COVER STORY


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R-30 insulation in the floor. (Note, current code only requires R-19 in the floors, however, due to in- stallation of the radiant-heated floor over an open foundation, additional insulation was warranted.


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Window glazing U factor of 0.35 and SHGC of 0.4—the previous code only required a U factor of 0.4 and no SHGC requirement.


Innovative and technologically sound methods used to meet the new code requirements included:


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2’ x 6’ wall framing to allow for a greater depth of wall insulation.


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Use of Building America’s “advanced framing” techniques to minimize thermal bridging and ma- terial consumption.


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1” rigid foam board insulation on the exterior of all walls.


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3/8” rain plane behind the siding to eliminate wa- ter buildup and potential damage to wood framing


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2” of rigid foam board over the roof sheathing, plus 12” of fiberglass insulation between raſters to meet the R-49 roof requirement. Careful aten- tion to ensuring that all windows, doors and gaps between sheathing panels were sealed to mini- mize air infiltration.


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CLOCKWISE FROM TOP: Installation of window flashing over external insulation; Installation of PEX (Cross-linked polyurethane) tubing, Rear of addition showing Core-a-Vent drainage system installed over external insulation


Use of “Zip System” panels by Huber Engineering to provide exterior sheathing, and act as a “house wrap” to minimize water penetrationwbut permit water vapor transmission.


Doman Custom Carpentry, LLC, in conjunction with Studio D, the clients’ architect, applied for and received one of the first building permits issued by the county that called for compliance with the new and more stringent code. Some of the new require- ments include:


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R-49 insulation in the roof—the previous code only required R-38.


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R-20 insulation in the walls—the previous code only required R-13.


10 create | A REMODELING RESOURCE FROM NARI METRO DC


James Doman, principal owner of Doman, met with Montgomery County zoning official before applying for a building permit to ensure that all technologies used would be acceptable and sufficient to meet the new energy conservation code. Computer modeling predictions indicates that the 400-square-foot heated addition will not increase the home’s heating load; in part due to the elimination of both a poorly insulated rear wall and unwanted air infiltration.


Another challenge to the remodeling effort was the county’s requirement that any addition over 400 square feet, that resides on a lot smaller than 15,000 square feet, employ a water run-off retention system. Originally, the design called for a rain garden but due to time and cost constraint, a dry well system was


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