Insulating a circa 1900 house (gut-rehab)

I live in VA, zone 4A. I am trying to decide how to insulate a circa 1900 house with the interior completely gutted. It is a two story ballon-framed house with a brick foundation and a tall, steep roof. It has a standing seam metal roof in good condition. It has lap siding attached directly to the studs (i.e. no sheathing). I am considering foam and fiberglass bats for the walls (2 in of spray foam) and cellulose for the attic floor. I have also been reading this site's posts about sealing up the crawl space and am planning to do this as well using foam board on the walls.

I am worried about spraying foam directly on the back of the siding. To avoid this I am considering installing 1 in. foam board and then an addition inch of spray foam.

Any thoughts about this plan? Any other suggestions for insulating the walls or other parts of the house?

Thanks,
Duane

Asked by Duane Barron
Posted Fri, 03/15/2013 - 21:48

Tags: Green building techniques

1.

Duane,
You're right: it would be a very bad idea to install spray foam directly against the back of the siding. Your suggested approach (installing a layer of rigid foam between the back of the siding and the spray foam) makes sense.

If the time ever comes to replace the siding, it would be a good idea to install wall sheathing and a water-resistive barrier (for example, a layer of asphalt felt).

Pay attention to air sealing at all phases of your rehab project. It's also important to upgrade any knob-and-tube wiring before insulation work begins.

Answered by Martin Holladay, GBA Advisor
Posted Sat, 03/16/2013 - 05:35

2.

Thanks for the advice. I'm learning a lot on this website.

Answered by Duane Barron
Posted Fri, 03/22/2013 - 23:19