Go to Forum Home Building Design external insulated cladding

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    • #30468

      What are members opinions and experiences of external insulation products.
      A lot of products out there

      Environmental credentials?
      Ease of use?

      looking to do something for solid slate walled welsh housing. difficult to fix to slate & lime rubble walls. Any non toxic but effective adhesive systems.

    • #32790

      Might be worth asking Natural Building Technologies (http://naturalbuildingproducts.co.uk) as they do an external insulation that can be rendered. Need to be careful with your detailing.

    • #32791

      Hi PB
      we have used their external insulations before (good for reducing thermal bridging of the timber studs in timber frame walls), but never rendered (always behind timber cladding). Have you had direct experience on a project of using their pavatherm plus with render? Also does your warning on detailing suggest you have had issues with this system?

      We are exploring externally applied (to dense concrete block walls) eps, cheapest quote so far is permarock, not sure if mechanically fixed or glued (issues are mainly thermal bridging of loads of metal fixings through the insultation, although need to know what the glue would be). This system uses a proprietry render, with plymer reinforcment.

      we are comparing costs with an external timber frame supporting timber sheathing and render carrier layers, containing cellulose insulation. this option is our preferred – for local upskilling reasons mainly – but is thicker, the insulation being less effective compared to the higher thermal performance of eps.

    • #32792

      I would also worry about the glued on solution, and will find out more. Mechanical fixings just add a bit to the thermal bridging so might have to add on another 25mm or so (will ask david) to the eps thickness to counter these losses. I still kind of hope the timber box and warmcell wall insulation solution will be as cheap as the eps system…

      I am not going to comment about cellulose and mice, wasps and birds….

    • #32793

      Hi James,
      what is the lowest u value achievable when this system is used over 100mm dense concrete block? Can you also supply same to go external to the walls below dpc and into the ground…approx. 750mm below ground level? Are you meaning steel or timber dowels?

    • #32794

      Have you had a look at the AECB Energy standards section on the web site and downaoded this…? https://aecb.net/PDFs/aecb_2pp_new.pdf.

      We are encouraging members to design to these standards, requiring backstop U values around 0.24 for Silver and 0.14 for Gold for walls (typical semi detached house etc..) ….where does this leave your system – can you deliver a system to this level of performance?

      best wishes


    • #32795

      Virtually all new German houses have glued-on external insulation, though more often on clay or calcium silicate blocks than on concrete blocks. The Passive House standard demands a maximum wall U-value of 0.15 W/m2K including the effects of any thermal bridging; usually it is nearer 0.10 W/m2K. They started building houses, flats and offices to this standard in 1990 and of the 6,000 built by 2006 some 70% were masonry walls with external insulation, the rest were concrete or timber.


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