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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
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      CommentAuthorfostertom
    • CommentTimeJun 18th 2020
     
    Well, it's very good to have so thoroughly explored one of the fresh-thinking ideas that GBF is good at producing.
    • CommentAuthorEd Davies
    • CommentTimeJun 18th 2020
     
    Posted By: fostertomMaybe the screws will be put in bending whether they like it or not, unlike the ropes.
    Yep, they'll bend a bit and stretch a bit till the strains equilibriate but the bending moment will be less than it would be with the screw straight out.
    • CommentAuthorgoodevans
    • CommentTimeJun 19th 2020 edited
     
    In respect of the 'sagging' issue...

    Screws perpendicular to the wall would work fine provided that you can be sure that the EWI, which I presume is EPS, will not compress or creep over time - this will not be true so is not an option in my opinion.

    Screws inclined at an upward angle would alleviate that - but much longer screws are required.

    My EWI is secured to the wall only by adhesive, and then a thin coat render was applied. So far no failures - and the render is heavy. So my guess is that all EWI can take significant vertical load if spread over a significant area.

    One solution would be to use screws to prevent the battens being pulled out by wind forces, but if you wish to prevent sag use a hot knife cutter with a right angled grove cutter like in the photo this to create horizontal groves into the eps and embed battens into the eps. Use EWI adhesive to ensure the horizontal battens interface with the EWI over their entire length and screws to prevent pullout. If a horizontal batten sits in a grove - even a shallow grove, it won't slide down unless the eps falls of the wall!

    A similar principle could also be applied to vertical battens - use adhesive to bond the batten to the eps to prevent sag and screws back to the wall to prevent pullout due to wind. This requires the adhesive to work well with both the EPS and the batten and over the long term. In this situation I would use adhesive to sick the batten to the eps first ensuring the adhesive has the corrrect thickness and is not squeezed out, then once cured screw the battens back to the wall to prevent pullout.
      IMAG1009a.jpg
  1.  
    If you have vertical battens then IMO the best option would be to sit the battens on the ground or hang them from the soffits or eaves - or both.
    If they are horizontal then fix with screws through to the wall and support the battens with 20mm EPS glued to the main EPS and abutting the battens. Gaps can be left if the space has to be vented, alternatively vertical in-line battens periodically placed between the horizontal battens to transfer the load to the ground. The aim in each case being to remove the sheer load from the screws.
    • CommentAuthorgoodevans
    • CommentTimeJun 19th 2020 edited
     
    for no slip battens without adhesive make the battens into 'gripper rods' (as in carpet gripper rods but bigger) by punching in stainless steel nails through the batten every 50mm or so before installation. The nail points need only protrude approx 10mm from the batten.

    Press into the eps, then screw back to the wall. Every meter of batten would have 20 points stuck into the eps. It would need a test but I bet they would need a tremendous force to slide against the EPS.

    With a nail gun a batten could be prepared within a minute or so and with 1000 S/S nails priced at ÂŁ15 it would cost less than ÂŁ1 per meter of batten.

    This would also work for roof tile battens. Provided the insulation is secured against slip a bunch of points sticking out of the battens would do a grand job to prevent slip (with screws throgh to the structure to deal with the pull out).
    •  
      CommentAuthordjh
    • CommentTimeJun 19th 2020 edited
     
    I don't know about everybody else, but my build-up goes, from the outside, horizontal cedar cladding, vertical battens, breathable membrane, graphite EPS, OSB, studs infilled with mineral wool, poly VCL, skimmed plasterboard.

    The battens are secured with long screws, angled upwards through the EPS to the OSB and studs, and yes, they're stood on the upright paving slabs that cover the outside of the floor/foundation insulation. The cedar boards are nailed in so perhaps the nails project into the EPS as well. I think this is known as 'covering your bets' :bigsmile: This is the unheated conservatory, BTW.
    • CommentAuthorgoodevans
    • CommentTimeJun 19th 2020
     
    That ain't falling off
    • CommentAuthorteach_glas
    • CommentTimeJun 20th 2020 edited
     
    Thanks so much for the replies, this thread is turning into a great resource. :bigsmile:

    I really like the idea of cutting a channel into the EWI and glueing + fixing a batten into the slot! I have plenty of depth (200mm) to play with.

    Posted By: goodevans

    A similar principle could also be applied to vertical battens - use adhesive to bond the batten to the eps to prevent sag and screws back to the wall to prevent pullout due to wind. This requires the adhesive to work well with both the EPS and the batten and over the long term. In this situation I would use adhesive to sick the batten to the eps first ensuring the adhesive has the corrrect thickness and is not squeezed out, then once cured screw the battens back to the wall to prevent pullout.
      http:///newforum/extensions/InlineImages/image.php?AttachmentID=7601" alt="IMAG1009a.jpg" >


    Vertical battens may be the way forward for me as to achive required ventillation behind cladding board.

    So: embedded and glued vertical batten, membrane then horizontal counter-batten then cladding boards.






    Plan view sketch below, can I use my EWI plastic mechanical fixings (in blue) through the vertical batten???
      cladding sketch2.JPG
    • CommentAuthorgoodevans
    • CommentTimeJun 20th 2020 edited
     
    On the above plan your counter battens will block the free passage of water that may get behind the cladding - your vertical battens need to protrude from the EWI to allow the free passage of water. You may need to use spacers or some other method to pull your horizontal counter battens away from the membrane.

    Your EWI fixings may be suitable but remember the suction forces on the battens may be significantly greater than on EWI. (like roof tiles, cladding has air behind) - during wind gusts the pressure difference either side of the cladding can create sizeable forces. I don't know the recommended fixing size and spacing for cladding - whatever it is I would not reduce that holding down capacity.
    • CommentAuthorteach_glas
    • CommentTimeJun 21st 2020
     
    Posted By: goodevansYou may need to use spacers or some other method to pull your horizontal counter battens away from the membrane.


    Hmm.. maybe a thin slating batten fixed vertically to the embedded timber. That way I could use it to fix the membrane in place before horizontal counter-batten.



    Posted By: goodevans
    Your EWI fixings may be suitable but remember the suction forces on the battens may be significantly greater than on EWI....


    This is a good point, I will try to talk to the plastic fixing manufacturer and see if I can get a response.. i'm guessing that they will say: 'do not use for anything other than intended use..' or similar. So it might have to be long metal screws that will cause a thermal bridge, but maybe not significant?


    Thanks so much for your help goodevans, this has really given me something decent to bring back to my engineer! :smile:
  2.  
    Not seen it done anywhere, but what if the 'horizontal’ battens were fitted sloping at an angle of say 20deg so they couldn't collect water? Maybe in shortish overlapping lengths so water would drain sideways along the batten then drip?
    •  
      CommentAuthordjh
    • CommentTimeJun 21st 2020
     
    Posted By: WillInAberdeenNot seen it done anywhere, but what if the 'horizontal’ battens were fitted sloping at an angle of say 20deg so they couldn't collect water? Maybe in shortish overlapping lengths so water would drain sideways along the batten then drip?

    I was going to suggest arris rails (though google shows me I'm actually thinking of cant rails :) Can be made by cutting a wider batten into two by sawing at an angle - but not good with treated timber.

    I went with horizontal cladding, initially with the idea that I could replace the bottom board or two if they rot faster than the rest, rather than have to replace all boards. Then when I realized just how much simpler it made all the mounting issues, I became doubly convinced! Not only are the battens vertical so there's no drainage problem, but it's easy to align them with the studs so there's guaranteed material to screw into.
  3.  
    Treated Arris/cant rails are widely available for fencing, but would still require a counter batten to make a drainage gap behind them.

    Sorry if not clear, I meant if you stand facing the wall, the 'horizontal' battens could slope down gently from left to right to drain water across the wall to the right, or vv. 'Inclined' battens rather than 'horizontal' I suppose.

    ISTR an earlier thread where someone cored holes into their 200mm EPS to insert 200mm lengths of 32mm pvc drainpipe, foamed into place and foam-filled. Then drove the screw through the middle of the pipe to hang heavy things off. When tightened, the fitting was compressed against the end of the pipe, which acted as a standoff, instead of crushing the EPS over time. Could be an alternative or complement to the idea of cutting channels in the EPS to recess the batten?
    • CommentAuthorteach_glas
    • CommentTimeJun 22nd 2020
     
    Posted By: WillInAberdeen

    ISTR an earlier thread where someone cored holes into their 200mm EPS to insert 200mm lengths of 32mm pvc drainpipe, foamed into place and foam-filled. Then drove the screw through the middle of the pipe to hang heavy things off. When tightened, the fitting was compressed against the end of the pipe, which acted as a standoff, instead of crushing the EPS over time. Could be an alternative or complement to the idea of cutting channels in the EPS to recess the batten?


    This is pretty cool!
  4.  
    Posted By: djhI went with horizontal cladding, initially with the idea that I could replace the bottom board or two if they rot faster than the rest, rather than have to replace all boards. Then when I realized just how much simpler it made all the mounting issues, I became doubly convinced! Not only are the battens vertical so there's no drainage problem, but it's easy to align them with the studs so there's guaranteed material to screw into.

    +1
    IMO horizontal cladding and therefore vertical battens stood on the ground or hung from above is a lot easier plus there is less chance of water seeping in long vertical cladding joints
    • CommentAuthorJonti
    • CommentTimeJun 22nd 2020
     
    Posted By: Peter_in_Hungary
    +1
    IMO horizontal cladding and therefore vertical battens stood on the ground or hung from above is a lot easier plus there is less chance of water seeping in long vertical cladding joints


    Could you not also do vertical battens stood on the ground or hung from above with lateral battens attached for vertical cladding? If you use full height cladding it too could be stood on the ground to ease weight issues.
    • CommentAuthorEd Davies
    • CommentTimeJun 22nd 2020
     
    Posted By: JontiCould you not also do vertical battens stood on the ground or hung from above with lateral battens attached for vertical cladding?
    You could but then you'd finish up with two lots of battens having to be “structural”.

    With vertical cladding the normal thing (e.g., in my gables) is to have thin vertical (counter-)battens (12x35) nailed to the structure behind (OSB and I-beams in my case) with heftier (38x50) horizontal battens across giving a total ventilated space of nominally 50 mm (12 + 38). If the vertical battens are also bearing the load of the cladding they'd been to something like this size too meaning more timber and a bigger ventilation cavity (say 38 + 38 = 76 mm).
    • CommentAuthorJonti
    • CommentTimeJun 22nd 2020
     
    Understood Ed and thanks for the answer. I would have thought that with the correct metal vertical and lateral battens the strength and weight issue would be addressed as well as the size of the gap. If the cladding is then stood on the ground then its weight would be largely self supporting.
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