I think Nick was asking about the specific project you posted photos of.

Posted By: Nick Parsons@djh, yes, thanks, I was.

@Bauwer, ''Sure if you improve U value of your 100 years old home at least by two or three times it helps a lot, as the rate of heat bleeding would be reduced by 2 to 3 times correspondingly''. Yes it does, but if you can improve it by even more it helps even more.

Not necessary Nick, especially if you improve traditionally built home with petroleum based non breathable insulation. The key requirement for old stone or brick walls without cavity is breathability in my view.

Just think about that - the target for 40 years old cavity wall insulation is 0.55 (building reg L1B) clearly you can not (and should not) request a more chalanging target for 100 years old wall design.

It is like asking a 100 years old car to drive with the speed of a modern car....it just does not make sense.

Sorry if I missed this, but what's the lambda (of the Light product)?

How does it compare in installation costs to stick block (EPS) and render?

I'm thinking maximum possible thickness (150mm on your calculator).

Hello Nick,
Sorry for my slow reply, we are extremely busy with the number of orders at that cold time.

My comments:
"I was involved with the EWI of a solid-walled house using 180mm of wood-fibre and lime render. Breathability and a massive reduction in U value (less than 0.22). The '100-year-old car' is doing very well"

a) 0.22 is declared performance while actual performance could be significantly worse due to links between boards being potential "cold bridges" while Bauwer delivers seamless insulation without a need to link boards.

b) stone homes have rough walls which must be leveled first before boards application, Bauwer does not require any leveling. Actually Bauwer likes rough wall as it is an additional key. Also Bauwer is the most cost efficient way to level the stone walls as it is light-weight and strong highly breathable material.

c) if wooden fibre board used internally it could lead to condensation issues.

d) Bauwer is inorganic and nutrural based on vulcanic sand Perlite while wood is organic material could be impacted by water, etc

e) Please advise what was the cost per sqm both material and labour. Bauwer material is times more cost competitive:
https://www.homebuilding.co.uk/how-to-insulate-solid-stone-wall-homes/

f) the main benefit of lower U value is saving on your energy bill and related carbon emissions. Sure the cost of the project should be balanced with the energy savings and improvement of U value by 3 to 4 times are generally sufficient for vast majority of stone wall customers assuming budget cost of Bauwer insulation.

I could continue with my bullet points:
http://bauwer.co.uk/templates/Default/images/Leaflet.pdf

Please do not hesitate to contact me should you require any further information at 0151 558 0890

Regards, Alexander
info@bauwer.co.uk

<blockquote><cite>Posted By: MarkyP</cite>can this render really compete with EPS or wood fibre where there is more than 50mm of additional build up available? How thick can it be built up per coat? 30 or 40mm of insulated render perhaps a good option where you are constrained on external build up thickness for some reason. But as soon as you can get a 40 or 50mm EPS board on the wall the render only option is going to be trumped. Much is made of breathability, indeed Bauwer's webiste says the render is both breathable and dehumidifying! If you really need a very vapour open wall then as mentioned wood fibre/lime will do nicely, but lots of period property out there with a coat of EPS and they seem to be doing just fine. I'd consider a product like this if I had less than 50mm to play with, otherwise I'd be willing to bet EPS or woodfibre will be faster, cheaper to install and achieve a far superior u-value.</blockquote>

Hi MarkyP,
as I mentioned earlier, not a very good idea using petroleum based EPS insulation for solid stone walls insulation. The reasons are well explained here:
http://greenbuilding.co.uk/insulating-masonry-walls-of-old-stone-cottages-and-listed-buildings/

The issues of trapped moisture in traditionally built homes are massive thanks to "experts" or not qualified architects who apply modern impermeable solutions in older buildings.

Could you please read my post above on wooden fibre boards insulation option.

We also offer modern insulation systems based on graphite EPS, XPS or stone wool with wide range of robust and flexible fibre reinforced finishes under Vimark brand:
https://www.vimark.co.uk/linee-prodotti/external-insulation-systems/

Please do not hesitate to contact me should you require any further information.

Best regards,
Alexander
0151 558 0890

*My (Nick Parsons') responses to Alexander at Bauwer are prefaced by an asterisk:

Alexander at Bauwer wrote:

Hello Nick,
Sorry for my slow reply, we are extremely busy with the number of orders at that cold time.

My comments:
"I was involved with the EWI of a solid-walled house using 180mm of wood-fibre and lime render. Breathability and a massive reduction in U value (less than 0.22). The '100-year-old car' is doing very well"

a) 0.22 is declared performance while actual performance could be significantly worse due to links between boards being potential "cold bridges" while Bauwer delivers seamless insulation without a need to link boards.

*Nick P response: Yes, I agree with you that all systems must be installed well. It is a particular concern of mine that some EWI firms leave gaps between insulation boards, or allow thermal by-pass, and cover it all up with the 'icing (render) on the cake'. While a good render finish is important to me, the extremely tight fit of all boards is of fundamental importance.

b) stone homes have rough walls which must be leveled first before boards application, Bauwer does not require any leveling. Actually Bauwer likes rough wall as it is an additional key.
*NP response: I agree with you that uneven walls are an issue. Each case needs to be weighed up. In the case I refer to we used a wood-fibre material with a rigid face but with flexible fibre behind, allowing the board to be 'pulled in' over the irregularities we encountered in this specific case.

Also Bauwer is the most cost efficient way to level the stone walls as it is light-weight and strong highly breathable material.



c) if wooden fibre board used internally it could lead to condensation issues.

*NP: My reply referred to EWI - External insulation of External walls. Any improvement to insulation of any wall could potentially lead, through poor detailing or installation or poor understanding of building physics, to condensation issues. In my view that's what fine attention to detail and dynamic condensation risk assessment tools such as WUFI are for.

d) Bauwer is inorganic and nutrural based on vulcanic sand Perlite while wood is organic material could be impacted by water, etc

*NP: You are quite right - wood-based insulation can be affected by moisture, and attention to detail, to avoid moisture ingress, is essential. I believe it is essential, though, for pretty well all insulants, even if the material of the insulant itself is not physically affected by water.

e) Please advise what was the cost per sqm both material and labour.

*NP: I do not know. I was engaged as a sub-contractor.

Bauwer material is times more cost competitive:
https://www.homebuilding.co.uk/how-to-insulate-solid-stone-wall-homes/

f) the main benefit of lower U value is saving on your energy bill and related carbon emissions. Sure the cost of the project should be balanced with the energy savings and improvement of U value by 3 to 4 times are generally sufficient for vast majority of stone wall customers assuming budget cost of Bauwer insulation.

*NP: And for those who wish to achieve lower U values other options exist.

Hi Delprado, is that loose beads in render, or render on EPS boards?

Edit: Forget that Q - a quick Google says it's the former.

**Nick Parsons' comments denoted by double asterisks**

Posted By: gravelld
Sorry if I missed this, but what's the lambda (of the Light product)?

**Stated as 0.068W/mK - see link provided above:

http://bauwer.co.uk/templates/Default/images/Leaflet.pdf**

How does it compare in installation costs to stick block (EPS) and render?

I'm thinking maximum possible thickness (150mm on your calculator).

**If we assume a 225mm solid brick wall, with a ,base case U value of 2.1W/m2K,and a lambda value for Bauwer Light of 0.068 as stated in Bauwer's leaflet, then the calc is as follows:

0.15(m)/0.068 = R1 = 2.2058

'Base Case R' of wall = 1/2.1 = R2 = 0.476

R1+R2 = 2.6818

1/R = 0.3728 = U value of 150 Bauwer Light on 225mm solid brick wall.**


Honestly speaking EPS should not be used for stone walls traditionally build homes insulation:
https://www.homebuilding.co.uk/how-to-insulate-solid-stone-wall-homes/" rel="nofollow" >https://www.homebuilding.co.uk/how-to-insulate-solid-stone-wall-homes/

Bauwer insulation is one of the most cost competitive way to insulate solid stone walls on the market.

Based on the Building regulations L1B, part 5.12 U value of 0.7 or lower need to be achieved by solid stone or brick walls.

**I have no connection with Bauwer and have never used the product. I am just trying to present the figures in a post (rather than in a link) to answer some of gravelld's questions.


I believe another of the links provides estimates of materials and application costs at 50 and 70mm.**

**Edit: Yes, this is the link with the cost estimates: https://www.homebuilding.co.uk/how-to-insulate-solid-stone-wall-homes/ **

This has been interesting reading and just though I might throw my thoughts/experience of breathability into the mix.

I have lived in houses over 100 years old, built from sandstone, for the last 10 years. I've read a lot about breath-ability from research done by historic Scotland and other sources and I agree that the expert opinion in this area is that it is absolutely the wrong thing to do to put non breathable insulation, or render on a house built with breathable materials.

The house I have been living in for the last year is at least 150 years old, exposed Ashlar Sandstone blocks on the front, but the side and rear walls have been covered in a cement render for the last 30 years. My initial thought was that I need to get that ripped off and replaced with a breathable render, and that this was probably the cause of the dampness in the house.

However, I pulled off a small section from a side wall and there is no dampness at all underneath the cement render. Having first used a dehumidifier to dry the inside of the house out, and then improved the ventilation it seems that the dampness has been due to condensation caused by water vapour produced inside the house and it is now under control.

It strikes me that as long as the outside wall was dry when the render was applied it shouldn't matter that it can't breathe out, because there is no water going in to be breathed out. As long as the inside walls of the house remain breathable, and the inside is at a low relative humidity then, any water entering the stonework from the ground should be able to breath to the inside of the house.

Not suggesting its good practice to cover a sandstone house with cement or EPS, but in theory a wall only needs to breathe water vapour out, if there is any going in.

Another Bauwer internal insulation project on the go

Hi @Nick Parsons,
Thanks for detailed answer to @gravelld, all sounds correct, thanks for that.

Also you could also our simple U value calculator in order to calculate estimated as build U value and improved U value with Bauwer permeable insulation:
http://bauwer.co.uk/Calculator.html?#CALCULATOR

It is consistent with your calculation.

Regards, Alexander
07553353931

Hi Bauwer,
I get the theory, but my point is that if the humidity inside the house is controlled then its not likely to be a major issue. If the RH inside is low enough inside and the house is well ventilated, and to be honest a 200 year old house is usually unintentionally fairly well ventilated from leaky windows to fireplaces etc.

If I was putting render on then I would use a breathable render, but I just saying I am no longer to take the cement render off now because in practice its not causing a problem.

Kenny

Ive found another one to consider, which performs twice as well from an insulation perspective. Bauwer do you have any comments on this product?

DIATHONITE EVOLUTION

https://www.diasen.com/sp/en/p/diathonite-evolution.3sp

Thanks

the downside is that its really expensive, 35 quid a bag, so I guess its only really plausible to justify the cost if you live in an old stone house or similar

£10+ VAT+ carriage. Yes, that £/R comparison would be very useful. Thanks.