Building Science

Air Sealing the Ceiling Joists in an Attached Garage

Posted on June 28, 2017 by Allison A. Bailes III, PhD

The I-joists in the lead photo here run across the top of the wall between the dining room and the attached garage in this home under construction in the Atlanta area. In the old days, before anyone worried about air moving through those joist cavities, the builder didn’t bother to do anything beyond securing the joists.

You can see here, though, that the builder of this home knows a thing or two about air sealing because they've put blocking between the joists. But what do they do next?

Combining Sheathing With a WRB and Air Barrier

Posted on June 22, 2017 by Peter Yost

Full Disclosure: First, there are a lot of different ways to get continuous air and water control layers on the exterior of a building enclosure. You can use housewrap, taped-and-sealed rigid foam insulation, liquid-applied membrane, or either the Huber Zip or Georgia-Pacific ForceField system. Each approach has strengths and weaknesses.

Climate Change Is Just a Theory

Posted on June 14, 2017 by Allison A. Bailes III, PhD

So the United States has announced it's withdrawing from the Paris Accord, the international agreement with nonbinding measures to mitigate the effects of climate change. Now everyone's up in arms, speaking in exasperated tones about the travesty of this decision.

"But... but... the science," they say. Yeah, let's talk about science.

Is Compressed Fiberglass Insulation Really a Problem?

Posted on June 7, 2017 by Allison A. Bailes III, PhD

I've been guilty of perpetuating a myth. Not long ago I wrote an article in which I said installing insulation, "cavities [should be] filled completely with as little compression as possible." But is compression really such a bad thing? Here on GBAGreenBuildingAdvisor.com, commenter Dana Dorsett wrote, "Compression of batts is fine (resulting in a higher R/inch due to the higher density) as long as the cavity is completely filled.”

Heating Degree Days Drop Again in 2017

Posted on May 24, 2017 by Allison A. Bailes III, PhD

We've had some beautiful cool weather here in Atlanta this spring. It's about 50°F outdoors as I write this, one week into the month of May. The high yesterday was only about 70°F.

We're getting a few more heating degree days (HDDThe difference between the 24-hour average (daily) temperature and the base temperature for one year for each day that the average is below the base temperature. For heating degree days, the base is usually 65 degrees Fahrenheit. For example, if the average temperature for December 1, 2001 was 30 degrees Fahrenheit, then the number of heating degrees for that day was 35.) in the middle of May. (Heating degree days are really just another way at looking at temperature, which I explained in more detail in a look at the fundamentals of degree days.) We occasionally pick up some HDD even in July and August. But it's the winter HDD that matter for heating — and that give us a clue about the climate.

Installing Basement Waterproofing from the ‘Negative’ Side

Posted on May 18, 2017 by Peter Yost

Negative-side waterproofing (NSW) is a tough topic that I have frankly been dancing around for quite some time. Manufacturer claims and homeowner anecdotes of successful interior waterproof solutions for basement walls and slabs did not completely add up. But I did not think that I understood the topic or the physics well enough to challenge the claims or explain my skepticism.

Three Easy and Essential Advanced Framing Techniques

Posted on May 17, 2017 by Allison A. Bailes III, PhD

Most new homes in North America are built with sticks. The early home builders used bigger pieces of wood — timbers — and when the smaller dimensional lumber that we use so much today hit the market, they scoffed at those new-fangled little woody things, calling them sticks. Now our home construction industry is full of people who do stick building and the home you live is most likely stick-built. And sadly, many of the techniques used to build many of those homes are the same used before we started insulating them.

The Difficulty of Updating Georgia’s Energy Code

Posted on May 10, 2017 by Allison A. Bailes III, PhD

Seven years ago, Georgia led the nation. Yep. We were the first state to adopt an energy code that made blower door testing mandatory. All new homes built in the state had to show through performance testing that they had an air leakage rate of less than 7 air changes per hour at 50 Pascals of pressure difference (ach50).

The Energy Conservatory’s New Blower Door Kit

Posted on April 27, 2017 by Peter Yost

I don’t do blower door work every day, but I do enough of it to appreciate the attention to detail that The Energy Conservatory (TEC) built into its new blower door kit. The kit features a digital pressure and air flow gauge, the DG1000.

Questions to Ask Your Prospective Builder

Posted on April 26, 2017 by Allison A. Bailes III, PhD

You're having your dream house built. You're into the design phase, working with an architect or looking through collections of house plans. You're doing your homework, trying to find out how to ensure you get a top quality house. And that's when you run into all this stuff about building science, high performance homes, HVAC(Heating, ventilation, and air conditioning). Collectively, the mechanical systems that heat, ventilate, and cool a building. design, blower door testing, and the like. Now you're hooked.

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