If you live in a house that is at least 75 years old, you are probably spending a lot of money keeping your house at a comfortable temperature. The cause is in the way your house is framed. Fortunately, there is something you can do about it. Insulation can be sprayed into your walls to help keep your home free of drafts. Here's what you need to know about your house's framing and how insulation should be installed.
Balloon framing was popular in the 19th and early 20th centuries. This type of framing consists of very long wall studs attached to the foundation sill and run all the way to the bottom of the roof. Floors were then secured to the wall studs, which created long open spaces that run the full length of the exterior wall from the foundation to the roof. Typically, there are no obstructions in these cavities within the exterior walls, unless plumbing and electrical wiring was installed.
Stack effect occurs in the long wall cavities of balloon framing houses. Since heat rises, the air located at the bottom of the cavities tends to be cooler than the air located at the top. As the air temperature increases, it causes the air to rise, which suctions more cold air into the cavities at the bottom.
This creates a draft known as the stack effect. It's similar to what happens in a chimney, so it's also referred to as the chimney stack effect. This phenomenon can cause the interior of your house to be drafty, especially if there are any cracks around windows, doors and electrical outlets.
Blower Door Test
The stack effect is usually tested with a blower door test by an energy auditor. However, when it comes to houses with balloon framing, the wall cavities allow for far more air leaks into the interior of the home due to the long expanses of empty spaces. Since there are typically no obstructions inside the exterior walls, it will be difficult for the blower door test to pinpoint the exact locations of the air leaks. It's better to err on the side of caution and consider all minor cracks as big air leaks when it comes to this type of structural framing.
Insulation in the exterior walls is necessary to cut down on the amount of drafts your house has from the stack effect of the balloon framing. The best type of insulation for balloon framing is spray foam. Since the cavities run from the foundation to the roof, a spray foam contractor can blow the insulation into the walls from the top where the walls meet the roof in the attic.
Spray foam insulation expands when it is applied. It's important for your spray foam contractor to make sure all cracks are sealed on both the exterior and interior walls so the spray foam insulation does not expand through the cracks. As you read earlier, cracks are typically found around outlets, windows and doors. You may also have cracks at the flooring and ceiling. These cracks can be sealed with caulking or putty.
Given that your house is older, you may want to consider hiring a structural engineer before doing a home improvement project with spray foam insulation. A structural engineer will determine whether or not your house has a balloon frame, and if the structure will be able to withstand the forces of the spray foam insulation as it expands inside the wall cavities.
Spray foam insulation can help reduce your costs to heat and cool your balloon framed house. Since sealing all cracks is important, it does take time to prepare the walls for the installation process.
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