[Greenbuilding] Insulating old house in zone 4A

[Sacie Lambertson]

All I really need some good advice here.  We've purchased an old (1883)
house in very good shape.  We planned to take off and reuse the exterior
siding after we had properly insulated the walls.  But the considerable
expense of doing this with the repercussions for the exterior trim, soffit
etc has forced us to reconsider our interest in doing this the ideal/best
way.

I've done a lot of reading about alternatives but find no conclusive best
way to give us a rainscreen behind the existing clapboard behind which is
sheathing and the interior.  Nor directions about creating an airtight
barrier without taking off the exterior cladding.  We are willing to build
slightly to the interior now but since the rooms are not large we don't
consider building a full second wall inside the exterior wall.

Of concern: rainscreen, air barrier, air tightness

Good article about rainscreens:
http://www.greenbuildingadvisor.com/blogs/dept/musings/all-about-rainscreens

The following is out of GBA:  Comments?  Better alternatives?

*For health and climate reasons I try to avoid foam. If done right
cellulose could work well here I think. A product like Mortairvent, though
designed to be used in masonry walls, can be used to create an air gap
against siding (or a roof deck in a cathedral ceiling.) It combines a
spongy spun polypropylene matrix with an insulweb-like backing and comes in
various thicknesses from .25-.80. Seems like it would work just as well
with spray foam if it was important to have that larger air gap.*

*And if there are not structural considerations, cross strapping the added
interior 2Xs would nearly eliminate thermal bridging.*


Would appreciate advice re best way to handle our situation of properly
insulating these walls to the inside.  The rest of the house will be done
well, new, well-insulated roof, insulated conditioned crawlspace.  It is
the air infiltration issue in the wall assembly that worries me.

thanks, Sacie
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