lime over gypsum plasterboard?

[piapiapiano]

Because I live in the Isle of Man, getting certain eco-friendly items is proving to be prohibitively expensive (eg. Ty Mawr gave me a quote of £135 to deliver one 20 litre tub of lime putty. After that dark day we found a friendly local lime plasterer who's agreed to supply putty for our urgent work, and obviously we're going to make our own putty for jobs further down the line). Rather than paying lots and lots for the delivery of breathable board, I'm wondering if we can't just use basic plasterboard for the internal stud walls.

The stone walls will be plastered with lime, inside and out, so they'll be breathable. Is it okay to have the internal stud walls basically non-breathable? Should we (and could we) skim over the plasterboard with lime to maintain the finish?

Thanks in advance!

 

[Feltwell]

Internal walls don't need to be breathable. If you're going to use plasterboard, you may as well use gypsum plaster - especially if you're getting a plasterer in. It does depend what sort of breathable finish you want though - if you're going to use something like a clay paint, it will be OK on gypsum and lime. If you want to limewash then I guess not, though I haven't tried.

I'm just off out now to be stoned by the angry PPUK mob for my heresy......

I can't say I've tried lime over plasterboard. I can say though that gypsum skim over original lime plaster does not always stick successfully - where previous owners have done that in this and my previous house, we had areas where the gypsum skim was "blowing" and has not stuck properly. Makes it easier to get off though

 

[robgil]

you might try a coat of limewash on the plasterboard first , ive also heard of people using pva.

 

[MdB]

Mike Wye sells stuff to paint onto plasterboard so that it can be rendered in lime.

Myself, I would either go the lime plaster and lath route or gypsum and plasterboard route. I don't think I would bother trying to combine the two.

 

[Andrew Bodenham]

What Feltwell said. Don't bother with lime on internal plasterboard walls - just use gypsum plasters. Cheaper, quicker, easier. If you really want to use lime for ethical or religious reasons then you'll probably want to skip the plasterboard and cleft your own oak laths.

At the risk of being gunned down for suggesting artifice or pastiche you can play around with different plaster mixes if you want to produce a 'not smooth' finish on plasterboard. I've seen a mixture of equal parts board finish and bonding used, which gives a slightly grainy texture. I've also seen a really awful 'rusticated' finish produced by attacking board finish plaster with a stiff nylon brush whilst green. Wickes 'one coat' gypsum finish is also a grainy plaster which is very forgiving of inept DIY application - I use it often for patching up where lime is not required. So it's worth experimenting until you get a finish you're happy with. Getting a 'not flat' finish is easy for the amateur plasterer; professionals may take some convincing.

 

[piper]

I agree with what Andrew says, and I have a little experience which may be relevant. We recently had an extension built which is a modern room on the outside (and on top of) older parts of our house. One of the internal walls of the new room is obviously a former exterior wall of the old house - thick limestone rubble stone gable end wall - and now plastered in lime, then painted with clay paint. It has a slightly uneven finish, and to blend better with that finish the other internal walls of the new build have been finished with bonding on insulated plasterboard, (except for the chimney breast, which was also done in lime - on modern blockwork). The whole lot painted in clay paint, and we think it works very well.
The passage leading through the old wall into the new room has one wall which consists of a mixture of an old lath & plaster interior wall, an area of plasterboard which extends above that into a new higher ceiling, and also a section of new blockwork where the hole was made through the thick gable wall. We used the primer stuff supplied by Mike Wye to paint on the new plasterboard and this was skimmed with lime to blend in with the old lath and lime wall section. This sort of situation seems to me to be the only time when you may want to put lime onto plasterboard, but it works well.

 

[Joiner]

What you were quoted for the lime putty was ridiculous!

Check out...

http://www.womersleys.co.uk/acatalog/

...which will also give you a source for "friendlier" board products.

They will DELIVER the stuff to your door, and even having to cross a stretch of open water I doubt it would cost anything like what that original robber tried to charge.

Putting such a premium on products that are essential to the well-being of a period property almost forces people to go down the cheaper route. Criminal.

 

[skier-hughes]

My lime plasterer advised to go the gypsum over plasterboard route for our few internal stud partition walls.
We used a white gypsum which meant when painted it blended better with the painted lime.
We used casein distemper to apint, as recommended by rose of jericho and you it all looks the same now it's been done.

 

[Joiner]

As one old guy said to me back in the 70s, although it had nothing to do with plasterboard or plastering, when I asked him why we should bother "doing it properly" because no one was going to see it:

"I've bloody well seen it and know it's there, so do it properly or bugger off home."

I did it properly.

(Oh God, I'd forgotten this forum's "bad word" sensibilities.)

 

[skier-hughes]

what's properly?

 

[inwood]

I've used Thistle's one coat plaster over plasterboard which gives (once painted) a similar finish to lime.

It's intended as a one coat plaster so is designed to be used up to (from memory) 20mm thick. As a result if you use it to skim (i.e. 2-3mm) the finish comes out very similar to a lime skim - i.e. slight imperfections due to the size of the small aggregate used to bulk it up. You can trowel it completely smooth but if you're going to do that you may as well use multi or board finish gypsum.

 

[robgil]

if you dont mind the extra cost why not use lime? if you are doing it for environmental reasons then why use plasterboard? i am in two minds about my ceilings , do i use lime or cement , i need to use lime on the walls but my ceilings could be plasterboard and cement however i think my mind is made up with using lath and a chalk based plaster on the ceilings simply because ive been told its easier.
i guess it all boils down to what ever you feel more comfortable with , your the one who has to live with it.

there are cheapish alternatives to plasterboard , reed matt for instance. check out e bay for reed matt screening for your garden. :wink:

 

[Joiner]

"Properly"? It was an adverb the last time I looked.

 

[skier-hughes]

How did you do it properly?

What counts as properly in the situation you describe in your post?

What counts as properly in the OP's situation?

 

[robgil]

What counts as properly in the OP's situation?

i think properly in the op's case will be whatever they are happy with and done to a good standard, whatever method they choose.
to me 'properly' would mean done in a chalk/hair/lime plaster over lath like the rest of the house.

 

[Joiner]

Skew nailing studs instead of trenching them in.

In the case of the OP, as Robgil suggests. I've no objection to modern materials where ones more in sympathy with the building aren't available, but where they are readily available then there's no excuse. Obtaining "traditional" materials and the information needed to apply them has never been easier.

 

[piapiapiano]

Thanks for all the replies, everyone. Sorry for the long delay in coming back to say that. I have only sporadic internet access at the moment, so my posts here are going to be of the hit-and-run variety, I'm afraid.

Anyway, cost is a concern for us. We're spending most of our budget on fixing the major structural, damp-causing problems with the house. If we can save a bit on the internal walls then we will. I'd love to be able to afford to do it all in an environmentally friendly way, but living where we live it's basically impossible.

As it happens, the plasterboard stud walls that are currently in place are not in a bad condition (as long as you don't look too closely), so we're going to keep them there and try our best to make them blend in with the finish we eventually give to the stone walls.

 

[Penners]

I've no objection to modern materials where ones more in sympathy with the building aren't available, but where they are readily available then there's no excuse.

Oh yes there is. Cost.

To lath and lime plaster that partition wall is going to cost piapiapiapiapiapiapiano a hell of a lot more than plasterboard and a gypsum skim.

And if money is tight, I think it's far more sensible to economise in areas where the building won't suffer, in order to be able to do a better job in areas where its traditional integrity is more important.

 

[christianb]

Applying lime plaster to plasterboard is a doddle. All you do is drill holes in it around 4 inches apart so that it becomes like a form of lath.

 

[BMcD]

Lime plaster will not adhere to plasterboard, nor will limewash. DG27 (as Piper mentioned previously, being supplied by Mike Wye) is a primer which prepares plasterboard and other surfaces for plastering with lime. The problem I've found with it is, it kills what little suction the plasterboard has so that when it comes to scouring and troweling up, the surface of the plaser can develop a crust whilst the plaster in contact with the background remains soft so it moves about. You will need to virtually let it go off and then knock it back with water and a sponge float to trowel it up, difficult to close in and get a good finish. Alternatively, you may try completely coating the plasterboard with a skim of Thistle Board Finish and whilst this is still wet/soft, apply your coats of lime finish plaster. The gypsum will mix with the lime where they meet so as you effectively have a gauged mix at that point. The gypsum will adhere to the plasterboard and pull in the lime. Ensure the gypsum covers the plasterboard well so as the lime doesn't come into contact with it, plasterboard and lime is not compatible. Try a test board first to see how you get on.