Re-plastering Victorian home

[danrhope]

Hello there!
My partner and I have just bought a Victorian end of terrace, in need of renovation. It has had work done in the 60s, 80s and in 2006.

The walls have no cavity and there is a sub-floor space. The dining room has some damp issues, around the outside wall and on the brick wall between the dining room and the under-stairs cupboard, which has a concrete floor. Either side of the chimney breast there are block walls skimmed in gypsum, built in the 80s, creating a cavity.

The first thing we have done is get off all the wallpaper from the walls and the ceiling. We have discovered that much of the original lime plaster is present. The ceiling appears to be original and is sound, but with hairline cracks all over. The fireplace has been blocked up and skimmed and the upper part of the chimney breast is lime, which has blown. The outside wall is skimmed with gypsum, which is damp near the ground and the wall between the dining room, and the under stairs cupboard is very damp and has a gypsum skim. The under-stairs cupboard is gypsum skimmed, with a concrete floor. There are varous other patches of gypsum around where things have been patched up in the past.

There are some obvious places that we can address the damp from the outside - repointing a few bits, lowering the ground level, lowering the level of the concrete floor in the under-stairs cupboard. We're now wondering what the best way forward is regarding the plastering.

We currently see the options as being:
Address the known potential causes of damp, re-skim in gypsum and hope for the best
Address the known potential causes of damp, hack off all the gypsum, and make good in lime.
Skim over the ceiling in....?

We basically don't know what to do, so we'd really appreciate any input from you knowledgable folk out there.

Very best wishes
Dan

 

[StephenStephen]

Are you thinking to do the plastering/skimming yourselves or pay someone to do it?
Speaking as an amateur with an old house, I use lime putty plaster if:
-I'm doing it myself - it's slower and therefore more forgiving than gypsum, and paying someone to lime plaster can be expensive
-It's an outside wall, or has damp in it
-I'm happy with a more organic finish

and I use gypsum if:
-It's a dry internal wall
-I want a clean sharp finish
-I'm paying a plasterer to do it, which is likely to be affordable in gypsum

If there's an area which is already a mix of gypsum and lime, I wouldn't always bother to remove all the gypsum if I was making good or/and skimming in lime

 

[danrhope]

Hi StephenStephen,
Thanks for your reply and for sharing your experience.

What lime products would you recommend, and how do you prepare/prime the walls before skimming in lime?

We'd be doing it ourselves. We have both done some plastering in gypsum before, with good results, but lime feels like a bit of a mine-field and there's not so much information out there.

Best wishes
Dan

 

[StephenStephen]

Hi StephenStephen,
Thanks for your reply and for sharing your experience.

What lime products would you recommend, and how do you prepare/prime the walls before skimming in lime?

We'd be doing it ourselves. We have both done some plastering in gypsum before, with good results, but lime feels like a bit of a mine-field and there's not so much information out there.

Best wishes
Dan

Well I'm absolutely no expert, and it's been a while...

I'd have a look at the videos from Mike Wye - I think they're on YouTube or buy the video, and get a copy of Lime in Building from here: https://www.blackdogpress.co.uk/product/lime-in-building-a-practical-guide-by-jane-schofield

Prep - if I remember rightly - get rid of anything loose, and makes sure the wall is wet enough before putting the lime on. Don't use any primer of any kind.

Products: lime putty and sand (kiln dried sand for top coat because it is finer)
I can't remember what kind of sand for the other layers - I tend to use whatever comes to hand.

...and then you can just water down the lime putty to make limewash to finish - goes on like water and takes maybe 4 coats.

In my experience, you don't get the sharp precision of a gypsum finish (though that's likely partly because I'm not expert).

I have one room which has lime on the external walls and gypsum on the ceiling and an internal wall, which I think works well.

I've never really understood the fear of lime putty that seems to be prevalent...
It is slower to go off, takes more coats, and you need to keep an eye that it doesn't dry between coats - all of that means that it works for DIY, but is expensive if you're paying someone.
It keeps for years - as long as it doesn't dry out then the older a bucket of lime putty the better.

If you're unsure about lime putty to infill or base coats, then a compromise would be NHL2 HYDRAULIC lime (comes in dry bags) with sand.
This is not the same as hydrated lime!

 

[Notch7]

If you want to keep the original lime plaster, especially on solid external walls, then you need to understand the importance of allowing the fabric of the building to breathe -so dont go and paint over it with modern vinyl paints, you need to use lime wash paints which are breathable

If you have lath and plaster ceilings then if you have dodgy patches which are coming loose you can strengthen those by pushing them back temporarily whilst spreading some board adhesive across the loose areas -from above by taking up some floorboards (Kirk from on the trowel youtube channel shows how to do it)


Your second problem is that solid brick walls will be cold and cold walls are more likely to suffer damp as they surface temperature is low and can easily take it below the dew point leading to condensation ..............If you want to have warmer walls and a more energy efficient house, you need to consider insulating those external walls -especially the end wall which is probably gable ended and the coldest wall of all. your best option would be to strip the plaster off those walls, put celetex direct on the wall, trap in place with battens then plasterboard (dont forget VCL)

 

[StephenStephen]

...or look at insulating lime render - cornerstone make one, but is pretty expensive, or you can use cork additive, or hemp shiv.
I've used auboise horse bedding (which is hemp shiv) successfully as a lime render insulating additive...