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What are Roof Penetrations?

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“Penetration” is one of many roofing terms that you’ll roofing professionals throw around that might not mean what you think it means. Along with “pitch” and “flashing,” we tend to use a lot of terms that sound like something you’ve heard before, but might not have a real grasp on what it all actually means. 

When I first heard “penetrations” used in a sentence, my first thought was that someone had a bunch of holes in their roof. While that is technically correct, what I didn’t understand was that those holes are supposed to be there. I don’t want you to be as confused as I was learning about roof penetrations, so that’s why we write blogs like this one! 

In this blog, we’ll go over what exactly a roof penetration is, what some different kinds are, and what problems might occur around them. 

Let’s get started! 

What is a Roof Penetration? 

A roof penetration is a common term us roofers use to describe anything that comes through your roof. You might think that means a branch or something that’s not supposed to be there, but actually, penetration refers to things that were designed to come through it, and were built as a part of your home and roof. 

So, these penetrations aren’t really a bad thing, and are super important for a variety of functions for your home, which we’ll talk about in the next section. 

They do make your roof more complex, though, which will increase the cost of a roof replacement. More penetrations require more flashing, which means more materials and more money that you have to spend. That being said, that number will be factored into your estimate that your roofer should give you, and they will be able to explain to you the affect that your specific penetrations will have on your replacement. 

black plastic boot covering the base of a white roof pipe_WebP

What are the different kinds of Roof Penetrations? 

A roof penetration can be anything from a chimney, a skylight, a dormer, or vents from your attic, kitchen, or plumbing system. 

It’s pretty easy to understand what most penetrations do. They act as a release for air you don’t want in your house. Whether that be smoke from your chimney, steam from your stove, or air coming from your plumbing system. 

Skylights and dormers are ways for you to get natural light through your roof into your home, but don’t serve much purpose other than being aesthetically pleasing. 

Dormer on an asphalt roof

What problems could happen at a Roof Penetration? 

Roof penetrations, as important as they are, create openings in what otherwise would be a flat, hole-less board. Holes and roofs don’t mix particularly well, a roof’s purpose is to prevent water and other natural elements from getting inside your home, and a hole would do a great job of countering that mission. 

To solve that, we use a material called “flashing” to cover up any areas that would be sensitive to water, like around a pipe, or in the area where the chimney meets the roof. Flashing is typically some kind of metal that won’t let water through, fashioned to fit the area it is put in. There is a lot more to learn about flashing than we can cover here though, so for that check out our blog on Everything you Need to Know About Flashing. 

With that, the most common problems we see at roof penetrations are issues with flashing, or pipe boots. Either the material wasn’t installed properly, or it wasn’t a high quality material, and failed long before it should have, exposing the hole to potential leaks. 

damaged flashing around a chimney

How do you fix a Roof Penetration?

For these flashing or boot related issues, you can have it fixed by having a certified roofing contractor come inspect the area, and replace the flashing or pipe boots that need it. You may want to have the other penetrations inspected at the same time, because chances are, they may be about to fail as well. 

Flashing around a brick chimney on an asphalt shingle roof

As for other issues like damage to your skylight or chimney, that will need to be fixed by someone trained in those areas. Your roofing or general contractor may have someone in house that does those services, or have a company they trust that they can refer you to. 

Need Some Advice on Your Penetrations?

I hope that this blog has helped you learn a little bit more about roof penetrations, and that you feel more knowledgeable about a roofing topic that can get confusing. 

If you’ve experienced some of the problems we mentioned above, or are worried that you’re having some other roofing issues, reach out to us using the “Contact Us” button down below! 

On Tops Roofing has been replacing and repairing roofs in the Raleigh area for over thirty years, so whatever your roofing project requires, we are happy to help! 

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