Are you seeing signs of poor attic ventilation (like mold, moisture, or curling shingles), but aren't sure what type of vent your roof needs? Have you been told your home doesn’t qualify for bird blocks or other common intake vents due to fire codes or soffit blockages?
Figuring out the right ventilation for your attic can be frustrating, especially because it’s something a lot of Seattle roofers don’t even acknowledge.
At RoofSmart, we replace hundreds of roofs every year, and pretty much every single home needs some sort of attic ventilation update. We’ve done everything from adding a few extra vents to working with an engineer to redesign your entire attic’s ventilation.
In many situations, we’ve recommended the O’Hagin vent to our customers because it’s the only vent that will work in their complicated ventilation system. It’s not the only type of vent we sell, but it is one of our favorites.
This article is an honest review of the unique features of the O’Hagin vent with examples of times when it has solved our customers’ ventilation problems.
In this article, we’ll break down exactly when an O’Hagin vent is the right fit for your Seattle-area home. You’ll learn what makes it different from other vent types, where it shines, and when you don't need it, so you can make a smart, informed decision.
How is the O’Hagin vent different from other attic ventilation options?
The O’Hagin vent is a versatile and durable option for ventilation on your Seattle roof. This is what it looks like when installed:
There are a lot of attic vent options out there (both intake and exhaust). So, what makes the O’Hagin vent different than others? Let me break down some key differences for you:
- Works for intake OR exhaust ventilation: The most unique feature of the O’Hagin vent is that it can be used for intake or exhaust ventilation. This means that it can be used in almost any situation. No other type of roof vent can be used for both.
- Does not plug with moss: Ridge and edge vents can sometimes be at risk of plugging with moss. This is a pain to clean out, and it blocks air from escaping the roof (or entering if it’s an edge vent).
Your roof needs a place for air to enter and a place for it to escape in order for your attic ventilation to work properly. O’Hagin vents don’t plug with moss, so they’re a good alternative for a ridge vent.
- Ventilates a bigger area than a standard RVO vent: An O’Hagin vent has almost double the net-free area coverage of a regular RVO vent. An RVO 38 has 38 square inches of net-free area, and the O'Hagin has 72. You’re getting about double the area coverage, so you can install fewer vents on your roof.
Standard RVO vents are used on a lot of roofs. For reference, this is what they look like:
- Low profile: The O’Hagin vent is also a good option if you want something more subtle that blends in with your roof better. Some other vents do a good job of this. But compared to an RVO vent or wind turbine, the O’Hagin is a fairly understated option. Plus, your roofer can install shingles over the top of it to help it blend into the roof even more.
When does RoofSmart recommend the O’Hagin vent?
The O’Hagin vent is a good choice for your roof, even if you’re not struggling with a ventilation issue. But it has come in handy for a lot of our customers with tricky ventilation situations.
Here are some examples:
1. Bird blocks won’t work due to fire code
In a lot of neighbourhoods throughout Seattle, it is very common that houses are built on small lots and are packed in very close together. This means that you have to be extra vigilant about making sure that your attic ventilation meets fire code requirements.
The O’Hagin vent sits on top of the roof (which helps it meet fire code), and it is the only vent that is California fire code rated to not suck in embers.
Sometimes it's not possible to do bird blocks because they don’t meet fire code, especially in new housing developments where they build the houses as close together as possible.
This is an example of what bird blocks look like.
You don't want flames from one to be able to suck up into the attic of the other, right? So they don't want intake vents (like bird blocks) next to the other house because it’s a high risk.
So, you have to do your vents on top of the roof. If you're going to do intake vents on top of the roof, again, you can do the edge vent, but it'll plug with moss.
You can do like a regular stem vent or an RVO vent, but they're not rated as intake vents.
2. You need ventilation in a small area
The O’Hagin vent is a great way to add ventilation to a small area. Of course, we can install several of them and do a whole side or a whole facet, but we often use them to get more air right where we need it.
Here’s an example of a small portion of the roof that needed ventilation:
We decided an O’Hagin vent would be the best because of its versatility and because you get so much area coverage out of just one vent (installing multiple vents on one small portion of the roof can get tedious).
3. The soffit blocked most other intake options
Sometimes our customers have tricky attic ventilation problems. Because the O’Hagin vent is completely different from most other intake vents, it’s a great solution for more complicated problems.
For example, we recently worked on an apartment complex with intake ventilation that was blocked by the soffit. Most intake vents are installed on the edge of the roof, so they would’ve also been blocked by the soffit.
That left two options: Edge vent (aka shingle-over-intake vents) and O’Hagin vents. Since edge vents tend to plug with moss, we decided O’Hagin vents would be the best option.
When is the O’Hagin vent not a good fit for my Seattle roof?
O’Hagin vents are not compatible with metal roofs or flat roofs because it is installed directly into the roof deck. There is no option to elevate it and make it curb-mounted.
Metal roofing is not compatible with this type of flashing. And anything installed into the roof deck on a flat roof will definitely leak. So, if you have a metal or flat roof, you cannot use O’Hagin vents.
It’s also more expensive than typical exhaust vents (like a stem vent), so if you’re looking to keep the budget as low as possible, it might not be right for you.
For example, an O’Hagin vent costs about twice as much as a regular stem vent. So, if a regular one is typically, you know, 50 bucks to the customer, the O'Hagan might be 100.
What should I do if I think my attic ventilation is failing?
If you’re noticing signs like mold, excessive moisture, curling shingles, or a hot, stuffy attic, you’re right to be concerned. Poor attic ventilation is one of the most overlooked causes of premature roof failure, and it can lead to costly repairs if ignored.
Whether your home was built with inadequate ventilation or your vents have become blocked or damaged over time, it's important to catch these problems early.
So how can you be sure your attic is getting the airflow it needs?
Read our article “What Are the Signs That My Attic Does Not Have Proper Ventilation?” to learn the most common signs that your attic doesn’t have proper ventilation. By the end, you’ll be able to spot the red flags before they turn into expensive issues.
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