It’s common knowledge that adequate insulation is essential to improving your home’s energy-efficiency. What many don’t know is that insulation and ventilation always go hand in hand. If your roof or attic doesn’t have enough insulation, warm air can enter your home and force your HVAC system to consume more electricity to keep temperatures at a comfortable level.
How can you tell if your roof doesn’t have enough ventilation? By keeping an eye out for the warning signs. Local residential roofing contractor KLIM Roofing & Construction lists the warning signs as well as the other things you need to know about the roof and attic ventilation in this guide.
Warning Signs of Inadequate Roof and Attic Ventilation
- Ice dams – If your attic doesn’t have enough ventilation, warm air becomes trapped inside and increases your roof’s temperature, which in turn melts the snow on top of the roof. (The floors or lower part of a poorly ventilated attic are cold while its ceiling or upper parts are warm.) As the melted snow slides down towards the much colder edges of your roof, it freezes and deposits ice near the eaves. Ice dams are a problem because they prevent water from flowing to your gutters, causing it to back up and eventually seep into shingles.
- Higher heating costs – Saturated warm air can hold more moisture than cold air. Without adequate ventilation, the trapped moisture may form condensation. If insulation comes into contact with condensation, it loses some of its R-value or insulative capability, which in turn forces your HVAC to consume more electricity to keep temperatures at a comfortable level.
- Water stains or frost on wooden rafters and beams – Trapped moisture can also cause stains or frost to form on your ceiling or wooden beams. What’s most concerning about trapped moisture is that it creates a damp environment that’s the perfect breeding ground for mold, which can easily affect other parts of your home.
If you notice any of the aforementioned warning signs, you should have your residential roofing contractor inspect your roof and attic as soon as possible.
Having More Ventilation Isn’t Necessarily Better
If your roof doesn’t have enough ventilation, more air vents need to be installed. However, keep in mind that more roof ventilation isn’t necessarily better. A properly designed roof ventilation system has just the right number of exhaust and intake vents to allow air to enter and exit your roof and attic in equal amounts.
How much attic and roof space should be allocated for air intake and exhaust? It depends on the square footage and volume of your attic area. In general, there should be a square foot of net free area (NFA)—the area through which air can pass through—every 300 square feet of floor area for attics with a vapor barrier. As for attics with no vapor barriers, they should have a square foot of NFA for every 150 square feet of attic floor space.
The Types of Air Vents
Not all vents provide the same level of ventilation. Remember: there’s no such thing as a one-size-fits-all approach in re-roofing projects.
To help you choose the right type of air vent, here’s an overview of the different types:
- Box vents – Box vents installed near the top of the roof. However, they don’t provide a lot of venting space, so you’ll need to install several of them, which won’t do your home’s curb appeal any favors.
- Off-ridge vents – Off-ridge vents have the same ventilation capacity as box vents. The only difference between the two is that the former is more rectangular in shape.
- Ridge vents – Most contractors agree that ridge vents are the most cost-efficient and effective choice. Since they run along the roof peak, they don’t draw attention to themselves, unlike box vents.
- Turbine vents – If you live in a windy area, turbine vents—which rely on wind to ventilate your home—would be a smart choice. On windy days, the vent’s spinning turbine mechanism can provide better ventilation than other types of vents. But on the downside, they won’t be able to provide much ventilation on calm days. Not to mention turbine vents are not that aesthetically pleasing. And if you decide to install this type of vent, you should keep an ear out for any unusual noises, which may be a sign some of the moving parts of the turbine are starting to break down.
- Gable vents – This type of air vent is installed on the exterior attic walls. Most air vents are installed in areas where they aren’t easily seen, but gable vents are meant to be part of the exterior design.
- Cupola vent – Like gable vents, cupola vents are intended to be part of a home’s architecture. However, since there’s usually only one cupola vent installed in a home, a supplementary vent is needed.
- Power vent – As the name suggests, power vents use electricity to extract warm air from your roof and attic faster than passive options. The downside is that it adds to your utility bill. However, if you want to reduce your electricity bill, there’s the option of installing solar-powered vents.
To learn more about your ventilation options, consult a re-roofing contractor.
Vents and Soffit Boards
Aside from air vents, your roof also has soffit boards to help improve ventilation. Soffit boards are located under the fascia board—the long straight board your gutters are attached to—and have holes in them. Keep in mind soffit boards are not a substitute for proper air vents. These are designed to supplement, not replace, air vents.
Types of Soffit Boards
Aside from providing supplementary ventilation for your roof, soffit boards also protect your roof’s rafters—the wooden beams providing structural support—from the elements. However, the level of protection varies depending on the material used to manufacture the soffit board.
Here’s an overview of the different types of soffit boards:
- Vinyl soffit boards – Vinyl soffits are affordable, easy-to-clean, and resist moisture damage. However, they’re prone to warping in high temperatures and cracks in subzero temperatures.
- Aluminum soffit boards – Contractors recommend installing aluminum soffit boards in areas that receive a high amount of rainfall. That’s because they’re durable, rot- and corrosion- resistant, and easy-to-maintain.
- Timber soffits – Timber soffits retain natural wood’s classic aesthetic, making it a good choice if you’re looking to give your roof a rustic feel. However, wood has high maintenance needs.
Flat Roof Ventilation: Warm vs Cold Flat Roofs
Keep in mind a flat roof will have different ventilation requirements. For instance, the enclosed space within a warm flat roof—which has insulation placed above the structural deck and either on top or below of the waterproofing membrane—doesn’t require ventilation. On the other hand, a cold flat roof—which has its insulation layer located below the structural decking—requires ventilation. That’s because cold flat roofs are prone to collecting higher amounts of condensation during winter. And in summer, trapped warm air that rises up to the flat roof forms condensation.
And don’t forget to check if your roof has enough insulation. Remember: ventilation and insulation always go hand in hand.
Not sure if your roof is well-ventilated and -insulated? Consult a local roofing contractor. Since they’re familiar with the local climate and building codes, local roofers can make better recommendations.
Important note: flat roof installations require a higher level of expertise since they’re more leak-prone (water tends to pond on flat surfaces). Here’s a vetting tip: the number of years a contractor has been in business should give you a good idea of their level of expertise.
KLIM Roofing & Construction, a GAF-Certified Weather Stopper roofing contractor with more than 15 years of experience, offer their expertise in flat roofing, re-roofing, roof repairs, and new construction. With our trained and experienced team, you can rely on us for quality workmanship. To learn more about our services, you can call us at (425) 485-5546. We serve homeowners in Seattle, Redmond, and Bellevue, WA, as well as the surrounding communities. Get a FREE Estimate Today!