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Do-It-Yourself (DIY) Spray Foam Insulation, Is It Worth It?


Professional foam install

We get asked this question quite a bit, especially from our South Florida Customers! We have composed a quick guide on how you can do DIY Spray Foam yourself and see if it's worth it to try it yourself or hire a professional. If you're local to South Florida, we sell foam kits and accessories too! Call us at 954-459-4419 to see how we can help.


First, What Is a Do-It-Yourself (DIY) Spray Foam Insulation Kit?

A DIY spray foam insulation kit is an advanced, low-pressure, two-component, portable spray foam insulation application system not to be confused with a single-component canned foams commonly found at hardware stores. DIY spray foam insulation kits are most suitable for small projects like a small shed, an exposed wall, a Florida Room roof deck and other projects typically smaller than 400 square feet. The components are sold as a two-part kit comprising of an isocyanate side and a polymer side. The kits also comes with a clear, reusable hose and replaceable nozzle tips. 

Most foam kits are closed cell foam. This is due to closed cell foam not being as heat-reliant during the application process. Though with new technology more open cell kits are starting to hit the consumer market.

How Many Inches of Foam Should I Spray?

This answer depends on where in the country you are located, what area you are spraying (roof deck, exterior walls, basement, etc.), and what the building will be used for. Colder climate zones like the Northeast and Midwest will require more insulation, warmer climate zones in the South, like Florida, will require less insulation. An air-conditioned space will require more insulation to keep the space cool to prevent the A/C from running. An unconditioned space won't require as much insulation to slow the rate of radiant heat.

If you plan on air conditioning the space, we recommend spraying 2" R13 closed cell in exterior walls, 3" R20 closed cell in a roof deck. If you have a basement or crawlspace, we recommend spraying 2" R13 closed cell in a basement or crawlspace ceilings.


If you don't plan on putting air conditioning and you just want to reduce radiant heat transfer to keep the space cooler, you can spray as little as 1" R6.5 closed cell spray foam. However, we do not recommend spraying less than 1" of closed cell foam in either application or you will not experience the maximum benefits of spray foam.

How Do I Calculate How Many DIY Spray Foam Kits I Need?

The number of spray foam kits that you need will depend on the amount of board footage that you require. Board foot is a unit of volume and is calculated by taking the square footage of the area being insulated multiplied by the number of inches of spray foam being applied. For example, an area that is 10' wide by 10' long is 100 square feet. Spraying 1" of foam in 100 square feet is equal to 100 board feet. Another example is 25'x10' area is 250 square feet. Spraying 3" of foam in 250 square feet is equal to 750 board feet. Calculating the amount of board feet of spray foam you need will help you calculate how many foam kits you will need to buy.

DIY Spray foam kits come in different sizes ranging from as little as 20 board feet (20 sq. ft. @ 1″) on the low-end up to 1200 board feet (1200 sq. ft. @ 1″ or 400 sq. ft. @ 3″) on the high-end. The most commonly available foam kits are 200 and 600 board foot closed cell kits. You can determine how many board feet are in a foam kit by the number that's included as part of its name. 

In the examples above, a 10'x10' area with 1" of spray foam requiring 100 board feet could be sprayed using one 200 board foot closed cell while still having some extra material left over. You can choose to spray more foam to have a thicker coverage or save the rest for another area of the house. In the second example with a 25'x10' area with 3" of spray foam requiring 750 board feet, one 600 board foot closed cell kit and one 200 board foot closed cell kit would be enough to cover that area.

Keep in mind that the labeled board footage shows the maximum amount of board feet you will get under ideal conditions. It is not uncommon to only get 90% or less than the advertised amount due to waste, uneven application of the foam, ambient temperatures and substrate conditions. You may need to order more than what you calculated to complete the project.

What Should I Wear When Using a DIY Foam Kit?

Spray foam is messy, hard to remove and releases fumes when it expands. Fortunately there are steps you can take to do it safely, efficiently and without having to ruin your clothes. We strongly recommended that you wear Personal Protective Equipment (PPE) when working with DIY spray foam kits to protect yourself from inhaling chemical fumes or getting the spray foam on your skin and hair. The PPE we recommend includes:

  1. Tyvek suit, or similar chemical-resistant suit, with built-in hoodie and elastic bands around your wrists and ankles to protect your body, hair and clothes from spray foam.

  2. Full-Face or Half-Face Mask with P100 Organic Vapor and Acid Gas Filters to prevent inhaling fumes during the process. If wearing a half-face mask, make sure to wear safety goggles to prevent foam from getting into your eyes. Ensure that the mask fits tightly and that no air is bypassing the filters.

  3. Disposable Nitrile or Latex Gloves to protect your hands and wrists. We recommend using duct tape to secure your suit to your gloves and protection spray foam from coming into contact with your arms and wrists.

  4. Disposable Booties or an old pair of shoes along with a long pair of socks that you don't mind throwing away to protect your feet and ankles.

Using the PPE listed above will greatly reduce your exposure to spray foam liquid and fumes. Spray foam is almost impossible to remove from clothing so make sure to wear something you don't mind throwing away in case you do get some overspray!


How Should I Prep The Area I'm Going to Spray Foam?

The goal when spraying DIY spray foam kits is to only spray foam in the area that you want to insulate. Clear out as many movable items from the room and make sure to protect the windows, floor, doors, electrical outlets, etc. to prevent overspray.  The best, and worst, part about spray foam is that it sticks to just about everything. Once spray foam gets on a surface, you will be able to scrape it off when it cures but it will often leave a residue that can be almost impossible to remove. 

We recommend using a 1.5mil or thicker plastic polyethylene sheeting that covers the area you want to protect and attach it using blue tape, spray glue or staples to keep it in place. You can also use Ram Board, cardboard or other protective products as long as it is completely covering and firmly attached to the area you want protected. Blue tape can be installed over electrical outlets to prevent foam from entering the boxes. The benefit of prepping the area is that it makes cleanup a whole lot easier when you're done.

We also strongly recommend adding ventilation to the area that you are spraying. When you mix the two parts of spray foam, fumes are released during the expansion process that are not particularly good for you. In addition to your PPE, you should open windows and doors in the area that you are spraying and consider running a fan to exhaust the fumes during the application and for a few hours after the install is complete. 

What Substrate Can I Spray to and What Conditions Should It Be Before Spraying?

Spray foam is an excellent product because it will stick to just about anything. However, you want to make sure you are applying it to the right substrate and that it is in good condition to ensure the best adhesion and a successful install. Spray foam works very well when sprayed against a solid substrate like plywood, OSB, metal panels, wood planks, rigid foam board, drywall, and lath and plaster. You will want to make sure that area is water-tight and that the surface is dry and is free from dust and debris. Ideally, you want to substrate to have a moisture content of 18% or less when applying spray foam. Any more than that and you may have adhesion issues as well as chemical reaction issues that could prevent the foam from sticking, cause poor yield, or cause it to start peeling and falling off the substrate. 

It is also recommend that the substrate you are spraying against be at least 65 degrees Fahrenheit, and Ideally between 75-100 degrees Fahrenheit to ensure proper curing and to maximize yield. Anything colder than 65 degrees Fahrenheit could cause the chemical to react poorly and prevent proper curing of the spray foam. You may also get reduced yield which will require more foam kits to finish the job. Generally speaking, the warmer the substrate and material, the more the spray foam will expand and the more yield you will get out of your kit. 

How Do I Get The Most Yield Out Of My DIY Spray Foam Kit?

To maximize the yield and make sure that you are producing safe and effective spray foam you want to make sure that the spray foam kit is heated up to between 75-100 degrees Fahrenheit and that you vigorously shake both tanks for one to two minutes immediately prior to using. This will ensure that the chemical will flow smoothly through the hoses and that the chemical reaction that causes spray foam to expand will be properly activated getting you the best yield possible for your project.

My Substrate is Ready, My Foam Kit is Warm and Shaken, How do I Spray Foam?

You're finally at the fun part! Before you start spraying you want to begin by attaching the hoses to the tanks and install the tip at the nozzle. Make sure that the hoses and tips are on tight. You will then turn the knobs on the tanks to release the chemical in the hoses. Before spraying the cavity, pull the trigger and spray some foam into a garbage bag to ensure the chemicals in both hoses are reaching the tip and creating a one-to-one ratio.

Once you you are ready to start insulating, start by picture-framing the cavity by slowly spray foaming along the top, bottom and both sides. Try to continuously pull the trigger while keeping the tip approximate 12"-24" from the substrate. When you are done picture framing, you can start spraying the center of the cavity by starting from the top and going side-to-side down to cavity while trying to have a 50% overlap from your previous pass. The initial liquid thickness of the foam should be between 1/2" to 1". It will expand about 2x-3x its liquid form in about 20 to 30 seconds before reaching it's final solid form.

Keep in mind that the foam will start expanding almost immediately and will reach its final position in about 20-30 seconds after being sprayed. However, it will soft and gooey for up to 20 minutes until cures when it becomes hard to the touch. This is completely normal. Do not spray another pass over the foam before it hardens if you have not reached your desired final thickness. Continue spraying the rest of the space and come back 20-30 minutes later to spray over the original area once the original layer has hardened.

If you've used up your tanks, make sure to close the valves on the tanks and dispose per your local guidelines. If you still have some foam in the tanks and want to use it later, remove the old tip and put a new tip on, then close the valves on the tanks and store in a conditioned space. You will only have about 30 days to be able to use them again, see our follow-up question below.

I'm Done! But There's Overspray and the Foam is Sticking Past the Studs, What Do I Do?

Once the foam has fully hardened and cured, which should take about 20 to 30 minutes, you are ready for the cleanup. If you've gotten foam on the face of the studs that will be drywalled, or the foam in the cavity has expanded past the face of the studs, you will need to remove the excess spray foam so you can drywall easily. There are a number of tools to be able to remove excess foam including a curry comb, an angle grinder, a Sawzall with a blade attachment, or even a knife. Closed cell foam will be much tougher to remove than open cell and will require more effort to remove. Open cell foam is much softer and can almost be removed with your hands.

How Long Does A Foam Kit Last Once Opened?

Almost all two-part foam canisters have a shelf-life of approximately 180 days before being opened and about 30 days after the first use when kept away from direct sunlight and inside a conditioned environment. However, we highly recommend getting your project completed within the first couple days after it's been opened. Once opened, the isocyanate chemical begins hardening inside the canister from reacting with moisture in the air and the aerosol inside the tanks begins to slowly deplete. It is important to judge the size of your project accordingly, for best results we recommend getting a kit just big enough to complete the project at hand. 

Why is my DIY Spray Foam Kit Dripping, Not Expanding or Not Hardening?

Even if you've followed the manufacturer instructions and this guide, there is still a chance that the spray foam will not expand properly and could appear to be drippy, gooey or isn't getting the the yield that you might have expected. The foam common problems are

  1. Temperature: This accounts for over 90% of DIY Spray Foam Kit problems. In order to function properly it is imperative that the temperature of the canisters stay at a bare minimum of 75°f during install and that substrate you are spraying against is a minimum of 60°f. If you are located in a cold northern climate the DIY kit must be stored in a heated conditioned environment and for best results that temperature threshold should stay above 75°f during the install process as well. Even Florida winters may be a little too cold to get maximum yield and your moneys worth.

  2. One Tank is Empty Before The Other: There is a chance that when you are getting to the end of the kit that one of the tanks will empty faster than the other one. This will cause the spray foam to go off-ratio and prevent the foam from expanding. You should be able to notice that one tank is dry by looking at the clear hoses and not seeing material flow through. When this happens it means the foam kit is empty and you should dispose of it. Do not try to attach another tank to your existing hose. Simply start using a new foam kit and continue with the project.

  3. Expired Material: If you just started using an unopened foam kit and the foam is not expanding or reacting properly after following all the manufacturer's instructions and this guide, check the tanks to see if the material is expired. The blowing agents that cause the foam to expand will start to break down over time. Usually you can get a foam kit to work if it is slightly after the expiration date, but if it is months or years past the expiration date then there is a high probability that the foam will not mix properly and you will have poor yield and a poor spray foam job. Check the side of the box prior to purchasing to ensure you get a spray foam kit that is still within it's expiration date.

  4. Improperly Stored Material: If you just started using an unopened foam kit and it is within its expiration date but it is not producing good quality spray foam, then there is a good chance that it was improperly stored. If the tanks are allowed to freeze or are exposed to sunlight for an extended period of time, the blowing agents inside the foam kits begin to break down preventing the foam from expanding when it is sprayed. You may be able to get a refund if you purchased the kit very recently, but otherwise there is nothing you can do to remedy this except to buy new foam kits. 

Is it Worth it to Hire a Professional Spray Foam Insulation Company?

That's a great question and the answer is it depends. If the project is small enough, you are pretty handy and you enjoy the satisfaction of doing the job yourself then it may be worth it for you to do the spray foam project yourself. After adding up the costs of the foam kits, personal protective equipment, prep materials and your time you may be surprised to find that hiring a professional spray foam company may actually end up costing less and you'll be guaranteed that the project will be done correctly.

Many spray foam insulation companies, Including us at Compass Insulation Services, have a minimum charge for smaller projects which can range from $1,500 to $1,800 depending on location, material, scheduling and the work area itself. The reason for the minimum charge is to cover material, labor and overhead. Even our smallest jobs can take up to half a day to complete because of the setup time and breakdown time involved with high-pressure spray foam.

It’s also worth mentioning that if you are just looking to do an area of less than 1 foot squared or other minor areas of air sealing around the house, including areas around leaky doors, windows, drain pipes, etc., you may be able to save a lot of money and simply purchase an inexpensive single-component canned foam setup.

For the reasons above we have found that it is both more cost effective and and a better overall outcome for our clients to perform all our installs with our professional rigs. If you are a homeowner or contractor considering the DIY spray foam insulation route, give us a call prior to go over professional install options. We'd be happy to talk to you.

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