As we have discussed previously, the frame of a vinyl replacement window is such an important element of the eight critical areas we were going to discuss it over the course of three posts. Today we finish this discussion by talking about window frame construction.
Ah, that is the question isn’t it? First, let’s do a quick history lesson…Do you know what the exterior walls of our homes were insulated with prior to 1960? It’s sort of trick question, but then again not. The answer: they weren’t in the sense that there was no physical material, but they were from the standpoint of what is called “dead air space.” Dead air space is the desired result of any “insulation.” So, by not insulating the exterior walls they were, in essence, insulating them.
Not that I have you all confused, let me ask a follow up question. Has anything changed about the exterior walls of your home today. The answer, obviously, is yes, as most building codes require some level of fiberglass insulation in the walls. The thought process with regards to dead air space and it’s relative insulating ability has evolved. Today, we believe that an area that needs to be insulated needs more numerous, and smaller, “dead air spaces.”
So How Do Manufacturers Handle Window Frame Insulation
Basically, there are three ways to insulate a vinyl replacement window frame. First, is by not using any physical material, but adding more hollow chambers. If you hear the words, “hollow core mainframe,” or “multi chambered pvc” this is what you’ll get. Close to 95% of the vinyl replacement window manufacturers choose this method of insulation. About 3% percent of the products available use Styrofoam. Most of us have experience the insulating qualities of Styrofoam if you’ve ever drank coffee or hot chocolate out of a Styrofoam cup. In a vinyl window, since Styrofoam is pre-made, it is cut into sticks and physically inserted in the vinyl frame.The remaining 2% choose polyurethane, which typically is shot into the frame in a liquid form. This liquid dries and shrinks rather quickly allowing the polyurethane to totally fill the cavity that it is in.
Which Window Frame Insulation System Is The Best
To get a formal answer to that question we’ll look at a chart, momentarily, from the website matweb.com. First, what do you think is the best insulated door in your home? Most people will talk about an exterior door, garage door, attic door or the like, but the best insulated door in any home is the freezer door. Think about it, it’s 70° in your home, and 20 some degrees inside the freezer; whatever is between your room and the inside of the freezer must be a great insulator. If you could pull apart the freezer door, you’d find a 1.5″ thick piece of polyurethane insulation. By the way, of all ways to insulate polyurethane is the most expensive way to insulate and is the one that Sunrise Windows chose.
The chart? Click on the image to make it larger. What you have is a comparison of R-values (insulating value) for various window frame materials. The thing to look at is the difference in the numbers more so than the numbers themselves. There’s a wealth of information here, but for our purposes, I want you to notice two main things…
- A wood window frame is rated as offering better R-values than the “hollow core” or “multi-chambered pvc product. This means, from strictly a frame efficiency standpoint, you’d be better off keeping your old wood windows.
- How much better is polyurethane than Styrofoam? According to this chart, polyurethane insulated almost twice as well as Styrofoam.
When you have a Sunrise window demonstration, make sure to take a look at the polyurethane. At the end of the day, the reason that polyurethane insulates so much better that the other materials goes back to the whole “dead air space” conversation. If you looked at a piece of that polyurethane under a microscope, you’d see thousands of tiny dead air spaces. Now you can see why Sunrise Windows thinks that polyurethane is the best window frame insulator.