Durability Experiments for Different Sill Sealers
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Over the years our backyard has been an unintended, highly successful outdoor lab for testing any number of materials against the Arizona sun. With furnace-like temperatures combined with a lack of humidity and sunshine seemingly 355 days a year, this is a place where many plastics meet their demise.
When I first wrote the article on Conservation Technology’s EPDM sill sealer house gasket I decided the backyard would be a perfect place for my first intentional experiments. I was curious about the answers to a couple questions. How well does the EPDM sill sealer house gasket hold up against the elements? Second, what is the performance of EPDM in comparison to polyethylene foam.
There are a couple factors to consider before throwing out a hypothesis on an experiment like this here in the Arizona summer.
During the summer the temperatures can go upwards around 120 degrees. It does not always cool down too much at night.
Another interesting factor is the difference in color between EPDM and polyethylene foam. Conservation Technology’s EPDM gasket is black. Polyethylene foam comes in many light pastel colors. My version is light blue.
Given the color difference the EPDM gasket is already at a disadvantage. The sun heats it up faster and hotter just based on the darker color.
Experiment #1:
The official setup where one sample of each product were placed in direct sunlight so the sun would hit it from about 5 in the morning to about 7 at night.
Light blue polyethylene on the left. EPDM on the right.
Of course, this is not the normal place where you install sill sealer on a house, but I wanted to see the effects of the sun on the much more advanced house gasket. At the same time, it isn’t entirely unrealistic. There is still a little sliver of gasket that faces the elements for many traditionally built homes. Not that the sun hits it directly, but there is some refracted light, exposure to air and water. Likewise, what happens when both sill sealers are exposed to dirt, rain and air. Will their elasticity change with prolonged exposure? What happens when you fast forward time about fifty years or so* over the course of a single summer?
The results after two months:
What polyethylene foam?
Oh, here it is!
Here is a little piece ten feet away under the orange tree! The rest is scattered through the yard.
I’m going to state the obvious: EPDM wins just based on still being there. It is more than just there though. It is still in the same shape and just as pliable. There are no signs of wear or decay.
The gaskets still under the brick look and feel like they did at the beginning of the experiment.
One major difference is the now smashed down bulbous triangles on the gasket. Notice how you can still see the exact surface of the brick reflected on the gasket.
You can also see how the house gasket contoured to the gravel scattered on top of the dirt.
The ability to contour is one of the major selling features of this kind of gasket. The ability to seal off the meeting point between to two kinds of uneven surfaces, generally between the concrete slab and framing of your home (not dirt and brick) helps make your house water and airtight .
The picture above was taken 24 hours after the brick was removed from the house gaskets. The EPDM house gasket still had some bounce back. This picture shows the triangle part of the gasket partially re-inflated. You can no longer see the surface of the brick. So there is also the ability to continuously seal as the house expands and contracts under different temperature and humidity changes.
Now at this point you might be saying, “How realistic is this experiment?” Agreed, a test based on UV exposure when these products are usually in the shade is not the most scientific of all tests. However, what it does prove that EPDM can take a beating, retaining it’s elasticity despite the harsh conditions. Second, for those of us unfamiliar with EPDM, it proves it is a very durable product.
Experiment #2:
The second experiment involved a 2 X 4 placed over two sections of the different types of sill seal.
This photo also illustrates the size difference between the polyethylene sill sealer and the EPDM house gasket. The gasket is much beefier. Even with the warped board on top, the house gasket fills the gap whereas the foam will allow air flow. Hopefully your framing does not have this kind of play, but if it does, you know the EPDM sill sealer has you covered!
I didn’t expect much with a much more realistic setup, but it seemed like a good baseline experiment.
Unsurprisingly, there was not a lot of change as both sill seals were protected from the elements. There was some warping of the polyethylene foam where it now curves. The leading edge has some open bubbles. Otherwise, both pieces are very much intact.
Conclusions for these sill sealer durability experiments
The performance of Conservation Technology’s EPDM sill sealer house gasket is impressive. It will outlast more traditional kinds of sill sealer. Seeing its pliability and ability to air lock a gap in action makes a convincing argument to spend extra for a superior product, protecting your house with less heat transfer, a capillary break, and better air quality.
If you would like more information on EPDM house gaskets read this previous article and check out the product on Conservation Technology’s website.
*A totally unscientific estimation, but you get the spirit of the experiment.
