No room for floor joists - Advice

[jamie192]

Hi all.

OK so here goes, I have a property and the joists and the flooring have collapsed in the kitchen due to being rotten. This is due to no damp proofing at all.. go figure!

So what was left of the suspended wooden floor construction was 2 by 5 wood on a wooden wall plate and they are spanning a gap of 1.8 meters. One side supported by the foundation of a brick wall and the other a sleeper wall. due to the age of the building these seem to be made of stone.
Because the gap between the top of the sleeper wall and the floor level was too small for the 5 by 2 joist they used they had cut away at the joist where the joist sat on the wall plate. Im guessing this is not good practice as a crosscut on a structural graded timber reduces that grading?

So my issue is because the gap between the sleeper wall and the floor level is about 2 by 4 I was going to rebuild with 2 by 4. However this does not leave me room for a wall plate.

Do I have to have a wall plate?

I was thinking of constructing a floor with 4x4 running along the walls on dpc with joist hangers on the side and running the 2 by 4 joists in the hangers all in c24 timber. Am I able to do this?

If I have to have a wall plate then i guess im going to have to lower the sleeper walls? or raise the floor height which is going to look bad because its open plan.

Thanks in advance for any help or guidance received.

Cheers jamie

 

[vinn]

Why not post pics of the kitchen, and the floor at both sides of the span?
Pics of the exterior at ground level will also help?
Are the walls solid?

Plates in walls are typically removed. Show the plate(s) in the above pics.
Notching joists weakens them.
Most properties since the late 19thC have some kind of DPC. How old is the building?

 

[jamie192]

Hi Thanks for your reply, I shall have to get pictures Wednesday when I go back. There is dpc in the main walls but there is none on anything the wall plates have been sitting on. This may have been how it was made but just as likely a bodge job which i would suspect due to the notched joists. If it helps this building is a flat and its in an old building that has been converted into multiple flats so may not be the original layout.

The walls are solid.


I don't know exactly how old the building is without pulling out all the files.

Cheers Jamie

 

[^woody^]

I've got a headache now.

 

[jamie192]

Joist Layout

• jamie192
• 16 Jan 2017

Does this picture make any more sense, so this is how it was, but they had cut out part of the joists to get them the right size for the floor height and to accommodate the wall plate. In the picture on the right is the brick wall with the "foundation" which was used as a sleeper wall. On the left there is a stud wall which is currently being supported by other means as the floor beneath it has collapsed entirely. Underneath the stud wall is the sleeper wall.

So as the cutting of the ends of the joists i think is wrong? I need to come up with a solution to replace the floor without raising the overall floor height.

 

[^woody^]

That's better.

Yes the existing joists are poor, and that type of extreme notching should be confined to a series on Sky Sports

I think you need to use hangers, as that will be easiest. You should not lower the wall plate from its current level as that could permit it to get damp despite any DPC below it.

 

[jamie192]

ok so I have drawn another picture to make sure I have understood you correctly. So the wall plate will have the hangers attached to the side. I will do the wall plate in 4 by 4 and have dpc underneath. The floor boards are ok to go onto the top of the wall plate?

Thank you for your help

Cheers jamie

 

[vinn]

Thanks for the diagram.
But pics would still help esp if the stud wall is temporarily supported - but how supported?
External pics usually give info as to the cause of damp.
Whats happening in the room the other side of the partition?
I'm assuming that the external wall plate is sitting on a brick ledge?
The external wall plate needs wrapping below and up the back with wide DPC material.

Jumping the gun but before doing any re-instatement why dont you lay a membrane (DPM) over the oversite soil and flopped up the walls.

 

[jamie192]

I will still get pictures when i go Wednesday so you can have a proper look. outside however you wont see alot, its terraced building but i can take a picture of the front and back. We have damp treatment specialists coming in doing the sort the damp parts out, we have to sort the floor out so they can also spray all the woodwork. I have a large amount of dpc so I will take your advice and cover the floor with it.

The other side of the partition wall is a bathroom and it is the exact same situation as the kitchen.

Im surprised the stud wall was still up, it was pretty much hanging there and had a cupboard built into it which had a full immersion tank in it. Currently the stud is supported by bits i added. It has been affected by wood worm and dry rot so we have had to cut some of it away and repair it. I have stands supporting the stud wall while I rebuild it.

Thanks again.