View Full Version : Spray Foam Insulation

Jim Benante
12-11-2006, 1:16 PM
Has anyone purchased a spray foam insulation kit? I have seen a few online. I have a small area to insulate (60 sq ft room addition) including a vaulted ceiling and want to use closed cell spray foam. I am considering doing it with one of the kits, but wanted to hear feedback on how to work with the foam and what problems I might encounter.

John Daugherty
12-11-2006, 9:11 PM
I had the band around my house sprayed with foam. I had looked at spraying it myself. I priced several of the kits. For the heck of it I contacted a contractor and got a bid. It was actually cheaper for me to have him spray the band than I could have done it myself. He also put in more than we had agreed.

Charles McKinley
12-11-2006, 10:34 PM
Hi Jim,

Make sure you have an air space between the faom and the roof or you will cook the shingles off in the SUmmer. If you put on a metal roof ignore this. I have looked at the kits several times and it has always seemed expensive for what you get.

edited because I can't remember when it gets hot outside.

John Hart
12-12-2006, 6:15 AM
I used the stuff to seal my new addition. The Amish recommended it to me and swear by it....and they are a very insulation-minded people.

Jim Becker
12-12-2006, 8:25 AM
Make sure you have an air space between the faom and the roof or you will cook the shingles off in the winter.

This is counter to industry practice in this area for closed cell spray foam.

Brett Baldwin
12-12-2006, 11:25 AM
It would be a good idea to check with a contractor for two reasons. It might be cheaper and there are fire code issues with making a total envelope of foam. It is usually a matter of a flame barrier between the enclosed space and the foam but I'd check. My company makes the foam for contractors and they often have disputes with inspectors over these things.

Ken Garlock
12-12-2006, 11:57 AM
Hi Jim,
Make sure you have an air space between the faom and the roof or you will cook the shingles off in the winter.

Charles, please elucidate on the roof cooking in the winter.

When we built here in Texas, we were given the option to have a sealed attic where the foam insulation was sprayed to the underside of the roof sheathing. I was told that it is becoming a popular method of insulating in Florida. It seemed a little too new to me, and we went with 4" of Icynene in the ceiling joists plus another 12" of blown fiberglass.

Articles I have read say that only one side of foam or 'bubble wrap' insulation needs to have 3 inches of breathing room, and that is on the attic side.

Maybe the industry has changed its mind in the 5 years since I have investigated the subject.:confused:

Andy Hoyt
12-12-2006, 1:05 PM
The air space thing is critical - at least a far as I'm concerned, and my experience comes from many years in the timberframing industry.

In a conventionally framed house the insulation is typically installed on top of or in between ceiling joists creating a thermal barrier between living space and the attic or truss area. A vapor barrier is also typically placed between the insulation and the living space. This arrangement allows any moisture that may enter the attic area (via whatever means) to exit through ridge or gable vents. Most of the moisture will be entering through the eave vents.

So if that's the case, why install the eave vents in the first place? The answer to this is that adequate air flow underneath the roof itself is needed to carry any moisture (that might have arrived via aging materials, leaks, poor installation, ice damming, and such) away from the roof. If the roof is not vented it will fail sooner or later - sometimes catastrophically and suddenly.

So when you place the insulation under the roof (as in a timberframe or any other structure with vaulted space) an alternate method of mositure removal must still be undertaken, but choices become less numerous.

If it's a conventionally framed roof with fiberglass batts the simplest way is to install eave vents and those styrofroam channel thingies between the sheathing and the insulation along the entire run of insulation until you're up into the attic space or all the way to a vented ridge.

If it's a timberframed structure (which won't used sprayed foam, but will use either SIPs or 4x8 sheets of rigid foam in a site built arrangement) the insulation goes outside the framing, decking, and the vapor barrier. And on top of the insulation you install strapping (one or two layers, and maybe also plywood sheathing; but this is dependant on the roof finish). We specified and built all of our roofs this way - nationwide. The only failure I'm aware of was one in which a second owner (in his hot arid climate) installed a decorative fasica element at the eaves and blocked up the vents.

With sprayed foam (which I used a few years ago on my barn/shop remodel) you need to know whether the foam is of the open or closed cell variety. Mine was closed cell (better) and when it came time to do the roof I opted to install those plastic channel thingies and spray right on top of them. The spraying was done professionally and that fellow disagreed with me at first about this procedure. We had a ten minute skull session over some quick scribbles on a piece of scrap plywood, and he became a believer. He now insists on venting all his roof installations - regardless of the finish roof material.

Why? Because the roof (as a system and regardless of finish material) will eventually degrade. Weather, low quality materials, the passage of time, and/or poor installation techniques will eventually make their presence known and introduce moisture into the structure. And if you're not properly vented, it will wreak havoc and you won't know it until symptoms appear. Fixing the symptoms might be inexpensive. Curing the disease won't.

Sure hope I said this right. Passing the soap box off to .....

Jim Becker
12-12-2006, 2:41 PM
When we built here in Texas, we were given the option to have a sealed attic where the foam insulation was sprayed to the underside of the roof sheathing. I was told that it is becoming a popular method of insulating in Florida.
This is how it is specified in our addition project...a full envelope direct to the roof deck. (R38 with R19 in 2x4 walls) Doing the envelope also simplifies installation of our HVAC system as it's going in the "attic" space...the contractor doesn't need to build an insulated room for it now.

Andy, your comments are intersting. I'll have to have that discussion with the GC and the insulation contractor. We are using closed cell.

Steve Schoene
12-12-2006, 2:58 PM
Lots of info on this. One of the sources that supports the closed attic method is www.buildingscience.com. I believe that they have done tests that show only a degree or two hotter roof without the ventilation with foam directly on the roof, compared to the ventilated roof.

Jim Benante
12-12-2006, 4:54 PM
I like the input. Looks like i may have hit one of those controversial topics.

I have found a bunch of web sites claiming that venting is unnecessary for closed cell foam applications in vaulted ceilings. It appears this is a relatively new way of thinking and there are still many who do not buy into this argument. I am leaning toward no air space at this point in time, but am open to listening to other opinions and logic.

I have recieved one quote at $1100 for open cell when I asked for closed cell quote, I guess the contractor must not be used to closed cell as he was trying to tell me it would be better to use open cell, but I disagree. I need to get another quote or two, but at about $700 for a kit that will be more than enough I might attempt at completing this myself.

Andy Hoyt
12-12-2006, 5:11 PM
Jim - One thing I learned when researching the spray stuff for my barn remodel was that all the contractor's I spoke with were aligned with a particular manufacturer of foam. I found no manufacturer that offered both open and closed cell foams. As such, my assessment was that each contractor was pointing out the features and regurgitating the sales-speak from their respective vendors. That is expected in this franchised society, but it doesn't mean I had to swallow the company line - just taste it for myself.

I posit that if the finish roofing material or its installation fails (to whatever degree) in an unvented application that the water will do damage to whatever is underneath that finish roofing.

But I'm open to learning and even re-learning. So let me ask this:

What is the downside to installing a vented roof system?

Jim Becker
12-12-2006, 6:57 PM
What is the downside to installing a vented roof system?

Not much if it can be accomplished merely with baffles...but if it requires something more labor intensive...major cost.

Ben Grunow
12-12-2006, 9:45 PM
Ditto on Hoyt's statements above with one addition. If you spray foam dirctly on the underside of your roof sheathing, you will be removing your insulation with the sheathing should the need ever arise (roof leak requires new section of sheathing). We spray foam and always leave an air space.

Jim- we have made this space using small rips (2") of plywood nailed to the rafters and strips of lauan over them for a more expensive but not too bad (used old lauan that was used for floor protection during framing).

I also think the air space does a better job of eliminating ice dams as the roof is "colder" with air flowing under it than just relying on insulation to keep the house's warmth away from the snow on the roof. And in the summer time I think the vents lower the temperature of the materials adjacent to the insulation and therefore imporve the efficiency of the insulation. The idea is that air drawn in at the eaves is cooler than the bottom of the plywood roof sheathing in the summer, by a lot I would guess. PLus the constant flow of air will keep things cooler rather than just keep cooking up until sunset leaving a big hot mass of roofing to cool. I also think (I dont know, I think) the vented systems would lead to longer roofing life due to cooler temps.

Just MHO.


Charles McKinley
12-13-2006, 10:18 AM
Thank you Andy and Ben,

You stated with more information what I was trying to say.

Ben do you use open or closed cell foam? Does the industry vary franchises to franchise or are some companies better at traninig their franchisees than others and doing quality control?


Brett Baldwin
12-13-2006, 2:50 PM
As I said before, I do have a bias since we make spray foam (both open and closed-cell) so I offer this as information to be evaluated along with all the other info you gather. I've been in the spray foam industry for 10 years now and the vent/no vent is a common arguement. In general, the industry standard is to foam to the sheeting (with closed-cell) because the liquid water won't go any further than that. Andy's point is well-made that if a leak were to occur in the finished roofing, the water would be trapped longer in the sheeting and therefore lead to a shorter service life, however, the closed-cell foam also provides a degree of structure as well so the overall longevity of the roof is probably roughly equal. As for replacing sheeting on a badly damaged area, that would require resealing the area.

Manufacturer control over the contractors that apply their products is, unfortunately, pretty limited. I strongly recommend you investigate any contractor you are considering for this job and be sure he is very familiar with under-roof application because there are many aspects to the job that are significantly different than wall or finished roof applications. Closed-cell is the way to go, especially in a cathedral application. It costs more but in your application, open-cell really isn't right to use. If you try this yourself, you will need to do some significant research into the proper installation methods to avoid some of the issues brought up already.

I'm putting a few links to related articles that are reprinted on our website from the SPFA which is a professional organization in our industry.

I know it is a lot of info and some is technical beyond your needs but I hope this helps in your decision making.

Jim Benante
12-13-2006, 4:38 PM
Good discussion going here. Has anyone sprayed their own foam? Seems to me if I can get used to the spray equipment and spray evenly I shouldn't really have any other problems. Am I overly confident?

Also there seem to be a few web sites selling the stuff. Anyone have positive or negative comments about any of these kits?

Here are a few:


I need to finish some wiring then I am going to be ready to insulate. I have doen all the work myself including the concrete and framing. I am putiing the last few pieces of sheathing up and then putting tyvek up this weekend and hopefully working on the wiring too.

You can see what I have done so far in this thread where I began to investigate how to insulate



Brett Baldwin
12-16-2006, 4:23 PM
I have sprayed these foam kits and they are relatively simple to use. Contractors use them frequently for patching penetrations that were installed after the job was sprayed with a spray rig. It is less costly than bringing an entire spray rig to the job site again to spray a few boardfeet worth of foam.
This foam isn't as good as the type you would have sprayed out a machine because it is formulated to be sprayed outside of ideal conditions. That said, it is good stuff (in general) and still better than other insulation types. I calculated the cost of spraying the roof area of a 60 sq.ft. area with a 6/12 pitch and an R-30 rating (4.28" average depth) and came up with $4750 not including shipping costs or tax (I used the TigerFoam published price for 50 cu.ft. kits). For that kind of money, I would really get some bids from a spray contractor. That seems like a lot of money for that size area (in my neck of the woods anyway). Plus you would have some sort of recourse if the job didn't turn out well.
If you do decide to do it yourself with these kits, do yourself a favor and buy both extra foam for the learning curve and lots of extra tips for the nozzle. It will take a little bit to figure out the best way to spray and every time you stop spraying you will have to change the tip because that is where the two components mix and when you stop spraying, the mixed components will set up inside the tip within a few seconds. Buy more than you think you'll need because you are dead in the water without those tips. DAMHIKT:rolleyes:

Jim Benante
12-18-2006, 6:31 PM
I calculated the cost of spraying the roof area of a 60 sq.ft. area with a 6/12 pitch and an R-30 rating (4.28" average depth) and came up with $4750 not including shipping costs or tax (I used the TigerFoam published price for 50 cu.ft. kits).


Thanks for the advice on the tips.

I am confused with your math. The site says "This kit yields 600 board feet (square foot at 1") or 50 cu. ft." So I figured 60 sq ft at 5.5 inches would use 330 bd ft of foam for the ceiling. I would use whatever remained for the floor and walls from a 600 bd ft kit. I calcualte that at about $700. Am I missing something?


Jim Becker
12-18-2006, 8:15 PM
The R-19 that I had sprayed under my great room floor (550 sq ft) cost $1450 or about $2.65 a square foot...which is an average of 3" thick, so about 90 cents a "board foot" if my math is correct. This is with a pro doing the work with closed cell foam. Now, that was two years ago and the price is a bit higher now due to the cost of petroleum...

So it sounds like your $700 kit "could be" a good deal if you can effect the work with no problems. Be sure to buy a tyvek throw-away body suit, wear gloves, hat, eye protection and a respirator--cover your skin and hair thoroughly. Disposable booties if you can find them...if not, old shoes you're willing to throw away when you are done. Try to avoid getting it on your skin as it's difficult to remove without using nasty solvents.

Jim Benante
04-01-2007, 3:09 AM
I ended up going with a contractor to spray the foam. If I had purchased a kit it would have been over $800 with shipping. I got it done by pros for $800 so while expensive, it was a good deal for spray foam. The contractor mostly sprays foam on commercial fishing boats that fish AK. I've been on boats he sprayed. He did a nice job other than the one electric wire his co-worker cut while cutting away some excess foam. It was a realitively easy fix, but I was a little bummed out with having mess with the the electrical again as I am ready to begin building a deck so we can use our front door again. Overall I am very pleased. I'll post some before and after foam pics soon.

Jason Roehl
04-01-2007, 4:02 AM
Jim, you probably made the right choice. My partner has used a couple of those kits on his house, and he said that every time, the total board-feet has worked out to quite a bit less than what he ordered (2/3, maybe, IIRC).

There's a new article in the latest Journal of Light Construction about the vented vs. non-vented debate. They support the non-vented system for a number of reasons now.

I can't believe I missed a good thread like this the first time around.

Jim Becker
04-01-2007, 10:34 AM
Jason, we're doing the non-vented application for our addition...a complete envelope which means no additional construction in the attic to provide conditioned space for the HVAC system.

Jason Roehl
04-01-2007, 3:41 PM
That was one of their major points, Jim (Becker--my last post was directed to Mr. Benante originally if that wasn't clear). HVAC can be leaky and the ducting can't be insulated to any great degree easily, so to install it in a vented/unconditioned attic space leads to a great deal of energy loss. I've been in plenty of vented attics, and even on mild but sunny days (75F), they get HOT, including the underside of the roof decking. There is very little airflow due to anything, including convection, not that that would matter, because cooling the underside of the decking a few degrees does little to cool the shingles. The article I referenced also pointed to several studies that seem to indicate that there is little difference in the longevity of the shingles in vented vs. unvented applications, and more manufactures are now spec'ing the shingles for use on unvented roof systems (otherwise they would give up a market segment!)

Brett Baldwin
04-01-2007, 6:13 PM
Glad your project worked out OK Jim. Did you go with the closed cell? Apparently a lot of the closed cell we ship up to Alaska goes into the fishing boats. You'd think they'd want it in there houses more but I guess those boats make the money and you've got to take care of the golden goose.

Jim Benante
04-02-2007, 12:43 AM
Here are some pics. The last one shows the the junction box I had to add and electric wire replacement I had to conduct (no pun) because of the cut line by the contractor. The others are general shots of the job. I experimented with the lighting. Since I was working with 2X6 roof joists and I wanted recessed lights that pointed straight down I came up with the design shown. Hopefully once the drywall is installed it will look OK.

Ryan Myers
04-02-2007, 12:56 AM
Jim, had you considered sloped ceiling recessed cans? They mount at an angle, but you can adjust the bulb to shoot straight down. Alot less finish work on the drywall end of things too. Insulation looks great! Can't believe it was only $800. Last house I wired that used that foam cost homeowner $16,000 to insulate.:eek: It was only a 2200 sq ft ranch.

Jim Benante
04-02-2007, 1:13 AM

I couldn't find a IC sloped can that would work with 2X6 joists. Found plenty that would work with larger joists. I spent a decent amount of time looking around and finally just needed to move forward. The foam is great. I wish I had the whole house insulated this way. I plan to install radiant hyronic heat under my floor in the future and I will spray in my floor joists when I do this.

I have heard stories of homes or trailers in AK that have the foam sprayed right on the exterior. Not so pretty, but would keep things well insulated.


Brett Baldwin
04-03-2007, 12:08 AM
Good to see you went with closed-cell. I think you'll find that room amazingly comfortable. Too bad they cut your electrical but the rest of the job looks pretty good.

Steve Schoene
04-03-2007, 8:11 AM
This is counter to industry practice in this area for closed cell spray foam.

Absolutely. And, studies have shown that the rise in roof temperature with unvented attics is only a few degrees, not nearly enough to impact the life of the roofing.