Thermal finishing plaster

[Bauwer]

U can't float the Bauwer Light

Bauwer Finish is 700kg/m3 density which is about 2 times lighter vs traditional finishes like Monorex GM (about 1,400kg/m3) thus few differences in the application specifics. Bauwer Finish 'firm-up' quickly after application and don't like to be trowelled much. You could achieve a reasonably smooth and flat finish, arguably better than Lime-Putty based render. When you apply Bauwer Finish suggestion is to be fast and not trowel much.

 

[Bauwer]

Yeah light is the finish coat ,have you used any of the products yet ?

Bauwer Light is an insulation layer while Bauwer Finish is a finishing layer, which protects insulating layer mechanically and from the outside environment. Both materials are highly permeable and designed for older buildings insulation.

 

[Dr.B]

Its a shame really to be honest

I know.
I hardly get to use my 8' feather edge these days, apart from cutting board!

 

[Bauwer]

Tbh I want to do a whole room with the base coat and then finish coat see how it all comes up,see if it comes up good enough finish for customer to just paint,what I don't get is how thick it would need to be to equal (lets say for example) a 27mm or 50mm thermaline plus board ( I know all info is in website somewhere ) but in simple language,how thick?
Same with the outside would like to do/ see a big area done tbh I can't judge anything with out doing it myself

Hello Pete,
Thermaline plus board is EPS based impermeable insulation which can not be used in older, permeable buildings.

27mm of this material would achieve thermal resistance of 0.82 m2K/W. In order to achieve similar level of thermal resistance you would need a thicker layer of Bauwer Light at 55mm. 50mm would correspond to 1.52 m2K/W or about 100mm of Bauwer Light.

About 70mm to 80mm of Bauwer Light is normally sufficient to meet U value of 0.7 of the solid stone or brick wall.

Regards, Alexander

 

[Bauwer]

I'm sorry, but some of your assertions are wrong.

Firstly there is no need to 'buffer moisture levels in the internal air'. It is as we all agree essential to allow a solid wall to breathe, which can be achieved either into the room itself, or into a cavity. That preserves the moisture flow through the wall structure, but prevents significant heat loss which is quite basic physics when you think about it. If that wasn't the case then cavity wall construction wouldn't work. It allows the outer skin to breathe and the cavity to dry to the outside.

Moisture levels inside the inner box formed by the insulation are balanced across extraction in the areas of highest moisture concentration, opening and closing doors, people exhaling, 'dry' heating systems, weep vents etc. Interstitial condensation isn't an issue as the cavity is vented which allows exchange of air yet still maintains drying to the outside. However, the drying effect is at a more constant rate as there is a much reduced temperature range of peaks and troughs because the inner face of the wall isn't exposed to the heating and cooling cycles caused by the houses heating systems.

So whilst I agree that an impermeable layer in contact with, or forming part of, the outer wall would be a bad approach, forming a vented internal cavity would most definitely not. As mentioned above, if it were then every building of cavity wall construction wouldn't work.

I agree with the above for the modern, impermeable buildings insulation, all correct really.

For the traditional, permeable buildings vapour control need to be very carefully considered when warm and moist internal air entering and condensing on the colder side of the impermeable insulation within the newly introduced cavity, or within vulnerable parts of the external solid wall.

Another obvious concern is the cost aspects and complexity of the cavity introduction.

 

[Danny]

I know.
I hardly get to use my 8' feather edge these days, apart from cutting board!

the trouble is that the less you do the worst you will be when you do need to do it... it will become a lost art... shame really

 

[whitebeam]

Just my view, why add modern materials to old lime mortar property's

 

[carys]

Anyone know where I can get thermal finishing plaster like aerotherm and the likes?
Need about 5 bags but the only ones I've seen require an "approved installer" lol

Anyone know where I can get thermal finishing plaster like aerotherm and the likes?
Need about 5 bags but the only ones I've seen require an "approved installer" lol

Are u on about cork lime plaster ?

 

[Bauwer]

Are u on about cork lime plaster ?

Cork lime plaster is a very similar material to Bauwer Light, with a number of positive characteristic, yet there are few differences like filler (cork and expanded Perlite) as well as performance characteristics:

Density: Bauwer Light is about 2.5 lighter at 280kg/m3 vs. 700kg/m3 of the EcoCork. Lower density typically corresponds to a stronger thermal performance: Bauwer Light is 50% thermally better at 0.068W/m*K vs 0.1 W/m*K of EcoCork

Output from one bag: 25% higher from one bag of Bauwer Light at 25 liters per bag vs 20 liters of EcoCork.
So each bag of Bauwer Light corresponds to 1.25 bags of EcoCork at the same sqm and application thickness. If you would compare at the like for like thermal performance as well, then one bag of Bauwer Light would correspond to 1.87 bags of EcoCork.

 

[carys]

Cork lime plaster is a very similar material to Bauwer Light, with a number of positive characteristic, yet there are few differences like filler (cork and expanded Perlite) as well as performance characteristics:

Density: Bauwer Light is about 2.5 lighter at 280kg/m3 vs. 700kg/m3 of the EcoCork. Lower density typically corresponds to a stronger thermal performance: Bauwer Light is 50% thermally better at 0.068W/m*K vs 0.1 W/m*K of EcoCork

Output from one bag: 25% higher from one bag of Bauwer Light at 25 liters per bag vs 20 liters of EcoCork.
So each bag of Bauwer Light corresponds to 1.25 bags of EcoCork at the same sqm and application thickness. If you would compare at the like for like thermal performance as well, then one bag of Bauwer Light would correspond to 1.87 bags of EcoCork.

U have lost me m8 i just put whatever the customer want on the wall get my money and walk away .and if the room is still cold tell them to put an extra jumper on

 

[Deleted member 23452]

I agree with the above for the modern, impermeable buildings insulation, all correct really.

For the traditional, permeable buildings vapour control need to be very carefully considered when warm and moist internal air entering and condensing on the colder side of the impermeable insulation within the newly introduced cavity, or within vulnerable parts of the external solid wall.

Another obvious concern is the cost aspects and complexity of the cavity introduction.

I agree with all of that. The careful consideration, and the much larger costs involved are part of the process for choosing a solution. That's why it's so important to properly plan insulating older buildings and take into account customer requirements along with considering the building as a complete structure.

Condensation in the cavity can be eliminated by constructing the cavity and it's ventilation properly.

Another consideration for the appropriate insulation method will be the location of the building. Terraced, detached, coastal, Scottish highlands, inland in Cornwall all require their own approach.

That's what I find most frustrating about the building industry and the retrofit/refurb side in particular. So often a particular product or method are touted as the answer to a particular issue. That's never been the case, and it's not going to change.

Part of the process will normally involve educating the customer, which is frequently the biggest challenge. It's not helped by conflicting opinions, pseudo scientific claims and poor policing of standards within the industry.

 

[Deleted member 23452]

Just my view, why add modern materials to old lime mortar property's

Sometimes it's what the customer wants or needs to achieve the finished 'look' they have in mind. Sometimes it's what's needed because of other changes to the property.

They may want a contemporary 'minimalist' look with sharp corners and clean lines. They may be making other changes to make the house more 'eco friendly'. They may be fitting modern central heating and extraction, underfloor heating etc.

Arguably if that's the case then buying a 300 year old stone built cottage was the wrong thing to do. You can't tell other people how to spend their money, so you just have to try and steer them in the right direction to acheive the best compromise.

 

[Dr.B]

Sometimes it's what the customer wants or needs to achieve the finished 'look' they have in mind. Sometimes it's what's needed because of other changes to the property.

They may want a contemporary 'minimalist' look with sharp corners and clean lines. They may be making other changes to make the house more 'eco friendly'. They may be fitting modern central heating and extraction, underfloor heating etc.

Arguably if that's the case then buying a 300 year old stone built cottage was the wrong thing to do. You can't tell other people how to spend their money, so you just have to try and steer them in the right direction to acheive the best compromise.

Like you say, when mixing the old with the new there has to be a compromise somewhere.