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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
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    • CommentAuthoraclarky
    • CommentTimeApr 15th 2019
     
    Hi,

    any advice welcome -

    renovating a 1900's house in Glasgow, 600mm stone wall.

    the previous owners had 'damp proofed' but really they just diverted the damp to other areas. We are controlling the ingress but just taking the walls back to stone let them visibly dry out in a day.

    So I want breathable and was thinking of this make up:

    Stone wall - 100mm wood fibre insulation in stud - rigid wood fibre board - lime plaster - clay paint

    1- do I need a membrane in there? I really don't want to put in anything that may concentrate damp etc and if the wall does get damp I'll sort it outside etc. So long as the walls are dry ish will the damp not disperse in/out naturally

    2- any other tips that jump to anyones mind welcome.

    Thanks
    • CommentAuthorjfb
    • CommentTimeApr 16th 2019
     
    I would be a little worried that there would be a danger of interstitial condensation in the insulation with that thickness of insulation. I have similar walls (though drier region) and went for : stone wall, lime render (as flattening layer and airtight layer) 60mm wood fibre board (fixed to wall with plastic pins), lime render, limewash. 20mm boards around window reveals. Airtight tapes embedded in backing render taped to windows/doors/joists. If possible make sure the woodfibre boards go all the way up the wall at ceiling level and is joined to too insulation.
    I also installed Mvhr (not knowing if it would strictly be necessary but I ended up with an air test of 1 ACH and anything better than 3 requires mechanical ventilation).

    It has worked very well for me - nice comfortable and dry environment. I had the advantage o taking the house back to a shell to do the work and maybe you don't. The backing layer online render is easier if you have relatively flat walls as you want to avoid voids behind the woodfibre board. But I think it is a better way to go than your plan.

    And just I be clear - no membrane in my build up!
    • CommentAuthorRick_M
    • CommentTimeApr 18th 2019
     
    You might find these interesting:

    Upgrading tenements to Passivhaus standard:
    http://www.cicstart.org/userfiles/file/FS-39-REPORT.PDF

    (BTW, does anyone know if the any of the above work took place?)

    Internal wall insulation to tenements:

    https://www.historicenvironment.scot/archives-and-research/publications/publication/?publicationId=651e6f16-087f-408b-ab3d-a59300fd971a
    • CommentAuthoraclarky
    • CommentTimeApr 26th 2019
     
    Brilliant thanks. sorry for the late reply, I work on an island now and then and so was out of touch for longer than is polite after asking a question..!

    Those articles are very reassuring, although wood fibre seemed to increase wall humidity the most, so perhaps blown cellulose may be the thing to use especially as it gets into all of the nooks.

    jfb - I have found myself looking at mechanical ventilation too, - I had a design done which looked a bit OTT but I was going to basically extract from bathrooms and kitchens and vent into far corners of bedrooms etc and hope fir the best.

    any advice on insulating up into the joist space above the wall??

    Andy
    • CommentAuthorjfb
    • CommentTimeApr 27th 2019
     
    I lifted or cut floorboards out to allow space for the wall insulation to run continuously up the wall. Pay attention to air tightness around the joists at the same time.
    • CommentAuthoraclarky
    • CommentTimeApr 27th 2019
     
    how do you make it air tight - say if you were using wood fibre? Do you mean tape it and put in a membrane? Really want to avoid membranes where possible.

    And on the off chance any knowledge on open cell pour foam insulation behind lath and plaster? I spoke with one of the scientists who has installed it in Aberdeen and actually the interstitial humidity is similar to the cases you pointed me to - slightly higher and slower to dissipate but never reaching worrying levels..

    cheers again!

    andy
    • CommentAuthorRick_M
    • CommentTimeApr 27th 2019 edited
     
    AFAIU blown cellulose is not dense enough to be called airtight so there would be a risk of condensation without a separate air barrier. As opposed to fibre board which is more dense.

    Posted By: aclarkyhow do you make it air tight - say if you were using wood fibre? Do you mean tape it and put in a membrane? Really want to avoid membranes where possible.


    As per jfb's description; you tape around the joists and embed the tape in your parge coat (lime render in jfb's case). I don't know if there are other ways to do it. I guess you would apply the parge coat first, let it dry then tape around the joists and then add a little more parge coat to embed tape. I don't know if the tape would stick well enough directly onto uneven stone/brick.

    I found these which show how to tape around windows to make them airtight.

    https://youtu.be/0WVIAC559ao

    https://youtu.be/BrQqDA25d24
    •  
      CommentAuthordjh
    • CommentTimeApr 27th 2019
     
    I don't understand the point of the first video. Blocks aren't airtight, so what's the point of sticking to them? I can see the point of sticking Fentrim to a parge coat and then overcoating with a finish coat.

    And the second video???? Stainless steel all around the window? What's the point? At least it's not mild steel. I'm happy with steel brackets or with a few pegs underneath like I think Tony used, but continuous metal all the way around the window??

    Posted By: Rick_Membed the tape in your parge coat

    This I understand :bigsmile:

    I don't know if the tape would stick well enough directly onto uneven stone/brick.

    The tapes I used had me prime a concrete surface and then use the non-setting glue product to secure the tape. I suspect that the tape in the video is relying on an airtight seal to the plaster above it.

    The bit about using a small, hard roller to make the tape adhere properly is important though. I also found the back of a box knife was useful in some circumstances.
    • CommentAuthorRick_M
    • CommentTimeApr 27th 2019
     
    1st video: If you plaster over the blocks and over the section of the tape that has all the holes in, I can't see why it would matter that the blocks aren't airtight, as they will be behind your air barrier. I must be missing something?

    2nd video: They look like brackets to me, not continuous sheet.
    •  
      CommentAuthordjh
    • CommentTimeApr 27th 2019
     
    Posted By: Rick_M1st video: If you plaster over the blocks and over the section of the tape that has all the holes in, I can't see why it would matter that the blocks aren't airtight, as they will be behind your air barrier. I must be missing something?

    My concerns are that I can't see (a) why is it important to stick the tape to the blocks and (b) what makes the plaster stick to the tape? The Pro Clima equivalent has a fleece layer on the non-sticky side of the tape to help it stick to the plaster, as well as a mesh on the plus version. I don't understand how the Siga version works.

    2nd video: They look like brackets to me, not continuous sheet.

    Ah yes, apologies. On second viewing I agree. Though I think there are a lot more than needed.
    • CommentAuthorGreenPaddy
    • CommentTimeApr 28th 2019
     
    I'd be very wary of making decisions based on the Historic Scotland case study.

    It shows some areas having a relative humidity of 20%. I think the measuring device was faulty. No chance of having RH of 20%, plus the other rooms were at 50-60%, which is more like the expected number. The mojave desert can have daytime RH values of in the 20%, not how I remember my years living in Glasgow.

    And what they mean by Aerogel I'm not clear. I've used Aerogel/Spacetherm before, and this can't be what they're referring to, as 40mm of Aerogel would (a) cost a fortune, like £100's per m2, (b) in itself is about 4 times better lambda value than the rest, so even at half the thickness would be MUCH better Uvalue performance than the others.

    It's a shame, as I was really hoping to get something useful from this report, but I would suggest ignoring everything in it, as so much of it is questionable.


    :sad:
    • CommentAuthorRick_M
    • CommentTimeApr 28th 2019 edited
     
    I agree, 20% sounds impossible. Hard to believe that would be published without being flagged. I read the paper years ago but didn't notice that. Also, I don't know if any follow up review has been published which would be more helpful.

    My understanding is aerogel is not 4x better than other insulants, but more like 1.7x better. As in, you'd need 17mm of rigid foam to match the performance of 10mm of aerogel.

    FYI I linked the videos above as they were the first ones that came up on youtube, nothing more than that.
  1.  
    Just to clarify, rigid foam wasn't included in the report. The other insulating materials were in the order of 0.038 - 0.04 lambda. Aerogel is closer to 0.01. Maybe 3 times better might have been more accurate, but the point is the report is worse than questionable.
    • CommentAuthorCWatters
    • CommentTimeMay 3rd 2019
     
    Not entirely sure about the quality of this report..

    Solid Wall Insulation:
    Best Practice and Innovation
    Report for the Department of Business, Energy and Industrial Strategy

    https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/658604/BEIS_-_SWI_Innovation_Final_Report_-_FINAL_Approved.pdf
    • CommentAuthoraclarky
    • CommentTime5 days ago
     
    Appreciate all of the comments, getting a much better idea of what should work..
    cheers
  2.  
    Award for the thread title that I have been waiting over 10 years for. :clap:
    • CommentAuthorgravelld
    • CommentTime4 days ago
     
    Well put :bigsmile:
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