Many people struggling through the tough economy are not going to be able to take advantage of the 2009-10 Energy Efficiency Tax Credit simply because they can’t afford new windows and doors, water heaters, or more insulation. However, there are a few things you can do around your home to air seal it to save money during the winter months and during the summer.
Because of the price and use of energy, architects and builders now design a home to be a “thermal envelope”. That is the sum total of the home’s insulation systems including walls, ceilings, foundation, floors, windows, and doors. These work more effectively with good, tight fits that seal out the weather and air. By having a tight seal on your home’s thermal envelope, the less energy you waste or lose by exchanging it too often with the air outside.
So, with this in mind, let’s start at ground level and work our way up to seal your house.
A moisture barrier (usually plastic sheeting) covers the earth beneath a structure to prevent moisture from infiltrating the structure from the ground. All-wooden structures last years longer if they are kept dry and out of contact with the ground. For a house, not only does it help prevent rot but it also helps keep the drier. Because moisture in the air holds heat, even during the most humid months, a moisture barrier will make your Texas home feel drier and cooler.
Most Texas homes are built on either a slab or have crawl spaces under them. Houses with slab foundations typically have concrete poured on top of a plastic moisture barrier. This limits the infiltration of moisture into the thermal envelope of the house. Homes with crawl spaces, meanwhile, feature a moisture barrier in their crawl spaces. Some older homes do not have one and these can be installed by the home owner very easily.
A moisture barrier is plastic sheeting, usually about 6-8 mils thick and is available at any hardware store, typically in sizes ranging from 25 × 25 feet to 100 × 100 feet. It also need not be one single piece of plastic. As long as the sheets overlap each other by about 6 inches or so, it will be effective.
To install, you will need to know the dimensions of your crawl space and buy enough plastic sheeting to cover the ground in that space. Simply cut the plastic sheeting to cover the earth from wall to wall, laying it flat. You can use either black or clear plastic, but I would use clear because black plastic would make your crawl space feel like a cramped version of Batman’s lair.
You should notice the difference within 24 hours. If your house feels too dry, simply fold back some of the plastic sheeting to expose the earth underneath. Continue adjusting until your home feels the most comfortable to you.
As mentioned, moisture barriers limit the infiltration of moisture into the thermal envelope of the house. The house feels drier: It will be easier to cool in the summer and less likely to develop mold or contribute to wood rot in the winter.
Mudsill and Rim Joists
The next place to check out is the mudsill. The mudsill is the board that is bolted flat on to the top of the foundation wall. An example of one is a 2×8 board bolted onto the final course of cement blocks. It provides a bed to attach the flooring joists and banding boards for the first floor of the house. Depending on how well it is installed, it can let in a lot of cold air and moisture.
Places to look for gaps is where the mudsill is fastened to the foundation. A common building practice now is to put down a plastic foam gasket over the foundation before attaching the pressure treated lumber that will be the mudsill. In older homes, either a paper-backed cellulose material was put down or nothing was used. To find gaps, get as close as possible to the mudsill from the inside and look for daylight shining through between the mudsill and the foundation wall and feel for a draft of cool air.
If your foundation is made of cement blocks, look for the vertical joints between the blocks. When these blocks are put into place, the mortar between the blocks often slumps leaving thin mortar or none at all. Over time as the house settles, holes can appear. While these might be small holes that let through tiny amounts of air, if your home has 10 or 20 of them, you’re letting in a lot of weather and insects. Seal every hole you find with silicon caulk or expanding foam.
Another place along the mudsill to look for is where the rim joists attach. The rim joist (sometimes called “banding joist”) is the piece of wood that closes off the end of the flooring joist or is the last floor joist underneath the exterior wall. The bottom edge is not necessarily an air-tight seal. In fact, I lived in one older house where there was a half-inch gap between the rim joist and mudsill. Now, while this seems small, the gap ran for the entire length of the house: 25 feet. It was the equivalent of leaving a 24 inch by 24 inch window open all the time. Some expandable foam quickly sealed this gap and there was a noticeable improvement in comfort and cost right away.
By LQD-Denver from Pixabay