Sorting different height joists

[Jdwood38]

Hi all,

I’m just replacing a downstairs ceiling as part of a refurbishment as it had water damage and would have been a nightmare to make good. Just put the first bit of plasterboard up and it’s wavy all over the place! Joists are completely level from above but below are not level at all. Most are 170ish mm in height but the biggest is 180 and smallest 160mm! Any ideas on how to level this off? Most differences seem to be in multiples of 5mm so I’m thinking 5mm stripwood to build them up and then longer plasterboard screws?

Any tips gratefully received!!

 

[Jdwood38]

Sorted. Cross battened with building packers to bring it level. What a pain!

 

[foxhole]

Could have just sistered all joist level at 180 .

 

[Jdwood38]

Can I just clarify your post Foxhole? You’re suggesting to battening down the side of the joists level with the deepest rather than across them all at a ‘new’ ceiling height?

 

[foxhole]

Can I just clarify your post Foxhole? You’re suggesting to battening down the side of the joists level with the deepest rather than across them all at a ‘new’ ceiling height?

That’s correct.

 

[Draughtsman]

Yup, fix any new (sisters) to joist sides where the existing joists are too shallow (ie. less than 180) such that the finished btm edges are all the same level. Fix the new ceiling plasterboard to the underside of the original unaltered 180 deep joists, but where there are sisters added, then you fix the plasterboard to them instead. Maybe put some string lines up to help determine the levels of the lower edges. Use kiln dried carcassing bought from a supplier that stores it undercover, so that further shrinkage of the timber, and possible cracking of plasterboard joints is less likely later on (you would wonder why some stockists leave their kiln dried stuff in the rain, but many do).

 

[Jdwood38]

Thanks both, one to remember for future!