Fixing Plasterboard to UnLevel Ceiling Joists, How...?

[Red Devil]

I have bitten the bullet and pulled down the ceiling and removed the laths. The problem now facing me is that the joists are 'all over the shop' in terms of being level. After all the hassle of completely removing the old ceiling, I don't want to end up with a ceiling that is all waves.

What is the best way to approach this ? I have seen some posts suggesting putting batons across the joists (levelling them in the process), and then fix the plasterboard to the batons.

Any suggestions on how to overcome this problem would be most welcome

Many thanks

Con.

[Al Reynolds]

That's what I did and it worked fine. Also saved me removing the majority of the nails from the previous lath and plaster ceiling. I used 2x1 battens.

Al

[Red Devil]

Thanks for that Al Did you find the lowest point of the ceiling as a starting point ?

[Al Reynolds]

I was a bit more haphazard than that. Just started and saw how it went!

[Michael Mcneil]

What caused the ceiling to fall out of shape? Check for problems and reinforce or replace as necessary.

Roof battens would be the cheapest. With a partner walk down the room holding up a string line to find the low point and if you don't want to make it higher, use that as your datum. Put a batton across the joists at that point. now put battons at the edges of the ceiling parallel to that using a straight edge and packers to get them level. (Cut up a load of ply pieces to suit ready.)

Now string two lines between them and tack the rest of the batons in place at whatever centres you want, 400 mm say. Go to the size of the boards you are using. Small ones are the easiedt to use.

Use the straight edge to mke sure they are straight and level as you nail or screw them and voila, une ceiling splondee.

If you want to raise the ceiling you might be able to pull it up with battons to the rafters. Not recommended.

[Ian Stirling]

A laser level can be most useful, as can getting your head up at ceiling level and having a look from all corners of the room. A bit of plastic hose with a clear bit on the end as a water level can be very handy too.

[Rob Griffiths]

I'd concur with the poster who suggested finding out what is the causing the joists to be wonky.

I bought an 1890's terrace a few years back, the ceilngs upstairs were all horribly cracked and at very bizarre angles.

Cause - heavy concrete tiles putting too much down force thru a single A frame on to fairly flimsy joists.

Remedy - whack in two more A frames (v. cheap, only a bit of heavy duty timber and a few bolts) - the joists relaxed and started to straighen up almost staight away, but to help 'em along that road I laid two lengths of 3*3 above the joists at 90 degrees and used long screws with bolt heads to rachet the joists up to 'true' where they were dipping. Five years down the line the new ceilings still look good and flat (and uncracked). For me it was a lot less hassle than battens, and I kept the original ceiling height.

Rob

[Michael Mcneil]

600mm centres I mean. I'd just been fixing skirting when I wrote that.

[Michael Mcneil]

Nice point and the reason we have building controls in this country.

Good old fashioned slates are wafer thin and the large ones cover a lot of ground with very little overall thickness. Old property utilised this lightness to build lots of houses rapidly as cheaply as possible in the days before building regs. (They are still standing though.)

I was thinking more of people using their attics as storage bins.

[Red Devil]

Are 600mm centres for the batons ok ? I am thinking about using 1200mm sheets. That would be easy enough if 600mm centres are ok.

Con

[Andrew Gabriel]

Bare in mind that walls and ceilings behind plaster of that age were often not flat/vertical/horizontal/etc. It was the plasterer's job to do that, and you can find the plaster thickness varying from 0.5" to 2" over laths in order to make the surface flat/vertical/horizontal.

[IMM]

You are in a brilliant situation to kill many birds with one stone. Fill the void with rockwool to suppress sound. Under the joists fit metal resilient bars to isolate the ceiling from the floor above. They can be lowered to make the ceiling level. This reduces sound travel. Fit Fermacell pre-finished plasterboard.

It can be screwed on and holes filled with their filler and sanded down, then paint over. No expensive wet trades and sound and heat insulated too.

[IMM]

Your A frames. What exactly did you do?

[Red Devil]

The fermacell looks interesting but unfortunately I have already bought the plasterboard.

What sort of metal structure do you fit to the joists ?

[IMM]

Details should on the fermacell site.

[Michael Mcneil]

600mm centres are what the modern trusses are set to. You can use any centres you like but stick to divisions of 1200 and 2400 if you are using those sheets. If you keep them all the same and parallel you can always find the "grounds" after covering them. Don't forget grounds to screw the lighting to.

Use a tee shape to wedge the board up once it is in place. I used to put a couple of wide headed clouts up against the last sheet to take the edge of the next if I was working alone. They just catch it as you offer it up. Then stick the shore in place and you can let go for a breather and get your hammer and nails.

[Lobster]

I was recently faced with precisely the same problem in an upstairs room; the ceiling joists were randomly warped all over the place. To be honest they were too thin too by modern standards, and by rights I should probably have ripped them down and started again with new joists. However, on the advice of my plasterer I jacked up a long length of 3"x2" timber against them (ie the full length of the room, down the middle, at 90 deg to the joists) using an Acrow prop at either end. Holding my breath, I cranked up both Acrows, and slowly but surely, all the joists came nicely into line, with no nasty cracking noises...

Next step was to screw each joist to the rafters in the roof using 2 lengths of 2"x1" timber per joist, to hold them in position; and finally, the Acrows were removed. The joists all stayed right where they were; we then plasterboarded the ceiling and the plasterer worked his magic - it looks fabulous! as good as a new build.

David