How are ceilings held up?

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essayer

Original Poster:

10,091 posts

207 months

Wednesday 18th November 2009
quotequote all
Basically in one corner of the sitting room the ceiling has detached from whatever's above it... it's dropped down by about 5cm and is now resting on a (thankfully substantial) curtain rail! It's against a beam, so I can't see "above" it to work out what's happened.

The house is of 17th century construction. Where visible, the ceiling doesn't look like modern plasterboard, it looks like old wood or some sort of layered material?

What could have caused it to drop? Now it may well have been like this for ages, but it's making for a nervy Christmas at this rate hehe

Munter

31,330 posts

254 months

Wednesday 18th November 2009
quotequote all
lath and plaster?

E.g. Small strips of wood nailed to the beams above and plaster put over them to create a flat surface...

http://www.diydata.com/general_building/plaster_ce...

This should demonstrate your christmas smilehttp://www.youtube.com/watch?v=b3r2bGpJ7Eo

Edited by Munter on Wednesday 18th November 10:01

essayer

Original Poster:

10,091 posts

207 months

Wednesday 18th November 2009
quotequote all
Hmm that doesn't fill me with confidence.

Yes, I guess it is lath/plaster .. it did seem much thicker than any plasterboard I've seen, there was at least 5cm of material visible at the edge. So now to find out why it's dropped, hopefully nothing has rotted .. if so we are into very scary territory

I assume the easiest(!) way to check condition is to lift floorboards above and look down?

Of course, it's a listed building too !


Munter

31,330 posts

254 months

Wednesday 18th November 2009
quotequote all
Ah now you see I can't help you there. I have a little understanding of what's up there having been in the odd building and poked around.

How you fix it, particularly if it's listed. No idea. But I'd start thinking about exactly what is listed and what you are allowed to do/use. (I'm seeing the words Lime Plaster coming up here)

BRGV8S

251 posts

219 months

Wednesday 18th November 2009
quotequote all
Seen repairs done to larger areas of ceilings in listed buildings where contractors have determined the line of joists above then drilled / counter sunk for stainless steel screws with large 60mm dia
washers in a diamond pattern. Of course the counter sunk washers are just below the ceiling finish ans finished with matching plaster.

On small areas it MAY be possible to re-aline the ceiling and secure it from above by pouring plaster of paris over the timber laths with layers of scrim cloth layered in. This method was originally used for securing ornate ceiling to the sub-structure.

Hope this helps.

Stegel

2,039 posts

187 months

Wednesday 18th November 2009
quotequote all
There are a variety of reasons why the ceiling would have dropped locally, but the most likely cause is the detachment of the plaster nibs which secure the plaster to the laths - when the wet plaster is applied, some of the first coat squeezes through the gaps, mushrooms above the laths and secures the whole lot together. If these nibs fail, the bond between the laths' underside and the plaster is unlikley to be sufficient to hold it in place, hence it sags.

As mentioned above, variety of ways of resecuring it from oversize washers to plaster and chicken wire above. If it is a small area and you are handy, the SPAB and Georgian Group can offer advice - if you are a "keen" owner it may be appropriate for you to join the appropriate group. Larger area may require professional repairs or replacement - I'd suggest sticking with lath and plaster even if you renew rather than going for plasterboard as a) you should have consent to change and b) it just seems wrong!

Of course could be something else - rot, structural failure, damp ingress - but only way to tell is to investigate.


ACEparts_com

3,724 posts

254 months

Wednesday 18th November 2009
quotequote all
We had this issue in the corner of our office- an 8" square piece droopped. I removed it, screwed up a bit of plasterboard and then skimmed it. Job's a good'n

herbialfa

1,489 posts

215 months

Wednesday 18th November 2009
quotequote all
Depending on the listing of the building, PB & skim might not be acceptable!

Horse hair/Lime etc...........