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Insulated Studs - What They Are and How to Use Them

By Frank Jossi Rise Writer
Nov 4, 2020

What if someone improved the standard old stud, made it more energy-efficient, capable of holding more weight, and decreasing the number of building materials? Insulated studs offer answers to the heat loss problem while adding to a home's structural integrity and ability to withstand winds, hurricanes, mold, and fire. 

Why do studs need an update, you may ask? Because home construction has not changed all that much for decades. Contractors and even modular builders frame houses with standard wood studs placed apart at standard lengths. Builders and architects have long struggled with stopping hot or cold air from coming into homes. Thermal leakage increases utility bills and causes indoor discomfort. The problem of "thermal bridging," or containing those leaks, remains an issue for contractors and homeowners who want efficient, cost-effective homes. 

A weak spot in high-performance wall construction continues to be studs, which allow interior heat to escape three times faster than adjacent insulation. Studs have lousy R values, meaning they transfer heat quickly.  Insulated studs are so effective they eliminate the need for house wrap. Let's take a closer look at how they work.

Table of Contents

  1. What Is An Insulated Stud?
  2. Are There Any Other Products Similar to Insulated Studs?
  3. Who Makes Insulated Studs?
  4. What Are the Standard Insulated Stud Sizes?
  5. Are Insulated Studs Code Compliant?
  6. Are Insulated Studs Energy-Efficient?
  7. What is a Thermally Broken Wall Assembly?
  8. What Types of Insulation Can You Use With Insulated Studs?
  9. Are Insulated Studs Load Bearing?
  10. Can Insulated Studs Reduce the Amount of Lumber Required?
  11. Are Insulated Studs Soundproof?
  12. Are Insulated Studs Fire Resistant?
  13. Are Insulated Studs Resistant to Mold and Mildew?
  14. How Do Insulated Studs Compare to Laminated Strand Lumber (LSL)?
  15. How Do Insulated Studs Compare to Laminated Veneer Lumber (LVL)?
  16. What Are the Pros of Insulated Studs?
  17. What Are the Cons of Insulated Studs?
  18. How Much Do Insulated Studs Cost?

What Is An Insulated Stud?

An Insulated stud is a replacement for the standard 2x6 stud with a sandwich of two boards separated by a 2.5-inch space. Angled dowel trusses hold the studs together. The studs come pre-insulated with closed-cell foam, or contractors can add their own during installation. Contractors can apply insulated stubs as studs, headers, or plates. 

Are There Any Other Products Similar to Insulated Studs?

Other options have inherent sustainable features, such as oriented strand board, the ZIP System R Sheathing, laminated sheer, and laminated strand lumber. The ZIP System comes the closest to incorporating insulation into the product line. InsoFast offers a system where metal studs hold insulated panels in place for basement wall and exterior projects. 

Stacked Bare Naked Tstud
Stacked Bare Naked Tstud. Photo Credit: Tstud

Who Makes Insulated Studs?

Brian Iverson invented insulated studs and formed the company Tstud to manufacture and sell them. Tstud also sells "Barenaked Tstud" which is the stud without the foam core installed, enabling homeowners and contractors to pick their insulation. The company's website offers average "R" and "U" values for different insulation types to help you choose the right insulation material. The "Tstud R. 19" comes with closed-cell foam already installed. 

What Are the Standard Insulated Stud Sizes?

Insulated studs replace 2x6 and 2x8. The 2x6 is more widely available. The width for the Tstud measures 5.5" and 7.5." Two 2x3s compose the sides of the sandwich.  

Tstud Closeup
Tstud Closeup. Photo Credit: Tstud

Are Insulated Studs Code Compliant?

Insulated studs comply with building codes in the United States and Canada and have met all ASTM (American Society for Testing and Materials) standards. The studs also meet hurricane and seismic criteria up to 24" on center framing in the US and Canada. Tstud achieved EPA compliance for 2020.

Are Insulated Studs Energy-Efficient?

Insulated studs are energy-efficient and carry an R-value of 20, compared to traditional framing's R-value of roughly 4.38 and 6.88 for 2x4 and 2x6, respectively. They create a 99.23% complete thermal break with the stud, meaning nothing gets through. Studies found the thermally broken wall assembly, like those made with Tstuds, is 150% to 280% more efficient than standard 2 x 6 framing.

Tstuds Factory
Tstud Factory. Photo Credit: Tstud

What is a Thermally Broken Wall Assembly?

Wall assemblies are generally broken by studs every 16 inches. Studs lose energy - they typically have an R-value of 4.38 to 6.88, depending on size, when placed between the insulation and insulated spaces.

The "thermally broken" wall assembly means the framing members have the same R-value as the insulation. The studs are R-19, but when next to the insulation, it goes up to R-22.

Tstud Exterior
Tstuds with ZIPsystem Exterior. Photo Credit: Tstud

What Types of Insulation Can You Use With Insulated Studs?

Closed-cell foam works best using an HFO (hydrofluoroolefin) blowing agent. Insulated studs offer studs already pre-filled with Polyiso foam. Contractors can install standard batt insulation between the studs, including fiberglass batt (R-13, R-19), cellulosemineral wool, continuous blown in and rigid fiberglass, and closed cell spray foam. Rigid insulation on the exterior makes the thermal shell even stronger.

Tstud Framed House
Tstud Framed House. Photo Credit: Tstud

Are Insulated Studs Load Bearing?

The double studs carry much more weight than typical lumber. Thermally broken wall assemblies are three times stronger than 2x6s. When used as top plates, thermal broken wall assembly offers 1.5 times more strength than 2x2s. Contractors can use insulated studs for walls up to 16 feet high and buildings up to 5 stories.

Can Insulated Studs Reduce the Amount of Lumber Required?

Using insulated studs and significantly reduce the amount of lumber used for framing. The strength of insulated lumber allows 24" on center framing instead of 16" on center in typical projects. On average home projects, insulated studs eliminate as many as 58 wall studs that would require 2,000 fasteners and 200 lineal feet of top plate. 

CharredTstud
Charred Tstud. Photo Credit: Tstud

Are Insulated Studs Soundproof?

That loud neighbor, those kids having a good time in another room? You will have to listen close to hear them because they have an extra dose of insulation that significantly dampens sound. Thermally broken wall assemblies reduce sound by 22% compared to a well-built party wall. The United States Gypsum found broken wall assembly offers a "sound transmission class" rating of a +6, equal to a wall being constructed with a "resilient channel" on both sides of a wall to absorb noise.

Are Insulated Studs Fire Resistant?

Yes, the studs rate Class A on the Y-axis fire rating compared to Class C for 2x6s. In an E84 flame spread test, the insulated studs retained 90% of their original structural strength. UL extensively tested Tstud's products.

Are Insulated Studs Resistant to Mold and Mildew?

Tstuds will be adding a coating to its R. 19 model to protect from fungal decay, mold, and wood-eating insects such as termites.

How Do Insulated Studs Compare to Laminated Strand Lumber (LSL)?

Both products have supporters and test well against competitors. LSL, made from a mixture of aspen and maple hardwoods harvested from sustainably managed sources, finds use as floor joists, wall plates, stair stringers, columns, rim board, wall frames, and window headers. Insulated studs replace only studs in structures.

How Do Insulated Studs Compare to Laminated Veneer Lumber (LVL)?

Composed of dried and graded wood veneer and usually coated with a waterproof phenol-formaldehyde resin adhesive bonded together with high heat, LVL differs from LSL. But it functions in buildings the same way. It serves as an alternative to solid lumber and works well in situations requiring load-bearing wood. Again, insulated studs have one primary use; LVL has several.

What Are the Pros of Insulated Studs?

Insulated studs offer a 6 in 1 solution. 

  1. The product's strength allows for more generous spacing between studs, to 24 inches, saving as much as 24% of studs.
  2. The thermal core has three times the insulation of traditional studs, keeping the heat in during the winter and out in the summer. 
  3. Insulated studs minimize noise. 
  4. The studs handle heavy wind loads. 
  5. They char rather than spread or melt during a fire. Tests show 90% of insulated studs remain intact after a 3,500 degree 10-minute long fire.  
  6. The product resists mold, termites, and rot, as tests will soon show.
Tstud Window Framing
Tstud Window Framing. Photo Credit: Tstud

What Are the Cons of Insulated Studs?

Insulated studs lack a long track record because they are a relatively new product that contractors have just discovered. Although the market responded positively to a video that Tstud launched last year, there hasn't been much installation information. The video attracted nearly 1 million viewers. The company has not released a 2x8 version yet. Electric boxes on exterior walls could pose problems, and plumbers must pay attention when installing near pipes to avoid cutting into dowels. Insulated studs cost more than everyday studs, but the total cost of projects makes them competitive.

How Much Do Insulated Studs Cost?

Insulated Studs cost between $2.00 to $3.00 per board foot. But being able to space studs at 24 inches and no need for deep headers around doors and windows saves on the amount of wood needed for products. One contractor put the cost at $1,800 to $2,000 extra per house compared to wood studs. "More than worth the cost," he told Green Building Advisor.

Exterior Tstud Construction
Exterior of Home with Tstud Construction. Photo Credit: Tstud

Insulated studs are an exciting innovation. We hope to continue to report on their uses and hear about your experiences with them as they gain popularity in the housing sector.

Disclaimer: This article does not constitute a product endorsement however Rise does reserve the right to recommend relevant products based on the articles content to provide a more comprehensive experience for the reader.Last Modified: 2021-06-16T02:47:39+0000
Frank Jossi

Article by:

Frank Jossi

Based in St. Paul, Frank Jossi is a journalist, editor and content strategist. He covers clean energy in Minnesota for Midwest Energy News and writes frequently for Finance & Commerce. His work has appeared in more than 70 local, national and international publications.