Lowest point of the ceiling

[Struggling100]

I have pulled down my old ( lath & plaster ) ceiling and exposed the ceiling joists, so I can put a suspended ceiling system up. The suspended ceiling system hangs off the timber joists with timber connectors. The joists are uneven and bow to varying extents in the middle. I need to find the lowest point of the ceiling to attach my first connector to ( this would give me max height for the new ceiling ). Any ideas would be greatly appreciated!

 

[jpq]

I'd use a large level attached to a larger straight edge.
Place it across the joists to find the lowest point and get it level. Then mark the walls for your new ceiling frame... another pair of hands may help if it's a big area!

hope that helps.

 

[noseall]

why don't you build the new ceiling independently from existing. this could be done by fixing a bearer plate around the perimeter and then filling in at recommended centres, i.e. 400, 450 or 600mm.

this bearer plate will be set just below the lowest point of the bowed joists.

the new ceiling can then be strengthened or stiffened by adding short lengths of timber connecting new to old.

 

[Struggling100]

8) Hi thanks for the replies, I did a combination of two suggested things, using string going at right angles to the joists ( at 450mm ) intervals, I could visually see which joists were the highest ( because the string didn't touch them). On the remaining joists, I used a long level at right angles to the joists to find which one was lowest ( relative to each other ). On the lowest joist, the middle of the joist was the lowest point ( as seen with level ). Marked it off and ceiling framework now up. Thanks again