Frequently Asked Questions:

​Q: What is spray foam? How does it work?

Spray polyurethane foam (SPF) is a spray-applied plastic that forms a continuous insulation and air sealing barrier on walls, ceilings, roof decks – any surface, really. SPF insulation is an excellent thermal insulator and stops air leaks through cracks, seams, and joints dead in their tracks.

It is made by heating, mixing and reacting 2 liquid components (we call them Iso and Resin) at the job site to create foam. The liquids react very quickly when mixed, expanding on contact to create foam.

Q: Spray foam is relatively new technology, right?

Nope. We’ve been spraying it since 1975. Closed cell foam first entered the “mainstream” back in the ‘60’s; open cell hasn’t been around as long – it marks its beginnings in the early ‘90’s, mainly as a cheaper alternative to closed cell. We explain the difference between open and closed cell here:
Open cell vs. closed cell

Q: What does it cost per square foot?

While internally we calculate the cost of your project primarily using the square footage of the area we are going to insulate, we do not give out that information. Every job is different: some may require hours of prep work, some will require much more cleanup than others, some are just more cumbersome to spray and will command higher rates (i.e. crawlspaces and attics). What you’re really looking for anyway is the total job cost – that’s what we’ll provide. We will gladly provide free estimates and, depending on the complexity of the job, we can often give you a close estimate over the phone.

OK, I understand. But can’t you give me a ballpark idea of what to expect?

Persistent, aren’t you? OK, maybe these numbers will help (as of 2017): 1” of closed cell starts at around $1.50/sq. ft., 2” around $2/sq. ft. and so on (the first 1” is the most expensive; upgrading to 2” or 3” does not double or triple the cost). For open cell, 3” starts at around $1.25/sq. ft., 5” around $1.50/sq. ft. and so on (again, the first 1” is the most expensive). Keep in mind that closed cell has twice the R-value of open cell per inch. Learn more about the differences between the two types of foam here:
Open cell vs closed cell

Q: OK – thanks for the pricing info above. So is spray foam expensive? (I’m not sure what fiberglass costs.)

You are most welcome. Now, "expensive" is a relative term; if comparing up-front costs to the baseline – fiberglass – then, yes, foam is more expensive. It will cost roughly 3-4 times more to insulate your house with foam compared to fiberglass.

That seems like quite a bit. Is it worth it?

Of course! (But we may be a bit biased.) Case studies comparing identical or similar houses insulated with foam vs. fiberglass across the US indicate potential monthly savings of up to 48% - see these documents for more details:

Henry case studies
Roanoke, VA (case study #2 from Henry brochure)
Rutledge, GA (case study #3 from Henry brochure)
Denton County, TX - Habitat for Humanity case study

As a general rule of thumb, we say you can expect a 4-6 year payoff in using foam over fiberglass. Obviously, this will vary depending on what you pay for gas and electric in your area. We know that budgeting more for insulation in a new house or remodel project isn’t as fun as, say, upgrading the kitchen but remember: it is one of the few items that will continue to pay you back, year after year, over the life of the house, long after your “new” kitchen has become outdated and the family room carpet has been replaced. You’ll only do it once. Do it right.

Q: Open cell vs. closed cell – what’s the difference?

Both will give an air-tight seal, and both will insulate well. But there are still many differences – see our page about this here: 
Open cell vs closed cell

Q: How does spray foam compare in R-Value to fiberglass batts or cellulose?

Fiberglass, cellulose and open cell foam all have R-values of approximately R-3.5 per inch. Closed cell is figured at R-7 per inch. (Yes, these values will vary slightly depending on the specific brand of foam but for all practical purposes, using R-values of R-3.5 and R-7 are close enough.)

The US Dept. of Energy has a nice page on different types of insulation: http://energy.gov/energysaver/articles/types-insulation

Q: Wait! Your quote you sent me says “Spray walls w/ 2” closed cell R28 fiberglass equivalent”!? That’s off by a factor of 2! What gives?

Good eye. We do that because most people are comparing our quote to their fiberglass figures, and we feel it makes a little better (but not enough) comparison to double the “prescriptive” (lab-based) R-value of foam to give its “effective” (real-world) R-value, when held side-by-side with fiberglass. However, it is still an apples-oranges comparison: because of foam’s air sealing qualities, 1” of closed cell foam will outperform 10” of fiberglass even though their “prescriptive” R-values are vastly different.

For the long answer, see the next question.

Q: So technically, an R-21 fiberglass batt has the exact same insulating value as 3” of closed cell foam since they both have the same “prescriptive” R-values, right?

That would make the most sense, right? But it couldn’t be farther from the truth. You see, the tests to determine R-values printed on a package of insulation are performed inside, in a lab, with no wind and with controlled humidity. And how many houses are built inside a lab? Exactly. In the real world, there’s wind. And moisture. And myriad unsealed joints and cracks. And it’s in these conditions that fiberglass must provide an insulating value of R-21. Go ahead and Google “fiberglass furnace filters” and look at the results. That’s right: the same product used to filter moving air is also supposed to insulate your home and stop wind? We could go on and on about the pitfalls of fiberglass insulation but the following article does a great job of explaining the ‘R-value myth’:

R-value myths (excerpt from Urethane Foam: Magic Material - And the Best Kept Insulation Secret by David South)

Q. If closed cell spray foam has an R-7 per inch, why have I been told from another contractor that 2” of closed cell is equal to an R-21?
We’ve heard this on at least two separate occasions recently: another insulation contractor explained that their closed cell foam provides an R-7 with 1”, but somehow, amazingly, also provides an R-21 by merely bumping up to 2”! Either they are using a complicated math formula for computing R-values that we are not privy to, or they are stretching the truth (we’d guess the latter). Most likely they are trying to convey how much more effective spray foam is compared to fiberglass (it is), and are mixing  “prescriptive” (lab-based) and “effective” (real-world) R-values without explaining the difference. (See the previous 2 questions for more detail.)

Q: So how can I tell exactly what the R-values are for a given brand of foam, “straight from the horse’s mouth”, rather than through the “questionable math” of some insulation contractors?
Go straight to the source! Most foam companies (if not all) make the technical and product data sheets for their foam products publicly available on their websites. Just ask the contractor which brand of foam he uses, then Google it. If his claims don’t match up with the manufacturer’s specs, call him out on it. Here’s a few links to the product information of some of the larger foam manufacturers (these are for their closed cell products):

Icynene (ProSeal) (PDF)
NCFI (InsulStar) (PDF)
Demilec (Heatlok Soy 200) (PDF)
Henry (Permax 1.8) (PDF)
BASF (Comfort Foam 178) (PDF)
Quadrant (QuadFoam 2.0) (PDF)
Lapolla (Foam-Lok 2000) (PDF)
Premium (Foamsulate 220) (PDF)
SWD (Quik-Shield 112 XC) (PDF)

Q: Won’t spray foam make my house too tight? My contractor/friend/neighbor tells me, “houses need to breathe”.

The proper mantra is this: “Build tight, ventilate right”. From an energy conservation standpoint, the last thing you want is a drafty, “leaky” house. Repeat after me: air seal, air seal, air seal. You want your house as tight as possible. Your goal is lower energy bills, right? (And unfortunately, even if you foam from the peak of the attic to the floor of the basement, you will still have leaky doors and windows - add kids and you often have “open door” problems too.)

Now, that being said, there are a couple of things you will need to actively manage once you have a tight, energy efficient home: humidity and fresh air. Winter typically means running a humidifier to fight against skin-drying, static-zapping dry air. However, with a foamed house, just the moisture from all your cooking, hot showers, even breathing will often raise the humidity indoors enough to require running a dehumidifier to lower the humidity (and stop that condensation on your windows), simply because your house is no longer leaking all that air out! Stale air can also become a problem but that can be easily fixed with an air-to-air heat exchanger (think: exhaust fan on steroids). These devices draw in fresh air from outside while expelling the stale air from inside and, in the process, transfer the heat from the warm outgoing air to the cool, incoming air (and vice-versa in the summer). These units are called ERV’s or HRV’s; for more information contact your HVAC contractor.

Again, remember: “Build tight, ventilate right.” Houses don’t have lungs.

Q: One of your competitors tells me their foam is better than everyone else’s. So I’m sure yours is “better than everyone else’s too”, right?

Nope.

OK, so why is yours bett—wait, you said no??

That’s right. Our foam is not better than “theirs”. By the same token, “theirs” is not better than “ours”. As much as they’d like to tell you otherwise, foam is foam. For all practical insulation purposes, all open cell products are the same, as are all closed cell (there are higher density closed cells made for use in roofing applications – but we’re talking interior insulation here). Yes, there are many different brands of raw material and some insulation companies will prefer to spray one over the other (for various technical reasons) but for you, the customer, our closed cell performs like their closed cell, and our open cell performs just like their open cell. No matter what “they” tell you.

Q: So if all foams are the same, why would I choose your company?

Same way you would decide with any other trade: years of experience (we’ve been spraying foam since 1975), quality of workmanship, knowledge level of the sales reps, jobsite professionalism, having proper liability/work comp insurance and finally, price.

Q: What can you tell me about this “flash and batt” system I’ve heard about?

While we usually don’t recommend it, it is a legitimate insulation technique - when done correctly! But in our opinion it’s not worth the small amount of savings you might gain. The basic premise is this: we spray a layer of foam (no less than 1”), then install a fiberglass batt over the top. You get the best of both worlds – a tight air seal, and cheap R-value from the fiberglass. Here’s the first problem to overcome: this system requires 2x6 framing to allow room for the foam and a 3 ½” batt – 2x4 walls will NOT work with this system. Now the second (and primary) concern deals with proper installation: it is very important that the foam be sprayed no less than 1” thick, even in the low spots (all thicknesses quoted are technically averages, but should vary less than ¼” from specified thickness). Any less than 1” and the foam could have cold spots, resulting in potential condensation in your walls, which leads to mold and rot. (Remember: warm, inside air will pass right through the “furnace filter” fiberglass and condensate on the cold foam.) It is also possible that some unscrupulous contractors may spray much less than 1” of foam, then quickly cover it up with fiberglass and you, the homeowner, are none the wiser. (We only mention this because we have witnessed this ourselves.)

You’ll only do it once. Do it right.

Q: Is spray foam flammable?

The foam we use (whether open or closed) contains fire retardant and is rated “Class I” or “Class A” meaning it has a “flame spread” rating of 25 or less – lower is better. Our foam will burn if you hold a torch to it, but once the flame is removed it will quickly go out. THIS DOES NOT MEAN OUR FOAM IS FIREPROOF! It merely indicates it is not match-light, nor will a few stray sparks ignite it.

If you have a house fire, the foam will burn. Do not expect it to do otherwise. Building codes usually require all foam to be covered with a thermal barrier – in a typical home, this will be drywall. In unfinished areas (basements, crawlspaces, attics) we have a code-approved white, thermal barrier coating that we can spray over our foam to meet code requirements.

Q: Does spray foam off-gas? Does it need to cure before drywalling?

No - unless it was improperly installed (primarily if the ratio of the 2 components mixed while spraying was not kept at a 50-50 ratio). However, while foam is being sprayed, there are fumes generated from the heat and chemical reaction that occurs while spraying which is why we wear respirators and will try to keep the jobsite ventilated (when possible). Once we are done spraying, there are no more fumes generated. Sometimes it can take a few hours to remove the lingering fumes, esp. if the work was done in a crawlspace or basement with few windows to ventilate. But generally, the smell is gone within a day or so. You can start hanging drywall as soon as we leave – there’s no need to wait days or weeks first.

Q. I have another question you haven’t answered here – what’s the easiest way to contact you?

We’d love to add to our FAQ! Call us at 309-377-3111, use our contact form or send an e-mail to info@slagelinsulation.com.