Lath and plaster beginner question!

[cakehoover123]

We have a collapsed lath and plaster ceiling, beyond repair.

We need to replace it with something breathable, as it's an old house.

Is the only option a whole new lath and plaster ceiling, with all the associated cost?

Or can breathable lime plaster be used with plasterboard, or any other suitable but less expensive option?

ask in the ‘Your Old House UK - repair and conservation’ group on Facebook - loads of helpful experts on there!

Ooh collapsed lath & plaster ceiling, that’s messy!

Normal plasterboard isn’t breathable so not much point using lime plaster on it. But you can get breathable plasterboard. You’d need to use breathable plasterboard, lime plaster to skim and breathable paint. More expensive than using standard materials but I expect less than trying to recreate lath and plaster.

How old is the house? Many Victorian houses have had lath and plaster walls/ceilings replaced with normal (non breathable) plasterboard, without issues.

The ceilings don't need to be breathable. It is only really important for walls. I would go with plasterboard and modern plaster (and I am a huge fan of using lime plaster).

Agree with @Geneticsbunny - old walls often need breathable plaster/paint because they are a bit porous (masonry and/or mortar) and the moisture needs to escape both ways - back to the outdoors, and in to the house (to be removed by ventilation).

Roof coverings like slates and tiles and the timbers inside can also get damp sometimes, but we're talking about less moisture and more to the point, a roof should be an open structure with air movement between slates, via vents in the soffit etc, which will dry it. And as the roof is usually colder than your living space (especially if the ceiling is insulated), it won't really be able to dry out into the house anyway.

If your roof is not vented properly (eg, bad insulation job that has blocked all the vents, spray foam under the tiles etc) you may have damp problems in the roof but that's a whole other issue that a lime plaster ceiling sadly won't solve! But while the ceiling is down is a good time to check the roof is properly vented (there are various ways rhis is done depending on whether there isa membrane or boards under the tiles etc - its not always immediately obvious but it's worth checking .

I had a partial collapse last year. They plaster boarded over the whole room and then skimmed it. Looks great and no issues with it and it wasn't expensive.

Commiserations for the mess and smell. It's not fun to deal with.

Ah thank you everyone! Super helpful.

It's an 18th century house and Grade 2 listed, so I'm sure the conservation office will have a view 🙀 we're seriously hoping we won't have to reinstate the whole thing in lath and plaster.

The ceiling had got damp because of a roof leak above - now fixed.

It's really useful to know that breathable ceilings aren't as big a worry as breathable walls, and that in any case there are breathable options.