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Weatherization Nation 8: Thermal Bridge Busting and Season Recap

Closed-cell spray foam in a two-part froth pack is a fast and effective way to eliminate thermal bridges and air leaks in building assemblies
March 10, 2023

Welcome to ProTradeCraft’s Weatherization Nation. A show about building smart from the start.

Last week we were installing a rainscreen product from Tyvek called DrainVent, which creates a drainage space behind the siding so any water that sneaks back there can be directed away from the house.

This week we’re headed inside to do some air sealing and thermal bridge breaking

One thing that MARK IV does on every large scale renovation project is to test in and test out with a blower door. It helps to quantify how much they tighten up a home, and it also helps to identify any big air leaks in the existing structure.

After air sealing the new structure, but before the drywall goes up, they run another blower door test to look for any leaks they overlooked.

Today, we’re going to watch Mike Beverley use a DIY Froth pack to spray closed-cell foam over some masonry thermal nosebleeds.

Mike: Alright, I’m going to start off by shaking part B. get that nice and shook up and then start the connection process.

Mike begins at the bottom and sweeps the nozzle back and forth, making sure to hit that inside corner where the masonry meets the studs.

Working behind obstacles is a little tricky, but much easier and more effective than relying on batts in areas like this.

Mike: Now it’s time to just let it cure until it is tack-free, which takes about five minutes.

After the foam has expanded to where it’s going to expand, Mike comes back with a hand saw and slices off the excess.

This reveals little pockets of opportunity to fill in. He also gives the whole stud bay the once-over to make sure it is completely full before giving the thumb’s up.

A look back at demolition, crawlspace, framing, WRB, window installation, roofing underlayment, and rainscreen

That takes us to the end of the first Weatherization Nation season for this brick home in Northwest Washington DC.

When we arrived, there was an unfortunate two-story addition that had a lot of water problems. After tearing it off the back, Ray and the guys got to detailing the new crawlspace to be warm and dry by sealing with plastic, insulating with Thermal foam boards, and tightening the edges with GreatStuff expanding foam.

With the addition framed and sheather, the team moved to install the WRB to act as more than just a water barrier, but detailing it to be an air barrier as well.

Next, we installed leak-free windows, and them we climbed up on the roof to do some roof flashing and lay down a Protec underlayment in preparation for shingles later.

With the roof dried in, we moved back to the ground and added some water resistance to the outside in the form of DrainVent, a rain screen product that creates a gap for water leaks to drain away.

And with the outside tightened up and ready to drain, we sealed the deal inside using a two-part froth pack to break the major thermal bridges left in this house.

At this point, we are ready to hit the road looking for the next project!

Previous: Rainscreen on a Roll

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