Top 5 Benefits of Exterior Continuous Insulation in a Wood Frame Assembly

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Continuous Insulation (CI) such as Halo Exterra has been in use since the 70s.

Despite its low cost and straightforward installation, CI excels at boosting a wall’s thermal performance and controlling moisture. What’s more, CI can be a cost-efficient substitute for wood sheathing (in many cases). 

In our post below, you will learn about the 5 key benefits of adding a layer of CI to your exterior wall assembly.

CI Adds Thermal Resistance (R-Value) to a Wall Assembly

CI gives the wall assembly a sizable R-Value boost.

For example, Halo’s Exterra rigid insulation has a Long Term Thermal Resistance (LTTR) of R-5 per nominal inch of width. That’s more than 20% of the R-Value your regular 6” batt-insulated stud wall boasts. So, to increase the thermal resistance of a wall, your simplest option is to add a layer of CI to the exterior face of the assembly.

Depending on the code requirements in your Climate Zone, you can increase the CI layer thickness as needed to get the desired R-Value boost. For instance, Halo’s Exterra is typically available in widths of up to 2 inches (thicker panels can be custom ordered), so you can add up to approximately R-10 to a wall with a single layer (or more with multiple CI layers).

CI Eliminates Thermal Bridging

Adding a layer of CI to a wall assembly is an effective way to eliminate thermal bridging. Thermal bridging occurs when heat is able to travel through and escape through a wall’s uninsulated components. These include the studs, sill plates, joists, various transitions, door and window openings, and other building elements.

These elements are generally good conductors of heat, and with no insulation in the way the heat wastes no time in using them as an escape route out of the building.

The batt insulation is typically stuffed into the cavities between the studs, leaving the studs themselves readily available as a heat transfer path.

With CI on the exterior side of a stud wall, on the other hand, the escaping heat runs into an obstacle — a continuous layer of foam insulation.

By eliminating thermal bridging, CI removes an important inefficiency from the exterior wall and dramatically increases its “effective thermal performance”.

Home with 1/2in Continuous Insulation

CI Enhances Moisture Control In Your Walls

A layer of CI, such as Halo Exterra, can also help control moisture accumulation within a wall assembly by resisting moisture ingress from the outside, reducing condensation within the wall cavity and allowing the wall to dry to the outside.

Exterra serves as an effective Water-Resistive Barrier (WRB).

Thanks to its specially designed laminate, Exterra is able to block a substantial amount of incoming moisture from the outside. This feature allows builders to eliminate the use of house wrap when using Exterra panels. Note that the panels must be taped to take advantage of these WRB characteristics.

What’s more, CI increases the temperature inside the wall cavity and that reduces condensation and moisture accumulation inside the wall.

And finally, Exterra’s perforated laminate allows the vapor and moisture to escape to the outdoors. A breathable layer of Exterra CI is not an impermeable vapor barrier. It will allow the wall assembly to dry to the outside.

This way, excessive moisture buildup within the cavity should not happen, and many moisture-related problems (such as degradation of insulation, dry rot, etc) can be averted.

Perforated Film on Halo Exterra

CI Is Easy to Install

A CI product such as Halo’s Exterra is remarkably easy to install.

There are several nailing patterns, which differ depending on the substrate to which you’re attaching the Exterra panels — you can read about these fastening patterns here. That said, you can follow these three easy steps to install Exterra as smoothly as possible:

  1. Stagger joints to minimize air gaps.
  2. Seal joints with sheathing tape.
  3. Drive the fasteners into the sheathing — no need to go as far as the stud.

HOW TO PROPERLY FASTEN RIGID FOAM BOARD INSULATION

Explore the common nailing patterns for fastening non-structural Halo Exterra panels to these different substrate types.

CI Can Help Drastically Cut OSB Use

Designing a home with CI insulation at all exterior walls can help you reduce OSB use and save you money. Unless you’re building in a locale with high winds or seismic activity, structural wood sheathing use can be kept to a minimum.

 

By using structural sheathing only on select shear walls and corners, you can follow other, more economical bracing methods while essentially sheathing the entire building with CI. Doing so will help you cut your project’s budget and increase the home’s energy efficiency at the same time.

 

Here’s a case study you can read to learn about an actual project that opted for CI over OSB sheathing.

HOW TO ELIMINATE OSB USING HALO EXTERRA (A CASE STUDY)

Check out this excellent example of how structural drywall, hold-down devices, structural ties, and minimal use of OSB can help builders save money and construct energy-efficient homes.

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Wrapping It Up

Continuous Insulation is a relatively inexpensive and practical building component that boasts many benefits. Above, we’ve discussed 5 of the key advantages of building with a CI product, like Halo’s Exterra:

  1. Add long-term R-Value
  2. Eliminate thermal bridging
  3. Control moisture
  4. Install quickly
  5. Save money on structural wood sheathing
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Halo® is the Advanced Graphite Insulation System that’s designed perfectly for specific applications. Each Halo® product features a high-performance graphite polystyrene core, plus an ingenious laminate surface that is customized to its precise usage application, giving you today’s most advanced rigid insulation envelope.
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Also See

Is Halo Exterra Structural?

Halo Exterra is not structural – it does not contribute structural strength to a home or building. However, despite not being structural, Halo Exterra can replace OSB sheathing if structural bracing is provided at the corners and certain sections of the wall to provide the needed resistance to wind and seismic loads.

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