InSoFast PLUS: Adding Extra Insulation

It’s easy to increase your R-Value beyond R-10 code minimums while maintaining the engineered benefits of continuous InSoFast panels. Simply layer rigid foam insulation board over top of InSoFast panels, a technique we’ve dubbed InSoFast PLUS. This saves money by utilizing locally obtained rigid foam to enhance the R-Value. Additionally, PLUS projects can be completed in a fraction of the amount of time because they start with a base of feature-rich, low-labor InSoFast panels.

insofast-plus-dow-blue-board insofast-plus-dow-electrical-raceway

Added R-Value with InSoFast PLUS

You can use either UX 2.0 or EX 2.5 panels to develop an InSoFast PLUS wall – giving you the ability to go from R-8.5 to R-21.

  • Embedded studs provide a continuous insulation (CI) barrier, eliminating thermal bridging which is a crucial task for modern construction.
  • Add any amount of rigid foam over the InSoFast base panels to acheive any desired R-Value.
  • Solid attachment can be achieved simply with adhesives. If preferred, they can be drilled or nailed.
  • Interlocking panels bridge over wall deviations to help level and plumb the wall.
  • Ventilated air channels control over moisture that can enter exposed masonry to allow for quicker drying.
  • Pre-engineered electrical raceways enable the insulation shield to stay complete and intact.
PLUS System** UX 2.0 PLUS (Complete wall assembly*) EX 2.5 PLUS (Complete wall assembly*)
InSoFast PLUS ½” Rigid Foam @ R-2.5 R-11.0 (R-13.58) R-12.5 (R-15.08)
InSoFast PLUS ¾” Rigid Foam @ R-3.75 R-12.25 (R-14.83) R-13.75 (R-16.33)
InSoFast PLUS 1″ Rigid Foam @ R-5.0 R-13.5 (R-16.08) R-15.0 (R-17.58)
InSoFast PLUS 1½” Rigid Foam @ R-7.5 R-16.0 (R-18.58) R-17.5 (R-20.08)
InSoFast PLUS 2″ Rigid Foam @ R-10 R-18.5 (R-21.08) R-20.0 (R-22.58)

InSoFast PLUS in Action

At an award-winning project in North Dakota, the developer wanted additional insulation without sacrificing interior space. They chose InSoFast to be directly install onto the masonry wall with an additional 1″ rigid insulation board placed on top to increase the R-Value to meet the local energy code requirements. It was a labor-saver for this fast track retrofit project.

The InSoFast panels were installed first so the studs would be securely fastened to the concrete substrate. The 1″ rigid foam was installed over top with the InSoFast stud locations marked on the floor and ceiling prior to adding the drywall. To attach the drywall, they used all-purpose 2″ drywall screws to penetrate through the drywall and rigid foam into the InSoFast studs.

Importance of Continuous Insulation


The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) standard 90.1 defines continuous insulation (CI) as insulation that is continuous across all structural members without thermal bridges other than fasteners and service openings. It is installed on the interior, exterior, or is integral to any opaque surface of the building envelope.

In cavity insulation systems, traditional stud framing can account for at least 25% of wall space. When the studs are uninsulated, there is enough thermal bridging to drop the R-Value from 19 to 12.5 – nearly a 35% loss, which can render any additional layers of insulation useless.

Building codes have higher requirements for cavity insulation to make up for the uninsulated studs or framing members. That is why basement wall code reads 10/13 in many climate zones. It can be R-10 continuous insulated sheathing on the interior or exterior of the home or R-13 cavity insulation along the interior of the basement wall.

See Finding your Climate Zone and Energy Requirements for more information.

Changing Energy Codes

New building codes are increasing R-Values minimums every 3-5 years so that new houses are will not be obsolete or un-affordable 30 years from now due to escalating energy prices. The projected codes for 2030 demand R-Values up to R-30 and the push toward net-zero housing is becoming a reality. While these codes are well-intentioned, they don’t always figure a return on investment into the calculation.

To prepare for rising costs and changing energy environments, you may need to exceed your current local energy codes. See the links at the bottom of this page for information on Climate Zones and changes to the International Energy Conservation Codes (IECC).

Related Information

  • Daniel Motta

    I am going to insulate my attick , I would,like to know if InSoFast would work there? I plan to put a hit barrier between the rafters , let me know your thoughts on this , thanks Daniel Houston

    • In general, the logistics of an attic space make it more difficult and more costly to insulate with InSoFast than it needs to be. You’ll probably be happier sticking with a basic rigid board + spray foam installation. It’s similar to a insulating a rim joist, where we recommend using our panels if/when you have scraps leftover from the primary installation.

  • As we mentioned to Daniel in this thread, while certainly possible it may not be your most practical option. Additionally, there are a lot of details about the roof and installation we would need to know before giving any accurate recommendation. If you have time, give us a call at (888) 501-7899 to discuss further.

  • If we understand you correctly, it sounds like the only purpose these studs hold is attachment for drywall (and maybe some space for electric, too). If that’s the case and the split block walls are structural, it would be far better to remove the studs altogether!

    InSoFast panels have built-in (and continuously insulated) studs that can be adhered directly to the block and support the drywall attachment. They also include electrical raceways, so no worries there. Placing the InSoFast between the studs would be a waste of time not only because there are less specialized types of insulation for that application but also because those studs would continue to decimate your R-value via thermal bridging.

    If you determine the studs are necessary, however, you can actually just attach the InSoFast panels directly over them – stud to stud.

    • Drew Peterson

      Awesome!! Thanks for the quick response.

      • Happy to help. Sounds like it’ll be a pretty rewarding renovation, be sure to get pics of the transformation!

  • We have concrete half walls in our basement. We have already glued pink rigid foam insullation to the walls in the two bedrooms (we were planning on building 2×4 walls until we found your product). Do we need to remove the pink foam insulation, or can we install the In so fast panels on top of it?

    • The built-in studs of the InSoFast panel are only as effective as the substrate they are installed against, so this application wouldn’t actually result in a framed wall if you adhered the panels to the rigid board. You could use long Tapcon screws to go through both the InSoFast stud and rigid board to securely fasten them into the concrete, but this is really not an ideal solution. At this stage, it would be best to frame the wall traditionally or replace the rigid board with InSoFast.

  • Ross- That is a good suggestion. We will put your question into our #AskInSoFast video answers soon. In the mean time electrical really does not change from our standard proceedures: At that page you will find another video about Carlon electrical box extenders.

  • Frank Feinstein

    I have a small all concrete block house that needs rehabbing. It is stucco on outside block wall and the interior walls are all block. The house is 67 years old. I can glue the insofast panels straight to the block? If i add drywall on top of that how do i handle the vintage large molding on the floor? Window seal?

    • Frank- Yes you can glue the InSoFast to the wall. Here is a page link that goes into technical detail: You will have to remove and reinstall the trim.

    • InSoFast can be glued directly to concrete block if the block is in a structurally sound condition. My recommendation for your vintage question is to carefully remove the molding and reinstall it on top of the newly insulated wall.

  • Don Mills

    Does Insofast have any termite protection? We previously used a foam board that had Borate treatment included for use in sealed crawlspaces. The foam will be about 4″ off the dirt. We are in Georgia