Removing foam insulation board backing can be a painstaking process as the insulation sticks to the surface, and it is very easy to damage the surface while taking it off. There are multiple methods you can try, but you must not be too rough with the insulation as you could end up damaging the walls or floor to which it is attached. Since the insulation is applied using a specialized adhesive, you need to make sure you use the right equipment while removing it. Over time, you will notice that the insulation will start coming off on its own, but if you are in a hurry to remove all of it without waiting for nature to run its course, try the methods below.
Use a Circular Saw or Handsaw
Before you start, make sure that there are no pipes or electrical wires beneath the surface of the insulation. If there are, you should shut off the water, gas or electric supply to be safe.
If the insulation has been applied in thick layers, you will need to use a handsaw or circular saw to remove it. A razor will not be able cut material thick ,so a saw will be more efficient. Usually, it is best to start the cutting process with a saw so you can thin down the insulation enough to cut it with a razor knife. Cut in a sideways motion, not at a 90-degree angle, to avoid damaging the walls.
Use a Razor Knife
A razor knife is one of the most popular tools for removing foam insulation. Use it to cut and strip away pieces of the foam. This will take time as you will need to be careful, but you should be able to get some large bits off if you start cutting in strips. Also, use a razor knife for cutting insulation foam that is up to 1 inch in depth in sheets and strips. Any thicker pieces will need to be cut in smaller pieces.
Use Chemical Solutions
Now that you have removed a majority of the insulation, you will need to use chemical solutions to remove the last bits. You can use either lacquer thinner, nail polish remover or even acetone. Acetone is extremely useful in removing insulation foam that was not cured. Lacquer thinner is great for removing foam insulation as well, specifically that foam which has dried out. Use with caution as both acetone and lacquer thinner are extremely flammable. Take care to avoid damaging the wall that the insulation is stuck to when you apply the chemical solutions and apply the solution bit by bit to one area at a time till you get it all off.