How do I level my old joists before subfloor, fibre board & tiles go on?

[Dudefinch]

Hi all, bit of background on my house/floor - 1930's detached. Suspended timber floor (100 x 50mm) on either side of a concrete pad which used to hold a wall up and old oven.

I've removed and replaced (with 95x45mm C24) all the joists on the smaller section of the suspended floor as they had woodworm, and checked and treated the other side. I think the woods ok, but trying to work out how to level both sides has got me scratching my head a bit. I've bought some u shims I was going to use on the smaller side, but on the bigger side some joists are 10mm different in height to the next one, and they're wedged into the wall pockets pretty well, so hard to adjust.

I was thinking to use the heavier grey blocks (trimmed down) in between the new joists, mortared in, instead of the old bricks. Was also going to paint the joist ends in black jack to seal them. Also going to whack some noggins in between all joists about 600mm apart for rigidity.

But the first step will be levelling it all, or rather, making it flat. Do I first go and record the heights of all the joists? Do I not worry too much and use self levelling compound over the subfloor (22mm moisture resistant chipboard 2400x600 with NoMorePly 1200x600 6mm sheets on top)? Do I sister the lower joists? Not sure how flat it all needs to be for the eventual tiles to go on top.

Any ideas or process you normally follow would be mighty helpful.

 

[Deleted member 323070]

Can use a stringline across the tops of the applicable joists, either end, and adjust each joist as required?

 

[Dudefinch]

Thanks Tom. The only problem is the joists are mortared into the wall pockets (in the first pic you can't see them as they're near my feet). So not sure how I can raise or lower these, when those ends are some of the ones that aren't in line with each other.

 

[Deleted member 323070]

Thanks Tom. The only problem is the joists are mortared into the wall pockets (in the first pic you can't see them as they're near my feet). So not sure how I can raise or lower these, when those ends are some of the ones that aren't in line with each other.

Are all the old mortared-in joists level with each other?
Do any of the mortarted-in joists need adjustment? If so by how much?
If it's just the new joists that need adjustment, attach the stringlines and work from that.

From what I can see, one end of nearly all the old joists can be lifted out of their sockets, then the other end can be withdrawn from the mortared-in hole.
Clean out the sockets, and work on leveling the joists to each other. Use bits of old tiles, etc as packing under the joists.

 

[Dudefinch]

Unfortunately the old joist are 10mm or so out from each other at the wall pocket end. The new joists I think I'm ok with as I can move them around easy enough.

 

[Deleted member 323070]

Unfortunately the old joist are 10mm or so out from each other at the wall pocket end. The new joists I think I'm ok with as I can move them around easy enough.

From what I can see, one end of nearly all the old joists can be lifted out of their sockets, then the other end can be withdrawn from the mortared-in hole.
Clean out the sockets, and work on leveling the joists to each other. Use bits of old tiles, etc as packing under the joists.

 

[Dudefinch]

OK, so just yank them out, clean the hole, and see if they can go lower or higher on that end. That sounds like an option, and a fair bit cheaper than sistering another 4x2 to every one. I might try with one and see how I go. Many thanks

 

[Deleted member 323070]

Use a length of timber or a pole to lever them out. Once the end that lifts up, is out, you can 'waggle' them about to pull it free of the other end.
Position them all loosely, then work on leveling them to a stringline either end.