Tim,
Not sure if you have seen the Building Science Corp. method for this deep
energy retrofit method, but I would check it out, they have it down pretty
good.  Furring strips are utilized to secure the siding.  I don't think they
would recommend polyiso or house wrap.  Essentially, if you seal the foam
well, you don't need the wrap.

Ben Graham


On 3/10/10 8:29 PM, "Tim Yandow" <[log in to unmask]> wrote:

> Hello all,
> 
> On the subject of green building, I am soon beginning renovation work on a
> 1960's home in Burlington. We are adding an addition to the south and west
> sides of the house. The new envelope will be 2x6 with damp spray
> cellulose. The existing house is 2x4 with fiberglass and the owners would
> like to bottom up the house more, so we are thinking about adding a layer
> of insulation to the outside of the house since all the old vinyl siding
> is coming down and the windows all replaced (most of them have broken
> seals). I am trying to figure out the best way to insulate from the
> outside and make provisions for new corner boards and hardi-plank siding.
> With polyisocyanurate, for instance, there is the problem of not being
> able to add house wrap and needing to use longer fasteners for siding and
> to secure window flanges. Or can strapping be used over that? Then there
> is the issue of extension jams either inside or outside...I would love to
> know if anyone has worked out a good solid system to do this. What I have
> read and seen so far does not satisfy me. Thanks.
> 
> Tim Yandow

Those who give up freedom for safety, deserve neither.
Benjamin Franklin
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Ben Graham
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