Home  5  Books  5  GBEzine  5  News  5  HelpDesk  5  Register  5  GreenBuilding.co.uk
Not signed in (Sign In)

Categories



Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

PLEASE NOTE: A download link for Volume 1 will be sent to you by email and Volume 2 will be sent to you by post as a book.

Buy individually or both books together. Delivery is free!


powered by Surfing Waves




Vanilla 1.0.3 is a product of Lussumo. More Information: Documentation, Community Support.

Welcome to new Forum Visitors
Join the forum now and benefit from discussions with thousands of other green building fans and discounts on Green Building Press publications: Apply now.




    • CommentAuthorwholaa
    • CommentTime7 days ago
     
    Hi,
    I have a theoretical question on the thermal mass of a typical partial cavity block wall that has uninsulated drylining in front. Some have argued that the dry lining will negate the thermal mass even if the inner block is is the airtightness layer. As we all know, the drylining in such builds sometimes becomes a sort of defacto airtightness layer, and may have more sealing the real airtightness layer, so does this eliminate the thermal mass effect of the build, or does it just come down to the airtightness of the inner block wall?
    • CommentAuthortony
    • CommentTime7 days ago
     
    Theoretical and real world are almost diametrically opposed, in the real world the gap behind the plasterboard lining is directly connected to the outside air so on all windy days people are living in plasterboard tents!

    In theory the blocks warm up to almost average indoor temperatures, if this is the case the mass of those blocks prevent rapid temperature changes, increasing comfort for the occupants.

    So yes if the plasterboard is the airtight layer then yes the blocks will be cooler and so less thermal inertia and colder to live in with higher energy use.
    •  
      CommentAuthordjh
    • CommentTime7 days ago
     
    It also depends on how airtight the block wall itself is and how well-ventilated the cavity is.

    If both leaves of the block wall were completely airtight (except for any deliberate ventilation holes) and the cavity were not very well ventilated, then in theory the inside of the inner block leaf would be just a degree or two below the inside of the dry lining, and its outside surface would be half-way between the internal temperature and the external ambient temperature (or greater if the reason for the lack of ventilation in the cavity was full-fill cavity insulation).

    In practice a block wall isn't airtight, and a parging coat must be applied to the inside to make it so, which is hardly ever done under dry lining. So in an uninsulated cavity wall, the external face of the inner leaf of blocks is near ambient, air is blowing through the block wall and the temperature behind the plasterboard is also quite low.

    So the effective thermal mass of the block wall will be a lot less than it might appear on paper.
    • CommentAuthortony
    • CommentTime7 days ago
     
    Tragic
    • CommentAuthorwholaa
    • CommentTime7 days ago
     
    Thanks for the helpful responses. I don't think this is an abstract situation either. Some people take down dry lining to parge and are left with a choice to return the dry lining as it was or fill with insulation. Naturally, there are condensation and soundproofing considerations as to whether or not to leave an empty void behind the drywall too.
  1.  
    What Tony said (I have camped in that tent too!).

    But even if the drylining were completely airtight, the air gap behind it would still reduce the heat transfer between the room and the blocks, and so it would reduce their ability to store and release heat.

    A rough calc suggests the air gap between plasterboard and block, would reduce the thermal admittance of the leaf by ~30%.
    •  
      CommentAuthordjh
    • CommentTime6 days ago
     
    Posted By: wholaaSome people take down dry lining to parge and are left with a choice to return the dry lining as it was or fill with insulation.

    Presumably their sane choice would be to use the parge coat as the base layer of a normal plastering situation, and simply add another coat or coats to finish it?
    • CommentAuthorwholaa
    • CommentTime6 days ago
     
    That would improve soundproofing too but I guess there might be issues of what to do with cabling for power points and home networks etc. but I might chat to some plasterers about this to learn how to dow deal with it. I wouldnt want to be chasing them in.
    • CommentAuthorwholaa
    • CommentTime3 days ago
     
    Just about of interest, would anyone have a ball park figure of how typical it is parge the blocks in new builds in England? Is it say 50% or more?
    • CommentAuthortony
    • CommentTime3 days ago
     
    Dream on, historically zero, try getting stats on sales of parge coat, a few percent, they should all be done, but dry liners on a price dont bother,
Add your comments

    Username Password
  • Format comments as
 
   
The Ecobuilding Buzz
Site Map    |   Home    |   View Cart    |   Pressroom   |   Business   |   Links   
Logout    

© Green Building Press