I’m sure pros will weigh in as well - but when we had our house spray foamed, it bulged out so far past the studs they had to “shave” it in places down to the studs… so ours filled every gap right up to the edges.

@Candace Was it closed cell or open cell? Open cell always expands like crazy, closed cell much less so.

I've used spf and probably on the current build as well.

But I spray first, then frame.

As your studs are mostly only one inch away from the wall, the best you're getting is R 7.1, which is well below Code in most areas. So you will have to add further insulation. Otherwise, looks fine. Just be sure to keep any flames away till you cover it.

And get a dehumidifier going right away or you will likely get warping in any finishing trim. The spf stalls the moisture drive from the newly-poured floor to the exterior. I didn't realize that the first time I used it and had to have trim re-installed.

Material cost using XPS sheathing instead is lower. But finding experienced installers can be difficult.

@worthy I would have preferred using XPS, but the walls were already framed when we decided to switch from the standard inclusion which was just R13 fiberglass.

There is at least 1.5" of foam everywhere and 2" in most, and 2.5" in others. Technically it is below code, as code in our region is 10 continuous or 13 between the studs and we are 7 continuous and varying between 10.5-18 total between studs. We thought it would have been 2" everywhere so were not planning on any other insulation other than maybe blown in if we find problems, but the builder said the 2" is average and there will always be peaks and valleys, but not sure if that is true.

Is this something that is probably okay given some parts are more and some are less or something that is definitely not okay. If it is not okay, is it something the inspector will verify and force the builder to do, or something that am going to have to force the builder to fix? Don't want to ruin the so far positive relationship with the builder.

All I can add is that it is the builder's responsibility to meet Code.

Since the jurisdiction I build in changed to a performance standard, minimum RSI values are determined as part of a "package." (RSI is metric.)

For instance, our current build is Zone 1 Package A5. Basement min of approx. R16.

Do you know if it is normal for spray foam to be varying depths with peaks and valleys? If so, is the 2" supposed to be an average or a minimum?

Here is the photo illustrating the product from the Spray Foam Coalition of the American Chemical Council's Center for the Polyurethanes Industry.

Your installation is what is often used in conjunction with a fibrous insulation to the interior.

Maybe a bit of both? The contract says 2" of spray foam and definitely believe the average could be 2", but I am not sure if the expectation when it comes to spray foam is average or minimum. My builder has been great to work with so far, so i don't want to unnecessarily damage our relationship if they actually did what the contracts says and I am just misunderstanding.

I'm puzzled why you are concerned with the insulation meeting the building code.

In any case, the IRC does not specify thickness of insulation so without the tested R-Value of the SPF there is no way to know if it meets the code.

Please tell us the manufacturer's name and specification for the SPF used and, if possible, the ICC-ES Evaluation Report number that was required for acceptance by the building inspector.

I suspect the installer is well acquainted with what the local inspector will accept.

Here is a sample ICC ES Evaluation Report for a closed-cell SPF.

Here is the R-Value chart from the above report:

2" of this SPF would have a total R-Value of at least 13.0

The aged R-Values would be less but that is not addressed in by IRC.

Here is another Evaluation Report for both open and closed cell SPF.

Here is the chart:

The thickness of the foam to meet the code is generally considered an average but even if the inspector thinks otherwise, your contractor can use the Total UA alternative method (sum of U-Factors times areas) to prove that the basement, as a whole, meets the code therefor code compliance is not likely to be an issue.

But the code is just an arbitrary minimum standard; the important issue is what level of energy conservation you want. And the insulation of a basement is not like that of above grade walls because heat loss is inversely proportional to the depth below grade.

So, how will the basement be used and what is the HVAC system?

And where is it? Climate Zone 5 and Marine 4 is a very big area.

I'll request the exact product from the builder but we were told the R-vale was a hair over 7 per inch but to assume R-14 for 2". We are located in Southwest PA, so maybe a little closer to Zone 4 than zone 6. It is considered a wetter environment. Winter lows average ~20F, though we did have the unfortunately increasingly common once-in-a-century cold snaps this year where it went below 0 for a day. We have a high efficiency (97%) gas furnace and a SEER 16 AC, both two stage and with basement and first floor zoned and are mostly planning on using the basement as an exercise and rec room.

@jhouse - not sure if it was open or closed cell 😉

What is normal here is called nominal fill. That means there are going to be lower areas and higher areas but the average should be at least two inches. If you feel like the under two inch areas are exessive or too low you could say something, it’s unfortunate you weren't informed of what you would be getting before your job was completed.

With an R-Value of 7 per inch, a thickness of 1 1/2" would meet the code minimum requirement of R-10 so why did you think the insulation might not pass inspection? The inspector is only empowered to enforce the code, not the construction contract. Bringing up the buildig code was a red herring; this is a transactional issue.

If you think your contractor might owe you a minimum of 2" of SPF everywhere with an R Value of 14, the only place you'll find that information is in the Owner-Contractor Agreement and the associated Drawings, Specifications & Addenda that make up the Contract for Construction. And you need to see it not hear it quoted by another interested party.

Adding 2" of mineral wool in the upper half of the walls would be cheap and might act as a sound absorber for a noisy basement. If you signed the contract, you should have a copy of it.

You might want to think about the ceiling for sound abatement too.

The code concern may be misunderstanding the code. I believe it is R10 continuous or R13 between the stud. I'm not sure what the spray foam would be counted as give that the studs are only 1 inch from the foundation so only R7 of that is continuous and then in the thinner valleys it would have been an additional 3.5 between the stud. Not sure if this would qualify as R10 continuous.

But really, if it does pass code and the peaks and valleys are fine, then I am also fine with it. I am just not sure.

You need not be a slave to the prescriptive component table R402.1.2 that only gives you 2 ways to insulate a basement wall.

Without going into the details, when insulation is not uniformly distributed in all assemblies of a house (or just the basement walls), the code allows an alternate method for establishing compliance. This is known as the "Total UA alternative path".

Since this method can be mathmatically complicated a free software program called REScheck is used.

Here is a sample page from REScheck showing how walls with different amounts and locations of insulation can be averaged for an entire house or just for a basement.

So, the contractor should be able to prove the installation meets the code if enough of the wall area above the requirement balances what is below it. I believe it would be successful because what is there is already so close especially the 1" behind the studs.

The software also helps you put insulation where it will be most effective instead of where an oversimplified table requires it.

Energy Code Compliance Paths, Which One Will Work Best For Your Project?

Apparently PA has adopted the 2018 IRC that has a prescriptive basement wall insulation minimum requirement of R15 continuous / R19 cavity. Was it amended to remain at the 2015 IRC level of 10/13 for your jurisdiction? Did the 2018 IRC become law after you filed for a permit? Some states allow a choice of which to use for a short period of time.

I've seem many communities raise the insulation requirements of the IRC/IECC but none that have lowered them.

Our home qualifies for the 2021 RAEP adjustments due to other energy efficient "enhanced measures" so the basement requirement is only 10/13.

Maybe I've missed someone else mentioning this above, but my understanding is an average 2" thickness of foam is not equivalent to an even application of 2" thickness of foam. The effectiveness of insulation doesn't have a linear relationship with r-value. See: https://www.energyvanguard.com/blog/flat-or-lumpy-how-would-you-like-your-insulation/

That’s why it’s necessary to convert to U factors x wall area to obtain an average

Agreed. I just wanted to call out if the OP (or anyone) was wanting to get R14 of spray-foam insulation and thus specified 2" thickness, and got average vs uniform 2" thickness, they likely don't have average R14 on the sprayed areas.

My SPF insulator's contract said deviation of +/- 1" was acceptable (for target 2" thickness). We updated the specifications to be minimum 2" thick rather than average as a result.

The building code doesn’t set insulation minimums in inches

therefore, design drawings must state R values in order to get a building permit and the contractor must be able to prove compliance when inspected

The construction contract wording should respect that compliance method rather than adopting another one

In this case the code min was R10/13 but not enough space behind the studs.

The construction contract wording should respect that compliance method rather than adopting another one

What you say makes sense, but this wasn't my experience. No clue what the inspector would have said/done, but the contract/purchase order with the insulation contractor did not guarantee the minimum R-value required by code.

Looking back at it, it's for "Closed Cell 2LB - 1.5" Avg Thick (R-10.5)"..this is in Zone 4 w/ 2009 IECC so 10/13 required by code. The contract states:

"Spray foam R-Values and Thicknesses represent an average. We will warranty any areas lower then 3/4" inch less than the stated average as requested. 0-3/4" inch less than the stated average is considered within tolerance. Guaranteed minimum thickness packages are available if this is preferred."

I mis-spoke above and said it was +/- 1" when it's only 3/4". Regardless, just pointing out that everything you say res2architect may be correct (and _does_ make sense to me), it doesn't appear it always works that way, at least not in my area.

None of this helps the OP, but I figured this might be helpful for others reading/searching for this topic.

Wouldn't the R value of the cement wall behind it also be included in the overall insulation total?

That may add an extra value of R1.

I'm asking because would think so, but not sure.