Continuous insulation is becoming the standard in colder climate zones. Even in areas that haven’t adopted the most recent IECC requirements, higher-end builders are increasingly installing continuous exterior insulation to increase energy efficiency. 

Traditional batt or closed-cell spray foam in wall cavities isn’t cutting it anymore in high-efficiency wall assemblies. Thick layers of foam or mineral wool insulation enhance cavity insulation and amplify energy savings. Increasing energy costs and HVAC systems that require more energy to run efficiently create the perfect storm for homeowners.

Continuous exterior insulation involves attaching mineral wool or polyiso rigid foam outside the stud wall to enhance efficiency. Standard practice in many colder regions, it has universal appeal for efficiency-minded builders. 

There isn’t a mystery around why continuous exterior insulation works. It reduces thermal bridging and protects the wall cavity and interior environment from drastic temperature changes. Like a sweater, CI helps maintain equilibrium inside, reducing the chance of damaging condensation and energy loss. 

Creating a thermal break against inclement weather and extreme temperatures increases the R-value of a wall assembly.

The Problem with R-Value Gaps

Most building materials have some sort of R-value. This metric considers how much energy passes through a material under normal conditions. Traditional stick-framed homes, for instance, take their R-value from sheathing, studs, and any cavity insulation added after the fact. 

Standard dimensional lumber has a relatively low R-value and relies on insulation to meet IECC and IRC code requirements.

Dimensional Lumber	R-Value
2” nominal (1-½”)	1.88
2×4 (3-½”)	4.38
2×6 (5-½”)	6.88

Plywood	R-Value
¼”	0.31
⅜”	0.47
½”	0.63
⅝”	0.77
¾”	0.94

Even when a stud wall cavity is insulated, without exterior insulation, the studs act as thermal bridges where they contact sheathing. Traditionally framed walls can contain up to 25% stud material, while Advanced Framing reduces that number to as low as 15%. Studies show thermal bridging accounts for 10-15% of residential energy use. 

Put another way, 25% of a wall assembly is uninsulated if builders rely on cavity insulation only. Thermal imaging shows how much of an impact this has on energy loss.

Even high R-value cavity insulation can’t reduce energy loss due to thermal bridging. Only continuous insulation combats these R-value gaps and has the potential to reduce energy loss to near zero.

How Continuous Insulation Solves the Thermal Bridge 

Continuous insulation disrupts thermal bridging by creating an insulative layer between studs and sheathing. Various building product solutions exist on the market for this application, each with pros and cons. 

Semi-rigid products like Rockwool Comfortboard^® are ideal for exterior insulation because of their hydrophobic and flame-resistant qualities. For CI applications, the mineral wool is attached to sheathing and then covered by cladding to allow any vapor to evaporate outwards. To achieve optimal performance, sheathing should have a WRB attached to ensure complete moisture and air control. 

Rigid solutions like Zip System^® R-Sheathing and LP^® NovaCore^™ combine polyiso insulation with sheathing for a structural solution. Sheathing is typically a 7/16” OSB and, in the case of Zip-R, includes a factory-applied WRB to help control moisture and allow vapor to evaporate out. NovaCore requires a secondary WRB, preferably self-adhering, to complete the installation.

Construction plans may include a combination of both interior and exterior insulation. Because exterior insulation is more effective at disrupting thermal bridging, less is needed for comparable performance.

This table outlines the necessary R-values for walls based on climate zones. The first number references cavity insulation, the second set includes both cavity and continuous insulation (X or X&Yci).

Code dictates the amount of insulation required for building projects based on the specific Climate Zone. Regardless of where you’re building, you’ll need to meet minimum R-value requirements.

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Use this calculator to see how much insulation you need based on your zip code.

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R-Value Gains from Continuous Insulation That Matter in the Field 

Increasing the R-value of your wall assemblies has an impact on the overall function of the building systems. Every structure must meet code requirements, but going beyond what’s required can have a powerful effect. 

Using this chart as an example, in Climate Zone 0, a wood-framed wall must have R-13 OR R-0&10 ci. This indicates that CI has a larger impact on wall assembly performance, between 20% and 30%, than cavity insulation. Further down the chart, you’ll see that there are options for cavity insulation, a blend of both, or only continuous insulation. 

Additional insulation impacts

• Wall Performance by between 20% and 30%
• Air Tightness and Durability with less thermal cycling and material movement
• Energy Efficiency from lower heating and cooling loads
• Comfort through reduced hot and cold spots around joists, corners, and outlets

Sheathing and Continuous Insulation: Compatibility Is Key 

Incorporating continuous exterior insulation in your next build is an ideal way to increase energy efficiency and durability. There’s a bit of a learning curve around installing some types of exterior insulation, and selecting the best materials for your project can be the difference between success and failure.

Sheathing and WRB Systems

Incorporating continuous exterior insulation in your next build is an ideal way to increase energy efficiency and durability. There’s a bit of a learning curve around installing some types of exterior insulation, and selecting the best materials for your project can be the difference between success and failure.

Sheathing and WRB Systems

Contractors must select continuous insulation materials that integrate well with the construction plan. This could include structural sheathing, WRBs, furring strips, and cladding. Some CI solutions include some or all of these elements in one, but not all do. 

While some CI systems include a factory-applied weather-resistive barrier, many do not. Grip-Rite ProWrap^® self-adhering, primerless house wrap and flashing tapes are the perfect complement to exterior insulation. 

• ProWrap-SA offers best-in-class protection against bulk water intrusion while providing air and vapor management. 
• Door and Window Flashing provides a comprehensive barrier around doors, windows, and other protrusions and penetrations. 

Fastening

Securing CI products is essential to stability and performance. For semi-rigid solutions, this generally means using large plastic washers and screws and including furring strips for cladding. 

Insulated sheathing, on the other hand, can be a one-and-done solution. When factory-applied WRBs are present, after fastening and taping seams, the process is complete. Screws aren’t typically approved for these applications, and nails must reach at least 1-½” of embedment into the stud. 

Higher R-value products pose a challenge for builders as they have 2” of foam on a 7/16” OSB sheet. Current options for installation involve time-consuming pre-drilling and hand driving. Grip-Rite is committed to meeting the needs of contractors, and the new Grip-Rite SpeedSpike^™ is here to fill a gap in the market.

SpeedSpike^™ is the first widely available collated fastener that is designed for use with high R-value sheathing applications. At 4-½”, it provides at least 2” embedment in the stud for a secure hold. Compatible with heavy-duty timber framers, it’s over 5 times faster* than hand-driven fasteners. With SpeedSpike^™, pros can drop the hammer and just spike it with this one-and-done solution.

Moisture Management

Regardless of whether you’ve used semi-rigid or rigid/sheathing insulation, managing moisture at transitions is a significant consideration. Around windows and doors, using flashing tapes and flex tape or liquid flashing around penetrations helps mitigate water intrusion. Additionally, incorporating a compatible weather-resistant barrier with air and vapor management enables any condensation to evaporate away from the sheathing. 

Products like Zip-R that include a WRB are primed to reduce condensation and allow moisture to move out to the exterior of the wall assembly. Other continuous insulation assemblies require a secondary WRB for proper moisture management. 

R-Value Only Tells Part of the Story

Continuous insulation requirements drive innovation across the building products industry. Manufacturers are developing higher R-value products that help builders achieve maximum efficiency. Combining highly effective building envelopes and other factors like fire and water resistance protects homes against whatever nature throws their way. 

Delivering efficiency, durability, and comfort is a byproduct of high R-value sheathing, one that’s not bound by Climate Zones. Contractors around the country are also implementing exterior insulated sheathing to reduce the energy burden in hot climates. Energy savings resulting from CI implementation are sufficient to offset the additional labor required for installation.

Find out Where to Buy Grip-Rite weather resistive barrier products near you. 

*“Over 5x faster” claim based on tests of pneumatic nail gun operation vs. traditional hand-driven methods by experienced operators under normal conditions. Actual results may vary based on job site conditions, operator experience, and material specifications.