Ridge in floor over breeze block wall

[Tom Snell]

Looking to re carpet one of our bedrooms, which has a pronounced ridge running the length of it, around 2ft from the nearest wall. Seems this is because the breeze block wall of the room below is higher (especially with joist hangers) than the joists that the chipboard rests on either side. Photo and a crude cross-sectional diagram attached.

What are my options for levelling it? The chipboard on one side has some white reside so assume someone has painted something on to try and graduate the 'peak' of the ridge in the past.

My current thinking is to cut a channel in the chipboard following the breeze block plus a couple of inches either side, and replace with thinner timber sitting on shims on the joists at either side.

Any better solutions? Since the chipboard is so brittle I'm guessing that planing it isn't very practical. Other thought was to add height to the joists on to the side nearest the wall, but this would lead to an even bigger gradient to one side.

Many thanks!

 

[jacko555]

How about run noggins along the length of the wall (so secured between the joists) and cut the chipboard so it rests on those, not the breeze.

Then you'll have a valley in the room with breeze block at the bottom. The chipboard will be level.

Then fill the valley with something? Maybe self levelling compound?

 

[JohnD]

I hate chipboard, so I'd chuck that out first.

I think I might seek to increase the height of the joists by laying battens on them so they matched the height of the wall. In the entire room with no slope or gradient.

In my own house I have a room with an RSJ doing something similar. The carpenter tried to deal with it by shimming the joists on each side, so the rise (about 6mm?) is lost over the 1220 width of the ply sheets, but you can feel it when you walk over it, especially barefoot. If I can be bothered I might have the ply routed out and some extra struts to give more support around the thinned area.