G2G Insulation Twin Falls
Home Improvement

Proper Insulation Techniques
For Your Crawl Space

It is not very hard to a good job of properly insulating your home if you live in an area that has a dominant temperature pattern. An example would be mild summers and extremely cold winters or mild winters and killer hot summers.

Home insulation in these areas are pretty straight forward and if your home was built in the last 10 years the insulation is normally sufficient for the climate, but what if you live in an area where the climate swings from hot summers to freezing winters?

We are talking about places like southern Idaho and Washington State east to southern New York State and south. These areas routinely see sub freezing (often sub zero) temperatures in the winter and triple digit highs in the summer (plus humidity).

Proper insulation techniques for your climate if you live in one of these areas is much more than simply living in a box with 12 inches of fluffy stuff nailed to the exterior walls, floor and roof (although that is a good start).

You need to control airflow for both temperature extremes, I did say stop I said control. Some times during the year you want a 100% restriction and other times of the year you want more than you can get.

In the winter time you want to do everything you can to stop all airflow under your home if you have a raised floor. In addition you want to stop all airflow in your walls, window and doors. Finally you will want to stop all airflow in your attic area.

Stopping the airflow under your floor is usually pretty easy. This is not very common any more because the practice was stopped in the late 70’s, but some homes were built with a venting system between the exterior sheeting and the foundation. This created a screened gap about 3/8 of an inch thick to promote airflow and reduce the potential of the wood from rotting due to dampness.  This proved to be a scam (or at least one of those useless building options) and the last homes to have this type of venting were built in ‘78 or ’79 I think. If you live in a cold winter climate seal this gap permanently with an epoxy or silicon sealant. Your crawl space opening and primary vents provide more than enough airflow.

On the primary vent openings take a measurement of the opening and cut out a piece of plywood that is about an inch bigger than the hole to plug it. Glue a piece of Styrofoam or thick cloth (or some other soft material) to one side of the plywood. The material is not for insulation purposes, it is to create and air tight seal on one side of the plywood.

In the exact center of the piece of plywood drill an appropriately sized hole to receive a bolt that is about 3 inches longer than the thickness of your foundation. Cut a 2 X 4 that is longer (or wider) than the height of the opening you are blocking.

You can get creative on your design here, but the concept is to use the plywood as the seal from one side with the bolt running through the vent hole and into the 2 X 4 “clamp” on the other side. Tighten the nut on the bolt and you have a removable and reusable air tight seal. Repeat this step for every opening in your foundation including the opening for the crawl space and any gap or opening under porches. On many older homes (‘30’s to 60’s) concrete porches we often poured in unison with foundations and they have an opening the width of the stairs.

On the first day of the year when the outside temperature is 15 degrees below the normal room temperature you like to keep your home at, pull out the foundation seals and occupy an afternoon. In the summer time you will want the airflow so when the daytime high is within 10 degrees of your favorite temperature pull the seals off.


When to insualte your home