Air Barrier Properties and Building Envelope Science
Stopping unwanted air infiltration into residential homes and commercial buildings is one of the most important and cost effective ways to reduce heating and cooling costs, improve indoor air quality, and provide a more durable, energy efficient construction. State-of-the-art building science is focused on increasing energy efficient construction through the design of, among other things, superior air barrier systems within the building envelope. The building envelope is the boundary which separates outside air, moisture, wind, etc. from the inside conditioned space. In fact, the importance of the air barrier is such that current and future air barrier testing standards are currently being incorporated into new residential and commercial building codes. The new codes will no doubt significantly impact construction techniques in the coming years.
ASTM E 283 is the accepted standardized test method for air barrier components and systems. This test determines the rate of air leakage through a material under a specified pressure difference across the specimen. Measurements using ASTM E 283 show that Handi-Foam, when properly applied, reduces the air leakage rate to less than 0.01 cubic feet per minute per square foot (0.05 Liters/second/square meter), below accepted building code requirements. The actual test results for Handi-Foam One and Two-Component foam and Handi-Seal Window and Door Sealant are as follows;
Air Leakage rate at;
1.57 psf (75 Pa) pressure differential= ‹0.01 cfm/ft2 (0.05 L/s/m2)
6.24 psf (300 Pa) pressure differential= ‹0.01 cfm/ft2 (0.05 L/s/m2)
These results show that Handi-Foam One-Component and Two-Component froth foam systems provide an excellent barrier against air infiltration. In fact, due to polyurethane foam’s unique ability to expand, bond, and seal, Handi-Foam products are the most effective unifying components for the completion of an effective air barrier system.
Numerous scientific studies have shown that energy usage can be dramatically reduced by sealing against unwanted air infiltration (as much as 55% reduction in air leakage rate @ 50 Pa pressure differential is common). The United States Department of Energy (DOE) supports research dedicated to meeting its goal of reducing energy consumption in buildings 25% by 2020, and 50% by 2030. The DOE states that up to 40% of heating and cooling costs are due to air infiltration in the building envelope. A recent NAHB study (1997) showed that a good caulk-and-seal (foam-and-seal) package reduces annual heating and cooling costs from $150 - $300, on average.
An effective air barrier also prevents a majority of the damage done to buildings associated with moisture. Most of the moisture (90%) which ingresses into the building envelope is carried by air. Air-borne moisture can condense on colder surfaces, leading to rot and deterioration of the substrate, and providing a necessary growing condition for mold. Thus, Handi-Foam products are important components of an air barrier system which helps prevent decay, deterioration, and mold. Building scientists, specifiers, and builders are convinced that an effective air barrier is the most cost-effective way to create durable, healthy, energy efficient buildings.
Theoretical Yield vs. Actual Yield, and Factors Affecting Actual Yield
In most cases, yields for polyurethane foam systems are published as "theoretical", for comparison purposes and for cost quoting purposes. "Actual" product yields will always be somewhat less than theoretical, due to a variety of application factors such as ambient temperature and humidity, application technique, etc. This is true regardless of manufacturer. Fomo Products also will clearly describe published yields as either "theoretical" or "actual", so that the end user can compare and purchase accurately. The information below will provide more detailed information regarding this subject, and the factors which may influence actual product yield.
The theoretical yield for all products is shown on the respective Technical Data Sheet. In addition, the product labeling or packaging may also show product yield. Most two-component non-refillable systems from Fomo Products have Model Numbers which reflect the product theoretical yield in board feet. For example, a II-205 kit has a theoretical yield of 205 board feet. Likewise, a II-605 kit has a theoretical yield of 605 board feet. Since there are 12 board feet in one cubic foot, simply divide by 12 to obtain the theoretical yield for each kit in cubic feet (for example, 605 divided by 12 equals 50. Therefore the theoretical yield of a II-605 kit is 50 cubic feet). This theoretical yield is calculated based on the amount of chemical in the kit divided by the final in-place density of the foam, For standard two-component products the final in-place density will be 1.75 pounds per cubic foot (p.c.f.). The actual product yield, however, will be affected by final in-place densities (which may be higher than 1.75 p.c.f., depending on the application) as well as gas loss and product loss during application (due to overspray, amount of blowing agent retention, etc.).
Actual two-component froth foam product yields will typically be 0%-15% lower than published theoretical yields, due to the factors described above.
In regards to one-component products, there may be a significant difference between one-component product yields (actual vs. theoretical) and two-component yields. The reason is based in the inherent differences between the two types of systems. That is, one-component foams are typically dispensed as a bead for filling small cracks and voids, so therefore the yield is typically shown as a linear coverage rate of a specific diameter bead. On the other hand, two-component foam yields are typically shown as cubic feet (cubic meters), square feet (square meters) or board feet (one board foot is defined as one square foot at one inch thickness, or 12"X12"X1". There is no metric equivalent to a board foot, by definition). In addition, one-component foam is moisture-cured, and therefore more subject to differences in ambient conditions. The end result is that there will typically be a much greater percentage difference between theoretical published yields and actual product yield for one-component products as compared to two-component foam.
For this reason, Fomo Products, along with a committee made up of representatives from some of the major one-component foam manufacturers have developed a standardized testing method to more closely determine the actual yield that might be expected from a one-component foam product. This testing method was recently published by The American Society of Testing Standards (ASTM) as test method ASTM C 1536. In the future, this ASTM test method will be more universally used and cited by the major one-component foam manufacturers. In the meantime, it is important that the end user of any one-component product properly compares whether a published yield is based on theoretical calculations or actual, such as by ASTM C 1536. Fomo Products will clearly state whether yields shown are actual or theoretical;
Actual one-component foam yields will vary greatly from the
published theoretical yield, and may be as much as 50% lower, due
to the factors described above.
Low Pressure One-Component Foam for Windows and Doors
One-component polyurethane foams (OCF) have been traditionally used for many years to successfully seal and insulate around windows, doors and skylights, in addition to a variety of other areas, such as along base plates, corner joints, around plumbing and utility penetrations, etc. As the use of alternative materials for manufacturing windows has become more common, in particular, vinyl windows, the potential for window failure or defects due to improper installation has also increased. One reason is that the materials used to make the windows have become increasingly lighter and less structurally robust, and therefore more prone to distortion.
Consequently, the proper use of one-component foam to insulate the rough opening gap has become more critical, so that the pressure exerted by the expanding foam does not distort the window frame such that the window fails to open and close easily. Knowledgeable installers are still able to properly apply most OCF products around any type of window simply by being more cautious not to overfill the cavity, and allowing for the necessary expansion of the foam prior to finishing the window installation. However, some window manufacturers have expressly voided any warranty for some of their products if it is found that foam was used during the installation process, regardless of whether the claimed defect is related to the use of the foam, in the first place (the reasoning being that if the foam was improperly applied, then it is more likely that other aspects of the installation may have also been done improperly, as well).
This trend has led to the development of low pressure one-component foam sealants that are specifically formulated for use around windows and doors, so that the window will not bow or distort from the pressure of the expanding foam. In addition, the industry is developing test standards and guidelines, such as the American Architectural Manufacturers Association (AAMA) Test Standard 812-04 "Voluntary Practice for Assessment of Single Component Aerosol Expanding Polyurethane Foams for Sealing Rough Openings of Fenestration Installations", to specifically quantify the pressure that is exerted by expanding one-component foam. It is recognized and accepted that it is not, necessarily, the expansion of the foam that can lead to a distorted frame, but the pressure that is exerted during the curing and expansion which is the most important property to control in order to avoid an improper installation (in fact, expansion is desired, as it helps the applied foam fill in the uneven surfaces and crevices of the rough opening gap).
Handi-Seal Window and Door Sealant was the first one-component low pressure foam sealant designed specifically for this application. The patented formula of Handi-Seal provides an insulating foam with one of the lowest pressure build properties available, and is fully compliant with AAMA 812-04. In addition, the predominantly closed-cell structure of Handi-Seal provides improved water resistance, compared to other, more flexible open-celled foams which can absorb or wick water, thus leading to increased chances for wood rot or mold formation.
Handi-Seal Window and Door Sealant is available as a "straw foam", as well as a "gun foam" that is dispensed through one of the professional one-component foam dispensing units available from Fomo Products, Inc. Handi-Seal is colored grey, for easy visual identification after application.
