Musings of an Energy Nerd

Three Code-Approved Tricks for Reducing Insulation Thickness

Posted on December 15, 2017 by Martin Holladay

How much insulation should you install in a ceiling or a roof? When the question comes up on GBAGreenBuildingAdvisor.com, I usually advise builders to install at least as much insulation as is required in the prescriptive table found in the 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.) or the International Energy Conservation Code (IECC International Energy Conservation Code.).

This prescriptive table is known as Table N1102.1.1 in the IRC (see Image #2 at the bottom of the page). In the IECC, the identical table is known as Table R402.1.2 (Image #3).

Sill Pans for Exterior Doors

Posted on December 8, 2017 by Martin Holladay

Most residential builders understand that window rough openings need sill pan flashing — either a site-built sill pan made with peel-and-stick tape, or a commercial sill pan made from metal or plastic. Window manufacturers’ installation instructions began requiring sill pans about 20 years ago, and by now these details are standard at most residential construction sites.

For some reason, though, many builders are neglecting to install sill pans under exterior doors. It's time for a gentle reminder: If you skip the sill pan under an exterior door, you are risking a very expensive callback.

Lumber from a Bandsaw Mill

Posted on December 1, 2017 by Martin Holladay

Let’s say that you own a piece of land and you want to build a house. If you live in a forested region, the first step is to cut down enough trees to create the needed open space for your foundation, lawn, and driveway.

As you’re cutting down the trees, you may think to yourself, “I’m going to need to buy lumber to build my house. I wonder if these logs can be milled into 2x6s and 2x10s.” The answer is: they probably can.

What’s the Definition of ‘Green Building’?

Posted on November 24, 2017 by Martin Holladay

Recently I spent some time accumulating definitions of “green building” from as many sources as possible. These various definitions included ten different characteristics of green buildings.

Of course, not all definitions agree, and none of the definitions include all ten of the characteristics that I identified in the various definitions.

The three most common characteristics appeared in most of the definitions. According to most sources, a green building:

  • (1) Is energy-efficient.
  • (2) Is water-conserving.

Revisiting Ventilation

Posted on November 17, 2017 by Martin Holladay

My comprehensive article on residential ventilation systems, “Designing a Good Ventilation System,” was published back in 2009. A few things have changed in the last eight years, so it’s time to revisit the topic.

Kitchen Design

Posted on November 10, 2017 by Martin Holladay

Every decade, kitchen design becomes more complicated. It’s gotten to the point where some residential designers subcontract the work to a specialist.

If you are a humble owner-builder, do your kitchen preferences even matter anymore? Of course they do. If you’re building a house, you should certainly have a say in matters affecting kitchen design — even if your ideas are different from those of the experts.

Rethinking the Rules on Minimum Foam Thickness

Posted on November 3, 2017 by Martin Holladay

When builders ask for advice about installing rigid foam on the exterior side of a wall, I usually refer them to one of my articles, “Calculating the Minimum Thickness of Rigid Foam Sheathing.” The article explains that the R-valueMeasure of resistance to heat flow; the higher the R-value, the lower the heat loss. The inverse of U-factor. of the rigid foam layer needs to be high enough to keep the OSB or plywood sheathing above the dew point during the winter. For example, a house with 2x6 walls in Climate Zone 6 would need rigid foam with a minimum R-value of R-11.25.

Living Without Electricity

Posted on October 27, 2017 by Martin Holladay

This year’s hurricane season brought extensive power outages to areas of Texas, Florida, Puerto Rico, and the Virgin Islands. In some cases, electricity was restored in two or three days. In much of Puerto Rico, however, the electricity has been off for weeks, and may not be restored for months.

A Better Bath Fan Termination for Soffits

Posted on October 20, 2017 by Martin Holladay

Most bathroom exhaust fans are installed poorly. Because of twisted ductwork, improper terminations, and (in some cases) inappropriate backdraft dampers, the actual air flow through the exhaust fan is much less than the fan rating.

‘Extended Plate and Beam’ Walls

Posted on October 13, 2017 by Martin Holladay

Production builders in the U.S. love 2x4 walls. They also love keeping the cost to build their homes as low as possible.

When energy codes ratcheted up in the 1980s and 1990s, cold-climate home builders eventually switched to 2x6 studs. But most production builders are still reluctant to install exterior rigid foam or furring strips.

In Climate Zones 6, 7, and 8, new codes are forcing builders to consider the implications of the “R-20 + R-5” requirements for walls. But many builders are unhappy with current options for building high-R walls.

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