Repairing blown lime plaster

[ireneadler101]

Hi all,

Having removed the awful woodchip wallpaper from our living room walls, there are a couple patches of blown lime plaster which we need to repair. We have called someone in to quote and they've indicated it will be £1000 to patch up the room (it has high ceilings but this still seems steep!) so we would like to try to do this ourselves if possible.

The wall seems to be solid brick, with a layer of coarse sandy lime plaster mixed with animal hair which crumbles if you touch it too much. It's the layer above this (the smooth one) which seems to have blown - so presumably can be patched up by a novice fairly easily?

Has anyone does this before and if so, what products did you use? I suspect a ready mixed one would probably be best.

 

[88v8]

Yes, that's the classic lime plaster as used into the 1930s. Horse or goat hair undercoat, skim topcoat.

Your quote sounds like a lot of money, but..... there are few plasterers who will work with lime. If you amend your profile to show your location, it may be that someone can recommend.

Speaking as someone who never mastered plastering, I became adept at not disturbing it any more than could be rectified with a bag of Pollyfilla!

But given you have two-coat plaster, in all but the most poverty-stricken abodes it would have been wallpapered, and this gives access to my preferred methodology which I used successfully over 30 years in a house which had some rather hollow plaster, a result of enemy action.

First, to repair the bits of plaster that have actually come off
https://www.lime.org.uk/products/lime/plasters-renders/lime-top-coat-finish-plaster.html

Now, the essential ingredient of my method, was/is to begin the wallpapering with a scrim coat.
The paper I used no longer exists. It was a thick lining paper with a scrim layer.
However, there are modern equivalents.
http://www.glassfabric.co.uk/index.php?gclid=COOm6OKNqNACFccy0wodlOAOcA
or
http://www.eclipse-wallcoverings.co.uk/glasstex/microlith-wall-liner/
and these will act as an excellent reinforcer and crack cover and basis for the decorative wallpaper. They will also conceal any, ahh, shortcomings, in the flatness of your repairs.
Note that any plaster which is blown but still hanging onto the wall, can be left in place.

I used this on walls and ceilings. The bedroom ceiling was particularly bad, cracked and loose. I put up two layers of scrim coat, criss-cross of course, then an Anaglypta on top of that and it was still impeccable over twenty years later.

Ivor

 

[paulc]

I've been busy patching blown lime plaster in my 1920s semi. In the worst affected areas, I drilled small holes through the plaster and injected some grab adhesive in after vacuuming out the holes and giving a good spray with water. (Probably get shot here for saying that....) Had a few areas that needed replastering from the brickwork out after chasing in for conduit - For these areas, I mixed kiln dried sand with lime putty (3 to 1 mix) with the addition of some polyester fibres. Slapped it in after spraying the wall with plenty of water and left it to dry/harden for a couple of weeks.

For the top coat, I was fortunate to acquire a bag of fine marble dust from (of all places) a glassfibre supplier. This was mixed 2 to 1 with lime putty, and a thin layer applied.

If the original plaster sounds hollow when tapped but doesn't move or crack, probably best to leave it in place. It is only when it is cracking and at risk of falling off that remedial action is required in my opinion.

 

[Flyfisher]

I mixed kiln dried sand with lime putty (3 to 1 mix) with the addition of some polyester fibres. Slapped it in after spraying the wall with plenty of water and left it to dry/harden for a couple of weeks.

If the OP doesn't fancy that level of DIY, ready mixed equivalents are also available, e.g. http://www.anglialime.com/products/wet-mix-plasters-angliamix-mortars-renders

Notes about usage here: http://www.anglialime.com/products/wet-mix-plasters-angliamix-mortars-renders/fibrechalk

 

[paulc]

If the OP doesn't fancy that level of DIY, ready mixed equivalents are also available,

For small quantities, shipping costs can quite often double the cost of ready mixed plasters & mortars. Lime putty does appear to be available at a reasonable price at a number of builders merchants across the country and it isn't that difficult to mix your own.

I've been getting my putty from a supplier in Aylsham and using a drill & paint stirrer for small batches - 15 litres has been my biggest mix so far.

 

[ireneadler101]

Thanks for the replies. A solution that is as foolproof as possible is required here I think! This is what I am looking to repair:

 

[Zebra]

Whereabouts in the country are you IreneAdler?

 

[ireneadler101]

Hertfordshire

 

[Zebra]

Oh. So am I. I've got some leftover lime putty you could have a go with if you wanted. Come over and I'll show you how to mix it up, if you want.