plasterboard with lime plaster

[NWhit]

I am looking to re-plaster the majority of the walls and ceilings in my house and use lime plaster. What type of boards would be best to use for under the lime plaster?
Also which paint companies are good for durable, breathable paints?

 

[jamest]

Don't use plasterboard. If it were me, I'd be using boards that offer a bit of insulation - woodwool boards or wood fibre boards. These provide a good substrate for lime plaster and insulation too, even the 20 mm thick ones offer significant insulation (compared to plasterboard, anyway). You could use cork boards as well, but these do need the walls to be nice and flat - I've used these quite extensively and really like them, the smell is great. Mike Wye provide lots of useful information on their site on the different types of board. You can use Farrow & Ball estate emulsion (which is highly breathable), just don't use the recommended primer (which isn't), primer isn't really needed, I just used a mist coat of the emulsion - it's quite durable in my experience. I've also used earthborn claypaints and Bauwerk lime paint internally, they seem OK too, but they are quite expensive and don't have the range of colours that F&B do.

 

[NWhit]

Don't use plasterboard. If it were me, I'd be using boards that offer a bit of insulation - woodwool boards or wood fibre boards. These provide a good substrate for lime plaster and insulation too, even the 20 mm thick ones offer significant insulation (compared to plasterboard, anyway). You could use cork boards as well, but these do need the walls to be nice and flat - I've used these quite extensively and really like them, the smell is great. Mike Wye provide lots of useful information on their site on the different types of board. You can use Farrow & Ball estate emulsion (which is highly breathable), just don't use the recommended primer (which isn't), primer isn't really needed, I just used a mist coat of the emulsion - it's quite durable in my experience. I've also used earthborn claypaints and Bauwerk lime paint internally, they seem OK too, but they are quite expensive and don't have the range of colours that F&B do.

Thanks very much for the information. I’ll have a look at what you’ve suggested. I’m trying to re-plaster without having to remove all the cornicing so hopefully I’ll be able to do that with wood wool boards.

 

[johnbanshee]

Don't use plasterboard. If it were me, I'd be using boards that offer a bit of insulation - woodwool boards or wood fibre boards. These provide a good substrate for lime plaster and insulation too, even the 20 mm thick ones offer significant insulation (compared to plasterboard, anyway). You could use cork boards as well, but these do need the walls to be nice and flat - I've used these quite extensively and really like them, the smell is great. Mike Wye provide lots of useful information on their site on the different types of board. You can use Farrow & Ball estate emulsion (which is highly breathable), just don't use the recommended primer (which isn't), primer isn't really needed, I just used a mist coat of the emulsion - it's quite durable in my experience. I've also used earthborn claypaints and Bauwerk lime paint internally, they seem OK too, but they are quite expensive and don't have the range of colours that F&B do.

I am looking at doing this too. Been doing all sort of reading up - my new (old) house is solid stone walls albeit with a fair bit of brick used (but ultimately no cavity). There are some major damp spots in certain rooms and I'm of the opinion it is gypsum plaster creating the issues. It may be the odd loose roof tile but I cant think that would allow enough rain in to cause a whole wall of wallpaper to have peeled off.

I believe I need to baton, insulate and cover in board and then lime plaster - but probably not plaster boards - thogh i can get me head around whether there should be moisture resistant sheet or not???

Anyway - how does one get a smooth finish tough - the woodwool & fibre boards seem to have a very rough finish on them...is there an alternative like plasterboard but breathable (I believe that is the key element)...?

 

[Toby Newell]

Wood wool boards are the accepted standard.

Take a look at Ingilby paints, arguably one of the top historic and breathable paint manufacturers in the world. Half of Suffolk is coated in them.

 

[johnbanshee]

OK will do!!!

 

[jamest]

The smoothness/flatness of your finish will depend upon how good you are at plastering! You can get lime plaster boards though, if you're desperate. But gypsum plasterboard is presumably vapour permeable, but it's not really moisture resistant, even in its moisture resistant version (which might be less permeable).

The idea I've been working with regarding vapour permeability, is to allow the insulation, plaster and finish to be as permeable as possible as per the recommendations for using the various woodfibre and cork board systems available (details can be found on the relevant websites such as Mike Wye and Ty Mawr) and not too thick (less than about 100 mm including the plaster and parging layers). This not only has the advantage of making the whole thing compatible with my building (old 17th century cottage), but also carbon neutral and sustainable. As I have an old cottage, I don't need to worry about my lack of ability to get a nice flat, smooth finish to the plaster - my efforts look much more like those likely to have been achieved by the original builders; a 'proper' plasterer would charge you extra for that.

 

[johnbanshee]

Wood wool boards are the accepted standard.

Take a look at Ingilby paints, arguably one of the top historic and breathable paint manufacturers in the world. Half of Suffolk is coated in them.

Hi Toby

I've found this stuff... https://insulationmerchant.com/products/15mm-skanda-savolit-plus-wood-wool-board-1200-x-600mm

So is my plan correct to add insulation to my stone walls:
- Breathable membrane
- Wood baton stud frame
- Insulate with 100mm Rockwool or similar
- Board with the woodwool board
- Skim with lime plaster

Am I on the right track...? It's all pretty alien to me assumed it would be a case of dot & dab plasterboard until recently.

Thanks

J

 

[a twig]

On my home I just installed the wood wool boards straight onto the stone walls with mechanical fixings and large washers, then skimmed over in lime. The wood wool boards come in thicknesses from 15mm up to 75mm so will give a decent insulating performance, still breathe and no need for membranes / batons etc

I’ve got a few posts on here where I’ve raved about it, others have done similar as well

https://www.periodproperty.co.uk/forum/threads/plastering-question.16738/post-227203

 

[CarolineTheChemist]

We had some rough solid brick walls that we wanted to insulate. The bricks had been really beaten up before being plastered with modern plaster, but luckily it was relatively easy to remove it. To smooth it out before boarding we had a roughish lime and sand coat to flatten it, followed by wood fibre boards (attached with washers and stainless steel screws) for insulation, followed by a scratch coat of lime plaster, topped with a smooth coat of lime plaster. It’s noticeably warmer and drier!

I’ve written a slightly longer post about how we did this, including links and photos, on another 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

 

[Toby Newell]

Hi Toby

I've found this stuff... https://insulationmerchant.com/products/15mm-skanda-savolit-plus-wood-wool-board-1200-x-600mm

So is my plan correct to add insulation to my stone walls:
- Breathable membrane
- Wood baton stud frame
- Insulate with 100mm Rockwool or similar
- Board with the woodwool board
- Skim with lime plaster

Am I on the right track...? It's all pretty alien to me assumed it would be a case of dot & dab plasterboard until recently.

Thanks

J

+++

I would defer to the guys above, I have never done the job, apart from helping clients out (I do wood mainly and occasional stone) all the installations I have seen from clients houses have been as per the above, make level, fix direct using the large plastic washers and SS screws and lime over the top. The wood wool boards are great, the plaster really adheres well to them. If it's a small area many of my clients opt to have a go at plastering themselves, it's much more forgiving than multi finish and you don't need to worry about getting it perfectly flat, it's quite easy with a bit of practice to get it fairly smooth. Matt breathable paint hides a lot of imperfections. As said, I wouldnt bother with a membrane unless you have a specific damp issue, 'breathable' membranes are less breathable than no membrane!

 

[johnbanshee]

OK thanks for responses - yes that looks the way to go, battening and Rockwool look to be overkill

I think my walls all have pink gypsum on them already - so that will have to be removed from all the external walls of the house, which I'm not looking forward to doing. There are a few damp areas, on high up walls - some have sagging wallpaper, so I'm hoping removing the gypsum will solve that issue.

 

[Toby Newell]

OK thanks for responses - yes that looks the way to go, battening and Rockwool look to be overkill

I think my walls all have pink gypsum on them already - so that will have to be removed from all the external walls of the house, which I'm not looking forward to doing. There are a few damp areas, on high up walls - some have sagging wallpaper, so I'm hoping removing the gypsum will solve that issue.

Well, that depends, check outside, most issues are caused by poor gutters, poor drainage, poor pointing, excess foilage, raised ground levels, or driven rain in high, exposed or S / SW facing elevations.

Having a more breathable exterior wall can actually let more moisture in! It just can evaporate faster. So do the obvious checks first.

 

[Toby Newell]

And yes, wood wool board is great stuff, fairly cheap, easy to fit, fairly low carbon, wood and cement are good insulators and then you have the trapped air pockets and it is an excellent substrate for lime, has a slim build and is breathable, I cannot think of any comparator.

Pretty certain if it was available hundreds of years ago no one would of spent hours riving their own lath!

 

[johnbanshee]

Here's where the noticeable interior damp patches are - not had a chance to get up on roof to inspect tiles / guttering yet...it's north facing as it happens.

Block paving at base runs right up to building and looks sodden - I'm thinking at the least I need to install a drainage grill - or maybe a french drain right around connected to a soakaway....plus all those wires need to go - they don't even run straight!

 

[Toby Newell]

What lovely stone you have, not the sharpest photo but it looks in great condition, I cannot see any staining or algae growth. Yes check roof and gutters, North facing is good!

Is that a public footpath? Yeah, not a fan of that type of paving, if so, you you would have to check the bounds of your property.

 

[johnbanshee]

Its on a private land, a gravel drive shared by several houses but well away from the road. It's also dawned no me today that the bottom floor rightmost room is on a floating floor...so I need to see whats under the floorboards too...should be a good project for 2024!

 

[Stevers]

Those clean patches on the paving could well be the gutter overflowing, or being missed completely.

 

[Toby Newell]

Those clean patches on the paving could well be the gutter overflowing, or being missed completely.

Nice spot, yes and looks a bit green.

 

[Toby Newell]

Always instructive to go out and have a look during a daylight torrential downpour.