Halo’s Exterra offers a ton of benefits, one of which is its ability to replace house wrap — if you tape and seal it properly. Even so, some builders choose to add a layer of house wrap to the Exterra. Call it “cheap insurance,” if you will.
And, if you’re one of these builders who likes to err on the side of caution, you may find yourself asking — where should the house wrap go in relation to the Exterra layer?
In this post, we’ll examine the 2 obvious scenarios — applying house wrap over vs. behind Exterra — and talk about their pros and cons.
Should House Wrap Go in Front of Exterra, or Behind It?
The short answer — it’s a matter of preference.
Now, most building science publications show house wrap placed behind Exterra. However, you’ll find that builders all across North America — from frigid Ontario to balmy Alabama — happily place it over the foam board. This just shows you that climate doesn’t really dictate the placement.
That being said, there are some pros and cons to each approach, so let’s see what they are.
House Wrap Behind Halo Exterra — Pros and Cons
Pros
- The Exterra panel will protect the house wrap membrane.
- Doing so may allow the wall assembly to dry to the exterior, but this depends on the permeance of the membrane.
Cons
- Flashing around openings must extend to the air control layer behind the rigid insulation panel
- The framing contractor will have to install the house wrap membrane, so it could see some damage before the walls are clad
- Damaged sections of the house wrap may be hard to fix
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House Wrap On Top of Halo Exterra — Pros and Cons
Pros
- The house wrap membrane protects Exterra from moisture
- Since the membrane is in front of the insulation panel, it’s much easier to integrate flashing around openings
- Fixing damaged sections of the house wrap becomes less tedious
Cons
- Depending on the permeance of the membrane, the wall cavity may not be able to dry to the exterior
- The front face of wood sheathing is left without protection
Wrapping It Up
If you’re wondering whether to place house wrap on top of, or behind Halo’s Exterra, there’s no right answer.
But the good news is that both approaches should serve you well. Applying the membrane behind Exterra protects the house wrap and promotes drying to the exterior. In contrast, placing house wrap over Exterra protects the insulation from moisture, but may be an obstacle to drying the wall to the outside.
