How to Install an Inflow Vent on a Shingle Roof

What is an inflow vent?

In this video, I’m gonna show you how to install Owens Corning intake vents on your roof. Inflow vents are a relatively new product, they’ve been around for about 5-10 years, Owens Corning just came up with their own line, so we’ve started using it. I think it’s a great solution for roofs that don’t have an intake.

So there’s multiple different ways to vent a roof. You can watch our video on how to properly vent and calculate the venting of your roof to figure out what exactly you do need. Venting is a science. So if you decide you wanna use inflow and outflow, an intake and exhaust, the inflow vent by Owens Corning is a very good solution. It means that you don’t have to open up damage walls, do stucco or make any other structural changes to the actual building into the walls. If you’re working on the roof, all the work can stay on the roof while still getting inflow vents. This is what they look like. This is a smaller piece. The back of it looks like this. Similar to ridge vents, there will be a slit hole cut in the plywood deck, which will allow air to get in, and into the attic. This mesh protects any bugs, termites, ants or any other critters from staying out of your attic. These get installed. This is a relatively complicated installation, so there’s quite a bit of steps, I would say more than most other accessories on a shingle roof, that you have to follow. Now, if you do follow all those steps correctly, it’ll definitely work, it’ll stay waterproof and do what it’s supposed to. However, if you’re not comfortable with it, if you think it’s too many steps, I don’t recommend it. It’s better not to do it than do it the wrong way, ’cause it can lead to future leaks if not done properly.

Locate where your attic starts, in order to install the inflow vent there

So we’ve located where our attic starts, you’re gonna wanna have to do the same thing on your roof, and it’s a little bit complicated. Essentially, first off, you wanna find out where your attic insulation stops, that way you know you wanna start venting from there. You wanna vent as low as possible in your attic, but be past the point of your installation to make sure you have proper airflow.

When you install this, it’s gonna be 5 inches, actually 5-6 inches above this line right here. So we’ve measured to determine that our attic starts right around here, for example, so we’re ready to start this inflow vent. If you’re right on the border, you can always go one shingle up, then start the same process, and the way we’re gonna install shingles is totally different. I definitely recommend if you’re looking to install these inflow vents, consult with a roofer, and make sure you read the manufacturer specifications because it’s totally different than the regular installation. We’re not gonna nail on this nail strip here and I’ll show you how.

Begin by installing shingles

So we’re actually gonna start by installing nails up here, and I will show you why shortly. This is something that you’ll generally never do, only in this scenario is an exception. Now we that we nailed that here at the top, what we wanna do is mark our lines for our secondary nail strip.

So our next step is to mark out the chalk line 4 1/2 inches from the bottom of your shingle. It’s very important that it’s exactly 4 1/2, because we’re gonna be cutting nearly half an inch on top of that. So we’ll mark one spot here at 4 1/2 then go to our other end of the roof and mark 4 1/2 inches there.

When laying out your inflow vents, you wanna make sure that your spacing is correct. So from any hips, valleys or rakes, you wanna come in a foot and a half. That’s where your inflow vent’s gonna start, but your cut’s actually gonna start 6 inches past from there, so 2 feet from any obstruction is where your cut’s gonna start. Let’s mark on a chalk line, and we’ll start nailing.

So we’ve got our chalk line marked right now, again, at 4 1/2 inches from the bottom of the shingle. We’re gonna start nailing the shingle down. Again, we’re not gonna be nailing on the nails strip, we’re gonna be nailing on this chalk line, and we’re gonna use the same pattern: one on each end and 2, 12 inches in. One thing I did forget to mention is, you wanna start halfway through a shingle, you don’t wanna start at the end, you wanna be in the middle of the shingle. So we’re gonna put one nail here, one nail at the end, and one nail at the middle.

Now we come to a full shingle. Again, we’re gonna put one nail at the end, one at each end, then space the same way, 12 inches. So we’ve got our shingles nailed down. Now anything past this line, we can start using our regular nailing pattern. So we’ve got our chalk line but we’re gonna be nailing again the same as we usually do, one at each end. Now we don’t wanna get too close to here, so we’re gonna keep this right at about 10-12 inches, and we’ll come here at our hip and install it here. So now that we’ve got our shingles nice and secured, we’re gonna chalk another line, and that’s gonna tell us where to cut our shingles and where to cut our plywood.

Measure where to cut your vent opening

So the next measurement, we’ll have to measure out is where we’re actually gonna cut our opening. So we wanna go one chalk line at 5 inches, and one at 6 1/2, and that’s gonna be width of our entire opening. Always make sure to come in 6 inches from your side, but it’s okay to chalk out longer lines, then install your vents as needed. So we’re gonna do one at this end and one at the other end here.

So we actually made a mistake here. We marked a line out at 6 inches. We’re gonna disregard this. We marked a second line here at 6 1/2. So this is where we wanna come out from 5-6 1/2 inches, we wanna cut this out. And the easiest way to do it, is we already have our plywood cut out from a previous demonstration, but the easiest way is to actually cut the shingle, underlayment, and plywood all in one shot using a Skilsaw. As I mentioned before, safety is always important and generally, you wanna wear safety goggles any time you’re using a nail gun or a Skilsaw, but especially when cutting through these shingles, safety goggles become very important, ’cause what happens is these granules actually just start flying out and act like little pellets flying all over the place. So, always wear your safety glasses when cutting your shingles.

Now that we’ve got our strip cut, we’re gonna start removing this material. Generally, you would have plywood installed in these areas. We already had our plywood removed, so you’re gonna be removing your plywood and your roofing material as well. And you can actually see here in our mock roof, this is where our attic starts. So this is a perfect location. You’re gonna have your attic intake from right here. If we were to cut this a little bit lower, we wouldn’t be in our attic space, and that would be completely useless. But this is a perfect location for intake.

Install the inflow vent

So we’ve got this cut already, we’ve got this opening done. We need to start installing our intake vent. So you wanna come 6 inches past this slit right here, past this hole. So from here, we wanna come 6 inches. This lip is meant to catch the bottom of the shingle. You can see there is a notch right here, this groove is gonna sit underneath our bottom shingle. And we wanna come, again, 6 inches. So that’s our mark right there, that’s exactly where this vent should be placed.

Now, Owens Corning gives us these 2-inch ring shank nails. These are the nails that must be used for this vent right here. They’ve thought this out, the length of it, the width, and the fact that it’s a ring shank galvanized nail is what’s important. So make sure you use the nails provided with the vents. They have specifically marked locations for the penetrations, for fastening these down. Make sure you follow their markings as it matters for the patterns.

So we’ve installed our first piece here. It’s fully nailed in the proper nail holes and we’re gonna be continuing in the same line, our second one here. And you can actually see they’ve done a great job with making an indentation here so this second slides right there. We have a nice clean finish right there, and that’s what we wanna see.

Alright, now we’ve come to our rake end here. I wanna show you two different ways of terminating the ends. One is gonna be a transition from this vent down to the regular slope, and we’re gonna do it on the other side, on the hip side. Now, if you wanted, you could bring your vent all the way to the rake right here and actually have this side exposed. In order to do that, you wanna make sure that your cuts are done on the inside. Similar to your shingles, you wanna leave the factory edge on the outside and your field cuts here in the middle. In this vent’s scenario, it’s extremely important, because the underside of this vent is extremely ugly, you don’t wanna leave this exposed. So let’s cut this here, and you can either measure it out or just make markings.

Cutting these vents can be done with a simple utility knife. The same thing you used to cut your shingles, we can use to cut these vents here. So we’ve already cut the top, and what we wanna do is flip it around and cut this fiberglass mesh here. Generally, scissors work best for here, but you can also use a utility knife. So you can see, our cut end is not perfectly level or perfectly straight, but that’s totally fine because it’s gonna lap here. The important thing is we’ve got our factory finish ending here.

How to waterproof your inflow vent

Now that we’ve installed our intake vent, we’re ready to start installing our waterproofing. So we’ve got our nails properly installed. For this edge right here where we’re transitioning down to the regular field, we actually came up with this detail with Owens Corning. The manufacturer specifications don’t call for a transition piece, but what we wanna do is install three layers. Essentially, what we’re doing is restarting our eave from this point without our drip edge. So we’re gonna be installing our ice and water shield on top of this; we’re gonna install our underlayment; then we’re gonna install our starter shingles; then we’re gonna continue with a full piece of shingles, so let’s get going.

So the first thing that we’re gonna do is install our ice and water shield. We’ve cut this down to a 20-inch length just to fit this dormer here, but you can really install a full piece if you’d like. We wanna have our factory finish on the bottom. Right here, we wanna have a 6 to 8-inch lap past this piece. We don’t wanna come all the way to the end of our shingle as we’re gonna taper this down, and I’ll show you what I mean here shortly. What we wanna do is make sure this bottom is perfectly aligned with the start of this vent right here. Then what we’re gonna do is install a few nails just to help us keep this aligned. Now, we wanna come to this end and start pulling the adhesive strip off. So again, this is probably a two-person job, just making sure that we stay aligned, then we wanna come close to this corner here.

Now, being that we’re gonna install a few layers here–we have our ice and water shield, we have our underlayment, we have our starter strip. Each layer we’re gonna go slightly more tapered, so break that off here, nicely fasten it. Then what you can always do is remove these nails and remove this adhesive strip back here. But just like we would during our regular eave installation, we’ve got our ice and water shield installed. Next thing we’re gonna do is install our underlayment on top of that. So we wanna come out slightly past this ice and water shield. A few inches past is enough, and again, we wanna make sure we’re nice and aligned with this line here. So we wanna have this past, the underlayment past the ice and water shield about 2 or 3 inches, and taper off.

So generally, if this were not a demonstration, we wanna make sure that our underlayment gets tucked underneath our existing underlayment. As again, we wanna make sure the bottom layer always goes first and the top layer underneath, or on top of that. So, for right now, we’re not gonna worry about that since we’re showing you how to install the intake vents. We’re just gonna be installing our underlayment. If you need help on how to properly install underlayment, you can refer to our video that we have specifically about underlayment installation. Now that we have our ice and water shield in place, we’ve got our underlayment in, it’s time to install the starter shingle prior to installing our regular field shingles. So again, we wanna come about 2, 3 inches away from this shingle right here. Make sure you’re aligned with the top of the vent. And just like any other starter shingle, I’ll place five nails. Now, anytime you’re nailing shingles on top of the intake vent, you wanna use the nails provided by Owens Corning.

Now, one thing you wanna be aware of during this process is that you don’t over-drive nails, since the intake vents are plastic. This dirt nail is a little bit over-driven, I don’t know if you can see it here. So, that’s an over-driven nail. You wanna make sure the nails are installed flush.

Now that we’ve got our starter strip in place, we’re ready to start installing shingles. This is gonna be the same installation method used on just the regular field with a slight variation. Now, we wanna start from this joint right here. So over here, we’ll be installing a new shingle, and over here we’ll just have one layer. Then our next row of shingles will come and take away this taper. You are gonna have a slight depth rate variation right here and we’re gonna get rid of that in the second row of shingles that we install. So you wanna come flush with here. We’re gonna put one nail right here, then align it. So, right here we wanna also be aligned with the top of this vent right here. Let’s put one nail right here, a regular nail. Now again, since we’re going on top of the intake vent, we’re gonna be using Owens Corning nails. Again, this is provided in any box of the inflow vents.

We’ve completed installing the inflow vent. After this point, it’s just like installing any other roof. The shingle will get aligned right here with this proper pattern, and we’ll continue installing. This top layer here is already past the inflow vent, so we can just use regular nails. This is what it looks like. Now, some people may be concerned about this opening here and how this may cause a leak. In reality that’s why we layered it up and we have this shingle that’s going underneath. So, if you have water coming in this cavity, I wanna demonstrate this right here, the water actually flows underneath the intake vent and flows out. So you have no concerns. Same thing with the water coming here. You can see the water will flow over the shingles. And whatever comes in here is gonna flow out. So that’s how you install the Owens Corning intake vent. Again, it’s a very detailed process as I’m sure you noticed. Make sure to look at the manufacturer installation instructions and follow them exactly.

Extend the Lifespan of Your Shingle Roof with Roof Maxx