Spray foam insulation like this works very well in a variety of situations.
This one happens to be a cathedral ceiling, so insulation is used to boost energy efficiency in the roof and in the walls, but there’s something you have to understand and that’s the difference between open cell and closed cell spray foam insulation and that’s what this video sets Out to explain for you all spray foam can be roughly divided into two categories: there’s the closed cell type, which is the most versatile and useful in cold climates, where heating is required, as opposed to open cell that I’ll be discussing in a few minutes. Now, as the name suggests, closed cell is made of a whole bunch of closed cells and this matters because it affects how this particular kind of spray foam behaves in the real world. When it’s applied thickly enough, it can act as its own vapor barrier and it’s a very important and useful quality. The sides of the fact the closed cell foam delivers, on average a whopping r6 per inch and the fact that it can block air movement completely so drafts and air leakage of all kinds. The ability to block water vapor is a hidden and really useful feature. So imagine for a moment, you’ve got a wall structure. The top part of our cross section is closed-cell spray foam and the bottom section is more conventional fiber based insulation. This works really well, but it’s it’s kind of vulnerable in a way to let’s say it’s: minus 20 degrees Celsius on the outside of the wall and plus 20 degrees Celsius on the inside. This is a pretty typical wintertime situation and, let’s imagine for a moment that there is no vapor barrier on the inside, as there normally is on a wall of this kind. If indoor air is allowed to pass into the wall because of the absence of the polyethylene vapor barrier, it‘s going to cool and eventually it‘s going to condense and drops of liquid water will appear within the wall. This, of course,is going to lead to mold and rot closed cell foam acts as its own vapor barrier, so moisture-laden air can’t get in the wall and condense. Now, if polyethylene plastic is applied to the warm side of a fiber insulated wall, it solves this problem too, but it’s not always possible to apply a vapor barrier like this accurately and completely closed cell foam also adds a remarkable amount of strength to a structure, because It’S so dense and it hears so well two framing structures. The other type of spray foam is called open cell precisely because the cells that make it up are more open, their number of advantages to open cell it’s less expensive and it uses less resources. But there is a drawback, and this makes it less useful than a closed cell in cold and heating climates, although there certainly are uses for open cell as I’ll explain specifically later. Imagine once again that we have spray foam insulation in a wall cavity except this time. It’S open cell. This type has a very powerful ability to block air movement so drafts and winds and things can’t get through, but what it can’t do, no matter how thickly it’s applied is to prevent water vapor from entering the wall cavity. So once again, we’ve got the hazard of moisture entering a wall, cavity, cooling, condensing and promoting mold and rot unless something is done about it of course, and that something could be the application of a polyethylene vapor barrier on the inside. That particular combination works quite well. Even with extremes of warm and cold as you’d find during winter from an insulation point of view, open cell is significantly less effective per inch than closed cell it’ll. Give you about our 3.5 for open compared with our six per for closed-cell, but on the plus side. Open-Cell is cheaper and it uses significantly fewer resources in its manufacturing, then closed cell. If you’ve spent much time researching the difference between open and closed cell insulation on the internet, you may have discovered something that I have and that’s there’s not a whole lot of recommended uses for open cell. So when exactly would you use this stuff? Well, one place is in a cooling climate, so a climate where you’re gon na have to cool down the inside of your house much more often and much more intensely than heating it. So once again, let’s start with a cross-section of some kind of a framing structure. This could be a roof or a wall or anything that separates indoor space from outdoor space. Now, let’s put some open cell foam inside this structure and on the exterior of the structure, let’s put on some sort of weatherproof covering it‘s going to shed water, but you can’t really rely on it to prevent the movement of water vapor. So you’ve got the outdoor side of the structure and the indoor side and there’s a temperature gradient between the two, but it’s reversed compared with our previous example. Let’S say it’s plus 35 C outside and the cooled air conditioned temperature inside is plus 20. So what do we have here? Well, if outdoor air is allowed to percolate through this wall, we‘re going to have the potential for some kind of condensation to occur? It’S not nearly the potential that would occur in a wintertime structure, but if there is any kind of condensation the beauty of the open cell is that it allows it to dry. It doesn’t hold that moisture in and that’s one of the reasonswhy you’d want to use something like this. A second instance when you might want to use open cell spray foam is in a vented attic situation, even in a heating climate. In fact, so imagine for a moment. You have a roof structure like you see here, and it’s insulated with some open cell foam on the bottom of the Attic, so above the joists that would form the ceiling of the interior space. Now, as I said, this is open, celled foam, which means it can’t stop the passage of water vapor, but it can dry and that’s kind of one of its pluses in an application like this, there would be a vapor barrier of some kind on the warm side Of the insulation that would be required for this to work properly now in a heating climate, the indoor air would be warm and it would carry moisture to the extent that it could cause condensation unless it was deflected so to speak by the vapor barrier. So let’s say it’s raining and we have a roof leak and some moisture gets – and this is just one of many examples of how moisture can enter a building envelope. The beauty of open cell is that it can allow that moisture to escape. It can dry, it won’t hold moisture in anywhere and that’s really one of the main qualities for why you’d want to use it in a particular application. So, to recap, closed cell spray. Foam has specific qualities that make it work well in certain situations. It’S most often the foam of choice for cold climates, especially where that cold is extreme and the heating expectations are high. Second of all, it’s strong and firm, so much so that it can actually increase the strength of a structure. Closed cell also does three things. Well. First, it blocks air movement exceptionally. Well, second, it blocks the passage of water vapor, that’s the quality that separates it from open cell. As long as that closed cell is applied, three inches or thicker and, of course, closed-cell does deliver exceptional insulation properties as well about our six per inch open cell spray foam is most useful in warm climates where you have air conditioned spaces or anywhere, where you’re not Going to have a condensation hazard, open cell costs less than closed cell, and it does two things particularly well. First of all, it blocks air movement and it delivers insulation. At a rate of about our three point, five per inch
Nice work done by you. You shared very important and useful knowledge with your blog. I got the best knowledge about vapor mitigation. Well done and keep it up.
December 30, 2021 @ 4:19 am
Nice work done by you. You shared very important and useful knowledge with your blog. I got the best knowledge about vapor mitigation. Well done and keep it up.