The most recent blogs at Green Building Advisor

How to Seal Sheathing Boards

Posted on November 4, 2013 by Scott Gibson in Q&A Spotlight

The use of plywood and OSB sheathingMaterial, usually plywood or oriented strand board (OSB), but sometimes wooden boards, installed on the exterior of wall studs, rafters, or roof trusses; siding or roofing installed on the sheathing—sometimes over strapping to create a rainscreen. is a fairly recent phenomenon. Before these sheet goodsMaterial, usually plywood or oriented strand board (OSB), but sometimes wooden boards, installed on the exterior of wall studs, rafters, or roof trusses; siding or roofing installed on the sheathing—sometimes over strapping to create a rainscreen. became readily available, builders nailed wood boards to the frame of a house for sheathing, and it is a house with this type of sheathing that Nick Welch is trying to update.

His 900-square-foot house in Climate Zone 4C is sheathed with 1x8 boards, apparently over a layer of asphalt felt. There is apparently no insulation in the wall cavities behind the sheathing. His plan of attack is to air-seal the house, then install foil-faced polyisocyanurate insulation over that. The question is how.

Monitoring Moisture Levels in Double-Stud Walls

Posted on November 1, 2013 by Martin Holladay in Musings of an Energy Nerd

Most wood-framed buildings have no insulation on the exterior side of the wall sheathingMaterial, usually plywood or oriented strand board (OSB), but sometimes wooden boards, installed on the exterior of wall studs, rafters, or roof trusses; siding or roofing installed on the sheathing—sometimes over strapping to create a rainscreen. . That means that the wall sheathing gets cold and wet during the winter.

A Vilified Insulation Material From the 1970s Returns

Posted on October 31, 2013 by Alex Wilson in Energy Solutions

In working on a major revision to The BuildingGreen Guide to Insulation Products and Practices (available bundled with a webcast), we’ve had an opportunity to dig into some of the lesser-known insulation materials on the market. Some of what we’re found has been surprising.

A Brief Introduction to WUFI, in 5 Easy Pieces

Posted on October 30, 2013 by Allison A. Bailes III, PhD in Building Science

If you have any involvement with the world of building science, you may have heard about something called WUFI and wondered what the heck it is. Maybe you've heard that it's a piece of software (several pieces, actually) that does hygrothermalA term used to characterize the temperature (thermal) and moisture (hygro) conditions particularly with respect to climate, both indoors and out. modeling. Well, today's your lucky day because I recently went through a two-day class on WUFI 1-D with Dr. Achilles Karagiozis and Mr. Mikael Salonvaara of Owens Corning, and I'll give you a brief explanation of what it's all about.

Making Green Affordable, Part 2

Posted on October 29, 2013 by Christopher Briley in Green Architects' Lounge

Part Two of this episode brings us to construction details for high-performance affordable homes. Again, I feel the need to point out that we are not talking about low-income housing or housing that makes a difference between shelter and non-shelter. I'm talking about high-performance homes that will compete, on a financial level, with those cheap vinylCommon term for polyvinyl chloride (PVC). In chemistry, vinyl refers to a carbon-and-hydrogen group (H2C=CH–) that attaches to another functional group, such as chlorine (vinyl chloride) or acetate (vinyl acetate). boxes that litter suburbia and urban areas alike.

Phil and I have refreshed our drinks and are ready to talk about building envelopeExterior components of a house that provide protection from colder (and warmer) outdoor temperatures and precipitation; includes the house foundation, framed exterior walls, roof or ceiling, and insulation, and air sealing materials. construction from the bottom up. Let's get started.

Keeping Green on the Right Track

Posted on October 28, 2013 by Vera Novak in Guest Blogs

Green building programs have a tendency to focus on the means rather than the end, to the point of not even identifying a comprehensive end goal. Two examples illustrate my point.

The first example is a bit like the game of “gossip” or “telephone” that we used to play around the campfire. You know, one person whispers something into the ear of the next person, who whispers what they thought they heard to the next person, until it has gone around the circle. Invariably, the final wording is absurdly different from the original.

Low-Road Buildings Are Homeowner-Friendly

Posted on October 25, 2013 by Martin Holladay in Musings of an Energy Nerd

There are at least two recognizable camps in the green building community. The older camp includes hippies, owner/builders, and those in the natural building movement. These builders prefer to scrounge materials from the woods or demolition sites rather than purchase new materials from a lumberyard. Their homes might be made of adobe, logs, or straw bales.

Heating with a Minisplit Heat Pump

Posted on October 24, 2013 by Alex Wilson in Energy Solutions

Thirty-five years ago, when I first got involved with energy efficiency and renewable energy, the mere suggestion that one might heat with electricity would be scoffed at by those of us seeking alternatives to fossil fuels.

Amory Lovins, founder of the Rocky Mountain Institute, likened using electricity for heating to “cutting butter with a chainsaw.” Electricity is a high-grade form of energy; it doesn’t make sense to use it for a low-grade need like heating, he argued.

The Ventilation Omission That Can Make You Sweat

Posted on October 23, 2013 by Allison A. Bailes III, PhD in Building Science

If you're designing a ventilation system, first you have to determine how much outdoor air the house needs. You can use the ASHRAE 62.2A standard for residential mechanical ventilation systems established by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers. Among other requirements, the standard requires a home to have a mechanical ventilation system capable of ventilating at a rate of 1 cfm for every 100 square feet of occupiable space plus 7.5 cfm per occupant. standard or the new BSC-01 standard for that task. Then you have to decide what type of ventilation system to use: positive pressure, negative pressure, or balanced. In many green homes, the balanced system is becoming a popular choice.

Most ‘Houses That Breathe’ Aren’t Very Comfortable

Posted on October 22, 2013 by Robert Swinburne in Guest Blogs

Recently I heard another comment from a builder who wants to build a house that breathes. I started to reply in an e-mail, and then decided to write a blog instead.

What we are doing nowadays in the world of high-performance homes is based on studying hundreds of thousands of houses built in the last half century that have failed — including the majority of superinsulated and passive solar homes built in the 1970s and 1980s in the Northeast — and applying those lessons to building a durable house.

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