Many of us know that insulation is a major component for keeping your building cool during the summer and warm during the winter. There are many different types of insulation but why is spray foam the preferred?
Batt Insulation - is probably the most common and most familiar to most people. Batt insulation is best used in wall assemblies and can come with or without an attached vapor barrier (also known as faced and un-faced insulation). The vapor barrier not only allows for vapor control but allows for the placement of the product much easier. It is important to know whether the vapor barrier is not only needed but required by code, or in some cases require to not be installed. This will depend on your climate and the permeability rating of the other materials in the wall assembly.
Blown-in Insulation - Is typically used in vented attics placed on top side of the ceiling finish. Blown-in insulation is easy to install but tends to settle over time allowing trapped air to escape and reducing its R-value (unit of thermal resistance).
Spray Foam Insulation - Is far superior to the more traditional systems but can be more expensive. Using spray foam cuts down on your homes air exchanges. No home is 100% sealed because of cracks and gaps between different building materials. Air is constantly passing inside and out of your building this is what is called an air exchange. Spray foam seals these gaps because of its fluid applied and expanding nature. This air impermeability reduces the amount of air movement through your wall and ceiling assemblies by an extreme amount. Spray foam insulation, when applied directly to underside of the roof sheathing allows for attic encapsulation. Attic encapsulation eliminates the need to vent your attic and allows it to be a part of the conditioned space making the home far more energy efficient.
Depending on the type of spray foam, it can be considered structural and offer structural rigidity. Spray foam, when dry, is rock solid and bonds to the materials it touches. According to some studies the lateral strength of the sprayed assembly can be triple when using closed cell foam.
Spray foam comes in two types, open cell and closed cell. Other than cost the primary differences are the r-value per inch and structural rigidity because of the amount of glue inside the products. Open cell foam is considered air impermeable after 4 inches of thickness and closed cell after 1-2 inches of thickness.
Building codes and more specifically energy codes are always changing and in most cases are getting stricter. It won't be long before products like spray foam are the most effective way to meet the new standards. These products may cost more but they offer more sustainable energy practices.
© 2019 by Clements Wimsatt Architects PLLC
Comments