collapsing ceilings!!!!!

[Border boy]

A few of us may have noticed recent stories by current affair shows about spontaneously collapsing ceilings in houses built prior to the 70"s. The ceilings in question are ones attached to the joists using "saddles" of fibrous plaster & that due to traffic from various tradies over the years, these saddles become compromised & all of a sudden, the ceiling collapses.The stories have focused on the fact that insurance companies are refusing to cover the damage caused as they consider this a wear & tear issue & that home owners have failed to maintain the ceiling???
My question is - what exactly is the preventative maintenance required for these old ceilings?

[rod@plasterbrok]

Really all you can do is go through and screw them up.

When they did the fibrous plaster ceilings they used timber battens, which were quite springy to nail to, screw guns were unheard of.

Stud adhesive did not come along until plasterboard either.

Therefore to prevent nail popping the ceilings were scrimmed with hemp.

Done well they should be in good order today.

The best thing is to screw them up before they let go. Once they have been in a sagged position for a while they want to stay that way!! So when you screw them up there is too much pressure and the srews pop through. Or the sheet will crack like mad when pushed back flat.

The best way to attempt rectification is take a prop using a couple of flat timbers and push the ceiling up flat over a wider area. While the ceiling is held in place with the props screw at 300mm centers, then release the props.

If it works great if not replace the ceiling. Really its a 50/50 proposition, you wont know until you try.

Cheers

Rod

[jags]

Great question Border boy and thanks again Rod for more great advice .

This is one of the many tasks that i have to do on my house and was wondering exactly what to do .

One suggestion was to restring them but i have heard that this is extremely tedious and the ceiling must be clean in oder to get a good sticking surface .
I have also been thinking about the screw method ,alot quicker and easier .
What do you consider alot of sagging ? In some areas of my place you can just get a finger under the battens will screwing still work for these areas ? (all the roof timbers are jarrah )
And what are the best screws to use are there some that have a larger head to resist the force apllied by the ceiling ?

thanks Rob

[rat52]

When we bought our 1st old house 30 odd yrs ago all the ceilings were sagging so I asked the senior citizen how to fix them.

His reply then was to replace with plaster board.

Needless to say, just married with a morgage we couldn't afford it and the more I looked at the patterns in the old ceilings the more I wanted to keep it.

The ceilings were only nailed up so I got some sisal/ hemp from a fribro plaster maker who was then surviving by making air vents and as Rod said propped a panel with boards to flatten it. I then vacumed the area above so it was clean then made a slurry of cornice adhesive. teased out some hemp about 600mm long and 10mm thick, soaked it in the adhesive, then stuck it to the board over the ceiling joist and onto the other side.

Where the panels were badly bowed I would make ribs of hemp/slurry between the joists to strengthen the panel.

By doing a panel every night after work I did a room a week and the results were great

I found nailing or screwing only cracked the sheets

[rod@plasterbrok]

Rat52 a tedious way of fixing them but a good way perhaps even better than the way I described above, since there is no chance of getting popped screws later on.

Cheers Rod

BTW use 25mm bugle head plasterboard screws, if you decide to screw them.

[Skew ChiDAMN!!]

Hmmm... I like that idea, Rat!

Our place was built over 100 years ago and doesn't have joists/rafters. Instead the owner/builder (a cabinet maker. :rolleyes:) installed exposed beams 4' to 6' apart (depending on room size) in a criss-cross pattern. Squares of fibro plaster were simply sat loosely on top, no nails, with a single 2"x3/4" batten supporting the middle, held by one single clout in the middle of each sheet. :oo::no: I rather suspect that the battens were added a few years later, when the owner realised his methods weren't the most practical. :doh:

Between the 4" or so of dust that's accumulated on top over they years and the possum highways, where they take shortcuts through our property, :~ the centres of most of these sheets are sagging by several inches. That's not surprising... what is surprising is that none have collapsed. Yet.

So why haven't I done anything about it? As I said: no rafters/joists and a 4" dust build up. ie. any fix will be a dirty, expensive job, probably making the place unhabitable for the interim. And the local property trend around here is to doze existing houses, subdivide the blocks and slap up 'orrible foam units. [shudder] In ten years, we'll probably be out of here anyway, so frankly I've considered it uneconomical.

But making fibro saddles over the existing battens (even if I replace 'em with pine studs) would work, methinks, even if only for 10 years. Hmmm...

Thanks again, Rat! :2tsup:

[Border boy]

Thanks Rod & Rat52 for your ideas. I wish current affair shows would deal with these issues in a sensible way ie. after ringing alarm bells - do a bit more research & perhaps interview someone who can offer solutions. In the story I saw, they were claiming that up to 3 million Ozzie homes were at risk:o
That's not alarmist:~

[rat52]

Rod
It was slow and tedious but I was a lot younger then and I never cost my labour when doing my own renos.

I shudder to think what it would cost to pay someone to do it.

I forgot to mention that a full respirator mask (not paper dust mask) is a must and try to do it in winter not summer like I did .

I reckon I lost 5k doing it:D