A interior wall with a spray foam insulation application

Spray foam insulation is relatively easy to apply. It’s designed to last several years, sometimes multiple decades. However, some homeowners want to remove this form of insulation to replace it with foam batts, boards, and other materials. 

You might be curious if you can remove this long-lasting, durable spray insulation from your home.

In this post, we’ll explain whether or not you should replace your spray foam insulation, detailed steps to do so, and why you should remove old insulation before adding new spray foam.

Can You Remove Old Spray Foam Insulation?

You can remove old spray foam insulation with a serrated knife or a saw. Scrape the remaining foam pieces with a putty knife, then use lacquer to freshen the surface for the new insulation you intend to install. Make sure you wear protective goggles and gloves throughout the process.

How Difficult is It to Remove Spray Foam Insulation?

It’s fairly difficult to remove spray foam insulation because it’s been designed to stick to almost any surface for several decades. Removing anything that’s made to be sustainable for the foreseeable future will be a challenging task. 

Especially in this instance, since spray foam expands and hardens. Therefore, the most challenging part of the process is getting the small pieces off the insulated surface.

A picture of spray foam insulation covering the floor and wood studs in a wall.

Another reason it can be challenging to remove spray foam insulation is that it hardens quickly. As a result, you can’t remove it by hand. Thus, some people use hand saws, hammers, and other tools to remove chunks of the insulation material. If you do this, ensure you don’t damage the surrounding wood, metal, and drywall.

Note: If you don’t want to go through the process of reapplying spray foam, you can consider using RetroFoam insulation around the gaps and edges instead. It’s great for handling air pressure and moisture. It’s always worth weighing the pros and cons of various forms of insulation after removing the old insulation material.

How to Remove Old Spray Foam Insulation

To remove old spray foam insulation, follow this process:

  • Use a saw or a serrated knife to remove as much bulk as possible – avoid power tools at all costs. It’s best to remove small portions at a time, then work around the edges once you get rid of the bulk of the insulation. Wear goggles, long sleeves, and gloves when removing the foam.
  • Scrape the edges of the insulation with a putty knife – you can also use a flathead screwdriver. Avoid using tools that might scrape the wood, metal, drywall, and other wall materials around the spray foam insulation. Instead, you can heat the putty knife to help it glide through the foam easier.
using spray foam between the wall and the hardwood floor for air sealing
Using canned spray foam to seal between the wall and the floor, which dropped over time, creating a huge air gap.
  • Spray on Foam suggests using lacquer to remove the remaining bits and pieces of the old spray foam insulation. Brush it all over the foam, wait a few minutes to let it dissolve the adhesive, then use a putty knife or an abrasive sponge to remove the lacquer and remaining foam insulation.
  • Let the area dry, then clean it with wood cleaner (or whichever material the spray foam was on) before adding new insulation – make sure there’s no moisture trapped in the surface, or it can create insulation gaps, mold, wood rot, and rust. If you want to use more spray foam, remember that it expands exponentially.

Do You Have to Remove Old Insulation Before Spray Foam?

You must remove old insulation before spraying foam because it needs a clean, dry surface to stick to. The spray foam will fall off if there’s dust, debris, or old insulation on the surface. However, you can use spray foam to insulate the edges and cracks of old insulation without removing it.

Here’s what you should know about using spray foam with old insulation:

  • Spray foam insulation can damage wood and nearby walls if you put it over old insulation – according to Cape Fear Foam, spray foam insulation expands enough to cause damage. It presses the joints, studs, and nails. You’ll notice minor stress cracks that cause permanent insulation gaps, too.
Rim joist insulation using spray foam to form an airtight seal.
  • Failure to clean the surface will cause uneven insulation – spray foam insulation can’t stick to anything wet, dusty, or loose. It also can’t adhere to old insulation because it is often crumbling, cracked, or damaged. So always thoroughly remove and scrub the old insulation beforehand.
  • You can’t patch damaged insulation with spray foam because the foam needs a solid support structure to expand – it’ll grow in all sorts of directions, preventing it from sealing. You’ll have perfectly insulated portions, but there’s no doubt that wind, moisture, and fluctuating temperatures will get around the spray foam.
  • Always clean and dry the surface after removal – removing the bulk of the insulation is not enough. Fortunately, foam batts and insulation boards are very easy to remove. If you’re removing old insulation foam, follow the steps mentioned in the previous section.
  • Feel free to use spray foam to treat small gaps but not cracks – for example, if you have gaps between studs, batts, or boards, you can use spray foam insulation without removing the old insulation. However, you can’t patch cracks in foam boards because the cracks will inevitably expand. So instead, replace the boards, then seal the edges with spray foam.

Final Thoughts

Removing old spray foam is tedious, but it’s more than worth it if you want to change the insulation in your home. Adequate insulation is required for net-zero living, but it’s highly beneficial for any building worldwide. Remember to stay safe with protective gear, and don’t forget to remove 100% of the insulation before adding a new layer.


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