have been granted for a block work outer skin. We have since been advised by a couple of different specialist heating experts that block work as an outer skin for a timber frame is a waste of money and the outer walls can be rendered directly onto a mesh over the timber frame. We are mindful of the cost saving and would be pleased for your advice as to this option. It is also suggested that a different type of render should be used over mesh – can you recommend a suitable type. Our builder has previously experienced “crazing” of render when applied over a mesh.

  • Ash Theasby

    You can get a render board that would go on to your timber frame. You would have to put baton on the exterior of your frame and then attach the render board to this which would allow you to render onto the render board and avoid the need for the block outer skin. The advantage of doing this is the render board (depending which one you use) has some insulation properties as well therefore it would increase the thermal efficiency of your building. As for saving cost I think both methods would probably work out similar as both need to be rendered (or cladded) still and the render board costs about the same as the blocks. I looked into doing this on my first house a few years ago and at the time the render board was relatively new and cost more than doing it in block work. If you have a specific product in mind post it you might get some more details. FYI block work costs about £5/m2 for materials and £12/£13/m2 to lay, it’s definitely not a ”waste of time” as an outer skin as it’s fairly cheap and quick if you have a good blocky BUT it doesn’t add anything to your insulation of the house.If you’re doing a timber frame this should be well insulated anyway so this shouldn’t be a problem. Hope that helps.

  • Vince Holden - Construction Project Manager Holden

    No matter what, you have to create a minimum of 50mm cavity to the outside of the timber frame.
    If you go down the block and render route, you could use an aircrete block (Thermolite or Celcon etc) which definitely WILL improve the overall uValue. You then have the choice as to what type of render you use

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