Rain, Roofing and R-Values

November may be an unpredictable month here in the Pacific Northwest, but there is one thing you can count on. Usually it will rain. Most years, it will rain a lot. The sky will open up and down will pour an amount of water other parts of the country would consider extreme. But here? People just shrug and say, “oh, it must be November. The salmon like it, after all.”

Somehow all this rain accompanied the stage of building everyone hopes to do in dry weather: roofing. Despite this, our roof trusses are on thanks to a small but tenacious crew who didn’t let the weather deter them. Like much of this house, the trusses were built offsite and transported here on the back of a truck thanks to Pacific Homes. Having them in place confirms the look and shape of the house(s), which we have waited for with anticipation.

From a distance, the house looks rather large, but this is a two-in-one job that will accommodate both our family and my parents. The long and narrow design is a feature of passive solar architecture that lets inhabitants enjoy more southern exposure in a greater number of rooms. The result is a building that looks rather, er, huge, but which isn’t really that big when you get right down to it.

Insulating the Foundation Exterior

After admiring the trusses, we spent the weekend racing against darkness (which is now coming one hour earlier in this part of the world) to install insulation around the foundation’s exterior. This included two inches of EPS foam faced with foil on one side and polymeric resin on the other.

We chose EPS foam for a few reasons. First, in our opinion, EPS foam is a better environmental choice than many rigid foams because its manufacture produces less potent greenhouse gases than alternatives like XPS. Second, it will provide an R-value of 9.2 for the bottom of our wall, which my husband notes is the weak point in terms of energy efficiency. (R-value refers to the material’s thermal resistance.  The higher the R value, the more resistance the material has to the movement of heat.)

“The perimeter foundation and footing leaks heat into the ground,” he reminded me as we slogged through the wet sand to install our foam in the pouring rain. “This will keep things warmer and resist insects.” The termite and ant illustrations printed on the foam’s backside suggested this was true. Who was I to argue?

Seeing all that foam encasing our house’s foundation gave me a warm feeling inside, as if I’d just wrapped a giant potato in aluminum foil. My five-year old daughter concurred, getting very excited by the activity. “I’m going to do this myself, mama,” she insisted when I started taping the seams. “I will do this entire one.”

And she did.