laying a new set of boards, basically giving a whole new floor.

Finally, someone suggested to me that some self-levelling floor compound could do the job. This does strike me as an easy option, which consequently make me very uneasy about it! Does anyone have any experience of using this stuff to level a floor? I'll be laying carpet on top of it eventuallly, if that makes any difference.

If anyone has been through the joys of doing this in the past, I'd be most grateful to get some thoughts and wisdom!

[adder1969]

2 inches per metre is a lot to level using a compound! If the boards come up easy it's easiest to screw battens to the side of the old joists and relay the boards.

[The Natural Philosopher]

Try two inches over a meter..

It's not worth messing with leveling compound on wood unless you want to tile..and in any case it gets expensive.

If you don't care about the original floor that much, the easiest thing is to replace it with flooring chipboard. Whether you lift whats there or put it over the top is more a question of final height, and condition of what's there.

Of course lifting a floor is a great opportunity to run wires and pipes underneath...

[TMC]

Do you really mean 2 inches drop per metre of floor as this would equate to

8 inches of height difference across a 4 metre wide room. I assume that you have no door opening on the side that you have to lift by this much.

What is the actual height difference across the whole room?

Are the walls out of vertical as well?

Tony

[stuartcotterell]

It is a fair old drop, but it isn't consistent across the whole room. Basically. there's a dip in the first metre from the doorframe that is probably just over an inch. There's then a much more gradual slope across the whole room. I really should measure it up properly to establish the severity of the slope.

The walls are surprisingly ok.

[Stuart Noble]

What caused it, and has it now stopped....?

[stuartcotterell]

state unambiguously that there were no recent signs of movement, and no cause for concern.

[TMC]

I would do some serious measuring over the whole floor to establish exactly what you are dealing with

Laying a new floor on top, tongue and groove chipboard would be easiest, supported at 400mm centres with appropriate thickness packing where needed.

You also need to consider how to manage door way as a step the thickness of the chipboard is easy to trip over

Ripping up the old floor and replacing with new after packing joists to level could be a better option as the doorway would not then have a step. However the old boards may not be in a good enough condition to use again. You also need to determine whether any of the walls are built on top of the existing floor as often happens with internal walls

Either way all the skirting will also need to come off and be refitted or replaced along with any electrical sockets that may end up being too close to the new floor or the new skirting There may also need to be adjustments to any central heating radiator

Final thought is there a room below and if so what condition is the ceiling of that room as it may be affected by the work suggested above

Tony

[Stuart Noble]

Then the quick fix would be self levelling screed by the door and leave the rest. Doesn't matter if it slopes as long as it's flat. Any movement and you're back to square one though...

[djc]

Does it matter? My 200 year old flat has a notable slope to the floor, part due to age, the heavily used area by the door, and probably because the whole terrace has probably drifted down toward the metropolitan line cutting. I simply put 1.5 inch blocks under the front of a wardrobe to maintain it upright and aligned with the wall.

[baxter basics]

Does the floor "bounce" at all? I had a bad ground floor lean and a lot of bounce...pulled up some boards and found several rotted joist ends. Trimmed these, then jacked them up to level and spliced in new ends.

If you have a big variation I reckon its worth investigating in case there is something seriously wrong...the extra weight of screed/false floor could just make it worse.

cheers