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Are DIY spray foam kits comparable to pro outfits?

mikeolder | Posted in General Questions on
I have a outside spray foam roof project and wonder if a diy sp kit would be better because I can only work so fast from the top, and a installer would have to wait for me to catch up replacing the roofing and adding 2’ overhangs to not risk having a open roof overnight.
Are DIY spray foam kits comparable to pro outfits? What brand should I look at?

Do I have to wear a respirator considering I’m outside? 


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  1. Expert Member
    BILL WICHERS | | #1

    The short answer is "no, the DIY kits are not the same as the pro level installer equipment". There is no reason you couldn't use a DIY spray foam kit for your application, but keep in mind that the spray foam will setup in the tip of the spray gun VERY quickly (a few tens of seconds or so), so once you start, you really want to keep going. The kits come with multiple tips, and you can buy extras, but if your plan is to open a section of roof, spray foam it, close it, open another, spray foam that, etc., then you're going to be replacing the tips a lot. You can't just set the kit aside for an hour while you work, then expect to pick it up and start foaming again -- you'll need to replace the tip, then run a test blast or two into a bag to "prime" the system, after every time you stop spraying for more than a few minutes or so.

    I also find the DIY kits don't seem to give as good of a layer of spray foam as the pro rigs, but you can get a good application if you're careful. The biggest issue here is that you tend to not get as much out of the kit as the manufacture claims you will (which is true for ALL the DIY kits), usually because you won't be applying the material perfectly as you're spraying. Plan to need more material than you think you will, which means you'll need more of the kits than you'd expect.

    Lastly, the DIY kits are *very* expensive for the amount of spray foam you get. Pro applications are usually cheaper per unit insulation applied for larger jobs, but you're correct that the pro guys won't be able to wait around for you to change things around on the roof.

    I would still wear a respirator while working outside, because you're still going to be physically close to the application area where concentrations of all the gasses are going to be highest. You also absolutely need to wear eye protection and protective clothing (a tyvek suit works well here). You don't want to get the stuff on your skin, since it can be difficult to remove, and you certainly don't want to get it in your hair! I do think it's safer to use the stuff outdoors though, since you're pretty much assured of having good ventilation that way, which is important.


  2. gusfhb | | #2

    Buy extra 'fan' nozzles, lots of them

    poof clogged

    You need to keep them warm, they get fussy about being like 60 degrees, and then they start not dispensing evenly and the foam isn't right.

    Looks like 1000 bucks for a 600 board foot kit. I think they were 400 back in the day! Still installers don't give away foam, I used it for the same reason you are, so I could do it incrementally

    Urethane is a sensitizer.
    This means take masks and gloves seriously.
    Day 1 using no prob
    Day 2 using no prob
    Day 343 using no prob
    Day???? you can never, ever get near it again
    Not trying to dissuade you, but I have two acquaintances who cannot touch the stuff anymore, one from spray foam used in packing, one from urethane paint.
    Once it has cured there is not an issue.

  3. mikeolder | | #3

    Thanks guys.
    There's a group on Facebook making it sound like the only way to get professional results( r value/sealing ) , is to hire a professional. To me it sounds like if you apply SF in the correct temperature range, and change the Tip nozzles often, you will always mix the foam in the correct ratio and never have a problem. The thing is though, is that if you do have a ratio problem, it can be deadly, and I can't believe I'm actually considering this stuff.

    1. Expert Member
      BILL WICHERS | | #5

      A problem with the mix won’t be “deadly”, but it can have serious stink issues that can be bad enough quite literally require you to rip out the entire assembly you spray foamed — including the structure — to get rid of the mess. That’s the one downside to spray foam: if it does go wrong, cleanup is a nightmare.

      All that said, problems are actually pretty rare in practice. I have used, or had my guys use, the DIY kits many times. I’ve never had a problem with the mix except for the first and last bits out of the kit, which is why you always start spraying into a bag until the mix evens out (which is easy to see when you’re spraying). When it starts to run out at the end, STOP. Do NOT try to get “every last drop”, stop as soon as it seems to spray differently since that’s the first sign you’re starting to run out.

      I don’t really have anything bad to say about the DIY kits aside from “they cost too much”. They aren’t great for projects with a lot of starts and stops either, but that’s a problem for the pro crews too. I don’t think you’ll have a problem if you’re careful with a DIY kit, or if you hire a competent and experienced (experience is key here) professional spray foam contractor.


      1. mikeolder | | #6

        OK maybe not immediate death, but this family had to move out and the child that remained in the house during the foam spraying, duh, I believe now has health issues..

        Ive also heard hvac guys say coils rot out quicker and leak in homes insulated with sprayfoam. Like I mentioned. I can't believe I'm actually considering this stuff, but sf would be the best choice IF it cured well and didn't gas me out of my own home. Or become home to a swarm of flying ants, or..

        1. gusfhb | | #7

          This is not directly related to DIY kits, professionals make mistakes too

          Like all things the directions must be followed and care must be taken, but used properly they can be quite useful

          In my experience I had no problem with smell, but a couple of small spots the foam was brittle and shrinky, so I tore it out and re did it.
          I am certain they are expensive when compared to a pro, but try getting a pro out 12 times during a rehab job and see what that costs. Or to bring the crew out to spray 200 square feet
          I had the pros come out to spray the 900 square foot floor of my last house. The big name local guys wanted a check for the balance on making an appointment months in advance with no actual guarantee that they would come that day. Many thousands of dollars.
          Another company used soy based foam and agreed to getting a check when they showed up. They showed up with a crew of Brazilians with no gloves masks or safety glasses, and only a cone type nozzle. Imagine a bunch of foam basketballs . Spent weeks and dozens of cans of foam to fix that.
          THis was ~20 years ago so no online rankings etc.
          So, yeah, I will use the DIY kits anytime

  4. DennisWood | | #4

    +1 to everything Bill said. I hire out spray foam after making a mess with a DIY kit more than once. Once I took a closer look at the spray truck for my go-to contractor, it was obvious that a lot of care goes into monitoring and maintaining chemical temps as well as ratios to the gun.

    Correct chemical temps and ratios get you the correct cure at the application side. I also found the DIY kits more expensive in every comparison I did...I won't use them again.

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