Insulation project

[Shawn Siegrist]

Has anyone used any of the DIY spray foam kits? I’m finishing up a rewiring project and want to air seal and insulate the attic floor above the rooms I rewired. Here’s what I’m debating doing:

option 1 closed cell spray foam 1-2” for air sealing and blow in on top.

option 2 using the can spray foam seal up penetration points and then blow in insulation on top

option 3 Cut foam sheeting to fit between the ceiling joists, spray foam around wires and electrical boxes, blow in insulation on top.

I’ve never used the DIY spray foam kits but it looks fairly easy to use and would be much faster to apply.

How would you insulate?

thanks,
Shawn

[Lee Schierer]

The small spray cans don't go far and aren't made for anything other than sealing cracks or small holes. I often see construction projects on TV using spray foam. I understand the insulation benefits, but wonder what happens when someone down the road decides/needs to do additional wiring.

Just remember that all electrical junction boxes need to be exposed.

[Paul F Franklin]

I used one of the tiger foam kits to insulate the rim joist prior to finishing my basement. I don't remember what size kit, but the two tanks were about the size of propane grill tanks.

I suggest you download the read the full application instructions to see what you might be in for.

A few points. Tank temperature is crucial to getting the correct ratio at the gun, and if you get the wrong ratio the foam either won't ever set, or will set into a crumbly useless sort-of-foam. I had to pre-warm my tanks and then set them in a tank of hot water to keep them warm enough through the process. Rather a pain when you are insulating all around a 2000 sq ft basement and the hose is like 15 feet long. I had to set the tanks and water bath on a rolling cart so I could move it quickly.

Speaking of quickly, you either have to work really quickly, or buy a large quantity of the disposable mixing nozzles for the gun. When you stop spraying, you have maybe 10 or 15 seconds before the foam sets in the nozzle and it's useless. It is not a huge deal to change the nozzle, although you have to coat the mating area with petroleum jelly each time. I had to keep repositioning my ladder and the foam cart and it was a real challenge to not plug up the nozzles more than I did. I probably went through close to 10 of them on my project. An attic would be easier because there would be less moving of the stuff.

It makes a huge mess; I still find little blogs of foam stuck to the back of stuff that was anywhere near where I sprayed. Part of that was that I was spraying overhead; again an attic would be less an issue.

Good luck disposing of the used tanks. The manufacturer warns you they are considered hazardous waste, and to dispose of them "properly". Our local hazardous waste drop off site wanted nothing to do with the used tanks, and of course the trash folks won't take them. I finally got a buddy who's company occasionally has to deal with hazardous waste to add them to one of his shipments.

So, bottom line...although the kit worked for me and I am happy with the result, I probably wouldn't do it again.

In your case, I'd probably see what a local spray foam pro would charge to do the area. The have rigs with temperature controlled tanks and hoses and have precise mixing heads to get the ratio right. The advantage of using foam is that it is an excellent air barrier.

My next choice for a fairly accessible area would be cut and cobble followed by blown in insulation. Cut and cobble is inserting pieces of foam board into the areas, cut a little undersize, and then foaming around the edges to get a good air seal.

Third choice would be to just air seal with can foam as well as possible and then blow in on top.

The green building advisor site has tons of info on this topic, so you might want to check it out.

[roger wiegand]

I did it with one of the large kits from the Borg, similar to what Paul describes. It was mid summer so temperature control was easy. I did not find that the nozzle clogged that quickly, I had several gaps of 5-10 minutes without a problem. Perhaps a different manufacturer and nozzle design. I thought it was a ton of fun to do, aside from being suited up in a moonsuit and big time respirator. I was able to do the whole rim joist of my son's house plus a lot of other air sealing with one kit. Any more than that and I'd recommend bringing in a pro. As I recall the kit was about $300 and a pro would have charged $1000 for that small job due to the fixed costs of travel, setup, cleaning, etc.-- 2-3 X more foam would have probably been the same price. I had no trouble getting rid of the containers at the local hazardous waste site, cost me another $15-20/tank, as I remember.

[Jeff Monson]

I purchased a kit from Menards last fall, it was spendy right around $750 for the kit. I was insulating a ceiling in our barn, it was old with 2' centers so I opted for spray foam. I wouldn't do it again, the kit claims 600 sq feet and I got 400 at the most before I started having issues. The tips clog super quick so you need plenty. So about 3/4 of the way through the cans I lost considerable pressure, it sprayed fine till then but then tapered off. I used it for filling cracks after that and ended up throwing out the cans with at least 10% left as there was no pressure. I called menards and the guy told me that they have issues keeping pressure. I'd consider your other options or hire it out if you have to spray it.

[Aaron Rosenthal]

I've been involved with insulation through my entire career as a handyman/contractor/non-profit House char;
The DIY kit feedback the respondents are accurate. I contracted to have the foam sprayed in by a subcontractor, and I was thrilled at my foresight.
IF IT WERE ME: I would look at 2" thick fibreglass faced panels, cut to size https://www.instapanels.ca/products/...smooth-panels/ or rigid foam panels you can cut to size. They made a huge difference in my house, for examople.

[Jim Becker]

The small spray cans don't go far and aren't made for anything other than sealing cracks or small holes.

There are kits with much larger containers available to consumers which are intended for doing larger areas, although they may still not be cost effective for doing whole structures. I'd consider them for renovation work where I wanted spray foam but the cost to get in a pro is offset upward because of the small scale, but for a big job...no question, I'd hire a pro. (Our entire 2200 sq ft addition put up in 2008 is done with closed cell spray foam)

OP. laying in a couple inches of spray foam and then a blown in blanket for additional R-value can be cost effective while providing the major benefits of closed cell foam...vapor barrier, excellent sealing and structural rigidity. It may be fine for DIY for the scale you mention. Do remember you need good PPE for working with the material.

[Shawn Siegrist]

Thank you the replies!

I have reached out to a local spray foam contractor to get a price, if it isn’t too expensive I’ll probably have them do it. More than likely I’ll be spraying it myself and then back filling with blow in. I could use foam sheets cut to fit but that would be a lot of trips out of the attic down two flights of stairs, out to the garage to cut foam, and repeat a million times!

[Jerome Stanek]

Thank you the replies!

I have reached out to a local spray foam contractor to get a price, if it isn’t too expensive I’ll probably have them do it. More than likely I’ll be spraying it myself and then back filling with blow in. I could use foam sheets cut to fit but that would be a lot of trips out of the attic down two flights of stairs, out to the garage to cut foam, and repeat a million times!

Sounds like a good reason to get a track saw

[Shawn Siegrist]

I already have a track saw, but have limited room in the attic area to work with 4x8 sheets.

[Zachary Hoyt]

Have you tried cutting foam sheets with a bread knife? It is surprisingly easy, and for a big job maybe one of those electric knives would work, I never had one to try. I've cut upholstery foam for chair cushions, and rigid foam insulation sheets with an old fashioned bread knife.

[Erik Loza]

I used my wife's bread knife to cut down a bunch of thick styrafoam panels. Worked great. DON'T TELL HER.

Erik