How to fix existing floor joists to new RSJ

[wwwebber]

ok, I am having an RSJ installed (supported each end on walls) in my loft so I thought this might be a chance to strengthen the existing understrength floor joists them by attaching them to the new RSJ which will sit literally 1 or 2 mm above the joists. I cannot disturb the ceiling that the joists are currently supporting so what method could I use to fix the joists to the RSJ above ?

Thank you.

 

[Ian H]

Bolt a timber into the RSJ and use hangers for the new joists.

 

[Celeronmanuk]

Bolt a timber into the RSJ and use hangers for the new joists.

He said he can't disturb the ceiling so how would he get hangers in under the ceiling joists?

 

[foxhole]

He said he can't disturb the ceiling so how would he get hangers in under the ceiling joists?

He also called them Floor joists, bit confused what’s trying to be achieved .?

 

[cdbe]

I did something similar - I used pairs of "twisted joist straps" (cut down) instead of hangers, secured with sheradised nails.

 

[Ian H]

He said he can't disturb the ceiling so how would he get hangers in under the ceiling joists?

Oh yes, timber into the RSJ and some metal straps onto the joist sides then.

Probably something available here:
https://www.toolstation.com/construction-insulation/builders-metalwork/c266

 

[wwwebber]

He also called them Floor joists, bit confused what’s trying to be achieved .?

Its the floor when you're in the loft and its the ceiling when you're in the room below

 

[wwwebber]

Thanks all - those suggestions look like just the job - I just need to get some timber into the RSJ and then use an appropriate strap to bring them together as suggested.

Good stuff - thank you.

 

[Celeronmanuk]

Our structural engineer offered twist straps as an option in this scenario. I preferred to cut some pockets in the ceiling and use joist hangers. But the ceilings getting replaced anyway.

If all you want to do is stiffen it up and take the bounce out, then i guess anything will do.

 

[Celeronmanuk]

Its the floor when you're in the loft and its the ceiling when you're in the room below

FYI, I would call them ceiling joists. They aren't there really to act as a floor.

 

[wwwebber]

FYI, I would call them ceiling joists. They aren't there really to act as a floor.

Yeah, the ceiling joists are only 3x2 and amazingly the two lofts have always been used as rooms since the 1800s. I'm putting steels in because the dormer windows installed by the previous owner 15 years ago are not supported very well so I am taking the chance to strengthen the floor / ceiling whilst I am at it. It wont be BCO compliant but these are old rooms and they never will be compliant to modern standards.

Cheers.

 

[wwwebber]

ok, next question - the floor / ceiling in question has sagged over the years (200 years to be exact). So when strapping it to the new RSJ - do I leave the sagging as is ? and simply strap it up where it sits ? or correct the sagging (using some acrow props underneath maybe) and thus push it up to meet the RSJ before strapping ?

Thanks again for your input.

 

[Ian H]

Has the RSJ been designed to take the load of the floor too? If it hasn’t i’d leave the sag as it is.

 

[wwwebber]

Has the RSJ been designed to take the load of the floor too? If it hasn’t i’d leave the sag as it is.

Yes I will getting the SE in next year to give final specs etc and yes it will include the floor loading. Also, the ceiling below has been boarded & skimmed over some years ago whilst it was sagging - I have no idea how this will affect things whilst correcting the sag.