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  • Writer's pictureAdrian W. Osgood

Let's talk insulation.

Hi there,

Its been a while since my last post so first thing first. Delta T Energy is expanding faster than we could have expected. In the process of taking on more people and training them I have let the blog gather dust so I sincerely apologize if you've been biting your nails into oblivion while anticipating the next deposit of green building knowledge to be delivered to your supple(always wanted to use supple in context yet haven't had a chance until now) brain. Today I wanted to touch base about something really important in construction but which 99% of people probably didn't know was a thing. That is quality insulation installation which is better know as QII.

Here is a little pretext. Recently, Delta T Energy has been involved in a number of Advanced Energy Rebuild or AER projects. For those of you outside of the Northern California area you're probably thinking, "What is AER and why do I care?" For many of you the appropriate answer will be, "nothing and you shouldn't", but for those of you who are living in fire ravaged Northern California the response should be something more along the lines of, "a home designed within the scope of the AWESOME green building rebate program designed to award homeowners for rebuilding their home with new/advanced green technologies and energy efficiency measures", and because your grand-babies will live on this planet -you should care.

One of the requirements for this type of project is that the home requires rigorous QII inspections throughout construction in order to achieve the level of efficiency set forth as the benchmark for the rebate program. Essentially the inspections consist of three major steps.

First, during the rough-in stage of construction, air-sealing must be completed and then verified by an inspector to ensure the entire envelope of the house is sealed.

As you can see as you flip through the pictures above this process includes sealing any penetrations through the floors including plumbing, gas, or electrical lines. This is really important. Insulation materials are designed to stop the movement of air, however, in a strong wind a house can have a pressure differential as high as 50 pascals from the inside to the outdoors. Pressure, like heat energy, moves from areas of higher concentration to areas of lower concentration -ergo your warm air inside your home rushes to the outdoors.

The easiest way to stop air movement is to fill in all of those cracks and crevices to the outdoors with a non-expanding foam. We seal around window and door frames, attic/ceiling penetrations, and top/bottom plates where needed. The goal is to achieve a low ACH (air changes per hour) test target -typically around 2 or 3 for a tight home. We will then perform a blower door test to ensure we are reaching the desired test out level.

The second step is also very important. Insulation must be installed perfectly.

That means insulation must be de-laminated and wrapped around conduits/electrical wiring, cut to fit electrical boxes, and applied in a fashion that retains the full depth and R-value of the insulation. Compression of batt insulation can ruin its thermal resistance properties which in turn will allow more of your hard earned winter heating through to the outside.

Insulation is designed with air-pockets in order to slow the movement of energy. When you compress the insulation you remove the air pockets and it cannot function as designed.

Another important aspect of the second stage of inspections if verification of spray foam insulation. For this the inspector must have the ESR report for the specific type of insulation being applied. We then cross reference the product specifications and depth requirements with our own measurements.

The idea is to ensure that the foam has dried completely (no more chemical reactions taking place) and fills the cavity as much as possible. While this sounds super high tech it is literally just sticking a yard flag into the insulation and measuring the amount it goes in-not exactly rocket science.

You might wonder what would cause a foam insulation to not be installed properly. Moisture is one issue. Many installers will not spray when there is a coastal fog. The moisture keeps the chemicals from combining which results in a gooey formaldehyde substance sloughing off your walls. It's not the desired effect, could potentially cause long term health issues, and would be a total pain in the ass to have to clean up. Alternatively you could have mechanical mixing components malfunctioning during the install. The components of spray foam are typically mixed on site at an exact ratio. Errors with equipment may result in poor quality application.

The third and final step of QII is the air-barrier inspection. After the walls and roof are closed in we make sure the air barrier is continuous and sealed/taped appropriately. This test seems crazy to most people as the air-barrier in question is the drywall and/or sheet-rock being installed on the interior surfaces. See the red outline in the image below to get an idea of what we are looking for. Most contractors wouldn't build a house and skip the part where you put the walls up right? You would think that aspect of building would be pretty straight forwards.

The focus of this particular inspection is really on areas where large amounts of air movement can occur like framed bump-outs for fireplaces or shower/bath inserts. We also often find people not installing drywall beneath stairs on exterior walls. That too can result in a large thermal loss because the space beneath is very large. This allows convection to severely reduce the performance of the insulation.

Take a look at this framed bump-out fireplace. You will see that we applied closed cell spray foam to a depth which achieves a vapor and air impermeable rating. In doing so we eliminate the need for installing drywall in an area which is next to impossible to access normally. However, were we to overlook an assembly like this there would be long term energy losses.

Looking at QII from an outside perspective probably seems like a crazy venture to most. Having discussed our QII practices with builders from outside of the State of California I've found our insulation requirements are far more stringent and require vastly more attention to detail. It may seem crazy but on the other hand when you look at the long term dividends paid in the form of energy savings it really does make sense to take these extra steps on the front end. With a few hundred dollars of increased costs (both materials and man hours) a home can see a lifetime savings of thousands of dollars in energy costs. Add on the fact that we can do a TDV calculation prior to the project even beginning to determine the ROI and its a win win for the homeowner.

As always let me know what you think about the topics I am covering. If you have any questions or anything else to add leave it in the comments. Thanks!


Delta T Energy

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