IWI using insulated lime plaster and the Green Deal

[Anonymous]

Hi
We recently had a Green Deal assessment done on our multi-period house with a variety of solid walls (brick and flint; brick; brick base with timber frame/cladding) with a view to installing IWI. We're finding it hard to identify natural/traditional breathable products that meet the Green Deal requirements and Green Deal installers able to use them. Our inclination is to add an insulated lime plaster internally as the wall surface varies with the different ages of the building and the oldest part features exposed timbers. We also have an issue with rodents and glis glis who could destroy anything fibrous so were thinking the compressed wood/fibre boards etc wouldn't be a good idea. A depth of up to 40mm would probably be bearable and we are envisaging stripping off the existing wall finishes to take them back to bare masonry to remove gypsum and woodchip. We've been in touch with some of the retailers of insulated lime plasters and understand that having a product with a European norm should be acceptable. Does anyone have any insights on that please? And does anyone know of an installer who is willing and able to use. We are based north of High Wycombe.
Many thanks
Ali

[Anonymous]

Hi,

I'm not sure I can help you with your particular query. However, if you haven't already done so, you'll need to consider the following:

With IWI, the existing structure will become significantly colder as it will be outside the insulation layer. Unless there is a really well sealed air barrier, moist air will pass through the wall from inside to outside. When this air reaches the cold original walls, surprisingly large amounts of water will condense inside the existing walls making them wet. Damage will likely occur.

Sorry if I'm insulting your intelligence! However, there may be others who benefit from the above.

Best regards,

Andy

[Author]

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