Confused about what to do with plaster

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jacko555

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I am buying a detached house, circa 1911 to 1926 (not on the 1911 OS map, is on the 1926).

Survey identifies empty cavity wall (rather than solid wall) original plaster internally and original lath ceilings. It suggests the exterior render is original, looks ok, however has some loose sounding areas when tapped. It also looks like its been repainted externally in recent years (Sandtex masonry) and some render cracks filled.

Internally, it has not been redecorated for a long time. Wallpaper downstairs is backed with polystyrene.

Plaster is blown around the windows, which are wooden single glazed and rotten.

Condensation damage / mold on north facing walls.

Ok - our plan was:

1) replace all windows with wood double glazing
2) dryline lath ceilings and plaster
3) remove all internal walls plaster and redo
4) cavity wall insulation

I then went down an internet rabbit hole after reading about old houses and lime plaster needing to breathe.

The plaster and render are likely lime based (when I looked at the blown plaster, it is grey coloured and sandy) and apparently removing and replacing with modern plaster is a bad idea.

Apparently I also need to use breathable paint. Apparently the Sandtex used externally is also bad.

My parent's house is 1870 solid wall terrace, which was replastered and rendered in the late 80's with modern cement plaster and 3 to 4 decades later hasnt had any issues with damp.

What is everyone's thoughts?
Is modern plaster a bad idea for this house?
Is lime plaster "best" for a cavity wall house of this age?
Have I gone down an internet rabbit hole and just worrying for no reason?
 
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forget about cavity insulation . you’ll regret it.
cement render on a cavity wall . pay for a decent plasterer. lime render is more beneficial for stone properties.
sandtex is the best external paint imo !
it’s breathable and suitable for all masonry.
i personally would go for pvc windows.
sash pvc are nice. traditional look / no maintenance .
surveyors are only interested in covering their own a$$es.
 
Thank you, this is what I wanted to hear.

The more I read about cavity wall insulation retrofitted into old houses collecting moisture makes me want to leave it as is.

There's lot of conflicting stories about everything- cavity wall in brilliant vs its a damp trap. Lime plaster must only be used bricks laid with lime vs modern cement/gypsum is fine. Etc.

I'm going to spend a lot of money and just want to make sure I dont do the wrong thing.

Wifey wants wood windows. I'd be happier with upvc (from a £ perspective).

Hey ho gonna be fun either way.

Latest thing is the house has original ceiling coving that wife wants to keep. They are large and nice, but, it means removing the lath ceilings, without pulling the coving down, instead of overboarding.
 
good luck removing those ceilings and not destroying the coving.
i’ve done loads with old covings over the years. tackle each ceiling individually.
its quite possible to overboard and skim some old ceilings with ‘run in’ plaster coves , depends on the profile of the coving.
taking the laths out will do more damage to the coving than just removing the old plaster. again its feasible to remove the old plaster, leave the laths and overboard and skim. find yourself an experienced, sympathetic tradesman.
 
If it were at all possible to insulate above the ceiling I'd personally do that, and leave the current ceilings alone.
If you're looking to replaster inside, then I'd recommend lime hemp (what I used) or lime cork. Personally I'd only plaster the walls which are clearly problematic, live in the house for a while, then see if more needs doing.

For the best thermal performance, external insulation makes most sense, but I think it's expensive - I've not tried it myself.

I'd agree with your wife on the windows - hardwood double glazed. Partly just my prejudice, partly because there's less to go wrong, and I have an idea they'll last longer
 
The ceilings are cracked and bowing in places. While I think they could be patched, or be fine for another 100 years, wifey wants:

1) flat ceilings
2) original coving intact (if possible)
3) flat walls

The plaster has blown around the windows (rotten, leaky, condensation). The rest of walls are behind polystyrene backed wallpaper (lining, polystyene, flock wallpaper). Where the paper is loose / we gently tugged some away, left a sandy rough surface.

Surveyor said (using the "tap it with a screwdriver" test) that is sounded hollow in many places and probably wouldn't survive stripping the paper off and to budget for / expect to have to remove and replaster the lot.

Why do you reccomend lime hemp/cork over cement/gypsum plaster?
 
stephenstephen ...... lime hemp? he said 1911 not 1811.

external insulation detracts from the period of your property and is a farcical concept. particularly on cavity walls.

you may insulate your ceilings , however my guess is at least 50% of your floors will be suspended timber , insulate the floors first.

just saying (y)
 
jacko555 said:
The ceilings are cracked and bowing in places. While I think they could be patched, or be fine for another 100 years, wifey wants:

1) flat ceilings
2) original coving intact (if possible)
3) flat walls

The plaster has blown around the windows (rotten, leaky, condensation). The rest of walls are behind polystyrene backed wallpaper (lining, polystyene, flock wallpaper). Where the paper is loose / we gently tugged some away, left a sandy rough surface.

Surveyor said (using the "tap it with a screwdriver" test) that is sounded hollow in many places and probably wouldn't survive stripping the paper off and to budget for / expect to have to remove and replaster the lot.

Why do you reccomend lime hemp/cork over cement/gypsum plaster?
Click to expand...
where do the ceilings bow upstairs or downstairs?
 
bennymultifinish said:
where do the ceilings bow upstairs or downstairs?
Click to expand...

Luckily downstairs, the plaster has come loose in some areas. Not big ones, just some spots. There's also signs of historical repairs.

Half of upstairs ceilings have already been replaced with plasterboard and the remaining ones are in ok condition.
 
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