Plaster disaster

[1900House]

Hi everyone,

Now at a stage with the renovations to put plaster on the walls, had a couple of quotes and nearly fell over. Solid walls so I’m needing lime plaster as I bought the house with “damp” opened windows, got the heating on and stripped the walls which has helped. I have some lime walls that are pulling away and sound hollow but not crumbling and some walls have been completely redone in gypsum or have been skimmed so still having damp spots on them.

After some advice, am I safe to plaster internal walls/ceilings in gypsum and external walls in traditional lime/lime alternatives was told it could cause issue as the moisture will find a way.

Also is lime only required on external walls that are touching earth and is it necessary to re do the walls that sound hollow if they aren’t crumbling yet? The plans is to lining paper the walls

I was only expecting a couple walls needing to be redone and now it’s turned into full rooms so looking at options to bring costs down

Thanks in advance

 

[a twig]

The short answer is “depends”

Depending on the causes of the damp you might get away with gypsum finishes on external walls but it’s not a guarantee.

This thread:

Plastering question

Hello all, After nearly a year of serious unanticipated structural work we've now finished and can get on with fitting windows, plastering and everything else that we thought we'd be finished by now. I have a question regarding use of wood wool boards on an external facing brick wall. This...

www.periodproperty.co.uk

details alternatives to traditional lime 3 coat which are at least partially/fully diyable depending on experience, work out cheaper and provide insulation as well.

Ground floor should be the priority, I was able to get away with leaving the gypsum skimmed lime in most of my upstairs rooms

 

[Lacan07]

As Twig has said it depends on the cause of your damp, most of the time its usually high external ground in which case you may be inclined to take a chance with gypsum once you've addressed the issue.

 

[paulc]

If you have stripped the external walls right back, do have a think about putting some insulation up. Either wood fibre or cork will give you a nice flat surface to plaster on to, and reduce the heat loss.
As for gypsum, it is "breathable", but turns to a mush if damp all the time. So if the internal walls are dry, I'm of the opinion that gypsum would be OK.

 

[1900House]

Thank you all for the replies, to summarise the post I’m just trying to see if I can plaster most walls in gypsum to keep cost down and then use lime on walls that would benefit and future proof from any problems arising

 

[saraheamorrison]

I'm a lime plasterer and I have gypsum on some of my walls and they're fine. (1880s Victorian House) It's all about where you will benefit the most as you've worked out. There are ways to save on plastering. Drop me a message if you need any advice.

 

[1900House]

Yeah, looking at the walls properly you can see what needs to be lime and where I can get away with gypsum. I’ll probably just plaster like for like on the walls that don’t look to have been messed with over the years and then gypsum or even plaster board now after talking to a joint and taper lad.

I’ve worked out and I’ve probably got my maths wrong but the lime alternative is around £30 per m2 and plaster board is £5 per m2 with a typical gypsum plaster being around half the price of lime, so mixing up the materials on walls will give me a massive saving and boarding is something I can do myself confidently so save on labour cost.

Than you all for your reply’s, if there is any more advice on what I plan to do please let me know.

My only grey area is where a wall is gypsum that meets a wall that is lime will that effect the edges where it meets (damp forming/pulling the plaster off the walls/crumbling) if that is a possibility I’d maybe use boards

Thanks

 

[Lacan07]

Yeah, looking at the walls properly you can see what needs to be lime and where I can get away with gypsum. I’ll probably just plaster like for like on the walls that don’t look to have been messed with over the years and then gypsum or even plaster board now after talking to a joint and taper lad.

I’ve worked out and I’ve probably got my maths wrong but the lime alternative is around £30 per m2 and plaster board is £5 per m2 with a typical gypsum plaster being around half the price of lime, so mixing up the materials on walls will give me a massive saving and boarding is something I can do myself confidently so save on labour cost.

Than you all for your reply’s, if there is any more advice on what I plan to do please let me know.

My only grey area is where a wall is gypsum that meets a wall that is lime will that effect the edges where it meets (damp forming/pulling the plaster off the walls/crumbling) if that is a possibility I’d maybe use boards

Thanks

The junctions between the walls should be fine, just remember to address the causes of the damp if possible.

Working out how you're going to paint the different the materials can be a bit of a headache I found, if you're a bit fussy about that kind of thing.

I was under the impression the average cost of a lime plasterer is usually £150 - 200 per SQM (brick to finish)

 

[1900House]

I believe I found most potential causes of damp and rectified them, just need to expose the brick on a wall that my neighbours cellar is on the other side as that is the only place still showing damp patches. Their main water pipe runs up inside my plaster on that wall and hoping it’s as simple as a weeping pipe

Ive done that just for the price of materials, based off of the average coverage from the bag but my maths could be wrong.

It will be lining papered as I’ve been told it should be fine with the right adhesive, so hopefully aslong as the correct paint is used colours should match

 

[paulc]

My only grey area is where a wall is gypsum that meets a wall that is lime will that effect the edges where it meets (damp forming/pulling the plaster off the walls/crumbling) if that is a possibility I’d maybe use boards

Where plasterboard meets lime plaster, I've been using scrim tape over the joins. Available in 50mm, 75mm, and 100mm widths - I've had any cracks develop yet.

 

[Lacan07]

Where plasterboard meets lime plaster, I've been using scrim tape over the joins. Available in 50mm, 75mm, and 100mm widths - I've had any cracks develop yet.

me too

 

[paulc]

Where plasterboard meets lime plaster, I've been using scrim tape over the joins. Available in 50mm, 75mm, and 100mm widths - I've had any cracks develop yet.

Sorry, that should have read "I've not had any cracks develop yet".
Was too early in the morning for me.