The most recent blogs at Green Building Advisor

The 2012 Code Encourages Risky Wall Strategies

Posted on July 18, 2014 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

Builders who follow the prescriptive requirements of the 2012 International Residential Code (IRCInternational Residential Code. The one- and two-family dwelling model building code copyrighted by the International Code Council. The IRC is meant to be a stand-alone code compatible with the three national building codes—the Building Officials and Code Administrators (BOCA) National code, the Southern Building Code Congress International (SBCCI) code and the International Conference of Building Officials (ICBO) code.) in Climate Zone 6, 7, or 8 are required to install a minimum of “20+5 or 13+10” wall insulation. What does this mean? According to an explanatory footnote in the code, the “First value is cavity insulation, [and the] second is continuous insulation or insulated siding, so ‘13+5’ means R-13 cavity insulation plus R-5 continuous insulation or insulated siding.”

GBA Welcomes New Readers

Posted on July 17, 2014 by GBA Team in Green Building Blog

Now that the Green Building Advisor website is more than five years old, it has over 36,000 web pages. That's a lot of pages. It's no surprise that it can take a while to find what you are looking for in GBAGreenBuildingAdvisor.com's massive archives.

If you are a relative newcomer to GBA, welcome! Here are a few pointers to help you find your way around GBA.

Energy Efficiency Requires More Than an App on Your Smartphone

Posted on July 16, 2014 by Allison A. Bailes III, PhD, GBA Advisor in Building Science

When it comes to air conditioning, there are a lot of bad products and bad ideas out there. Here are a few: You can buy a cover for your condenser that could kill your compressor.

Foundations — Part 2

Posted on July 15, 2014 by Christopher Briley in Green Architects' Lounge

Phil and I have returned to continue our discussion on foundations. In Part One, we covered slabs and frost walls, and in this part we cover basements and crawl spaces.

The Highlights:

Do you really need a basement? If there's no programmatic need for a basement (like the need for a workshop), then perhaps you can do without one.

Insulation: Inside or outside? There are many reasons to insulate on either side. We weigh the pros and cons.

When the Problem Is Heat

Posted on July 14, 2014 by Scott Gibson in Q&A Spotlight

If you have problems dealing with the heat, you probably wouldn't like the desert Southwest, especially when conventional air conditioning is simply too expensive to use on a regular basis.

That seems to be the case for a GBAGreenBuildingAdvisor.com reader who's trying to learn more about building in a climate where the challenge of staying cool far outweighs the minor and occasional inconvenience of staying warm.

Every House Needs Roof Overhangs

Posted on July 11, 2014 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

Many residential designers pay too little attention to roof overhangs. Roof overhangs have several important functions: they can protect exterior doors, windows, and siding from rain; they can shade windows when solar heat gainIncrease in the amount of heat in a space, including heat transferred from outside (in the form of solar radiation) and heat generated within by people, lights, mechanical systems, and other sources. See heat loss. is undesirable; and they can help keep basements and crawl spaces dry. A house with improper overhangs can overheat in the summer, can suffer from water entry problems at windows and doors, and can have premature siding rot.

The most common design error is to make roof overhangs too stingy. It’s also possible (although much rarer) for roof overhangs to be too wide.

South-Facing Skylights: Threat or Menace?

Posted on July 10, 2014 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

There are two kinds of sunrooms: those that have sloped glazingWhen referring to windows or doors, the transparent or translucent layer that transmits light. High-performance glazing may include multiple layers of glass or plastic, low-e coatings, and low-conductivity gas fill. and those that have only vertical glazing. Sunrooms with sloped (or in some cases, curved) glazing are more common (and, of course, more uncomfortable). In order to make sure that these rooms are sunny, they are often located on the south side of the house.

Four Ways to Find the Size of Your Air Conditioner

Posted on July 9, 2014 by Allison A. Bailes III, PhD, GBA Advisor in Building Science

Do you know what size your air conditioner is? In the world of building science, you'll hear a lot of talk about why oversized air conditioners are a bad idea. Why? Briefly, they don't dehumidify as well, short-cycling wears them out quicker, and your home will probably be less comfortable if the air conditioner is too big. But to know if your AC is oversized, first you have to know what size it is.

Foundations — Part 1

Posted on July 7, 2014 by Christopher Briley in Green Architects' Lounge

Not too long ago I found myself in a deep conversation (pun intended) about frost-protected slabs with some other architects and building professionals. I was surprised at the energy surrounding the topic. We all seemed to have developed substantial differences in the details on our own and we were all learning from each other.

I was equally surprised at how fresh this concept seemed — I mean, haven’t we been founding our wood structures on the ground for centuries now? Millennia, even?

Polyethylene Under Concrete Slabs

Posted on July 4, 2014 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

What goes under the concrete in a slab-on-grade home? In the old days, not much — just dirt. Eventually, contractors discovered that it made sense to include a 4-inch-thick layer of crushed stone under the concrete. The crushed stone provides a capillaryForces that lift water or pull it through porous materials, such as concrete. The tendency of a material to wick water due to the surface tension of the water molecules. break that reduces the amount of moisture flowing upward from the damp soil to the permeable concrete.

Since the crushed stone layer provides a fairly uniform substrate, it also may also reduce the chance that a concrete slab will be poorly supported by random pockets of soft, easily compressible soil.

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