Preparing Your Basement for Insulation

There are several steps you must address and plan before you start stacking your InSoFast panels. Think of it as a game plan, charted specifically for your project space. To make the process easier to jump-start, we’ve mapped out all the Project Prep Steps you need to tackle:

1. Determine the Condition of Your Walls

Make a “map” of your space by taking note of any wall protrusions, pipes, windows, etc. You’ll need to cut the panels accordingly. The video below shows a quick demonstration of the dry stacking method which helps to determine the layout and cuts of panels before they are adhered to the wall. If it’s possible to remove any of these obstacles, do it. It will make your job easier in the long run.

One of the advantages of using InSoFast is an adhesive-based application.

Loctite PL Premium’s 3X Stronger Adhesive is tested and approved for use with InSoFast panels.

It is designed to cure 3 times stronger than the average construction adhesive without shrinking. Additionally, it is not a solvent-based chemical. This means it won’t melt the foam and can be used in insufficiently ventilated spaces like basements.


In order for Loctite to “lock tight,” you must prep your walls. This means removing any dirt, debris, loose paint or anything else that may disrupt a wall’s surface. Cleaning the walls also helps prevent future mold and mildew issues.

Mold grows on concrete because of the organic components like dirt and dust that stick to it. You can protect against these issues and ensure a strong adhesive bond by thoroughly scrubbing your walls with a masonry cleaner such as Trisodium Phosphate (TSP) mixed in warm water. If you are still unsure about your wall conditions after cleaning you can try an adhesive test (See Step 4 of this guide).

A wall must be structurally sound before installing InSoFast (or anything for that matter), so you’ll need to check their levelness or plumb. InSoFast panels can cover the worst of walls and their interlocking design helps self-level to an extent. You need to survey your walls and decide if you have the skills necessary to tackle any advanced techniques that may be required.

For more information on this topic, check out our Shimming Uneven Walls help page and the downloadable Uneven Walls technical guide.

2. Prepare Windows, Doors, and Openings

In order to prepare the windows and doors for your InSoFast project, you will need to frame any openings with wood or metal furring that meets the thickness of the InSoFast panels. This step is easier to accomplish with EX 2.5 (2½”) panels because they are the same thickness as standard 2×3 lumber. Framing openings for UX 2.0 (2″) panels may require additional work.

You also need to make sure the framing is at least 2″ wide for attachment purposes. You can use pressure-treated lumber, western cedar, or cellular PVC for the material. This framing will ensure an even attachment point for things like drywall in case the InSoFast’s embedded stud does not perfectly meet the edge.

To attach the furring to concrete, you can use the same methods you’ve selected for the InSoFast panels. To keep it simple use PL Premium adhesive. We also recommend Tapcon concrete screws or Perma-Grip nails.

3. Plan the Electric

Electrical wiring chases are one of the many features built into the InSoFast panel. They run vertically at 16″ on center and horizontally at 24″ on center in the panels. This grid-work provides easy access to pull the wiring to any location. The chases also address the necessary separation from the drywall that’s required by electrical code.

Before you start your project you should plan out how you intend to run the electrical wiring. Use the built-in wiring chases as a guideline. If there is pre-existing electric running along your walls that does not match up with the InSoFast chases, you have a few options:

  1. Measure the distance of your channels to the floors and corners. Cut the first row of panels to adjust for this distance so that the built-in channels will line up.
  2. Carve a custom groove into the panels to add the necessary space for the wiring.
  3. Re-run your electric to follow the channels.

Some projects may require the consultation of a certified electrician.

4. Adhesive Tests

It’s generally a good idea to perform an adhesive test if you are unsure about the conditions of your walls. Start the test by spreading a bead of Loctite PL Premium 3X Stronger adhesive onto a 6” long scrap of 2×4 wood or a sample InSoFast stud. Press the “test block” against the wall with one end resting on the floor. This helps to keep it from sliding down and falling off the wall.

Support it in place if necessary. You’ll need to wait 24-48 hours for the adhesive to cure, but always remember that PL Premium takes 14 days to reach its full strength.

When the curing time has passed you are ready to test the strength of the bond! Try to pry the test board off the wall. If you can manage to pull it off with your hands, you will need to mechanically fasten the panels to the wall.

You can either use 3” mechanical fasteners by themselves or in addition to the adhesive. Our President and inventor recently noted that, “There have been some unnecessary doubts in terms of the adhesives…it’s easy to understand why it would seem unbelievable that an 8-ft stud section could hold 7,000 lbs of straight pull off, but we’ve engineered our product to meet those capabilities.” Believe in the stud!

5. Fix Water Issues

This is your last chance to fix anything before you cover it up. It is always better to keep water out than to try to manage the water inside. InSoFast panels have built-in drainage planes designed to channel water out of a wall system, but it’s important to understand that InSoFast panels are not a substitute for waterproofing.

Before blocking the walls with insulation you also need to correct any water intrusion problems that already exist.

Drylok Extreme Masonry Waterproofer is tested and approved for use with InSoFast Panels.

This smooth waterproof paint is perfect for the most demanding conditions including interior, exterior, above or below grade masonry walls, basement walls and more. It is also specially formulated to resist mildew growth. Another option is Emecole Pene-Seal-Crete which is easy to install and will penetrate up to 3 inches into concrete walls. Learn more about waterproofing on our Waterproofing and Moisture Management Page.

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  • MarkD

    The link to the waterproofing and moisture management page above doesn’t work.

    • Thanks for the catch! Everything should be up-to-date now.

  • Jim

    I have a cinderblock wall foundation in my home and there is product called WhiteCap Vapor Barrier installed on all the walls. It is installed with masonry anchors in regular intervals to adhere it to the walls. Can the InSoFast product be glued to this Vapor Barrier and provide the support required? Thanks!

  • TTAH

    Hi – the base of my walls, where it meets the floor, is curved slightly with concrete (I guess some old attempt at water sealing in this 1954 ranch). What would you recommend since I cannot sit the first set of panels flush with the floor (short of removing the concrete, which I don’t want to do since the basement is dry). perhaps just start it up the wall a little bit above the curve?

    • As opposed to removing the concrete, we’d recommend carving out the back of the InSoFast panel assuming the size of the curve is within the depth of the panel. This is the same process one would use to set panels over pre-existing features or obstacles in a wall – check out our playlist for Advanced Installation Techniques for examples.

      If your curve extends too far past the panel’s depth, you can build out the wall to offset it and create a new, flush surface for the panels to sit.

  • sne

    How long should I let the Dry-Lok cure on block walls before it’s safe to glue on the Insofast?

  • Tony Kowalski

    My basement walls are poured concrete but have been covered with masonry stucco. Will I need to remove the stucco to glue the panels to it?

    • You’ll need to be the final judge in the matter, but if the masonry stucco is in good structural condition it shouldn’t be an issue. Don’t install the panels if the stucco is chipping off the wall. Try performing an adhesive test, as described above, if you are uncertain of the condition.

  • Adam Heese

    I’ve never had water issues in the basement but i’d rather be safe than sorry. However, Is it necessary to use Drylok Extreme or would normal Drylok masonry waterproofing latex paint be sufficient? Thanks!

    • We know that Drylock Extreme Masonry Waterproofer will work with our approved adhesive (PL Premium 3X) and partly recommend it for that reason. If you intend to use a different formula, we suggest performing an adhesive test along some part of your wall to make sure there won’t be any issues.

  • Doug Lade

    We have lived in our house for 10 years now since it was built in 2007 and had never had any water issues. Is it really necessary to put on the Drylok?

    • Doug- That is a judgement call that you have to make. InSoFast does not require Drylok water proof paint.

  • BTolerant

    I have poured concrete walls with a brick design on them. Will that be a problem with the adhesive since there are so many grooves and valleys?

    • Your condition, the brick pattern wall, is pretty common in the mid-west and does not present a problem.
      Brick pattern walls adds a layer of difficulty when compared to a flat smooth concrete surface and uses more glue, about 10 -15% more. With brick pattern walls the panels may need to be braced until the glue sets… like when you were a kid building a model airplane or cabinet maker who has to clamp the wood parts until the glue sets. On brick pattern walls the InSoFast EX panels works better because of the tighter inter-locks and you will need less bracing. Additionally you can always screw the InSoFast panels into your concrete walls. But I feel that is way too much work. Additionally why poke holes into a perfectly good wall. Here are a few more resources on our website:

  • bruce flagg

    I have a concrete block cape cod built in 1936 in Pennsylvania. The exterior walls consist of stucco on the outside concrete block and the horse hair plaster on the inside. my question is what would I need to do in order to install the 2.5 insofast to the interior. would I be able to secure the panels with pl premium to the plaster or would I have to do something else. the plaster is in good shape and not peeling from the block. I would like to do the interiors because I would like to have drywall inside instead of plaster.

    • That is a pretty common condition and one we have written about try this blog post:

      It is always best to test the adhesion if you have any doubts about your wall’s integrity.

      Adhesive Testing

      If you are unsure about the conditions of your walls, we recommend performing an adhesive test. Find a scrap 2×4 measuring at least 6 inches long and run a 3/8-inch bead of adhesive along it. Press the “test block” against the wall with one end resting on the floor to keep it from sliding down. Support it in place if necessary. You’ll need to wait 24-48 hours for the adhesive to cure, but keep in mind that PL Premium takes 14 days to reach it’s full strength.

      When the curing time has passed you are ready to test the strength of the bond. Try to pry the test board off the wall. If you can manage to pull it off with your hands, you will need to mechanically fasten the panels to the wall.