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  • Writer's pictureCorey Provencal

“Is Spray Polyurethane Foam Insulation right for you?”

Spray Polyurethane Foam SPF insulation is a great way to tighten up your home and save a few of these precious energy dollars.  We are seeing more SPF use in new construction than ever before and the retrofit market is a boomin.

This article will discuss some of the critical questions all prospective SPF consumers must ask when deciding if Spray Polyurethane Foam Insulation is right for them.  As good as SPF insulation is for energy savings, sometimes it’s just not a good choice for an existing home.

The takeaway… I hope readers understand that there are specific issues that should be taken into consideration when making the decision to install Spray Polyurethane Foam SPF insulation in your home.

We should probably begin with a short explanation of the objective for installing SPF insulation.  It seems simple, right, you’re just adding R-value to your home to save a few energy bucks.  Well, yes and no.  Most importantly is the how you would be improving your home to save those energy bucks.  The SPF will literally seal your home with the intent of preventing air infiltration and exfiltration.   Infiltration is the unintentional or accidental introduction of outside air into a building, typically through cracks in the exterior walls, ceilings, attics, and through use of doors and windows. This outdoor air infiltration is often refered to as air leakage.  In laymans terms, unconditioned outdoor air from getting in your home and conditioned indoor air from escaping your home.

In typical newer U.S. homes, about one-third of the HVAC energy consumption is due to infiltration, so reducing air infiltration saves energy bucks.  Controlling the air infiltration in turn makes it easier for your home’s HVAC Heating Ventilation and Air Conditioning system to heat, cool, and maintain your indoor thermal comfort.  That’s right, were talking about indoor thermal comfort not indoor air quality.

The energy savings is the direct result of substantially reduced air infiltration and exfiltration due to the sealing capability of the SPF insulation.  It truly is great for reducing the amount of energy bucks needed to heat and cool your home.  Your homes HVAC system now only has to contend with the newly sealed indoor environment which now includes the semi-conditioned attic.

We’ll get to the “semi-conditioned” attic in a bit but for now, let’s first talk about something else that is substantially reliant on the home’s air infiltration and exfiltration rate.  That would be the home’s necessary ventilation rate.

The infiltration rate is the volumetric flow rate of outside air into a building, typically in cubic feet per minute (CFM) or liters per second (LPS). The air exchange rate, (I), is the number of interior volume air changes that occur per hour, and has units of 1/h. The air exchange rate is also known as air changes per hour (ACHs).  ACH can be calculated by multiplying the building’s CFM by 60, and then dividing by the building volume. (CFM x 60)/volume.

The American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) has had a residential ventilation standard since 2003, ASHRAE 62.2.  The ASHRAE 62.2 minimum ventilation rate formula was set at 7.5 cfm per person plus 1 cfm per 100 square feet.

The standard assumes that the number of occupants in a home equals the number of bedrooms plus one. The ASHRAE 62.2 asserted that the formula used to determine the minimum airflow rate of ventilation equipment was based on the assumption that all homes deserve an “air infiltration credit” of 2 cfm per 100 square feet.  This was the assumption that the homes in and before 2003 had a good amount of air infiltration.  The homes built today with or without the use of SPF insulation are much tighter and have a substantially reduced air infiltration rate.

So while your home’s recommended minimum ventilation rate remained unchanged for many years, ASHRAE has recognized the tighter construction of today’s homes and 10 years after the initial ASHRAE 6.2, there are new changes to the 2013 version of ASHRAE 62.2.  Under the new formula, newer tightly built homes will need to be ventilated at a much higher rate, namely 7.5 cfm per person plus 3 cfm per 100 square feet. This means that for a tightly built 2,400-square-foot home with 3 bedrooms, the minimum airflow rate of the ventilation equipment has jumped 89%, from 54 cfm to 102 cfm.  Long story short, the 2013 version of ASHRAE 62.2 has eliminated the air infiltration credit on new tightly built homes.  Guess where SPF insulated homes fall?  Right smack dab in the middle of the (as designed) tightly built category.

Questions to Ask Your SPF Contractor Prior to Install SPF Consumer Question Number 1; How will you determine whether or not my home will meet or exceed the minimum ventilation rate once the SPF insulation is installed?

This is one of the most important questions every prospective SPF consumer must ask.  It involves the necessary air changes per hour (ACHs) to ensure that your home does not accumulate indoor contaminants and you have healthier air to breathe.  With SPF insulation, you will most likely require dedicated outdoor air supply to meet the minimum ventilation rate.  If your newly SPF insulated home does not meet the minimum ventilation rate, your home will accumulate contaminants and there will be occupant complaints.

I’ve inspected homes with reported SPF nusiance odors that are well over 50 years old all the way to homes that are only a year or two old.  The issues with new and old homes by and large remain the same.  The most critical is the ventilation rate of the home.  Unfortunately, the extremely important and necessary ventilation rate of the home is rarely discussed and almost never addressed when the home is changed from traditionally ventilated to sealed and semi-conditioned.  Your home’s HVAC system and ventilation rate must be discussed.

Now let’s talk about the “semi-Conditioned” attic.  Semi-conditioned means that your attic that was once naturally cooled through traditional attic “outdoor” air circulation, soffit, gable, and roof vents, is now cooled or conditioned through “indoor” air circulation.  The code refers to these two attics as vented and unvented attic assemblies.  With your new sealed attic you must seal these soffit, gable, and roof vents.

The unvented or semi-conditioned  state of the attic is critical.  For example, if the old attic insulation is left behind to save a few bucks the attic cannot be properly cooled.  If the home’s attic isn’t properly cleaned, the accumulated attic debris will enter the home and cause issues with the occupants.  To put it to you straight, what’s in the attic will now be circulated within your home.  It’s as simple as that.

SPF Consumer Question Number 2; How will you clean my attic and prepare it to be a semi-conditiond attic space? Anyone interested in installing SPF in their attic must take into consideration the age of their home and the condition of their attic.  Any home that is retrofit with SPF can have some rather odd contributors to occupant discomfort and nuisance odors that will now become much more concentrated when the SPFI is installed.   Most of these contributors come from the old now sealed and semi-conditioned attic.

Some of these contributors to occupant discomfort include the storage of materials in the now sealed space, attic insects and/or rodent activity, routine household pest control applications, the previous insulation including the condition and material, and the proper ducting of kitchen and bath fans.  The possibilities are endless and all must be considered and reviewed prior to the installation of the SPF.  Remember, what has accumulated in the attic is now trapped within the now sealed semi-conditioned attic.  The semi-conditioned attic now shares circulated air with the living space of the home.

Our Example Home To help our readers understand the SPF sales process a little better, let’s establish an example home; one that I actually assessed.  Let’s say our example home is a three bedroom, two bathroom, two car garage, 60 year old single story ranch style home.  Our homeowners have lived in the home for the last ten years and have decided to save a few energy bucks on their quest to be greener. Their first step was to install open cell SPF insulation at the roof sheathing.   This was a pricy step in the green direction, but they were able to shave a few bucks off the bottom line by not removing the old insulation or cleaning the attic.  No big deal according to the SPF applicator.

So what, who really cares if the insulation remains in the attic and the attic wasn’t cleaned? It’s really about the energy savings right?

Oh and what about the bathroom exhaust fans in that 60 year old home.  The 60 year old code allowed the bathroom exhaust fans to be ducted to the old ventilated attic and that’s exactly where they are now, ducted to the newly sealed attic.  Many homes built back then also had the kitchen exhaust hood ducted to the attic.  These bathroom exhaust fans must be ducted to the exterior of your home or you may continue to save energy but you’ll slowly be filling your home with humidity and contaminants.

Oh and what about the bathroom exhaust fans in that 60 year old home.  The 60 year old code allowed the bathroom exhaust fans to be ducted to the old ventilated attic and that’s exactly where they are now, ducted to the newly sealed attic.  Many homes built back then also had the kitchen exhaust hood ducted to the attic.  These bathroom exhaust fans must be ducted to the exterior of your home or you may continue to save energy but you’ll slowly be filling your home with humidity and contaminants.

I’m not stretching the example here.  These are real issues with many retrofit SPF applications.

What about the series of rodent issues in that 60 year old home?  Let’s face it; there are a lot of homes out there with rodent and insect issues.  Some pest control companies trap the feisty little critters while others choose to poison them.  In our example home, a liberal use of poisons and traps were used.  There were several remaining bait pods and traps with rat carcasses at different stages of decomposition.  The remaining pesticides can be a serious threat to occupants if not properly cleaned. The rodent urine and fecal matter are a substantial concern when trapped inside a now sealed semi-conditioned attic that shares circulated air with the living space of the home.

Well, to say the least, as with our example home, you can easily have a huge list of contributors to occupant discomfort and nuisance odors if the attic space isn’t properly addressed.

Most of the SPF insulation investigations I am called in to review the above issues were overlooked simply because of the recent application of SPFI.

Indoor Environmental Professionals IEP’s conducting SPF investigations must remain unbiased and open minded and remember that it’s not necessarily the SPF insulation that is producing the odor or contaminate that’s causing occupant discomfort.  It is however the SPF insulation that is now eliminating the natural ventilation of the attic which is now preventing the odors and contaminants from leaving the home.  This causes an accumulation of odors and contaminants if the necessary ventilation rate is not met and the source has not been properly addressed.  In the above examples, that source of the odors and contaminants were the remaining insulation and debris in the now sealed attic.  The SPF was the last change in the home and therefore the scapegoat or go-to cause and origin of the odor, the straw that broke the camel’s bake so to speak.

The newly installed SPF insulation has now trapped the odors and contaminants within the semi-conditioned space.  In the cases above, the home also had no dedicated outdoor air supply necessary to meet the minimum ventilation rate.  If the home met the minimum ventilation rate, the accumulating VOC’s from daily use of products could quite possibly have been adequately diluted ending the nuisance odors and occupant complaints.

So we come to the point where you’ve decided to move forward with your SPF insulation and your contractor has agreed to install dedicated outdoor air supply and thoroughly clean your attic once he has removed all of the old insulation.  Good start.  Now you need to address the issue of exactly how the application contractor will be ventilating your home during the application to prevent the accumulation of the SPF chemicals from entering your home.

SPF Consumer Question Number 3; How will you ventilate my home during the SPF application to prevent the contamination of my home and personal belongings.

There are many factors to consider when planning your SPF installation.  One of the most important is how the application contractor will protect your home while insulating your attic.  Your application contractor should assess the home’s ventilation needs before the job starts and develop a ventilation plan to ensure the SPF chemicals do not enter the home during application.

Understanding ventilation requirements is essential. For example, shut down HVAC systems during a SPF application. System shut-down stops dust, aerosol and vapors from being drawn into the HVAC system. Once the project is completed and the spray area ventilated, SPF odors generally dissipate. Lingering odors may be the result of several contributing factors as previously discussed and can be a combination of numerous sources, making it difficult to identify them. Sources of odors in new construction and retrofit applications can include: SPF; other construction materials, such as paints, cleansers, lumber, finishing treatments; occupant life style; nearby industrial or other emissions; pre-existing (“old house”) odors; construction defects, such as misrouted plumbing vents; or high individual sensitivity.

For interior applications, this can help prevent airborne materials from being distributed from one part of a building to another. Once the HVAC system is shut down, seal the air intakes with plastic sheeting and tape to prevent dust and spray from entering the system. Some SPF manufacturers recommend that the HVAC system stay sealed and inoperable for up to 24 hours after the SPF application. A home that is not properly protected by correctly ventilating the attic can be irreversably damaged.  The chemical odors can remain for extended periods of time.  Often, occupants can become sensitized to the remaining chemicals.  Proper ventilation during application is necessary.

In many homes, the HVAC system is located in the attic.  If your home’s air handler and ducts are in your attic, you must ensure that they are properly sealed and protected to ensure you don’t end up with an additional and costly repair to your HAVC system.  If your HVAC system isn’t properly shut down, your HVAC sytem can very easily contaminate your home by circulating the SPF chemicals through your air handler directly into your home.

Odors may be noticed within areas of the building; for example, specific rooms, or when taking or examining a core sample. Document the presence of odor, describe its characteristics with specific adjectives such as “fishy,” or “rotten egg,” along with where and under what conditions it was noticed.

U.S. Environmental Protection Agency’s “Ventilation Guidance for Spray Polyurethane Foam Application”:

SPF Consumer Question Number 4;  How will you ensure that my home’s HVAC system is shut down and protected during the SPF application?

It is critical that your SPF application contractor turn off your HVAC system and seal the air handler so overspray does not enter the system.  If your home has gas powered equipment, your SPF application contractor must direct the exhaust fumes to an open environment to prevent a buildup of carbon monoxide in the work area.

I’ve seen many air handlers destroyed by overspray and chemicals that were drawn into the air handler and distributed throughout the home.  I’ve even had one contractor tell me that the shut down was not necessary because his SPF was so safe his installers didn’t need to wear protective equipment other than goggles.  By the way, that couldn’t be further from the truth and that application contractor was immediately reported to the manufacturer.

There must be a more than passive attempt at protecting your home and properly ventilating your attic during and after application.  Remember to ask for the application attic ventilation, HVAC shut down and protection plan in writing.  You will want this as a part of your permanent record.  Then prior to the start of application, ask the application contractor to walk you through and show you the ventilation and HVAC protection.  It’s your home and nobody will be as dedicated to the protection of your home and personal property than you.

Then leave your home until the application is complete and do not return until the manufacturers established reoccupancy time has elapsed. No peeking!

SPF Consumer Question Number 5;  When will it be safe for me to return to my home?

Vacate building occupants and non-SPF personnel from the building during the application of SPF and for a period of time following the completion of spraying. Where this is not possible or practical for large commercial buildings, the use of containment and ventilation techniques can be utilized. For residential applications, the homeowner needs to vacate the home and return only after the specified re-occupancy time.

Communicate with other trades working in proximity to the spray application area. Giving notice to other trades is an important aspect on larger commercial projects due to the number and kinds of workers in and around the jobsite.

Provide notice to trades and occupants The focal points for this communication are the general contractor, building owner, home owner, or other responsible personnel for the project. Educate the onsite supervisor or project manager at the start of the project long before the actual spray application starts so  they have a complete understanding of the jobsite safety requirements before the beginning of the spray application process. Critical jobsite safety concerns include proximity of open flame sources and personnel to the spray application area.

If you are present during application or too soon after application, you run the risk of SPF sensitization due to exposure. With sensitization occupants have either re-entered the property shortly after the foam is applied or well before the manufacturer recommended re-occupancy time of 24 to 48 hours. In the most severe cases of occupant sensitivity, the exposure actually took place during the application of the SPFI.

There are many occupants who have become sensitized or allergic to the odors given off from SPF for simply wanting to see the application, or refusing to leave their home during application, or returning to their home too soon.  Regardless of the reason for the exposure, the SPF application contractor should never continue to apply while anyone is present and must ensure that no body is present or reoccupies before the manufactures reoccupancy time period has elapsed.

Adding to the sensitization of the occupants is the lack of proper ventilation during the application. Venting of the off-gassing of the SPFI during application is critical and often not conducted at all. In all cases of occupant sensitization that I have been involved with, the SPFI application was not properly vented to the exterior which created a substantial accumulation of the off-gassing chemicals within the property. These trapped volatile organic chemicals VOC’s are what sensitizes the occupants who have either re-occupied too early or were present during the SPFI application.

Unfortunately, any attempt at reducing the occupant’s exposure to the newly installed spray polyurethane foam insulation may not provide any relief. I’ve had no luck in helping sensitized occupants. I’ve been involved in everything from the introduction of outdoor air through a pre-filter and dehumidifier to control the temperature, humidity, particles, path, and pressure to full SPF removal.  Unfortunately, some bells can’t be un-rung.

If you’re interested in saving those energy bucks with the application of SPF you must ensure that these steps are taken to ensure the proper application and safety of your family.

So back to our Example House What exactly went wrong with our 60 year old example home discussed earlier?  Who was responsible for the occupant complaints associated with the newly installed SPF insulation?

Well, the application contractor sold the homeowner SPF for the purpose of greening up the home and saving a few of these elusive energy bucks.  It was an expensive step in the green direction but one that was going to pay off at the end in the form of saving a few energy bucks.  What the contractor didn’t discuss were the issues reviewed in this article.

Here is what our homeowner should have discussed with their application contractor prior to install; 1. The possible need to re-evaluate the homes HVAC system 2. The newly sealed home’s ventilation rate and possible need for dedicated outdoor air supply 3. The condition of the home’s 60 year old attic 4. The removal of the home’s existing insulation 5. The sealing of the existing open soffit and roof vents 6. The possible termination of the bathroom exhaust fans into the attic 7. The possible termination of the kitchen exhaust hood into the attic 8. The sealing of the home’s HVAC system during the application of SPF 9. The ventilation of the home during the application of SPF 10. Occupancy during the application of SPF and Re-occupancy after SPF application

Our example 60 year old home was later blower-door tested and as expected, it didn’t even come close to the minimum ASHRAE air exchange rate.  With the SPF insulation and without dedicated outdoor air supply, the home had no chance of meeting the minimum ventilation rate.  Unfortunately, for the occupants, the semi-conditioned attic had 60 years of accumulated dust, debris, fiberglass, rodent and insect urine, fecal matter, pesticides and who knows what.

In an effort to keep the bottom line sales price of the SPF as low as possible, the SPF contractor sold the SPF insulation without the following additional considerations that would have led to additional expenses and an increased bottom line sales price.  Let’s face it, while most reputable SPF contractors will review all aspects and necessary steps involved with SPF.  There remain some SPF application contractors who are there to sell SPF and don’t want to lose a sale.  Remember to pay attention to the SPF sales rep that has not listed the following in their sales price or stresses that they are unnecessary expenses.

With our example house, the SPF salesman omitted the following; 1. Sealing the existing soffit and roof vents 2. Removing the existing Insulation 3. Properly cleaning the attic 4. Relocating the bath and kitchen exhaust ducts to the exterior of the attic 5. Installing dedicated outdoor air supply to meet the necessary minimum ventilation rate

Remember the ventilation rate and dedicated outdoor air supply is a critical part of SPF insulation.   Unfortunately, I find the ventilation rate all too often overlooked.  As a professional investigating SPF insulation, you have to ask questions beyond the obvious.

You have to ask relevant questions such as; • “What is the condition of the new semi-conditioned attic space?” • “What have the occupants been sealed in with?” • “How is the ASHRAE minimum ventilation rate being met?” • “How is the semi-conditioned attic space actually being semi-conditioned?”

In addition to these permanent and critical physical changes to our example home, the SPF salesman also omitted several temporary but also very critical steps necessary to protect the occupants, their personal belongings, and the home’s HVAC system.

These very critical and necessary steps included; 1. Sealing the homes HVAC system 2. Properly ventilating the attic during and after application 3. Properly vacating the home during and after application 4. Establishing the necessary reoccupancy times for the occupants

Both the permanent and temporary steps associated with SPF insulation must be addressed for the proper installation of SPF.  Exposure to the old filthy attic can be very unhealthy to occupants.  Exposure to SPF during application or too soon after application can cause irreversible sensitivity to SPF and the related SPF chemicals.

The Bottom Line When it comes to Spray Polyurethane Foam Insulation, the product, when correctly installed, is great and can be a wonderful energy saving feature to your home new or old.  However, all potential SPF consumers must do their due diligence and ask the right questions to ensure the proper temporary installation steps are followed during application.  In addition, you’ll need to know the questions to ask to identify any possible permanent alterations to your home to ensure that the SPF performs properly and does not have a negative impact on you and your family.

So “Is Spray Polyurethane Foam Insulation right for you?” 

The answer is in the sum of all of the above questions once asked and answered.  Ultimately, you’ll have to weigh the cost associated with properly installing the SPF insulation.  You’ll need to balance that with the possible cost associated with retrofitting your home to ensure your sealed attic and home performs as designed.  To get your long term energy savings and maintain your home’s indoor air quality, you’ll need to pony up these energy bucks up front and reapply the energy savings return over time.

It’s your money and your choice; hopefully, this article helped you make a more informative choice.

To learn more about Mr. Lapotaire or Indoor Air Quality Solutions & Microshield Environmental Services, LLC, please visit, email or call (407) 383-9459.

About Indoor Air Quality Solutions & Microshield Environmental Services, LLC

Since 2001, Florida residents have turned to the indoor environmental experts at Indoor Air Quality Solutions & Microshield Environmental Services, LLC.  The family owned and operated companies, based in the Orlando area, offer a comprehensive approach to identifying and correcting comfort and indoor air quality problems.  Their expert staff utilizes the latest technologies and industry recognized standards to identify and resolve indoor environmental issues.

John P. Lapotaire, CIEC

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