Q+A with Jason Peacock of Performance Building Supply in Portland on three key products included in an eco-conscious home currently being constructed in the city

When Mariella Lengua-Balbi, an architect from Peru, and Fernando Leon Prado decided to build a modern barn-style home­—on Fernald Street in Portland’s Bayside neighborhood—with Raymond-based Big W’s Carpentry, they sought assistance from Performance Building Supply to make the house as efficient as possible. LEED AP and certified building scientist Jason Peacock recommended Intus Windows for the windows and glass doors and Siga Tapes in place of caulk to make the building envelope rain- and airtight. The clients also fell in love with a durable siding and decking product called modified wood.

Q. Why Intus Windows?
A. These triple-pane windows from Lithuania are our most popular product and were perfect for Fernald Street because they are priced competitively with double-pane windows but provide increased thermal comfort and reduce exterior noise pollution from the in-town location by 32 decibels. They also decrease utility costs 20 to 50 percent by limiting heat loss in winter and keeping the heat out in summer. We provided the windows, doors, and a large sliding glass door for this project for $35,000.

Q. What are the benefits of Siga Tapes?
A. By creating an airtight shell, these nontoxic tapes from Switzerland help decrease utility heating and cooling costs. For this project we used Zip System R-Sheathing with one-inch foam for a continuous thermal break and taped it with Siga Wigluv and then used the Siga house wrap, Majvest, to protect against bulk moisture and to maintain dryness (with a high perm rating of 68, which allows moisture to move through). The resulting building envelope has R-30 walls and an R-55 attic. The tape cost about $1,500, and the house wrap was $1,500 for a 3,000-square-foot home.

 Q. What do you like about the Modified Wood siding and decking?
A. The owners found out about modified wood products from architect Chris Briley of Briburn, who was a consultant on the project. This wood performs like old-growth, quartersawn heartwood lumber but is made from sustainable southern yellow pine modified with acetic anhydride, a nontoxic treatment similar to vinegar. The resulting boards are rugged, bug- and rot-resistant, dimensionally stable, and low-maintenance. Big W nailed the clapboards to strapping to allow an airspace called a rain-screen wall detail. This ensures that the wood will be able to dry out, hold paint better, and last longer. At about $5 to $6 per square foot, these products cost more than fiber cement but are nearly 50 percent less than western red cedar, which has similar properties.