Did your roofer say your ventilation looks fine, but your attic still feels humid and stuffy? Are you dealing with condensation or water stains in your attic despite having proper insulation?
If any of this sounds familiar, your home might have what we call a complex roof—a roof with multiple levels, peaks, or cut-up attic spaces that interrupt natural airflow.
This means that you’re facing unique ventilation challenges that can cause costly damage to your home without you even realizing it.
At RoofSmart, we identify and fix attic ventilation problems for hundreds of Seattle area homeowners every year. We have done everything from adding a few new vents to working with a design professional to redo entire attic ventilation systems on complex roofs.
In this article, we’ll break down what a complex roof really is, how it affects ventilation, and what your options are to fix it.
By the end, you’ll know if your roof has complex airflow issues and how to address them confidently.
How can I tell if my roof design is causing ventilation problems?
Looking at your roof from the outside is typically the easiest way to tell if you have a standard roof or a complex roof.
A standard roof is common in many homes. You can tell it’s a ‘standard’ roof because it has just one level. There aren’t a bunch of layers and roof levels stacked on top of one another. The attic runs underneath the entire roof, creating a connected space that helps air flow throughout.
With these types of roofs, you can clearly tell by looking at the outside that there is only one attic.
Here’s an example of a standard, basic roof:
Some roofs with a few levels or peaks might still be considered as ‘standard’ (for example, it might have gables, hips, or dormers). What is most important is how connected your attic is and how well air can flow through it.
A complex roof is choppy and has many levels—think dormers, valleys, hips, and sometimes even extra stories or wings of the house.
This creates spaces where the attic is cut off, so air doesn’t flow freely throughout the whole attic.
With these types of roofs, your roofing contractor can look at it and point to multiple places where the airflow patterns are difficult to follow because there are too many places for the air to go.
Here’s an example of a complex roof:
See how many peaks and valleys this roof has? There’s a lot going on here, which can cause airflow and ventilation issues.
What attic ventilation issues are common with complicated roof layouts?
You might be wondering why having a complex roof with many levels is bad news for ventilation.
Here’s why this is a problem: the attic gets cut up and divided. In an ideal world, your attic is connected throughout the whole roof so that air can flow in and out properly. That way, there are no dead zones that get no airflow.
When the attic is cut up and there are multiple places where the air might end up, that means air is flowing to random places instead of where it should go. Air enters through intake vents near the bottom part of the roof. It’s supposed to flow upward to the highest point and then exit through exhaust vents.
However, in a complex roof, the air won’t always reach the highest peak. Or, it will move from a lower section to a higher section and mess up the airflow in that lower section. In other words, some peaks might be getting little to no airflow, while others are getting a lot.
What happens when there’s no airflow in your attic? In a rainy, wet area like Seattle, a lack of airflow in the attic is highly likely to eventually lead to mold.
How can I fix or prevent ventilation issues on my complex roof in Seattle?
If you’re reading this and you’re worried that your roof is not properly ventilated, there are a couple of different solutions.
You can hire a design professional or a roofing contractor. A design professional is most qualified to create a solution to your roofing problems, but a roofing contractor will be cheaper.
1.) Should I hire a design professional to fix my attic ventilation?
A design professional is someone who can assess complex engineering or design problems on your roof and create a plan to fix it. It’s very likely that what they come up with will be very expensive, but it will be the right way to fix it.
The total cost depends on your roof size and what kind of issues your roof has, but hiring a design professional can cost as much as $10,000. Keep in mind that this is just the cost for their recommended fixes—you’ll still have to hire a roofer to do the actual roof work.
Here’s an example of the two options suggested by ASIRI Designs on a job we did recently with a customer:
If you’re looking at this image and feeling very confused, that’s ok! It’s our job as roofers to help you understand what these suggestions mean for your home.
Basically, what this is suggesting is to add another layer to the existing roof to bring it up and then add a self-adhering membrane (underlayment) to act as a moisture barrier.
Often, with a complex roof, your design professional will suggest either building on top of the existing roof or tearing everything out and starting over.
2.) Can a roofing contractor fix complex roof ventilation problems?
A more affordable option is to hire a roofing contractor who is competent and experienced in working with design professionals to fix ventilation issues. A lot of roofing contractors DO NOT have this experience.
This makes finding a roofing contractor who can actually meet your needs difficult. But if you want to keep your costs down, you can look for a roofing contractor who offers custom design and build services.
Make sure to ask your roofer if they have any experience collaborating with a design professional to fix ventilation in complex roofs.
An experienced contractor can offer suggestions for redoing your roof based on what they’ve learned from design professionals. Your roofer’s solution probably won’t be the same level of expertise that a design professional can offer, but it might be good enough for your needs.
What Should You Do If You Suspect Poor Ventilation in Your Roof?
At this point, you’ve learned how a complex roof design can seriously interfere with proper attic ventilation. The more cut-up your roof is, the more likely it is that air isn’t flowing where it should—which can lead to moisture problems, mold growth, and expensive repairs down the line.
This is especially true in rainy, damp climates like the Pacific Northwest, where poor airflow in your attic can create major issues even if your roof looks fine from the outside.
If you’re wondering whether your complex roof is already showing signs of ventilation problems, your next step is to learn what symptoms to look for inside your home and attic.
Read our article “What Are the Signs That My Attic Does Not Have Proper Ventilation?” to find out how to spot the early warning signs of poor attic ventilation before it becomes a bigger problem.
At RoofSmart, we specialize in diagnosing and fixing tricky roof designs just like yours. If you’re feeling unsure about what’s really going on with your attic airflow, we’re here to help you understand your options and make the smart move for your home.
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