Steps (and Tips) for Fastening Halo Subterra or Subterra Plus to the Exterior of a Foundation Wall


If you’re wondering whether installing Subterra or Subterra Plus on a foundation wall is a hassle, let us put your mind at ease — it’s really not. And while there are some nuances you should keep in mind, plenty of options exist for securing the panels to the wall surface, and ultimately, it only takes 4 steps to fasten Subterra vertically to a foundation wall.

In the post below, we explain the steps for fastening Subterra or Subterra Plus to a foundation wall, list your fastening options, and offer handy tips to streamline your installation process.

Steps for Fastening Halo Subterra/Subterra Plus to a Foundation Wall

Fastening Subterra panels to a foundation wall is not a complicated matter, as long as you follow the four steps below.

1. Get the foundation wall ready

The foundation wall should be clear of any items that could damage the Subterra panels or prevent it from coming into contact flat against the wall, including backfill or dirt. What’s more, the foundation wall needs to be waterproofed before the insulation panels can go on. To this end, you should clear the wall of any protrusions, apply a waterproofing layer, and allow it to set.

2. Attach the Subterra panels

With the wall surface prepared, you can go ahead and install the Subterra panels. The panels should be installed vertically, with no more than a 1mm gap in between the panels. The bottom edge of the panels must sit flush on the concrete footing.

There are plenty of methods for attaching Subterra, or Subterra Plus, vertically to a foundation wall. These options include clips, hangers, and adhesives. We’ve provided examples and summarized the pros and cons of each.

Option 1: InsulFast clip by ITW

  • Thermally broken
  • Fast and easy to install
  • High holding strength
  • Compatible with poured concrete or CMUs
  • Works with insulation panels up to 6 inches thick
  • Works in all temperatures
  • Costs more than alternative fastening products
InsulFast clip

Option 2: Thermal-Grip insulation pin by TruFast Walls

  • Quick to install
  • High holding strength
  • Compatible with poured concrete or CMUs
  • Works with insulation panel thickness of up to 6 inches
  • Works in all temperatures
  • Not thermally broken
Thermal Grip Insulation Pin

Option 3: Plasti-Grip PMF Anchor by TruFast Walls

  • Limits thermal bridging (but no full thermal break)
  • High holding strength
  • Compatible with concrete or CMUs
  • Works with insulation thickness of up to 5 inches
  • Works in any temperatures
  • Installation takes longer because the anchor requires you to pre-drill the wall
Plasti-Grip Anchor

Option 4: Perforated Hangers by Tactoo (requires adhesive)

  • Quick to install
  • Works with insulation thickness of up to 12 inches
  • Highly durable
  • Requires you to apply and cure adhesive before attaching the insulation panels
  • No thermal break
  • Limited holding strength
  • Cannot be installed in low temperatures
Perforated Hangers

Option 5: PL300 Foam Board Adhesive by Lepage

  • Thermally broken
  • Relatively low cost
  • High bonding strength once cured
  • Does not damage insulation panels
  • Adhesive takes a while to cure, so you may need to brace the insulation panels for some time
  • Cannot apply the adhesive in low temperatures as it will not cure
PL300 Foam Board Adhesive

Which of the five options you choose (all of which have alternative equivalent products from other brands) is up to you.

However, note that adhesive works best if you have a smooth foundation wall, whereas anchors or hangers are the more suitable alternative if the wall isn’t perfectly flat.

3. Seal the joints

Once the insulation is installed and you’re able to remove the bracing (if you need it), you must seal and tape the following:

  • All joints between the Subterra panels (foam-fill joints wider than ⅛ inches before taping)
  • Around windows, openings, and vents

You may need to use a primer in cold weather, so that the tape or flashing bonds properly to the insulation. Water-based primers work if you’re installing in temperatures of -4°C (25°F) or up, but opt for a solvent-based primer if you must work in colder conditions.

4. Place backfill

With the Subterra panels taped and sealed at the joint, go ahead and place backfill against the foundation. As you do so, keep in mind the following:

  • Subterra panels should be sealed at the top to prevent moisture ingress behind the panels.
  • The above-grade portion of the Subterra panels should be clad with suitable parging materials, such as Stuccoflex or Styroflex.
  • In high-risk termite regions, you need a termite shield that overlaps the parging, the Subterra panel, and the concrete foundation wall. A properly installed shield protects the wall assembly from termite infestation.

Don't miss a thing!

Subscribe for exclusive content, insider industry news and limited edition webcasts.

Wrapping It Up

Attaching Subterra or Subterra Plus vertically to a foundation wall is a breeze, and there are many options for securing the panels to the wall.

Just remember that to protect the Subterra boards and to ensure the integrity of the wall assembly, you must also do the following:

  • Remove protrusions from the wall and waterproof its surface before installing Subterra
  • Seal and tape all joints between Subterra panels
  • Protect the top of the Subterra panels, as well as the exposed surface above-grade
  • Install a termite shield to protect the entire foundation wall assembly.
Latest Posts
Insight. Advice. Inspiration.
Subscribe to our newsletter and stay informed with the latest from Halo
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.
If you want help with or more information about the issues we blog about, then let’s talk.

Also See

Don’t Miss a Thing!

General Inquiries

Whether you are just starting out or well on your way toward your next big project, we would love to hear from you. 

By submitting the form, you agree to our Terms and Conditions and our Privacy Policy. This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.


Search Anything

Almost there...

For unlimited access to all of our technical and marketing resources, please enter your information. We will also email you a copy of each of the items you select for quick future reference.

By submitting the form, you agree to our Terms and Conditions and our Privacy Policy. This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.