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.

Buy individually or both books together. Delivery is free!


widget @ surfing-waves.com




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.




    • CommentAuthortony
    • CommentTimeNov 10th 2015
     
    In the early days of wall insulation building control would not let us put it in below dpc.

    I think they were wrong, did at the time, still do now.

    On a recent SIPs build the insulation in the panels started 125mm above finished floor, after a massive fight with the SIPs technical department they allowed us to do something to mitigate this thermal bridge by adding insulation on the outside across the sole plate area.

    On the majority of masonry builds insulation still stops at dpc leaving a thermal bridge at the edge of the floor just where you don't want one.

    With timber frame insulation starts 97mm above dpc, again a thermal bridge leaving the sole plate prone to pick up condensation. It is the most vulnerable piece of wood in the home apart from any near a shower.

    So I ask how far down should wall insulation go? To dpc? Below dpc? To footings? To bottom of foundations?
    • CommentAuthorgyrogear
    • CommentTimeNov 10th 2015 edited
     
    I'd say, at least to slab level, if slab-on-grade; preferably 1 foot below if suspended slab...

    (if there's a basement, it is easier and cheaper to insulate inside; and if there's a crawlspace, it should be insulated inside anyhow...)

    gg
    •  
      CommentAuthorfostertom
    • CommentTimeNov 11th 2015
     
    Way back, with cavity wall construction (in those 65-75mm cavity days) I used to take the cav insulation right down to top of the strip found, instead of filling it with conc below DPC. Must have helped.

    Trouble with the question, is that it assumes an insulation filled stud frame is OK on its own. The uninsulated sole plate is replicated all over the stud frame, at every stud, nogging and head plate.

    The insulation-between-studs bit of the sandwich should be as thin as structurally possible - say 95 - and it should be sheathed externally with 150-200 EWI, which kills all the stud thermal bridges, and is easily taken down as deep as you like - pref to foundation level.
    • CommentAuthorEd Davies
    • CommentTimeNov 11th 2015
     
    Posted By: tonyOn a recent SIPs build the insulation in the panels started 125mm above finished floor, after a massive fight with the SIPs technical department they allowed us to do something to mitigate this thermal bridge by adding insulation on the outside across the sole plate area.
    What was their objection? I can see they might think it unnecessary (if meeting building regs is the only requirement) but what harm could it do? Concern it'd set a precedent? Worry about water running down the wall and getting trapped behind the extra insulation? Something else?
    • CommentAuthortony
    • CommentTimeNov 11th 2015
     
    They would only allow additional insulation internally, until we started to explain to the facts of life, a year later and they now accept additional insulation outboard so sips panels at least at sole plate level.
    • CommentAuthorEd Davies
    • CommentTimeNov 11th 2015
     
    OK, but what was their objection?
    • CommentAuthortony
    • CommentTimeNov 11th 2015
     
    Certification and guarantee/warranty, I reckon early SIPs could find problems down the line because the technical department clearly didn't understand the issues, on comment was that there could not be any damp as it was above a dpc!
    • CommentAuthorTriassic
    • CommentTimeNov 11th 2015 edited
     


    Trouble with the question, is that it assumes an insulation filled stud frame is OK on its own. The uninsulated sole plate is replicated all over the stud frame, at every stud, nogging and head plate.
    I've often wondered why the twin or insulated stud approach to timber frame construction never caught on?
    •  
      CommentAuthorjoe90
    • CommentTimeNov 11th 2015
     
    I plan to carry cavity insulation down to strip foundation as per the Golcar passive house, yet to get it pass building control but the inspector is open to new idea,s.
    • CommentAuthorShevek
    • CommentTimeNov 11th 2015
     
    Recently took our external wall insulation down to top of footing.
      insulation-down-to-footing.jpg
    • CommentAuthorringi
    • CommentTimeNov 11th 2015
     
    I recall being told by an ICF vendor some time ago, that using ICF instead of “trench fill” costs about the same, as the cost of the ICF is offset by using less concrete. Why are ICF not used below ground for new build, even if it is timber frame above ground?
    •  
      CommentAuthorfostertom
    • CommentTimeNov 12th 2015
     
    What a studio-perfect pic of a messy process! Can I use it?
    •  
      CommentAuthordjh
    • CommentTimeNov 12th 2015
     
    Posted By: fostertomWhat a studio-perfect pic of a messy process! Can I use it?

    He must have had my wife there, hoovering out the trench :devil::bigsmile:
  1.  
    Nice picture. Is that Compacfoam below the door threshold or a different grade of EPS?

    David
    •  
      CommentAuthordjh
    • CommentTimeNov 12th 2015 edited
     
    Posted By: djhHe must have had my wife there, hoovering out the trench

    In fact, is that a Dyson-like cylinder cleaner I can see at the far end of the trench?
  2.  
    Shevek, nice work, looks good. Ours would very similar, just wondering what you will backfill with and will you put a french drain at bottom?
    • CommentAuthorShevek
    • CommentTimeNov 15th 2015 edited
     
    Ha, thanks guys. Feel free to use the pic Tom. That is indeed a Dyson vacuum cleaner you can see.

    You would laugh if you saw how we use the hoover when working with EPS (it's not far behind any rasping and held directly below anyone doing any sawing). I've also been seen hoovering our garden and the neighbour's driveway.

    The white bit below the door is 250 or 300 kPa EPS. We were originally going to butt the EWI up to the underside of the existing brick sill but this really bugged me (as it would be the only very cold thermal bridge in the house). Fortunately at the last minute it occurred to me to simply cut off the brick overhang and do the whole section in a different grade of EPS (of which we had some left over from elsewhere). We're going to fit an aluminium sill over that section.

    We backfilled with 200 mm thick of leca, partly because it has some insulation value but also because it absorbs some moisture so I was thinking perhaps that will help prevent the trench from filling up with water.

    Despite the garden sloping slightly towards the building we didn't put a french drain in. We've done a lot of things the right way on this project but I just couldn't be assed with this one. My main concern is that it would eventually silt up without maintenance and be useless anyway. We dug down 100-150 below the top of footing so there's a little channel down there to fill up with water before it reaches the insulation. We're also going to put a line of paving along the wall there and fall it towards the garden slightly.
    • CommentAuthorTriassic
    • CommentTimeNov 15th 2015
     
    Nicely supported gas meter!
    • CommentAuthorgravelld
    • CommentTimeNov 16th 2015
     
    I thought the Dyson was R2-D2.
    • CommentAuthorShevek
    • CommentTimeNov 16th 2015
     
    Yeah the gas meter was an ass. A new one was put in before we did the insulation so we had to work around it. Fixed to the wall now.
Add your comments

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

© Green Building Press