Q&A Spotlight

Radon Mitigation in a Leaky House

Posted on November 23, 2015 by Scott Gibson

RadonColorless, odorless, short-lived radioactive gas that can seep into homes and result in lung cancer risk. Radon and its decay products emit cancer-causing alpha, beta, and gamma particles. mitigation in new construction is now routine when testing finds that concentrations of this odorless, cancer-causing gas exceed government-recommended levels. Writing from southeastern Wisconsin, Andrew S. has a slightly different problem: How to control radon levels when you live in a leaky log home built in the 19th century.

Designing a Low-Slope Roof That Works

Posted on November 9, 2015 by Scott Gibson

If only Kevin Hoene's choices for a new roof boiled down to a choice between an EPDM membrane and metal, his life would probably seem a whole lot simpler.

But Hoene, building a new home in Illinois and on the boundary between Climate Zones 4 and 5, will soon be weighing the pros and cons not only of different roof coverings, but also of what type of insulation to use, whether it should go above or below the roof 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. , and whether the roof should be vented or unvented. In other words, nothing seems off the table.

The Best Way to Insulate a Foundation

Posted on October 26, 2015 by Scott Gibson

Nethaniel Ealy, a builder in Idaho who's about to pour a concrete basement foundation, is trying to come up with insulation and waterproofing details that will be effective and within the budget.

The current plan is to place 2 inches of extruded polystyrene (XPSExtruded polystyrene. Highly insulating, water-resistant rigid foam insulation that is widely used above and below grade, such as on exterior walls and underneath concrete floor slabs. In North America, XPS is made with ozone-depleting HCFC-142b. XPS has higher density and R-value and lower vapor permeability than EPS rigid insulation.) on the outside of the foundation walls. At some point in the future, the homeowners would place another 2 inches of foam on the inside of the foundation walls between 2x2 studs, and then apply drywall over the studs.

Detailing Exterior Walls in Minnesota

Posted on October 12, 2015 by Scott Gibson

In Minnesota, Jeff Fredrickson is planning a new house, and his research has included lots of reading on the design and construction of exterior walls. His goals are twofold: a wall that will stay mold-free for decades, and one that is "somewhat energy efficient."

Starting at the inside, the wall would go like this: drywall, a polyethylene vapor barrier, JM Spider insulation in 2x6 stud walls, 1/2-inch plywood 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. , a water-resistive barrierSometimes also called the weather-resistive barrier, this layer of any wall assembly is the material interior to the wall cladding that forms a secondary drainage plane for liquid water that makes it past the cladding. This layer can be building paper, housewrap, or even a fluid-applied material. (Benjamin Obdyke HydroGap), fiber cement and stone veneer claddingMaterials used on the roof and walls to enclose a house, providing protection against weather. .

Battling Condensation on Attic Ducts

Posted on September 28, 2015 by Scott Gibson

Jimmy Miller is trying to solve a condensation mystery in a Florida ranch-style home that is being renovated. Even though the air conditioning equipment appears to be operating normally, humidity inside the house is between 60% and 65%, and return ducts located in the attic show significant condensation.

Should I Skip the Radiant Floor Heat?

Posted on September 14, 2015 by Scott Gibson

With an R-90 roof and R-60 walls, Jenz Yoder's new off-grid house will be well insulated. Yoder's quandary, outlined at Green Building Advisor's Q&A forum, is whether radiant-floor heat is a good idea.

"I had two consultants tell me that I will not need radiant floor heat, [that] it will be too much," Yoder writes. "We will have a whole-house air circulation system and a gas fireplace. I am worried about not putting in the pipes in the floor and then being wrong."

Do Ductless Minisplits Work With Every Floor Plan?

Posted on August 31, 2015 by Scott Gibson

Clay Whitenack, planning a new home in central Kentucky, had assumed that a ground-source heat pumpHome heating and cooling system that relies on the mass of the earth as the heat source and heat sink. Temperatures underground are relatively constant. Using a ground-source heat pump, heat from fluid circulated through an underground loop is transferred to and/or from the home through a heat exchanger. The energy performance of ground-source heat pumps is usually better than that of air-source heat pumps; ground-source heat pumps also perform better over a wider range of above-ground temperatures. would be a "no-brainer" for heating and cooling. Then he began reading about minisplit air-source heat pumps, and suddenly the situation didn't seem so simple.

He's intrigued with the possibilities for minisplits, but he's not certain he'll have a floor plan that would be compatible with this type of system, he writes in Q&A post at Green Building Advisor.

How to Finish a Third Floor

Posted on August 17, 2015 by Scott Gibson

Joe Watson lives in a three-story 1993 house in Richmond, Virgina, with a walkup attic, part of which he'd like to turn into living space. The question is how.

Trouble on the Roof

Posted on August 3, 2015 by Scott Gibson

Jeremy Ballard is living in a relatively new home built with structural insulated panels (SIPs), and he's already spotted something that's keeping him up at night. The weather in Kentucky is turning hot and humid, and with the humidity has come condensation on corrugated metal panels installed on the interior of the roof.

Why Are Houses Built This Way?

Posted on July 20, 2015 by Scott Gibson

Readers of GreenBuildingAdvisor's Q&A forum, and the bi-monthly Q&A Spotlights, are probably used to thorough parsings of seemingly small details in high-performance construction. But GBAGreenBuildingAdvisor.com reader Peter L. brings our attention to an elemental question: Are we still in the dark ages of residential building?

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