Friday, December 5, 2008

Bio-based Insulation in action!

A few days ago, the crew from Northend Barriers arrived with their trendy Bio-Based trailer and generator, ready to knock out our little row house project in just a day.

We were lucky to get them, as Northend is currently booked straight through the spring, installing BioBased on a number of very large jobs. Because our project is several months behind schedule, we were afraid that we might have lost our place on the list. After a few pleading phone calls from us and our contractor, reminding them that we've been in touch periodically with schedule updates, the good guys at Northend finally agreed to fit us in between two of their larger jobs. Two men dressed from head to toe in white jumpsuits arrived mid-morning and stayed on until nearly 9pm to finish the job. The suits are primarily projection to keep the guys clean and adhesive-free. The foam itself is not hazardous to the touch but is very sticky.

Check out this stuff out in action!

After learning more about the cost difference between closed cell and open cell spray foam, we specified a combination of the two for the project, depending on the thickness of the wall, its location, and the desired R-value. By making these changes, we were able to reduce the overall quote by about 40%. The closed cell foam is roughly twice as much money as the open cell, and we had originally planned to use closed cell throughout. Finally, something has turned out to be LESS expensive than we had anticipated. It's a good thing.

After installation, the foam is shaved off so that it's level with the studs, and fills the void between the studs. In reality, the stuff is rarely perfect as there is some variation in depth and consistency (at least in our case). We had the crew save the scraps, which can be used to fill up any major gaps- such as behind pipes or other hard to reach areas- or thrown into a typical unconditioned attic space to beef up the existing insulation. We have a few quirky spaces where new and old construction meet and were able to fill in a few holes by using the leftovers, and a few cans of that off-the-shelf expandable foam. We still have about 8 bags left in the back yard and will probably offer it up on Craigslist or Freecycle soon.

By the end of the day, the only casualty was our truck, which had been parked out front for a few hours. Turns out there was a small gap between the brick facade and the cornice. The foam made its way through the crack, through the air outside, and down onto the side of our truck. The foam part came off easily, but the adhesive part was the problem. It looks like it will scrape off of the glass fairly easily with a razor blade, but we're still waiting to hear back from our contact at Northend Barrier (Tom Purcell) to find out how (and if) this stuff can be removed from the truck body without damaging the paint job.

The lessons learned on this job (other than keeping the truck far, far away) are that next time we would strongly consider waiting until the heat is turned on to spray the foam. The next day, we noticed several places where the foam pulled away from the studs about 1/4" due to the temperature differential. The foam is heated and pressurized in canisters before being sprayed into the wall cavities. The house itself was definitely cold, especially so after sundown, when the work continued late into the night. Because of the scheduling difficulties, we were hesitant to wait any longer and it was unclear when the next opportunity would be to get a crew. We filled some of the gaps ourselves the next day but Northend has agreed to come back and hit the larger areas. We decided to hold off on "taping and mudding" the drywall for a few days so we could simply remove the drywall screws and pop the boards off in the areas that need more insulation.

The other downfall to the spray foam is that it could make rewiring extremely difficult (especially the #1701, the closed cell). Also, for architects that are used to working with precise, exact materials, this stuff is not going to be in your comfort zone. The stuff is messy and blobby and the control is modest at best. The overspray can't help but get in places it shouldn't, like J-boxes and around pipes. It has a life of its own. I admit, it does take some getting used to. The performance is where the spray foam excels- we've been able to achieve R-20 in just a 2x4 stud wall. And in a renovation project, we feel comfortable knowing that the foam is going to keep the old envelope (and the new) super tight and efficient.

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