Exterior Insulation

This blog post will detail how we went about creating a continual layer of insulation around this (completely uninsulated!) 1895 solid brick home.

Here is a picture of the home in more or less original condition. The original color was grey, but here you can see that much if the house is white after painting it with the Sherwin Williams “Sherlastic” Elastomeric Paint. More on that later.

First I cleaned and prepped the brick, and painted it with 2 coats of the Elastomeric Paint.

Ignore the window installation for now. Just take note of the 2 x 4’s attached to the brick wall. Note that they are attached “on the flat.” They were attached using tapcon masonry screws.

In between the 2 x 4’s rigid polyiso insulation boards (they are silver because they are foil faced) were glued to the wall. These boards were 1.5 inches thick so that they are flush with the 2 x 4’s.

Next a second, continual layer of polyiso insulation was installed over everything. For our project with used a 2 inch board thickness for this layer, to bring the total R value to 19 (3.5 inches x an R value of 5.5 / inch).

Then 1 x 4 furring strips were attached over the continual 2 inch layer of polyiso. The furring strips were screwed into the 2 x 4’s on the flat which were beneath the 2 inch boards of polyiso.

Finally siding was mounted to the 1 x 4’s using a rainscreen detail. Since the polyiso boards were foil faced, we did not use a house wrap.

But now on to the roof!

We used similar approach was used for the roof. Firstly the old shingles were removed, a Henry Blueskin Membrane (air tight, vapor open) was placed over the entire roof.

Note that during earlier during the project we had applied some Blueskin directly to the brick and then lapped it up under the shingles. This way after the shingles were removed, the Blueskin on the roof would overlap this “lapped up under the shingles” Blueskin.

Next we put 2 layers of 2 inch polyiso board insulation over the Blueskin, and then OSB on top of that. Note that every layer of polyiso was both glued and screwed into the roof sheathing underneath, and that the seams of the polyiso boards were staggered to create a better layer of continual insulation.

A roofing underlayment went over the OSB, and finally a standing seam metal roof.

And this is what the house looks like in the end (well, almost — still need the gutters). Basically we coated the entire home, walls and roof included, with a continual layer of insulation.

Finally, in the basement we coated the walls with a 6 inch layer of spray foam. This was applied directly to the wall with the walls basically “as is.” The basement was not a very usable space to begin with (other than storage) so are not going to drywall over the foam, and as a result a flame retardant coating was sprayed over the foam to meet code.

The home was previously completely uninsulated, and was very cold and drafty in the winter. With a new continual later of insulation we are looking forward to a much more comfortable (and energy efficient) home this winter!

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