Hold the Foam! This Home is Already High Performance!

Before spray foam insulation was installed in the walls and roof-line of this Atlanta-area home, it tested better than the 2012 IECC requirements in climate zones 3-8 for building envelope tightness.

Atlanta Arlene Dean Home Decatur ZIP System R Sheathing LG Squared, Inc.

The High Performance Home

Several weeks ago we reported that the Proud Green Home at Serenbe, built by the Imery Group, achieved a blower door (air leakage) test result of 0.70 ach50 immediately after spray foam was put in to the walls and roof-line, and just before the drywall was installed. That’s 10 times better (less) than maximum allowed by the current 2009 Energy Code (7 ach50), and more than 4 times better than the not-yet-adopted 2012 Energy Code. When the house is finished, we will perform the final blower door test, and we expect to be even tighter.


Recently, we performed two similar tests on a home in Decatur, Georgia (built by Arlene Dean Homes). Instead of waiting for either the foam or the drywall to be installed, we first tested the home before the open-cell spray foam was put in to the walls and roof-line. Our second test was just after the foam was installed. We expected the foam to fill many of the gaps and cracks, but testing before gave us an idea of how tight or leaky (half-full, half-empty) the house was before the foam. The follow up test (about a week later), when the foam was installed, showed us how much the foam contributed to the tightness.


Both the Serenbe and Decatur homes were built with conventional advanced framing techniques, using 2×6’s spaced at 24″ o.c. for the above grade walls, and either engineered trusses or I-joist for the floors and roof. On the outside of the above grade walls, an insulated sheathing product  was installed. These 4×8 sheathing panels are like an open-faced sandwich made up of an exterior layer of ZIP System OSB wall sheathing, and an interior layer of either 1/2″ or 1″ polyiscyanurate rigid foam.

Hold the Foam Above Grade Wall Assembly LG Squared, Inc

All joints, seams and penetrations were sealed with tape. Then, a ventilated rainscreen was installed over the sheathing and behind the cladding. In an earlier post, we discussed how this assembly performs like a “Perfect Wall” (J. Lstiburek, Building Science Corp). The roof was sheathed with ZIP System Roof Sheathing, and all window/door openings were properly sealed with a combination of tape and low expansion foam. All the wall and roof framing cavities were then filled with an open-cell spray foam. Below grade walls for the Decatur home were 8″ concrete, with continuous exterior rigid foam and closed-cell spray foam within the framed cavities on the inside.

The Test

Since we were testing the Decatur Home so early on, things like the duct for the range hood, bath fans, and plumbing stacks needed to be sealed off to simulate actual conditions when all appliances and fixtures are installed.

The blower door test we performed on the Proud Green Home was a single point test. We de-pressurized and pressurized the house to a single pressure “point” of 50 Pascals, and then converted the results in to a metric common in the home performance industry and in current energy codes, ACH50.


For the Decatur home, we ran what is called a “multi-point” test. This means that we de-pressurized and pressurized the home at 5 different pressure points (10 Pa, 20 Pa, 35 Pa, 50 Pa, and 75 Pa), and used the average of the results to come up with a more accurate conversion to ACH50. We took the readings from each point, along with required building data (e.g. square footage, volume, house pressure, etc.), and entered them in to a software called TECTITE. The software performed all the calculations and conversions, and immediately give us our results.

The Results

As mentioned above, the 2009 IECC, which is adopted by most states, requires an infiltration rate of less than 7 ACH50. The 2012 IECC, which is adopted by only one state, requires 3 ACH50 or less. Below are the results of our tests performed before and after installation of foam. As you will see, the house tested pretty well. Before foam, the house is below 2012 IECC requirements.

Negative Pressure without Spray Foam – 2.71 ACH50

ZIP-R-Sheathing-Blower-Door-Test-Decatur-Georgia-LG-Squared-Inc. Negative Pressure without Spray Foam

Positive Pressure without Spray Foam – 2.84 ACH50

ZIP-R-Sheathing-Blower-Door-Test-Decatur-Georgia-LG-Squared-Inc. Positive Pressure without Spray Foam

Negative Pressure with Spray Foam – 0.89 ACH50

ZIP-R-Sheathing-Blower-Door-Test-Decatur-Georgia-LG-Squared-Inc. Negative Pressure with Foam

Positive Pressure with Spray Foam – 1.09 ACH50

ZIP-R-Sheathing-Blower-Door-Test-Decatur-Georgia-LG-Squared-Inc. Positive Pressure with Spray Foam


What could have been done to make the house even tighter before foam?

When we walked through the house before and during the tests, we noticed that there was no blocking or sealing done between trusses on the second floor. Most of the leakage we detected (with smoke stick) was coming from this area and one other, at the connection between the stepped foundation and the above grade walls.

Hold The Foam Air Leakage at Foundation and Above Grade Wall LG Squared, Inc.

Hold The Foam Air Leakage Top Plate and Roof Eave LG Squared, Inc.

Hold The Foam Air Leakage Roof Eave LG Squared, Inc.

If more attention had been paid to these areas, the results could have been as low as 1.5 ACH50 or less.

Note that none of the air sealing in this home was done using caulk. Tape has proven to be a very effective way to air seal, and it’s almost exclusively used in many Passive House projects.

P.S. 2012 IECC and the R-20 Wall

Right now, under the 2009 IECC, putting R-13 insulation in the wall cavities is the requirement. When jurisdictions in Climate Zones 3 and 4 adopt the 2012, all above grade walls will need to have a minumum R-20 wall assembly. Both the Decatur and Proud Green Home meet this requirement with a standard 2×6 wall with a full cavity of insulation, and ZIP System R Sheathing with it’s continuous layer of either R-3.6 or R-6.6 rigid insulation (Total: approx. R-25.6 or R-22.6).

If you’re interested in reading about whether the 2012 IECC will cost more to do, or actually save us more energy and money that we spend to meet it, here is a website with the results of a study done for the Department of Energy showing what a home built to the code in most states will potentially save. There’s a downloadable report for each state.

Here’s the one for Georgia, where both of these homes were built.

Georgia Residential Cost Effectiveness 2012 IECC 


To Arlene and Debbie of Arlene Dean Homes, thank you so much for getting the house ready, and for allowing us to perform this test. Well done on another high performance home, and we look forward to many more!

Thank you, Danko Davidovic, Building Scientist at Huber Engineered Woods, for all the work you put in to performing the test with us and for generating all the test results. It’s always a pleasure working with you, and we look forward to many more opportunities!

I also want to thank one of our custom home clients, Mr. Rowe, for his assistance in setting up and overseeing the testing. Mr. Rowe, it’s great to have you so interested in high performance, and we look forward to delivering even better results on your home!

LG Squared, Inc. provided building science consulting and HVAC Design for the Decatur home, and provide full service architecture, interiors and HVAC Design, along with EarthCraft House certification for the Proud Green Home at Serenbe.

19 Responses so far.

  1. Lance Beaton says:

    Your title is misleading. Spray-Foam still improved the overall performance by 300%, not to mention w/ foam you will be brining all the systems (assuming they are in the attic), into conditioned space. Foam is not an end all be all, but it is far superior to any other insulating method on the market.

    Now, if this were a conversation about cost vs. benefit, maybe you could make the case for what the cost would be w/ standard batt/cellulose insulation vs. the cost of the foam and project that over time to determine what the better investment is.

    My guess is that with foam prices being driven down so low in this market, foam will win that challenge.

  2. JANET says:

    There is a wall system that surpasses all of this. It is an engineered insulated system that interlocks and does not need anything more than sheetrock on the interior and outside finish (whatever a client wants) and does not need sheathing or waterproof wrap. it is made in the USA and has been made here for 30 years. Walls R-33. I built a home for a client, 5000 sq. ft. and the energy bill is less than $200.00 without any LED lights. Can’t beat this system!! Faster, easier, cleaner, and no waste on the job!

  3. Richard Beyer says:

    I’m guessing Janet described SIPS panel systems.

    Lance foam prices are rising and will rise higher as training criteria will become a demand on SPF installers in the very near future. Chemical shortages will also rise the costs as the demand for SPF increases.

    What I continue to ask when I see on site manufactured spray foam installations is,
    “What is the before and after IAQ tests to prove the home is in fact “safe” for the occupants to live in this structure”? What tests were performed, if any? What chemicals were searched for in the IAQ test? Did you hire a third party inspector outside of the spray foam company which installed the product to verify the foam was mixed properly?

    Spray foam ingredients are protected by proprietary laws so this information is a trade secret that not even the SPF installer knows what he is spraying. Testing would require the chemical companies sole input.

    There is plenty of room for concern since there’s no published human studies to prove living in a tight SPF home is safe.
    There’s no current or past studies published to prove the claims. Only manufacturer claims without scientific supporting data.

    To many builders are striving for the perfectly tight home without testing the air quality and worse, not knowing what to look for in a indoor air quality (IAQ) study relating to a spray foam house. In many cases an air exchanger may not be enough. Food for thought.

    Be safe, work safe. Check your SPF installers credentials and years of on the job experience and ongoing training.

    Air sealing with specialized tapes, caulks and wrapping films alone could perform as good if not better than spray foam and it’s safe. See: 4-7-5 Building Supply and their blogs relating to SPF -v- air sealing.

    SPF made this house air tight, not the construction as shown in the framing details.

  4. Kerry says:

    Richard, please email me at my personal email address as I will be able to provide you with before and after Air Quality Testing results when using closed cell spray foam. My email is: rausch04us@yahoo.com. the “0” is a zero.

  5. Farr says:

    To Richard Beyer & all, I understand some foams are “Open Cell”. The type of Engineered Panels I talked about are not SIPS. There is no wood in the walls thus no need for termite treatment. They will not delaminate and are approved in Dade County, FL and can withstand winds of over 200mph. The manufacturer is in VA. and have been making them for over 30 years. This product has been used in all 50 states and 30+ countries.
    I am very happy to see more testing and interest in superior built homes for all of us! Just in the past few years have interest been shown in conserving energy and building a more healthy home.
    Thanks for all the work by so many for all of us. JANET FARR

  6. John Peters says:

    “Richard Beyer is Everywhere!” …. That was supposed to rhyme with a melodic tone.

    For residential design, we can build walls out of a variety of materials and achieve high R-value with an air barrier. I have seen ZIP wall systems with OC SPF cavity fill leak like a wet diaper. Seal the stud seams and you have a winner. Foam presents a distinct performance advantage for roof assemblies, rim joists and crawl spaces. Cathedral ceilings are a no brainer. Gable end vents, soffit vents and ridge vents present more problems than they are worth. Put a foam hat on the house (roof and gable ends), foam the rim joists, don’t spec a crawl space foundation and get creative with the rest.

    Ecologic SPF
    Rhode Island

  7. Richard Beyer says:

    Good to hear from Mr. Peters again! He’s actually a good decent man with a stubborn mentality but, you have to love this man. He does mean well and is PRO spray foam. I respect him for his beliefs.

    Janet… Please share your description so readers can better understand what your talking about. Did I miss something somewhere? If you prefer…here’s my email: patayastonellc@prodigy.net

  8. Lance: The title and the post was really up for interpretation. The results are what they are, and the takeaway depends on the reader.

    There are a million opportunities to improve the building envelope (and it’s tightness) with different techniques and products. I point out that air sealing can be done before foam is installed, and it can be done very effectively. There were quite a few opportunities missed here, and I mention a few of them. If those opportunities were not missed, I think the 300% improvement you mention would drop to 100% or less. Many homes are achieving 0.6 ACH50 and less without a drop of foam.

    I included the after foam results to point out that it is an effective way to air seal, but like insulation is more effective on the outside, so is the air barrier. Even when you put closed-cell foam in the walls and roof line, most of the components of the building shell are still “exposed” to the elements without a properly installed and effective air barrier on the outside.

  9. Janet: I like the continuous thermal and air barrier of the ThermaSteel, and the idea of the ease of installation. In all climate zones, that’s a good thing to have.

    I wonder if you could dig up and post the testing conditions (e.g. indoor and outdoor temperatures) that resulted in an effective R-33 for a 5-1/2″ wall. Like most insulation, other than polyisocyanurate that actually gets less effective at colder temperatures (see Building Science Corporation Info-502 http://www.buildingscience.com/documents/information-sheets/info-502-temperature-dependent-r-value/), polystyrene is more effective when the outdoor temps are colder. So, is the R-33 for very cold climates? 2.0 pcf polystyrene has been tested and has achieved as high as R-4.4 per inch with a mean temperature of 75F, but R-33 would mean the product is achieving R-6.

    Would love to have your feedback!


  10. Thanks, Richard: Is spray foam “worth” the environmental or IAQ price to achieve the energy savings and comfort? I agree with many that the IAQ can be reduced dramatically, and even to an “acceptable” level in the home by the time the homeowners move in, or “back” in after retrofit, with adequate ventilation. Continuous ventilation, when appropriate with weather, for at least 2 weeks would go a long way toward “clearing the air”. This is often ignored because of schedule and convenience. I’m interested in the test results from Kerry, and if they include having this continuous ventilation, or if it just relies on natural ventilation…or both.

    Here’s the thing, though. Even if we could completely eliminate the toxins from the home, it goes somewhere. That effects us all, not just the homeowner. The challenge is to produce harmless products and processes. Is it possible? I’ll save that “debate” for another time…

    Thanks, again, Richard!

  11. Lance Beaton says:

    Given the source you can take it with a grain of salt but here are some “facts” about the eco friendliness of foam compared to other “standard” alternatives..



    Prices have gotten so low here (Atlanta) because of what you describe…untrained installers using bad practices with no knowledge of building science. R-13 walls are going to contractors for $1.30 a square. R-19 Rooflines to contractors for $1.40….just a year or so ago prices were more like $1.85 and $2.00 for the same.

    For the record, we are SPFA certified and we try to do it right. We were Chris’s contractor at Serenbe and at pre-drywall w/ foam we are at .6 ach50.

    I am not saying Foam is the only option, but, I am saying net, net, it is part of the “best” solution in terms of performance and dollars and cents. I get that people are freaked out because it is a chemical but so are many things in a home.

  12. Matt Redmond says:

    Hi All, Very nice post numbers. One question, In regards to the many lawsuits nationwide on improperly installed SPF.Did the builder do post installation air monitoring of MDI concentrations after the 24 hour outgassing period? My feeling is that this should become a general requirement nationwide. The tests results will protect the builder from future liabilty and assure the homeowner that IAQ issues related to SPF are not present

  13. Richard Beyer says:

    Lance and LG,

    Spray foam without question has tremendous energy saving benefits when done “right” by “properly trained” contractors who work with “over sight” and who have “third party inspection” to verify they did their job right, as in this case study. Everything in this model was done “right”. This is the real world outside of this model. This almost never happens which is why their are failures.

    That may be the less than 1/10th of 1 percent that SPFA used in their comments to my state legislature. Definitely is not the failure rate they referred to.

    We are human and when you have that single bad day who is going to pay for that error when it’s not learned about for 12 month’s after completion?
    Every family should be able to live in a safe home without guessing if their spray foam contractor was certified or he did not have a “late night” prior to spraying.

    This “spray foam issue” requires “mandatory state licensing” across the country. Without it, the men who elect to do it right will consistently be shoved against the wall on price over quality. Frankly, I’m not sure why so many are against licensing when plumbers, electricians and hair dressers are required to be licensed. This will help reduce the hacker’s you go up against. It won’t eliminate them all but, it will give a consumer accountability which is lacking badly in the spray foam industry.

    As for SPFA certification, it’s a start but, it’s not the only answer.

    LG… To answer your question “Is spray foam “worth” the environmental or IAQ price to achieve the energy savings and comfort?”

    It’s not worth it if you are the unlucky one to get that bad installer.

  14. Richard Beyer says:

    One more thing to add regarding spray foam insulation. There’s a reason chemical companies are prohibited by law from advertising spray foam insulation as “SAFE”.

    They can not provide the un-bias proven science or medical data to substantiate those claims. However, chemical companies “IMPLY” safe in their marketing photograph’s of a family standing in front of their home with smiling children.

    “Marketing Claims can be misleading and illegal”

    From the EPA,
    Misleading Marketing Claims (Goal 3)

  15. Richard Beyer says:

    Previous post cut out the pasted text.

    Misleading Marketing Claims (Goal 3)

    “No off-gasing”, “non-toxic”, “Safe”
    “green” and environmentally friendly”
    “is plant-based”, “made from soy beans”
    Federal Trade Commission
    Federal law prohibits deceptive acts or
    practices, including, product inserts,
    catalogs, and sales presentations.
    FTC Green Guides – provides guidance.

  16. John Peters says:

    All SPF installation contractors should have CPL insurance (Contractors pollution liability). State law should not allow any contractor to install SPF without it. Any contractor dealing with products that emit odor should have CPL (paint, ashpalt, gypsum board, fiberglass, cellulose, contruction adhesives, carpet, plumbing adhesive, tile, etc). We all have different levels of sensitivity to the world around us.

    Licenses and certifications are tough to enforce. I am all for them – but budgets are tight everywhere. If the plantiffs involved with SPF lawsuits had CPL to turn to for property damage or bodily injury, these lawsuits would probably not exist. SPF contractors who hurt people with permanent injuries from SPF should go to jail. If someone came into your home and ruined it with bad foam you would want to sue too.

    Efficiency related building code improves every year and its no longer about increasing assembly R-values, ACH is a measured variable as well. Reducing air exchange with proper HVAC specifications reduces energy usage and improves IAQ. Foam is one of many ways to achieve compliance.

    This qoute was taken from another blog post…”some people swear by foam, other people swear at it.” When its done right, SPF is a high performance system with verifiable data to validate its worth for efficiency and IAQ. Do a background check on your contractor and make sure they have CPL.


  17. Richard Beyer says:

    John Peters makes excellent points here.

    When a consumer requests the contractors insurance after they learn of a problem (as is the case in most unresolved problems), the contractor does not have to provide the entire insurance package to the consumer. There’s no law to force them to.

    Just one more obstacle for the homeowner to overcome.

    Chemical companies, SPFA and other industry trade organizations need to hold all of these contractor’s to higher standards of practice or prohibit them from purchasing and using the chemicals. It’s no secret the raw chemicals are hazardous.

    SPF is not a finished product that is set in ready mix adhesive. This product is manufactured on-site inside private homes and can cause real life harm to unsuspecting consumers. Consumers should not be forced to learn about this industry before they ask for the product.

    Installer’s should be educated and it’s their duty to inform the consumer. Not the other way around.

    This industry needs more men like John Peters. Proactive installer’s will force chemical companies to become more responsible. This will only benefit installer’s, their helpers and their customer’s.

  18. Ed Minch says:

    We work in MD where the 2012 code has been in affect since last July 1 – a year ago. We deliver Energy Star and other above code programs, and air seal houses.

    Doing the math, the tested house was 58,000 ft3, meaning either a 7200 ft2 house on a slab with 8 foot ceilings, or a 4800 ft2 house on a basement with 8 foot ceilings – this is a BIG house.

    The code has chosen to use a volume based measure for building leakage when the leakage occurs at the surface area. We have seen houses this size with NO air sealing below 3 ACH50 because the volume grows faster than the surface area as a house gets bigger. Big houses are at an advantage. The smaller a house the harder it is get to 3. The hardest house to seal is the 1200 ft2 on a slab.

    We regularly deliver houses below 2 ACH50 with no 2 part foam in site.

    Just this morning one of my techs measured a house we sealed at 480 CFM50. The house is 1800 ft2 with a crawlspace, and the result was 1.4 ACH50. This is a 2X6 fiberglass batted house on a block crawlspace. There are plenty of kneewalls around the 320 ft2 second floor of this contemporary design.

    2 part foam does nothing to seal an otherwise properly sealed house. The application of this foam on the exterior sheathing is an air seal on an already airtight surface- in fact, if this was making the house tighter, why wouldn’t spray the attic side of the drywall once it was installed.

    I believe the foam is actually a deficit because it is not stopping the thermal bridge of the framing lumber – the code correctly notes that an R-13 batt with R-5 of foam sheathing is the equivalent of an R-20 wall with no foam sheathing.

    With a blower door, a can of single part foam, and 2 hours, we have reduced the leakage in a 2 part foam house by 50%, showing that it is not always applied as thoroughly as we would hope.

    The cost effective solution is intelligently applied spot air sealing of a conscientiously constructed shell.

  19. geoff hartman says:

    Contrary to popular belief, spray foam as an air sealing strategy is NOT a sure-fire no-brainer. Some of the leakiest homes were spray foam. Poor installation is not always the reason. In some cases, design simply hid, or blocked access to areas. Mostly though one, or both, of2 associated reasons are to blame. 1st) poor overall attention to air-sealing. You can’t just ignore framing, drainage planes, and good airtight design, then hope foam “solves” these shortcomings. 2nd) Poor, often incomplete installation. At eaves, the roof-wall connection is often missed, sometimes w several inch gap allowing venting through soffit or other gaps. Same at floor-wall and between levels at rim. And between conditioned/unconditioned ares such as garage (open joist cavities), porch/patio roofs, and attic connections. In short, same as every other house or building! Oh, a 3rd reason. Just plain poor training, inexperience, and downright wrong information provided to the actual installers and sales reps.

    in short – any product and design choice CAN work well. BUT, the details, and rules, of building science must be followed. There is no silver bullet!

Leave a Reply