Removing Wall with Chimney Breast

[jamesgs]

Hello,

 

I bought an 1890’s house (well, the back half of it is) about 18 months ago and am looking at putting an open plan single storey extension on the back - so I have a question about supporting chimney stacks…

 

When the house was renovated back in the 90’s the chimney breast upstairs was removed along with everything above it, however, it is still in once piece downstairs where it takes up a lot of room in the kitchen.

I am looking at removing the back wall of the house, complete with these remnants of the chimney (the chimney breast is contained entirely within my house, no overlap to neighbours) but have a question about the support of the upstairs floor. When I removed the carpet upstairs, the footprint of where the chimney was/is is covered by a concrete slab and the floor beams appear to only go from one end of the house to the edge of this concrete slab, not all the way to the back wall (obviously i suppose, or the beams would have originally gone through the flue!).

 

My question is, when it comes to removing the wall, clearly I will need some sort of support for the wall anyway, but will I also need an additional RSJ or such like running under the “front” of the chimney to support the upstairs floor beams?

 

I have attached my terrible rough plan drawing of what upstairs basically looks like - what I’m wondering is if I’m going to need 2 RSJ’s (or any other solution) essentially? Apologies if my description of all of that is absolutely awful by the way….

 

Thanks very much!

 

James

 

Edit: OR... is is possible/cheaper/legal to just extend the shorter joists and just take out all of the concrete?

[Russell griffiths]

You will need some technical drawings done by either an architect or structural engineer as you will need to submit them to building control. 

 

You would remove the concrete hearth upstairs

you would extend the short joists out to the same to the same length as the others by fitting a new joist directly to the side of the original short one, this will extend out to the rsj that will support upstairs. 

 

How do you intend holding upstairs in place whilst you install the beam. 

 

This is not a small undertaking, proceed with caution. 

 

 

[Brickie]

+1. 
The typical detail for joists round a stack would involve ‘trimming’ as it’s known,like this,so it’s just a case of filling the void where the stack & hearth were,once removed. 
 

[Conor]

You'll need an engineer (+drawings) plus building control approval before you start. 

 

When we did similar in our last house, we had an interred "T" beam put in along where the supporting was was, and new joists spliced in where required. Ceiling was then reboarded. The inverted T beam allowed the beam to be inserted without having to remove existing joists. Builder just had to cut a notch though the joists and slot in the new beam.

[jamesgs]

Perfect, thanks for the replies! I’m definitely not considering touching this myself, I’m going to get all the structural drawing and building regs stuff done when things allow - all I wanted to do was get a bit of an idea how big a job this was before I launched into things and so I can try and get a handle on costs early on. Doesn’t sound tooooo bad so far!

 

Thansk again, glad lengthening the beams sounds like an option rather than having to have a second RSJ

[CC45]

Does the chimney shrink in size higher up?

 

I had similar to you but upstairs it slimmer down to ~ 12" x 12".  I made up 2 gallows brackets & bolted them in place - BC was fine with that.  Just depends on load I guess.

 

Good luck

[jamesgs]

I think it does actually, now you mention it - I'd have to remeasure it. Might see if they can do that then if that's a viable option. 

[Russell griffiths]

2 minutes ago, jamesgs said:

I think it does actually, now you mention it - I'd have to remeasure it. Might see if they can do that then if that's a viable option. 

I thought you said upstairs had already been removed.