Page 45 - Green Builder Sept-Oct 2016

Two for One. DuPont Tyvek ThermaWrap® R5.0 offers the air and water management benefits of all DuPont Tyvek weather barriers
with an R-value of 5.0. www.dupont.com

ENHANCED DURABILITY
Building above code shouldn’t compromise durability.
C HANGING CODE REQUIREMENTS
are prompting builders to increase while also enhancing durability. Here are a few
the insulation values of roofs, walls recommendations to ensure optimal performance
and foundations. One strategy for of a hybrid system that includes exterior insulation:

When using a water-resistive barrier in tandem

increasing the R-value of wood-framed walls is to with exterior insulation, it is not necessary to tape

increase the width of the cavity by using 2 x 6 or 2 x the seams between panels of rigid insulation; in

8 framing members, or by utilizing “staggered-stud” fact, open seams will allow the assembly to breathe.

or “double-stud” walls, which also reduce thermal compromise the taped seams between butt joints It is more important to ensure proper shingling

bridging. Builders are also going with a hybrid and eventually cause them to fail, allowing moisture when the house wrap is installed.

strategy that includes both cavity insulation and to penetrate the assembly. Housewrap can be installed over or underneath

exterior rigid insulation. While this strategy has a Horizontal Seams. The taped horizontal seams exterior rigid insulation, but a housewrap with

number of benefits, including enhanced R-value between rigid foam panels cannot achieve proper enhanced drainage is recommended if installing

and reduced thermal bridging, it’s important to shingling that ensures water will shed off the building. underneath.

not compromise the durability of the building for Window Flashing. The thickness of rigid exterior Install housewrap at the same plane as the

the sake of energy efficiency insulation can create a “reverse shingle” at the head window flange for the most effective performance.

Although building code allows the use of exterior of windows; consequently, proper detailing and Consider using a vapor permeable alternative

rigid foam with taped joints without an additional reliability of tape or self-adhered flashing at these to exterior rigid foam, such as rigid mineral wool

weather barrier, eliminating this step could invite locations is critical. or an integrated weather barrier and insulation

trouble. Here’s why: Including a wrap product that serves as a product such as DuPont Tyvek ThermaWrap® R5.0.

Butt Joints. Rigid foam products swell and permeable weather barrier can eliminate these
contract with changes in temperature. This can concerns, increasing thermal performance Source: DuPont

www.greenbuildermedia.com September/October 2016 GREEN BUILDER 43