Can you spray closed cell spray foam DIY?
Installing closed cell spray foam DIY can seem like a daunting task but really isn’t that hard with proper preparation. If you have ever painted a room with an airless paint sprayer, you can install closed cell foam DIY. That being said the chemicals involved are pretty nasty and should be treated with caution. When installed properly closed cell foam is an excellent insulator that has tremendous R value per inch.
What is the R value of DIY closed cell spray foam?
The spray foam kit I bought and installed DIY boasts an R value of R-7 per inch.
Is 2 inches of closed cell spray foam enough?
The R value of 2 inches of closed cell spray foam is R-14 of insulation. This alone will not be enough to reach insulation requirements for local building codes. Insulation requirements vary but typically warmer climates require R-14 in the walls and R-20 in the ceiling. Colder climates require R-20 in the walls and R-35 in the ceilings.
Where to install closed cell spray foam DIY?
Closed cell foam is best installed in wall cavities, ceiling cavities and even under a house. Closed cell foam can be rather expensive so I would recommend installing it in ceiling cavities only. This is because when heating a house heat escapes mostly out of the ceiling. Likewise during the summer when its hot the heat comes in through the ceiling when the sun is beating down on the roof. Cost can be cut by installing cheaper insulation in the walls where less heat escapes or comes in.
I personally chose to install spray foam in the ceiling and floor but chose mineral wool batts for the walls.
When should closed cell spray foam be installed in the building process?
Closed cell foam should be installed after the sheathing is installed and the gaps between sheathing sheets are closed up. This way no foam can escape out of these cracks in the sheathing. It is important to install closed cell spray foam DIY before plumbing, electric and gas. Any utility services must be reachable in the wall in the event of future repairs. You also want to install closed cell insulation before flooring or any other finishes because the process is very messy and will likely get on the floor.
How much to install closed cell spray foam DIY?
The downside to closed cell foam insulation is that it is rather expensive. Even when the process is completed DIY it can cost between $800-$900 for 600 board feet of closed cell foam. These prices come from June 2022 prices of closed cell spray foam kits on ebay. This breaks down to between $1.3 and 1.5 per board foot when installed DIY.
I was able to to snag my insulation kit for $675 in 600 board feet of closed cell spray foam in June 2020. Keep in mind closed cell foam is a product of oil so if the price of oil goes up the price of this product goes up.
How do I install closed cell spray foam DIY?
Step 1:
Make sure there are no gaps in the sheathing for the closed cell foam to creep out. There needs to be a fully airtight enclosure of sheathing for the closed cell spray foam to be applied to.
Step 2:
Tape off and cover any windows, doors or any other finishes that have already been installed. The stream of the spray foam gun will be fairly easy to manage can be wide enough to accidentally spray something you want untouched.
Step 3:
Its super important to to cover all the skin of your body and have a proper respirator to provide safe air to breathe. The chemicals in the spray foam kit are pretty noxious and this is the main danger in applying closed cell spray foam DIY. Many professionals will ward you away from doing this DIY but when prepared properly it can be safe.
You can wear one of those disposable body suits or just cover yourself with old clothes you aren’t afraid to throw away after. Gloves, Long sleeves, long pants, shoes, hooded jacket to cover neck and head. An old hoodie sweatshirt that aren’t afraid to throw away is a good choice. Goggles to protect eyes and respirator to provide safe breathing.
Step 4:
Set up proper ventilation of the job site. I would recommend opening every window and door available in the house and get box fans pointing out those windows. This will reduce the amount of noxious gas in the house during application but will ensure the spray foam cures properly.
Step 5:
The spray foam kit will come in a part A and Part B tanks. The tanks will be screwed onto the applicator hose which will come with two ports to be screwed into. Screw on the tanks and look to see if the fluid is flowing into the hose from both tanks. The fluid will mix in the hose and flow out the tip of the applicator gun. Its crucial both fluids mix properly otherwise the foam wont cure properly.
Spray the foam on a scrap piece of plywood first to test how the components are mixing and if the final product is suitable.
Step 6:
Its important to note that closed cell spray foam kits are a one and done process. All 600 board feet of the tanks should be applied within one session. I would recommend moving rather quickly because the fluid in the hose will eventually cure and you wont be able to spray anymore. Move the tanks within the range you want to start applying and start spraying into the wall or ceiling cavity.
Only spray each surface once meaning don’t go back and re spray previously covered areas. Keep in mind that the foam will expand over time so as long as the wall gets a quick spray it will be covered. It may appear shallowly applied at first but will expand to desired depth. In order to get a full 600 board feet you will want to apply an even 1″ of spray foam. Don’t over think it just hit the spot once lightly and it will grow to 1″.
Step 7:
Move from open stud by to open stud bay filling the cavity with 1″ of spray foam. After filling all the cavities if you have any more liquid in the tanks you can go back and touch up spots that didn’t get as much spray foam.
Step 8:
Let the spray foam cure for at least a week before entering the area without a mask. Keep the windows open with fans running to help air flow. Most spray foam brands would claim a 24 hour cure time but I want to be extra cautious because this stuff is really nasty.
Step 9:
The finished spray foam can be covered in the stud bay a mineral wool or fiberglass batt to complete a flash and batt approach. I opted to leave the closed cell spray foam open so it was a minimalist design feature. Might not be a look for everyone. If you do dare to use spray foam and not cover it in the wall cavity its important spray paint over the spray foam to seal it in. The spray paint will stop any potential left over fumes from off gassing from the closed cell foam.
Are DIY spray foam kits worth it?
Yes they are worth it when the correct precautions are taken and installed correctly. Closed cell spray foam is a high performance insulator. However spray foam is an expensive insulator and can be less cost efficient than easier to install alternatives. These cheaper alternatives are mineral wool, fiberglass and foam board.
How much does closed cell spray foam cost?
| Type of insulator | Closed cell spray foam | Foam board | Mineral wool | Fiberglass |
| Price for 600 board feet at R-15 | $947 | $747 | $530 | $549 |
Conclusion:
Closed cell spray foam can be properly installed by pretty much anyone that has home building experience. By learning the correct preparation this high performance insulator is available to everyone.
More resources: https://www.greenspec.co.uk/building-design/insulation-materials-thermal-properties