Q&A Spotlight

Making the Best PEX Connections

Posted on June 20, 2016 by Scott Gibson

Building his “forever house,” Dean Sandbo is mulling what type of tubing to use for his plumbing supply lines. He has narrowed the choice to one of two types of cross-linked polyethylene (PEXCross-linked polyethylene. Specialized type of polyethylene plastic that is strengthened by chemical bonds formed in addition to the usual bonds in the polymerization process. PEX is used primarily as tubing for hot- and cold-water distribution and radiant-floor heating.): PEX-A or PEX-B.

Key issues, Sandbo notes in his Q&A post at GBA, are how long the tubing will last, and whether there are safety concerns — that is, will the PEX tubing leach chemicals into his drinking water?

"I am on a well," he writes. "Any input as to the longevity and safety of these two different types of pipes?"

Solving a Roof Dilemma

Posted on June 6, 2016 by Scott Gibson

Joe B is building what he hopes will be a PassivhausA residential building construction standard requiring very low levels of air leakage, very high levels of insulation, and windows with a very low U-factor. Developed in the early 1990s by Bo Adamson and Wolfgang Feist, the standard is now promoted by the Passivhaus Institut in Darmstadt, Germany. To meet the standard, a home must have an infiltration rate no greater than 0.60 AC/H @ 50 pascals, a maximum annual heating energy use of 15 kWh per square meter (4,755 Btu per square foot), a maximum annual cooling energy use of 15 kWh per square meter (1.39 kWh per square foot), and maximum source energy use for all purposes of 120 kWh per square meter (11.1 kWh per square foot). The standard recommends, but does not require, a maximum design heating load of 10 W per square meter and windows with a maximum U-factor of 0.14. The Passivhaus standard was developed for buildings in central and northern Europe; efforts are underway to clarify the best techniques to achieve the standard for buildings in hot climates.-certified home in Port Washington, New York, a town on the north shore of Long Island in Climate Zone 4. The house is well underway, but Joe worries about the potential for trouble in a very complex roof design.

Installing a Concrete Slab the Right Way

Posted on May 23, 2016 by Scott Gibson

As part of a remodel of his San Francisco area home, Torsten Budesheim is converting the 700-square-foot lower level into living space. An existing slab has been removed, and Budesheim has removed a few inches of material to increase the finished ceiling height. Now, he's nearly read to place a new 5-inch-thick slab that will include tubing for radiant heat.

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.

Register for a free account and join the conversation


Get a free account and join the conversation!
Become a GBA PRO!

Syndicate content