Proper Insulation Means a Dry Home

In Texas, a very important component in our homes is the insulation.  The question for homeowners is which one is best and most effective.  So to answer that, let’s take a look at where we live. 

Here are the facts. Our climate in Central Texas is hot and humid.  The average daily high temperature for 6 months out of the year is 80 degrees or higher and the average humidity levels for Austin is 83% in the morning and 59% in the afternoon.   With this humidity, we have a greater chance of moisture accumulating in our homes creating mold and other problems, not to mention an uncomfortable space to live in! 

Moisture can enter our homes through gravity, capillary action, air leakage, and vapor diffusion.  Moisture entering by gravity is through leaks in your roof or driving rain into a window or door.  Water can wick up through your slab or between tight crevices by means of Capillary action.  Humidity from the air can enter our homes through leaks in our building envelope.  Vapor diffusion is the ability for either standing water or humidity to pass through a material.  Of these means of movement, air movement through small holes and leaks in your building envelope account for more than 98% of all water vapor movement.  When we run our HVAC, air pressure is created which moves air from a high pressure to a low pressure forcing air and moisture through small holes and cracks in the envelope.

If we can get moisture in our homes through these means, we must eliminate these holes in our houses!  So, how about a vapor barrier?  Consider an impermeable sheet of plastic, hot and humid on the outside and cold on the inside 6 months out of the year.  What is going to happen?  Just like an ice-cold glass of water on a hot day, condensation will collect on the outside.  If we have allowed humidity into our home, condensation can happen on the inside of the vapor barrier as well.  This is why a vapor barrier does not work in our climate.  An air barrier is what is best.

An air barrier will not let air leak through it but is permeable to water.  This does not mean that water can drip through it; it means that if water permeates in, it can dry out, though it is not an absorbent material.  Tyvek is a good example of an air barrier material and is used on homes everywhere.  What’s important in an air barrier in our climate is that our homes should be able to dry from the inside and outside surfaces.  So, what does this have to do with insulation?

There are many different varieties of insulation, but one in particular can create an air barrier while providing excellent insulation for your home.  Open cell foam insulation is the popular spray-in expanding foam that we are seeing everywhere.  When sprayed in your walls and roof it sticks to any building material, takes only 20 seconds to dry and cure, totally fills all crevices and can be covered with other building materials immediately.  It is not harmed by insects, it is flame retardant and it does not shrink, settle or degrade over time.  The R-value stays constant and it is an excellent thermal and sound insulator.  Additionally, this foam provides a complete air and moisture barrier using carbon dioxide rather than CFCs and produces no out-gassing.  The most popular brand name is Icynene, but there are other brands to choose from.   When checking brands, be sure that your choice is a brand that does not use CFC’s as a blowing agent.  This is what causes out gassing and is harmful to our ozone.

If you choose to spray your walls and roof, you will create sealed attic and a seamless air barrier throughout your whole envelope. The energy savings are about 40 – 50 %!

Jesus Rodriguez with Hill Country Insulation says that out of all the types of insulations he installs, the spray foam is his personal favorite because of the energy savings and quality of the product.  His company uses the Bayseal brand of spray foam insulation. http://www.bsna.com/architects.html.  Hill Country’s services, for Bayseal insulation, costs from .32 – .40 per square foot / per inch of thickness.  Contact Jesus at 830-515-9451.

Foam insulation is more expensive than fiberglass batt insulation but considering the installation will have no gaps and basically eliminate potential moisture issues and then mix with the energy savings; it’s clear to see that your return on your investment will be quick!

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