Q&A Spotlight

How to Attach a Thick Layer of Exterior Insulation

Posted on May 9, 2016 by Scott Gibson

Adding a layer of insulation to the outside of a house, over 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. , makes all kinds of sense from an energy perspective. But the thicker the layer, the more challenging becomes the actual means of attaching it to the building.

In a post in the Q&A forum at Green Building Advisor, Burke Stoller shares some of his concerns, as well as a proposed solution. Stoller is working out the details for a 6-inch-thick layer of Roxul ComfortBoard mineral wool, consisting of two layers of 3-inch-thick panels, each 2 feet by 4 feet.

Do Earth Tubes Make Any Sense?

Posted on April 25, 2016 by Scott Gibson

Daniel McKinney is reaching four decades into the past for two important features of a new house he plans to build. Both notions were mostly discarded after early attempts at energy efficiency ledLight-emitting diode. Illumination technology that produces light by running electrical current through a semiconductor diode. LED lamps are much longer lasting and much more energy efficient than incandescent lamps; unlike fluorescent lamps, LED lamps do not contain mercury and can be readily dimmed. builders in new directions, but McKinney thinks they may still have some merit.

Finding Insulation That’s Safe

Posted on April 11, 2016 by Scott Gibson

On top of all the other problems anyone building a new house is bound to encounter, Carolyn Farrow has a concern that outweighs all others: her daughter's health.

"Our toddler has a lot of chemical sensitivities and respiratory issues and insulation decisions are completely overwhelming me," she writes in a post at GBA's Q&A forum. "I can't find any contractors that I trust."

The allergist and pediatrician treating Farrow's daughter say she could react to virtually any type of insulation, and they are not comfortable making any specific recommendations.

If Ants Like Rigid Foam, Should We Stop Using It?

Posted on March 28, 2016 by Scott Gibson

Writing from the Pacific Northwest, Malcolm Taylor dives into a problem experienced by many homeowners and builders: a carpenter ant infestation in rigid foam insulation.

"I am involved with two projects right now that have carpenter ant infestations — and in both cases they are in the foam," Taylor writes in this Q&A post at GreenBuildingAdvisor. "One is particularly difficult to fix as it is a flat roof with tar and gravel above and a wood tongue-and-groove ceiling, making it hard to get at the nests."

Do Green Roofs Temper Urban Heat?

Posted on March 14, 2016 by Scott Gibson

Luke Morton sits on a green building committee that's been asked to advise local officials on a green building code. The code will feature both mandatory and elective features. One of the electives currently on the list is for a "green," or vegetated, roof, but Morton has his doubts whether the case for this type of roof is very compelling.

Is This Ground-Source Heat Pump Plan Workable?

Posted on February 29, 2016 by Scott Gibson

Jordan Garrow is getting ready to build a new house in New York State, on the cusp between Climate Zones 5 and 6, and he's planning to heat and cool it with 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.. His contractor wants to install a horizontal "slinky loop" heat exchangerDevice that transfers heat from one material or medium to another. An air-to-air heat exchanger, or heat-recovery ventilator, transfers heat from one airstream to another. A copper-pipe heat exchanger in a solar water-heater tank transfers heat from the heat-transfer fluid circulating through a solar collector to the potable water in the storage tank., one of several possible options, and Garrow is seeking a second opinion.

A heat load calculation for the house specifies a 4-ton system (one with a capacity of 48,000 BtuBritish thermal unit, the amount of heat required to raise one pound of water (about a pint) one degree Fahrenheit in temperature—about the heat content of one wooden kitchen match. One Btu is equivalent to 0.293 watt-hours or 1,055 joules. /hour), but the contractor wants the heat exchange loops designed as if they were serving a 6-ton system.

Solar Now or Later?

Posted on February 15, 2016 by Scott Gibson

Prices for photovoltaic(PV) Generation of electricity directly from sunlight. A photovoltaic cell has no moving parts; electrons are energized by sunlight and result in current flow. (PVPhotovoltaics. Generation of electricity directly from sunlight. A photovoltaic (PV) cell has no moving parts; electrons are energized by sunlight and result in current flow.) systems have been dropping steadily, making the investment in residential-sized arrays more appealing than ever. Lower prices and a decision in Congress to extend the federal investment tax credit means that ever larger systems are within reach of more homeowners.

But what about homeowners whose construction budgets strictly limit the size of the PV system they can realistically afford? They are people like James Timmerberg, who is building an all-electric house in Ohio and would like to invest in solar — if it makes economic sense.

Foundation Plan for a Snowy Climate

Posted on January 18, 2016 by Scott Gibson

Nathan Scaglione's central New York State building site gets plenty of snow and cold weather during the winter, and that's proving to be a sticking point in his plans for a new house.

He'd prefer a slab-on-grade foundation rather than a basement, even though a full basement would be a more typical choice in this part of the country. The foundation would consist of concrete-block stem walls extending to a footing below frost line. Exterior walls would be framed on top of the block walls, roughly 24 inches above grade. Inside the block walls, Scaglione will pour a concrete slab floor.

Solar Panels or Exterior Foam?

Posted on January 4, 2016 by Scott Gibson

Apollo S has been making steady energy upgrades to his pre-war Cape Cod style house in Massachusetts. He's replaced a steam heating system with a heat pumpHeating and cooling system in which specialized refrigerant fluid in a sealed system is alternately evaporated and condensed, changing its state from liquid to vapor by altering its pressure; this phase change allows heat to be transferred into or out of the house. See air-source heat pump and ground-source heat pump., and with help from the state's energy efficiency program, he air-sealed and insulated his attic with cellulose.

As a result, his $250-a-month energy bills are one-quarter what they used to be, and Apollo now has his eye on the next round of upgrades.

Choosing the Right Water-Resistive Barrier

Posted on December 21, 2015 by Scott Gibson

Yes, James Timmerberg's new house will have 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. (WRB) on the exterior walls.

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