hello. thanks for this video! can you use gypsum plaster over wood fibre boards? i plan to use lime plaster over external walls only. for the internal walls i plan to us gypsum.
Hi @lizziemcbizzierobin. I wouldn't generally recommend applying gypsum plaster directly to wood fibre boards although on very specific occasions it is possible to PVA them first and then apply. I would suggest adding a layer of standard (not foil backed) plasterboard over the surface and then skimming that.
Would this be suitable material for a kitchen wall? Can you attach kitchen cabins on the wall like that? I would like to add wall insulation from inside on a brick cavity wall in a kitchen where the outside humidity and cold-condensation are a problem.
Hi. You can fix lightweight attachments to wood fibre insulation but for heavier things, like kitchen cabinets, you'd be better off fixing through to the masonry using the Fischer Thermax fixings. You can also see what specification you'd need to use by running through our Material Specification Generator - www.backtoearth.co.uk/specification-generator/
Hi Elisha. Thanks for your comment. The render used is a breathable, lime-based render, designed to bond well to wood fibre boards. If you have any questions about the render please feel free to come back to me. Thanks.
@@BacktoEarthLTD Thanks, you could edit the description maybe to make it more clear. So you would use the same type of coating of plaster/render inside and out? I'm thinking of using this on my house restoration (old house, solid walls), but am a bit confused over yours and others use or recommendation of pb as an internal lining/finish? The wood fibre handles moisture well, but gypsum doesn't, so wouldn't you end up with soggy, stained and mouldy walls if you put pb on a solid walled house? Or is it (more likely) that you would specify according to the risk factor of a specific case and wouldn't recommend using Pb if there was a risk of more moisture movement than it could cope with?
Hi@@lksf9820. Plasterboard is actually a very low embodied energy, breathable material that can very safely be used over wood fibre insulation and will not end up as a soggy mess. Once you insulate your walls, you raise the surface temperatures and reduce the RH at the surface by doing so. This prevents surface condensation and the soggy plasterboard issue. You can also use lime plaster on the wood fibre insulation with no issue too. To read more about these options, please see - www.backtoearth.co.uk/internal-wall-insulation-with-plasterboard-finish/ or www.backtoearth.co.uk/internal-wall-insulation-on-masonry-how-to-detail-window-door-reveals/ I'll have a look at the description and see how we can change it. Thanks for the tip.
@@BacktoEarthLTD Sorry I don't get it, I did read those guides yesterday though. Millions of people have found out gypsum based products are no good when used with solid walled houses. They get damp, hacked off, thrown away and a product which can handle vapour (like lime) put back on again. I know this too, I have a whole house where someone has skimmed over the lime and it's all mouldy and flaking off. The PB they used here and there has black mould on it and is soft. If I insulate my walls they don't automatically heat up. They heat up when I put the heating on, If I don't they stay cold and are at risk of damp. If wood fibre boards (WF) work with gypsum then why do you skim over them with lime? You might aswell use a gypsum skim..... I get that pb may well be breathable (but amazingly nobody seems to be able to provide proof, evidence and give it an SD rating), but it certainly doesn't handle moisture very well like lime, or even like you say your WF boards do. I want to use Pb over WF as it'll make the job much easier and cheaper, but can't risk it going wrong.
It might be easier to have a chat on the phone about this because I'm wondering I'm not conveying the message very well. We are assuming that you are heating your house during winter and when you add a layer of wood fibre insulation to the interior, the surface of that insulation is much warmer than the surface of the masonry was. This in turn means the surface of the insulation is drier (The building physics side of this we can discuss on a phone call if you wish). You're completely right about gypsum not being suitable for uninsulated solid walls (because you get so much condensation and very high humidity at the wall surface) but it is perfectly suitable for use on the inside of insulated solid walls. Gypsum cannot be plastered over lime as they slowly react with one another, hence the flaking. In terms of vapour permeability, plasterboard has a Mu value (vapour diffusion resistance coefficient) of 8.3 and lime plaster is typically between 10-20, making it more permeable. As I said, please feel free to call and discuss this further if it still does not make sense.
@@bet_big9917 Yes, that is a common misconception. If you look at the data sheets for products you will find that cement plasters are similarly as breathable as limes, although not quite as breathable. We prefer to use lime based (although still contain cement) products though as they tend to be a little more flexible.
@@bet_big9917 OK, thanks for your response. Should you ever wish to look into building physics a little more and understand the differences between the materials, we can let you have the actual data. If you have any questions, please do not hesitate to contact me.
@@hugh3sy7 Very helpful thanks, renovating my 17th century cottage and looking at all ways to be thermally efficient and using chalk lime plaster as a finish. Is this board flexible in any way? As it is going between oak beams of a timber framed cottage. I am thinking of using lath and plaster. What would you suggest is best? Thanks
Thanks Chris, great demonstration and very helpful. 👍🏻
hello. thanks for this video! can you use gypsum plaster over wood fibre boards? i plan to use lime plaster over external walls only. for the internal walls i plan to us gypsum.
Hi @lizziemcbizzierobin. I wouldn't generally recommend applying gypsum plaster directly to wood fibre boards although on very specific occasions it is possible to PVA them first and then apply. I would suggest adding a layer of standard (not foil backed) plasterboard over the surface and then skimming that.
Would this be suitable material for a kitchen wall? Can you attach kitchen cabins on the wall like that? I would like to add wall insulation from inside on a brick cavity wall in a kitchen where the outside humidity and cold-condensation are a problem.
Hi. You can fix lightweight attachments to wood fibre insulation but for heavier things, like kitchen cabinets, you'd be better off fixing through to the masonry using the Fischer Thermax fixings. You can also see what specification you'd need to use by running through our Material Specification Generator - www.backtoearth.co.uk/specification-generator/
Just to check, this is for internal insulation?
That's a good question! Correct nomenclature is generally that plaster is internal and render is external, but he uses both terms so it's unclear.
In the UK you're right, we tend to do that. Sorry for any confusion.
What products have you used for plaster ?? It's that cement or what?? Didn't get it
Hi Elisha. Thanks for your comment. The render used is a breathable, lime-based render, designed to bond well to wood fibre boards. If you have any questions about the render please feel free to come back to me. Thanks.
How long should the render stifft before sponge??
Is this internal or external? You don't say which.....
Hi. The procedure is the same for both but this video is a guide to what to do externally. Hope that helps.
@@BacktoEarthLTD Thanks, you could edit the description maybe to make it more clear. So you would use the same type of coating of plaster/render inside and out? I'm thinking of using this on my house restoration (old house, solid walls), but am a bit confused over yours and others use or recommendation of pb as an internal lining/finish? The wood fibre handles moisture well, but gypsum doesn't, so wouldn't you end up with soggy, stained and mouldy walls if you put pb on a solid walled house? Or is it (more likely) that you would specify according to the risk factor of a specific case and wouldn't recommend using Pb if there was a risk of more moisture movement than it could cope with?
Hi@@lksf9820. Plasterboard is actually a very low embodied energy, breathable material that can very safely be used over wood fibre insulation and will not end up as a soggy mess. Once you insulate your walls, you raise the surface temperatures and reduce the RH at the surface by doing so. This prevents surface condensation and the soggy plasterboard issue. You can also use lime plaster on the wood fibre insulation with no issue too. To read more about these options, please see - www.backtoearth.co.uk/internal-wall-insulation-with-plasterboard-finish/ or www.backtoearth.co.uk/internal-wall-insulation-on-masonry-how-to-detail-window-door-reveals/
I'll have a look at the description and see how we can change it. Thanks for the tip.
@@BacktoEarthLTD Sorry I don't get it, I did read those guides yesterday though. Millions of people have found out gypsum based products are no good when used with solid walled houses. They get damp, hacked off, thrown away and a product which can handle vapour (like lime) put back on again. I know this too, I have a whole house where someone has skimmed over the lime and it's all mouldy and flaking off. The PB they used here and there has black mould on it and is soft. If I insulate my walls they don't automatically heat up. They heat up when I put the heating on, If I don't they stay cold and are at risk of damp. If wood fibre boards (WF) work with gypsum then why do you skim over them with lime? You might aswell use a gypsum skim..... I get that pb may well be breathable (but amazingly nobody seems to be able to provide proof, evidence and give it an SD rating), but it certainly doesn't handle moisture very well like lime, or even like you say your WF boards do. I want to use Pb over WF as it'll make the job much easier and cheaper, but can't risk it going wrong.
It might be easier to have a chat on the phone about this because I'm wondering I'm not conveying the message very well. We are assuming that you are heating your house during winter and when you add a layer of wood fibre insulation to the interior, the surface of that insulation is much warmer than the surface of the masonry was. This in turn means the surface of the insulation is drier (The building physics side of this we can discuss on a phone call if you wish). You're completely right about gypsum not being suitable for uninsulated solid walls (because you get so much condensation and very high humidity at the wall surface) but it is perfectly suitable for use on the inside of insulated solid walls. Gypsum cannot be plastered over lime as they slowly react with one another, hence the flaking. In terms of vapour permeability, plasterboard has a Mu value (vapour diffusion resistance coefficient) of 8.3 and lime plaster is typically between 10-20, making it more permeable. As I said, please feel free to call and discuss this further if it still does not make sense.
Once rendered, is it possible to tile on to Udi reco?
Yes. Absolutely. For bathrooms best to use 2 layers of plaster though.
Is this lime plaster ?
Yes, a modern lime plaster but if you're asking is it breathable, this and most modern cement plasters are too.
@@BacktoEarthLTD cement is not breathable
@@bet_big9917 Yes, that is a common misconception. If you look at the data sheets for products you will find that cement plasters are similarly as breathable as limes, although not quite as breathable. We prefer to use lime based (although still contain cement) products though as they tend to be a little more flexible.
@BacktoEarthLTD it's not a misconception, cement is like a sponge without waterproof additives. I have been in conservation for 20 years.
@@bet_big9917 OK, thanks for your response. Should you ever wish to look into building physics a little more and understand the differences between the materials, we can let you have the actual data. If you have any questions, please do not hesitate to contact me.
That was painful to watch. You are no plasterer
Sadly not, just trying to demonstrate to our customers how the product is applied. Sorry the video wasn't helpful for you. How can we make it better?
Wasn’t it just! To make it better get a plasterer to do the video!
Fuck off mate, it's a demonstration. Plasterers are the whiniest of the trades.
@@BacktoEarthLTD what a pleasant reply to a rude comment. Nice guy
@@hugh3sy7 Very helpful thanks, renovating my 17th century cottage and looking at all ways to be thermally efficient and using chalk lime plaster as a finish. Is this board flexible in any way? As it is going between oak beams of a timber framed cottage. I am thinking of using lath and plaster. What would you suggest is best? Thanks