Patching a ceiling on an old house

[geordief]

There are beams to which are attached what I would call "latts"(?) and there was a thick (half an inch) layer of rough plaster.

I would say it is a 3 by 5 foot area .

The remaining plaster is hanging below the level of the latts (not dangerously) and so the area to be repaired would need to be quite a bit thicker to be at the same level as the rest of the ceiling .

I don't want to take down the wider area as there are pelmets and electrical fittings involved

Any advice.?

Here's pics

 

[KenGMac]

geordief, good evening.

Looks like a Georgian / Victorian bay window ?

The ceiling is Lath & Plaster, the plaster will have horse hair as a reinforcement.

It would appear that there has at one time been an ingress of rain water from what may be the flat roof above, the lath nails are rusted.

The entire area of the bay [if it is indeed a bay] will need to be carefully taken down and replaced with two layers of Plasterboard and a skim coat of plaster.

As an aside? there does not appear to be any insulation above the ceiling now would be a good time to get some in there?? and? what state is the roof above the ceiling in now?

I have surveyed dozens of such damage as Insurance claims

Ken.

 

[geordief]

You have described it to a tee.

Yes there is a leak above that I have been unable to eradicate and even the builders struggled with (it was a crack in the lead guttering at the time, about 20yrs ago)

There is actually only a very small flat roofed area and it is where the slated (sloping) section meets it that I suspect strong winds occasionally blow water up under the bottom of the slates.
The roof is not too bad (old Bangor slates) but the winds can be fierce on the Atlantic coast -amazingly only a handful of slates over the past 25 years have needed attention ,and its a big house.

 

[KenGMac]

geordief, good evening again.

The scenario you have I have seen many, many times, it is almost as if it is an inherent weakness in this form of construction?

At least you will be able to inspect the underside of the timber on the small roof and who knows see the entry point [hopefully not points] of any rain water ingress, it will allow you to see if indeed the water is blowing up and under the slate ?

Ken.

 

[geordief]

geordief, good evening again.

The scenario you have I have seen many, many times, it is almost as if it is an inherent weakness in this form of construction?

At least you will be able to inspect the underside of the timber on the small roof and who knows see the entry point [hopefully not points] of any rain water ingress, it will allow you to see if indeed the water is blowing up and under the slate ?

Ken.

Yes that had occurred to me also. After 20 years or so of intermittent water ingress and post hoc odd jobbing it may he something of an ah ha moment if I can actually pinpoint all the places it comes in at. Not that I am holding my breath; these leaks seem to take delight in waiting for your back to be turned