We designed the Window Dryer Vent so it could be permanently installed or be put in the window when in use and removed when not using. If you're going to be using the window dryer vent as a permanent solution and you live in harsh climates, we suggest you insulate it. Foam board or blanket insulation works well and is available at most home improvement stores.
In this article, we show how to insulate the window vent with rigid foam board insulation which is our preferred method. We then describe insulation effectiveness, briefly discuss three common types of insulation, and end by describing how to adequately weather seal the vent.
We are in no way advising that you use specific brands or that you should purchase from certain suppliers. We are just giving you an example to provide a clear view of appearance, cost and availability.
Foam board insulation is a type of rigid insulation that is easy to cut, form and fit so it works great for insulating the window dryer vent. In the video above, we used 3/4 inch thick but you can find it in all different thicknesses. We choose 3/4 inch insulation because the inside lip of the vent is about 1 inch. You can use insulation that is thicker than the vent itself but it will be harder to cut and work with.
The effectiveness of insulation is measured by R-value; The higher the R-value, the greater the insulating power. To achieve a higher R-value the insulation manufacturers usually just add more material, which means that the insulation will continue to get thicker as the R-value increases.
We have found that in most cases an R-value of 4 (R-4.0) is sufficient for insulating the Window Dryer Vent. To test insulation effectiveness, we have had a window dryer vent insulated with R-4.0 XPS foam board and weather sealed with open cell foam in a window since April 2015. Vent Works is based out of Massachusetts, a New England state with cold winters that require heating and hot summers that make it desirable to run air conditioners. Air flow testing reveals no significant heat loss or cool air escape using this insulation method.
Image of R-4.0 XPS Foam Board Insulation
Although foam board is my preferred method, there are other insulation options, including using fiberglass and denim.
There are three options when looking to purchase fiberglass insulation. They include blown in, rolls, and batts. Blown in insulation is not suitable for insulating a window dryer vent. Rolls and batts are most often used for home insulation. Rolls come in different thicknesses and lengths,while batts are pre-cut sections that usually come in a bundle. Fiberglass insulation is inexpensive, fairly easy to trim and work with, and has variable fire resistant properties depending on product specifics, including faced vs unfaced. Faced insulation is easier to handle but has slightly less fire resistance than unfaced. The biggest drawback to the use of fiberglass insulation is that it’s very irritating to the skin and lungs. On a positive note, most people have some of this insulation in their attic or basement; you could steal a small amount and use it to insulate the vent.
Recycled denim insulation is generally made with scraps left over from the manufacturing of denim clothing. Although this insulation is essentially cotton fibers, it’s usually treated with a solution that has a Class A fire resistance rating.
There are pro’s and con’s to using Denim insulation. This insulation usually contains 80% recycled material and absorbs sound well, about 30% better than traditional insulation. It’s flimsy, which makes it difficult to trim to size and attach to the vent, and it can cost up to twice as much as fiberglass insulation, for similar R-value.Roll of Denim Insulation
Because not all windows are the same, the window dryer vent may fit differently depending on your window. If there are any gaps between your window frame and the window vent, use foam gasket weather stripping. You can use foam weatherseal around the outer edge of the window vent or just in the areas where a gap needs to be filled. If you're using foam weatherseal to fill a gap make sure that you choose a foam that corresponds with the size of the gap, the foam must expand to fill the gap. If there are no gaps but you still want to weatherseal it, use a thinner foam around the outer edge of the entire window vent.
Open cell foam weather stripping is available from online retailers, hardware, home improvement, and big box stores. Below is a link followed by an image of the weather stripping we used.
Vent Works goal is to provide thorough and easy to understand information, in order to make your life easier. If you found this blog helpful, want to give feedback, or have any questions, please post in the comments section below!