The Construction of a High Performance Home: Week 4

Posted by Tim Biebel on Feb 28, 2017 9:23:45 PM

Vermont High Performance Construction

At the risk of sounding more like a blog about the weather than one about the construction of a high performance home, I will keep the weather comments brief. Here’s the skinny: the weather changed our schedule yet again!

The roads, which have “never in history been posted in February,” were posted on Thursday, February 23rd. Record high temperatures spelled their demise. After scrambling to find the town road agent and pleading our case, he has given us permission to truck heavy loads early in the morning following cold nights. We are thankful that he was willing to work with us! Otherwise, production would have come to a complete halt for a couple of months by the end of this week. It’s kind of hard to frame a roof if you can’t get the roof framing material to the site.

Last week was a big week. The walkout wall was framed, the basement slab was poured, and 95% of the first floor was framed.

We install 4” of insulation under the slab. Believe it or not, quite a bit of heat loss takes place through the slab if there is no insulation underneath. In addition to the insulation, we also use 15 mil vapor barrier (Stego Wrap) and tape every seam. This also creates a great airtight barrier under the slab that we can count on.

Another insulation detail we employ is at the rim joist. Because of the Insulated concrete forms (ICF), there is an unconventional transition from the top of the concrete wall to the floor system to the wall framing. Normally, the rim joist would line up with the outside of the wall framing above and the outside of the concrete below, but the two inches of insulation from the ICF poses a bit of a challenge. If the Rim joist is set flush with the exterior of the concrete, there is a two inch bump from the ICF. The bump will look odd when the house is completed.

To overcome this mathematical dilemma, we set the rim joist flush with concrete as we normally would, but we “hang” the subfloor and the walls out so they are flush with the outside of the insulation on the ICF. We then cover the rim joist with two-inch rigid foam and everything lines back up. It can be best visualized in the picture here:

Rim Joist, Insulated Concrete Form

With a double 2x4 wall, the interior 2x4 wall becomes the load bearing wall in this situation. More on that in a future post.

This week we hope to finish the exterior wall framing and set the roof trusses. When I left the site this morning, the boys looked well on their way to achieving that goal. Here are some more pictures from last week.

Click here to read week 3 update.

Click here to read week 5 update.

Underslab Prep High Performance Home Vermont

Underslab insulation high performance home Vermont

Concrete Slab Vermont High Performance Home

Walkout Framing High Performance Home Vermont

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Tim Biebel

by Tim Biebel

Tim Biebel is Vice President of Prudent Living, a leading net zero and energy efficiency building company located in Windsor, VT.

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