Making good joists following chimney breast removal

jimfromcov

I have my chimney breast removed upstairs and supported in the loft but am now looking to remove the section downstairs as well, and am looking for clarity on what to do with the ground floor ceiling / first storey floor joists with regards to making sure they're properly supported.

I don't believe that they are currently fixed into the chimney breast, but may well rest on it as it was slightly smaller upstairs, so i am not sure that they are trimmed around / self supporting currently.

I am looking to temporarily support the joists by screwing down a length of timber across the ones which will run short, fixing into these and also into one / two joists either side to provide support whilst I make the amendments - If the consensus is that this is not enough I will hire acros and support that way.

I will then remove the top few courses from the breast to take it to below ceiling level downstairs (only this many as I wish to finish the bedroom ASAP).

I will trim the ends of the shorter joists with a double trimmer using the same sized timber as used for the existing joists, so these pieces will be perpendicular to the shorter joists and will fix to the full length joists either side of where the chimney is / was using joist hangers.

The double joist trimmers I will bolt (M12's) back to back and use timber connectors between the two.

I will then run a length of timber between the two existing full length joists halfway between the new trimmer and the wall to provide support in the gap.

I guess my questions are a) does the above sound acceptable, and b) should i be adding a second joist back to back with the existing full length joists to re-inforce these (if so i have more questions on how to do this).

The below is effectively what i mean with x's where the joist hangers will go, and the dashed line where my new joist(s) will go - I cannot post links so delete the space between the dot and com...

diynot. com/diy/media/untitled.70793/full

Le_Kirk

Here is your picture: -
https://www.diynot.com/diy/media/untitled.70793/full

Furts

Your current proposal is far from acceptable. You are more than doubling the load on the two existing joists, so this will need strengthening. This would have to go into the bearing points (the existing walls?)

All this should be subject to the Buildings Regulations, you are doing structural alterations, and you should have it all signed off with a Completion Certificate.

It is a bit cheeky asking folks here on the forum for foc structural advice when all this should be above board and funded by you. You may say I am being harsh, but when the Building Inspector asks for structural analysis and you respond this came from the mse forum, I doubt you will be taken seriously. So why take this risk of embarrassment?