Hi all, I'm building a modern house in Seattle (http://phinnymodern.blogspot.com). We're considering upgrading our insulation from standard batt, and one of the most-effective proposals is a very new system by Knauf, called Ecoseal (http://ecoseal.knaufinsulation.us/). It seems to be an elastomeric glue that is sprayed into all joints for airtightness; then standard batts are used after that. Anyone have any thoughts? It sounds good, but I'm wary of choosing a totally new and untested product.

Sealing every stud bay is good, but new standard batts have all of the same installation issues as old standard batts- easy to install perfectly in a lab, not so much in the real world, leading to cavity convection issues, gaps, compressions etc. Typical real world installations of batts underperform test lab conditions by double-digit percentages.

It's easier to get a gap-free near-perfect job with sprayed or blown goods. Flash-foam sealing/insulating the sheathing/stud transition with 1" of closed cell polyurethane with sprayed cellulose for the remainder of the fill gives you ~ R15 clear-wall in 2x4 construction or ~ R22 clear wall in 2x6" construction. If you want higher R than that you can buy a couple more using 1.8lb density ultra-fine new school blown fiberglass like JM Spider or Certainteed Optima. (Cellulose is usually the value-leader for price/performance.) Standard density batting loses R value at high temperature differences due to high convection rates within the insulation layer, where cellulose & high-density fine fiberglass show very little loss (if any).

Air sealing all framing joints (not just the stud-bay framing) is always a good idea, as it pressure testing/remediation of the building shell before the insulation goes in. The EcoSeal system may or may not outperform other air sealing methods over time, but clearly doing ANY amount of air-sealing of the framing is a long step ahead of traditional methods where no sealants are used.

I would like to try EcoSeal for air sealing. It sounds like it would  work for a minumum cost. Has anyone seen, tried the product? If so what was the results?

As an owner-builder planning on doing my own air sealing detail work I am interested in this, or other similar products. Until now I had been thinking of using a caulking gun to do the interior air sealing work – but the airless sprayer seems much faster/easier.

EcoSeal’s website implies they sell only to contractors and I’m not clear on whether they sell just the sealant without their batts, so that would take some investigation. However a google search on “water based elastomeric sealant” turns up a variety of similar products sold in 5 gal pals. Some of them are even rated for fire blocking.

Are the use of water based spray-on elastomeric sealants common for extensive air sealing in a house (i.e. not just the odd wall penetration)?

Thanks!

Hi all, I'm building a modern house in Seattle (http://phinnymodern.blogspot.com).

I think the link to your place is misspelled. If you fix that people could see your cool project.

Sorry, http://phinneymodern.blogspot.com.

BTw, we ended up not going with ecoseal, because the contractor who offered it was already substantially more expensive just for the batt component of the job. (Though the ecoseal component was well priced.) We just had our contractor go through the house and spray foam anywhere daylight was coming through before batts were installed.