I have 3x2 ceiling joists (ties) in my house covering a 12ft span. These were deflecting and unsuitable to hang plasterboard from, particularly as I want to board over in the loft and use it for light storage.
A structural engineer came around and recommended I sister the existing joists wth 7x2.
I've had a builder come and do the work, but rather than fix the new 7x2's directly to the rafters as I was expecting. He has fixed them to the existing joists. I guess this is pretty common practise?
It has stiffened the old 4x2's up great, but when you put any kind of weight on top of the 7x2's they are flexing and twisting at the ends. There is only a single row of nails holding the 7x2's along the bottom edge, nothing holding them in at the top which is presumably why they are twisting outwards when load is applied.
A structural engineer came around and recommended I sister the existing joists wth 7x2.
I've had a builder come and do the work, but rather than fix the new 7x2's directly to the rafters as I was expecting. He has fixed them to the existing joists. I guess this is pretty common practise?
It has stiffened the old 4x2's up great, but when you put any kind of weight on top of the 7x2's they are flexing and twisting at the ends. There is only a single row of nails holding the 7x2's along the bottom edge, nothing holding them in at the top which is presumably why they are twisting outwards when load is applied.
