Welcome to “At Home With Tom and Sandy!” This month, we are going to talk about insulation. Yep, in the middle of summer, we are going to talk about thermal mass so keep reading and you will discover the facts about insulation.
Sandy: Tom, where has the time gone? How time flies, as they say. Here we are, 2/3 of the way through 2017 and Christmas decorations are starting to show up in the stores. Tom, what did you think about the monsoon season this year? The rains were pretty healthy. It is amazing when the rains hit how the temperature drops as much as 15 to 20 degrees and when that happens, I hit the off button on my A/C and smile about the dollars I am saving and at the same time am thankful for good insulation in my home. So because of the rains, hitting the A/C off switch and saving money, that made me think about insulation and what that could mean to homeowners in the summer AND winter.
Tom: Oh yeah, I am loving the cool as well. As for thinking about insulation, you are spot on, Sandy. The benefits are felt summer and winter in our homes because of that unattractive, itchy stuff called insulation, which is a primary component of creating a “Thermal Envelope” for our homes. Wall construction, windows and doors are also components, but those are matters for another discussion.
Sandy: How do you figure out how much insulation, why type of insulation to use and where it goes in a home? I know there are building codes that dictate minimums and areas, but do builders exceed these?
Tom: Well, yes, we can exceed them, but it is part of an overall system. The basis or measurement for determining insulation needs is referred to as the “R Value.” Every building material has an R Value that measures the resistance to heat flow through a given material. The higher the R value, the greater the resistance. While this in not the only component to determining a thermal envelope, it is key and the simplest way to understand the concept.
Sandy: We have homes in Yavapai County that range from over 100 years old to new. I know the older homes don’t have much, if any, insulation. Can they be retrofit to have better thermal envelopes? I have heard of blown-in cellulose and spray foam as two possible products to get this done. What else is there?
Tom: Again, you are spot on. Those are the typical products. In some older homes made of masonry there is no additional insulation on the outer walls. In this case, we need to either add insulation by putting in on the inside or the outside of the walls. The best place to put insulation is on the outside of the masonry and cover it with a weatherproof material such as stucco. This allows the mass of the masonry to help stabilize the temperature inside the home.
Sandy: So I am going to use one of my “Life Lines” and call for Wikipedia to define thermal mass. In building design, thermal mass is a property of the mass of a building that enables it to store heat, providing “inertia” against temperature fluctuations. For example, when outside temperatures are fluctuating throughout the day, a large thermal mass within the insulated portion of a house can serve to “flatten out” the daily temperature fluctuations, since the thermal mass will absorb thermal energy when the surroundings are higher in temperature than the mass, and give thermal energy back when the surroundings are cooler, without reaching thermal equilibrium. Thermal mass is the ability of a material to absorb and store heat energy. A lot of heat energy is required to change the temperature of high density materials like concrete, bricks and tiles. They are therefore said to have high thermal mass. Lightweight materials such as timber have low thermal mass. Appropriate use of thermal mass throughout your home can make a big difference to comfort and heating and cooling bills.
Okay, Tom, back to my one of my original questions, how do folks determine if there is adequate insulation?
Tom: Several ways, really. The simplest is to look and measure the depth of insulation, whether blown in or batts under floors and in the attic where access is available. Knowing the thickness of your wall construction can assist in making an educated guess as to what is behind the drywall or plaster.
Knowing the thickness and the material we can back into the R Value. There are several Insulation R Value Calculators on the Internet. You input material type and thickness, it will tell you the R Value.
Some will be pretty sophisticated and ask about wall construction to value all the materials, but that is really not necessary for folks to know what their circumstance is.
Sandy: What about those areas you can’t get to – how do you know if there is or may not be R Value material? What magic calculations do you have for that?
Tom: No magic. If you can’t see what is there and measure it, the next best test is a thermal imaging of your home. Good insulation contractors will have this capacity, or know someone with whom they can contract. This process visually identifies thermal leaks. With “Hot Spots” identified, solutions to fix them can be instituted.
Sandy: What are some minimums of insulation that need to be considered?
Tom: The Energy Code, as adopted by all our local jurisdictions, has set some very high standards, really. Walls are generally an R 20 to 21, roofs an R 49, and floors an R 19. That being said, Yavapai County has developed standards that differ depending on the area in the county you are building in.
Sandy: There are five climatic zones in Yavapai County based on elevation. From Crown King to Camp Verde, there is a wide array. Each of these zones has requirements specific to it.
Wow, lots of stuff. What are some of the materials used for insulation these days? I know about fiberglass, cellulose and Styrofoam; aren’t there others? And of course, the amount of space available to place the insulation in would dictate the appropriate product to use.
Tom: Oh yeah!
There are products made out of rock fibers, recycled blue jeans, treated natural products such as hay bales as well as other recycled material. No shortage here. Just google “Recycled Insulation Materials.” You will spend hours looking at what is out there.
Tom: In our renovation and remodeling world, we often are working on homes that were constructed prior to the Building Code being adopted in the early 2000s. As a general rule (varies per jurisdiction), if you remodel less than 50 percent of the home, the existing insulation can remain. The area being remodeled or any additional space being added needs to meet the current codes.
Sandy: Do you have a favorite insulation that you like to use?
Tom: Our favorite standby is spray foam. This sprays on as a liquid filling all the nooks and crannies and then solidifies in a very short time frame. Due to its density, the R Value per inch of thickness is better than fiberglass.
Sandy: Let’s leave our readers with one last important comment and that is the effectiveness of an insulation material’s resistance to heat flow also depends on how and where the insulation is installed. The amount of insulation or R Value you’ll need depends on your climate, type of heating and cooling system, and the part of the house you plan to insulate. Also, remember that air sealing and moisture control are important to home energy efficiency, health and comfort.
Tom: Insulate and be like a YETI.
Thanks for stopping in and reading “At Home with Tom and Sandy.” You’re in good company and we love sharing educational, fun and important information with you. Until next month. QCBN
Tom Reilly, Architect, Contractor, Renovations 928-445-8506 www.renovationsaz.com
Sandy Griffis, Executive Director, Yavapai County Contractors Association. 928-778-0040.
Leave a Reply