What exactly is roofing felt? Simply put, roofing felt is an extra layer of insulation on the roof that acts as a barrier against the elements. This means that even if there is no other way to prevent or protect your roof, you can at least rely on this one layer to do its job. Basically, it’s used for three main purposes – thermal, aesthetic and structural.
Thermal qualities of roof felt are pretty much what you’d expect. It’s a very thick and insulating material, which makes it perfect for sealing the seams of the shingles and for helping to prevent heat loss. In terms of aesthetics, roof felt is also pretty standard – it adds a bit of style to the home while also providing protection from elements such as wind, rain and snow. And finally, while it does add some strength to the roof, its flexible nature means that it can also be used to install a number of different types of flashing.
Now aesthetic properties are a bit more difficult to define. To start off with, roofing felt isn’t actually composed of anything at all; it’s simply sheets of tar paper that have been attached to asphalt shingles. Despite this, the sheets usually end up looking quite a bit like wood fiber shingles, which is why many people tend to confuse it with them. The thickness of the felt varies, but it’s usually no more than an inch thick (sometimes a bit more is even possible). It’s these sheets that give roofing felt its ability to resist both hot and cold air, and to act as a barrier to moisture – two elements that are important in preventing rot, which is what often happens to shingles.
The fact that it resists water, however, also makes it highly effective at stopping leaks from occurring. Think about it – not only does it act as an impenetrable barrier against moisture, but it also repels water. While it’s hard to imagine an area of the roof deck that won’t be damp from rain or melted snow for quite some time, applying what is roofing felt is a great way to solve the problem right away. At the very least, you won’t have to worry about your shingles getting ruined due to water logging. At best, you’ll have an easy to clean surface that won’t hold any sort of odor.
Another unique property of the layer of what is roofing felt paper is its ability to provide structural support. Think about it – asphalt shingles are essentially a series of short, thin metal strips that connect the bottom of your roof to the underside of your attic. While they do a great job of keeping your roof dry and your attic structure in place, they’re not particularly sturdy by comparison. What’s more, the layers of asphalt rubber that make up the shingles wear down after a certain amount of time, leaving you with an unstable and easily blown-up piece of wood on the ground. What’s more, as the rubber loses its grip on the roof decking, it becomes susceptible to collapsing, and – in the case of smaller residential roofs – actually starting to leak through to the house below.
By placing what is roofing felt between the rubber layer and the attic insulation, you can avoid these issues altogether. Not only will the felt be able to give your roof a little bit of added protection, but it will also allow the roofers to more easily work on the roof. What’s more, it may even encourage roof repair due to the fact that it decreases the amount of moisture that is able to penetrate the roof itself. At the end of the day, all that you really need are a few shingles to look nice, but if you can avoid having to replace them in a few years you’ve already saved yourself a lot of money.