InSoFast vs. Traditional Exterior Wall Assembly

In order to highlight the differences between InSoFast EX 2.5 panels and Traditional Exterior Wall Assembly methods, we have compared the two in terms of materials and cost. All numbers are based on the idea of working with a 2,400 sq-ft surface area, a wall that is 120 ft long by 20 ft high. We are not designing this wall for today’s minimum standards. We are exceeding them in preparation for future Net-Zero energy requirements.

For simplicity of comparison, we are ignoring the existence of windows and doors. Admittedly, InSoFast panels would require such openings to be framed, but in this scenario the overall cost would only increase by about $100.

Our comparison accounts for the rainscreen and R-10 insulation of an exterior wall. It is part of an advanced building approach that only 10% of the most energy efficient builders are using today. The other 90% won’t be forced to do this until after the 2020 building codes are adopted and most of them see no reason to aim higher. This is about durability and efficiency.

where insofast fits into your exterior wall assembly

Our point of interest resides between the weather wrap that seals the exterior sheathing and the outermost aesthetic finish. We decided to finish the project with siding board because, in both applications, you can optimize your costs by using screws that were already purchased for other steps. Don’t let this limit your creativity. Both methods support a wide variety of finishes including stone veneer, stucco, brick and more.

All prices are based on the online sources represented in the hyperlinks below as of May 21th, 2015. Home Depot pricing varies by zip code, so our calculations reflect pricing found local to our office in Reading, PA. The totals do not reflect additional costs levied by taxes, shipping or labor and on that note we’d like to point out our free shipping and speed of installation.

We honestly spent a bulk of our time researching the most cost-effective products and places to purchase those products for the Traditional Assembly. If you think you could do better, please feel free to refute our claims in the comment section below!

Rainscreen System

Product: SlickerĀ® Classic Rainscreen

This is a drainage layer that ensures moisture is able to flow away from the interior of your home. The project requires 16 rolls priced at $142.50 each direct from the manufacturer’s website.

$142.50 x 16 = $2,280.00


Product: 1-1/2 in. Plastic Round Cap Roofing Nails

These fasteners are required to secure the SlickerĀ® Classic Rainscreen every 3 feet. They need to penetrate the sheathing by at least 1/2 inch to ensure optimal attachment of the product. The project requires 4 boxes priced at $5.86 each.

$5.86 x 4 = $23.44

Rigid Foam Insulation

Product: Owens Corning FOAMULAR 150 2 in. x 4 ft. x 8 ft. R-10 Scored Squared Edge Insulation Sheathing

This is that nasty pink stuff people use to insulate things. We don’t know why. The project requires 75 panels priced at $32.00 each.

$32.00 x 75= $2,400

More Fasteners

Product: EIFS PB Washer PBH & Wood Lite Metal Screw

These specialty fasteners are used to secure the pink stuff to the sheathing (after penetrating through the rainscreen). The project requires 3 boxes priced at $175.00 each.

$175.00 x 3= $525.00

Building Flashing Tape

Product: 3M All Weather Flashing Tape, Tan, Slit Liner, 4 in x 75 ft – 8067

Now you gotta tape all the seams because your insulation’s r-value is utterly moot without this finely laid millimeter of material. Yay. The project requires 12 rolls priced at $28.05 each

$28.05 x 12= $336.60

Furring Strip Boards

Product: 5/4 in. x 3 in. x 8 ft. Furring Strip Board

Now add some organic matter to this 6-layer sponge in a location just barely tucked away from where it will actually be dumping buckets of rain on your building. Space them 1 per lineal foot. The project requires 330 strips priced at $1.98 each.

$1.98 x 330= $653.40

Even More Fasteners

Product: HeadLok 6 in. Heavy Duty Fastener – 250 Pack

The final penetration! Use these fasteners to attach the furring strips to the structural sheathing, passing yet again through both the insulation and the rainscreen. With the furring for attachment, you can now use these screws to attach siding. The project requires 13 packs priced at $129.00 each.

$129.00 x 13= $1,677

Insect Screen

Product: Home Slicker Screen

Make sure bugs don’t nest in your assembly by running this screen along the bottom of your wall. The project requires 1 roll priced at $75.50.

$75.50 x 1= $75.50


InSoFast EX 2.5 Panels

Product: InSoFast EX 2.5

Add InSoFast. The EX 2.5 panels are an all-in-one solution to the rainscreen/insulation/attachment fiasco depicted above. Yep, it’s all there. This project requires 60 boxes priced at $73.60 each.

$88.40 x 60= $5,304.00

Starter Track

Product: Starter Trac w/Drip Edge, 2-1/2 inch, 8′ Length

This serves as your bug screen for InSoFast. It also provides a drainage area and nice place to rest your first run of panels. This project requires 15 starter tracks priced at $22.81 per 8 ft length.

$22.81 x 15= $342.15


Product: Grip-Rite #10 x 4 in. Phillips Bugle Head Coarse Thread Sharp Point Polymer Coated Exterior Screws

First, screw the panels to your structural sheathing. It’s always best to line up stud with stud and the EX’s embedded studs are located every 16 on center. Next, attach the siding to the InSoFast stud. This project requires 9 boxes priced at $25.64 each.

$25.64 x 9= $230.76


So there you go! We highlighted each material and step to the last tack and the results blew us away. One more time, that’s $7,970.94 and a whole lot of work compared to $5,876.91 with our single interlocking panel. It’s a difference of over $2,000 for a 2,400 square foot project.

Believe it or not, we didn’t engineer our product to be cheaper. We were way more focused on eliminating all the complex variables that can muck up your good intentions. We wanted something simple and effective. A secure, future-ready investment. The overall cost is just a bonus.

InSoFast panels reduce the complication of building an exterior wall assembly with an all-in-one rainscreen and insulation solution
  • Jeannine Hinman

    My question is this: How do objects attach and stay, with your insulation? It just looks like styrofoam to me. Don’t get me wrong, styrofoam seems like a great insulator, just as we see in coolers we use for our picnics. BUT I have doubts that it’s something to which I could attach heavy cabinets. Help me understand what it is that can support heavy weight on those walls. What are the studs made of and where are they?

    • The studs are made of a high-strength polypropylene plastic. We use a co-molded manufacturing process in which the foam body is expanded around three studs (spaced 16″ O.C.) to become one fully-encapsulated product.

      You’re correct in thinking that the EPS is not structural. The rigidity of the foam material is intended for features like electrical channels, moisture control, panel alignment and continuous interlock. The studs are the only component of the panels that should support weight.

      We’ve had our studs tested by Intertek, one of the world’s leading quality assurance testing corporations, and you can read their architectural report here:

      The report focuses on two specific metrics for testing stud strength, withdrawal and shear (or lateral) strength. The maximum withdrawal is the point at which a screw will pull out of the material and the maximum lateral is when weight will cause a shear break on the screw or material. The report adds a very conservative safety factor of 5:1 to calculate design load for construction. Basically, they divide the maximum loads by 5 to get 65lbf of withdrawal strength and 94lbf of lateral strength per screw.

      So how strong is the InSoFast stud? You can hang a 65lb cabinet with just one screw and then fill that cabinet with 250lbs of stuff before having to worry about it. Thanks for posting this question! Let us know if there’s anything more we could add.

  • xmas_shopping

    Is this an insulation product for use in residing your home?

  • Charles

    How does it compare, feature-wise, vs Levelwall, Enerfoil, Dow, etc?

    • We believe the features of our InSoFast panels are the most complete that any product on the market could provide, but we understand every project to be 100% unique and determining the best features for your own project will rely on your own research.

      We encourage you to start here where you can read all about the technical features and specifications of the EX 2.5 panels, but we’d also like to hear from the community in regards to your question. If anyone has anyone tried the products listed, please add your input!

  • Tom

    I live in Hawaii in a single wall house and wonder if I use this on the outside, can I just paint it or does it require a cover material. My Son in law ion mainland just installed in 2500 sq ft basement and it’s very impressive. Also, do termites bother it?

    • Foam products are required to be covered with a 15-minute thermal barrier to pass fire-safety codes. You should check this with your local code official as there may be a type of paint that satisfies this requirement in your area. Regardless, the foam body of our panels is definitely not intended to be a finished material.

      Termites have no interest in InSoFast panels because they don’t contain or retain any organic material that would pose as a food source.

  • coldfusion101

    Very interesting product! Is it possible to install on a light wood frame (w/ Zip sheathing) assembly that is 24″ O.C. stud spacing? I wonder if 1×6 cedar siding can be applied over your EX 2.5 panels, fastened @ 24″ O.C..

    • It is possible. You will just need a few extra fasteners to ensure strength and wind-load resistance against your sheathing since only 1/3 of our embedded studs can actually match up with your wall’s structural framing. You may find this bulletin on screw fastener capacities in OSB helpful for figuring out how many you will need per our stud.

      Check with the manufacturer of your cedar siding to see what they recommend for attachment. It’s possible they’ll allow 24″ O.C. attachment, but with InSoFast panels you’ll at least have the option of 16″, too.

  • Islander361

    So in a retro fit situation. Removing Masonite siding, hoping to install Hardie Plank . Could I use nails to install the Hardie Plank or have use screws?

    • The InSoFast stud itself will support either attachment method. Whether one is better than the other for the Hardie Plank will depend on Hardie’s own recommendation, but we’ve seen most installations use nails. Here is a video example of a contractor nailing Hardie Plank to our EX 2.5 panel’s embedded studs.

  • Ethan Nelson

    How many 4″ screws per 2.5 panel do you recommend in and exterior application?

    • You should 6 screws (2 per stud) spaced every 12″ on center vertically.

      As per our Code Report you would need this amount of #9 x 3.5″ screws to achieve the maximum wind loading of 146mph or 46psf positive/negative wind resistance.

  • Wotton

    Can you install this product so the studs are horizontal? I am doing board and batten on the exterior of a house.

    • You can, but this will largely eliminate the effectiveness of the moisture drainage channels (the built-in rainscreen) which will then also run horizontally. Vapor will still have a place to move and be released, but gravity will no longer be at your disposal to carry away any potential liquid water. Check it out with your local code official.

      We do this on shipping containers in order to get continuous attachment across the corrugation, but in that instance we are sealing the panels around steel which will not breathe moisture.

  • Chris

    To achieve R19-R21, in Southeast Texas, what would be you suggested application on a shipping container (interior/exterior, etc.) I have seen a YouTube video on how to apply your product inside a shipping container, but, I would assume that gives R8.5-R10?

    • Indeed, insulating both the interior and exterior would be our first thought. Depending on the R-value of your finishing materials, you may be able to achieve this solely with UX 2.0 panels (combined to R17). We may also have a solution that involves filling the corrugated cavities, give us a call for details on that.

      One of our customers in the Houston area is insulating a shipping container right now and may offer some insight on her process blog.

  • onebigelf

    How would the exterior application be done on a shipping container?

    • In order to maintain the inherent vapor barrier of a steel shipping container, it would be optimal to adhere the panels to the exterior. We recommend running the panels horizontally in order to capture more contact between the studs and steel corrugation. You can find out more information related to shipping containers on this page.

  • Sebastien Desrochers

    Can you use this product as a replacement to perimate. I want to use the 2.0 panels with the drainage plane facing the interior of a exterior block foundation after a spray on waterproofing membrane has been sprayed on on the block walls. Can this product stand up to UV lighting and the hydro-static pressure that will be on the wall once it is back filled

    • This should work. Always make sure the UX 2.0’s drainage channels are against the wall as this is also the correct direction for the embedded studs to attach. You can learn more about how EPS performs in below-grade applications from the EPS Industry Alliance. If the panels are exposed to UV lighting, you should use a product like Insul-Guard or Groundbreaker to protect them.

  • Rich Johnson

    I have a low slope roof/ceiling combo (2×6 T&G) in Calif. I plan to frame out on top of exstg T&G, adding EX2.5 Panels, then sheeting over, which will then have new roofing installed. I get differing opinions on handling any excess moisture 1) Put down Tyvek first, taped seams, and caulk framing to stop air flow. . .trying for zero air, or 2) Same thing, but install framing about 3/4″ beyond lower roof edge, allowing excess moisture to drip behind facia.

    Bottom line question is: What is best way to install for this application? Thanks

    • This may be easier to discuss over the phone. Give us a call at (888) 501-7899 and ask for Ed, our chief engineer.

  • Erik Bang-Birge

    Your numbers for the InSoFast system are incorrect. In the picture the fasteners are labeled three, and the starter track is labeled 2. In the description, these are switched.

    • Thanks for the catch! All fixed.

  • Brian

    I have a concrete block garage that I want to heat and cool. I wanted to insulate the outside only to have more room inside. I want to use vinyl siding. Do I use a housewrap first then screw in the insofast to the block and then screw the siding to the insofast or do i use furring strips on top of the insofast to secure the siding? Thank you.

    • You have the right idea. InSoFast gets attached to the block and then siding gets attached to the InSoFast. All of these attachments are handled by the InSoFast panel’s embedded studs (the black T-shaped things in the diagrams on this page) so you don’t have to add furring strips to the mix.

      • Brian

        Should I go below grade with the insulation? Is taping the corners recommended?

        • Going below grade can definitely help the insulation value of your building and protect it from freeze-thaw cycles. Whether or not it is necessary will be up to you and depend on your unique situation. We’d recommend getting more information on this topic from a local building inspector who knows the codes and requirements in your area. With regards to taping, we don’t typically expect a need for it and feel you’d be better served by sealing any potential corner gaps with an expanding spray foam.

  • Tom

    I am considering this for a concrete block building just as Brian mentioned earlier. I’d like to be able to talk to Brian and compare notes.

    • Care to share some notes on concrete block building with Tom, @disqus_EOduXfE7IT:disqus?

  • April Johnson

    Can I use this over top of flat siding ?

    • No, our panels are not a finishing layer. They should be underneath the siding.

  • A well-timed question, Nick. We have actually offered this product as a custom call-in order for about a year now, but as of today it is available for purchase directly from our website: It is indeed much easier and more effective than spray foam fills!

    You can achieve continuous R-11 walls by combining our UX 2.0 Panels with Container InSerts and continuous R-13 with the EX 2.5 Panels. By insulating the interior with UX 2.0 and exterior with EX 2.5 in combination with the Container InSerts, you can achieve continuous R-24. This is the common approach for constructing Zero-Energy Ready homes and is 53% better insulated than a standard 2×6 Wall with R-21 batt insulation which performs at R-14 when factoring the loss from un-insulated studs.