One of the main purposes of a house is to keep the elements out—to be a barrier between yourself and a blizzard or a heavy spring rain. But your attic is a very important exception to the rule. In fact, many aspects of attic ventilation may surprise you.
Here at Christopher Ross Contracting (CRC), we’ve noticed that poor attic ventilation is one of the most common problems Wisconsin homeowners face. The symptoms are easy enough to recognize: ice damming, excessively large icicles, warm attics, and heat blisters on the roof. Knowing about common ventilation problems and some inexpensive solutions will help you save time, money, and stress.
When a roof is properly ventilated, it will be close to the outside temperature. This is why insulation is normally on the bottom of your attic and not the top. In the diagram, you’ll see that the poorly ventilated attic is warmer than the air outside, which then heats up the roof. The snow melts and travels down to the eave of the roof. Once the water travels to the eave, it cools because it’s no longer heated by the attic. It freezes on the eave or in the gutter and expands. The snow keeps melting, and the ice dam keeps growing up the eave of the roof. The ice pushes up under the roof shingles and then melts from the attic’s warmth. Many unfortunate Wisconsinites don’t notice until the ice melts in their attic and drips through the ceiling.
Good ventilation circulates the attic air with the outside air. The amount of ventilation required on the top and bottom of your attic can be found in your local building codes. The idea is to create air circulation from the bottom to the top of the roof. Venting in the middle can actually make things worse because it will disturb the air flow. Usually the bottom of the attic is vented with the soffits and the top with box, ridge, or gable vents.
CRC has noticed some common construction mistakes while working around Dane County. Some vents are just installed for looks and not cut into the attic. Bill from Sun Prairie recently found out that his vents were just for looks after living in the house for two decades. His roof had been suffering from ice problems and heat blisters for years.
Another common mistake is hooking up bathroom vents directly to the attic vents. CRC finds this a lot, and it basically stops the attic vent from working properly and also doesn’t allow adequate ventilation for the bathroom. There are roof vents made for the purpose of venting bathrooms, and it’s important to use them because they close when air isn’t being pushed through. It should be noted that a common shortcut is to not hook the bathroom vent up at all, and just let the oftentimes moist air blow into the attic. This is a bad situation and commonly goes unchecked for years until mold starts to grow in the attic. As a homeowner, it’s recommended to check the attic in the area above your bathrooms to make sure the bathroom vents are hooked up with duct work.
Some houses have the roof insulated rather than the attic. In an unfinished attic, the insulation belongs on the bottom. It’s important to insulate your living spaces but not the attic itself, as you want this to be as close to the outside temperature as possible. If you have a finished attic, it’s recommended to have a ridge vent. Ridge vents can be installed without replacing the entire roof and allow continuous venting between the roof rafters.
Be aware that if you own an older home, common practice was to not include bottom ventilation. Upgrading to vented soffits is a great way to fix this problem. The best solution is to wrap the soffits entirely because then not only will your soffits be ventilated properly, but you’ll also have improved the look of your property while making your soffits completely maintenance free (no more painting fascia and soffits every few years). But if you’re looking for a low-cost, do-it-yourself solution, upgrading to circular vents on the soffit should give your attic the air it needs. Just be sure to use the right-sized hole saw bit.
Proper roof ventilation isn’t something homeowners generally think about. If this is true for you, consider contracting an expert to either install or inspect your roof to ensure you don’t encounter any costly repairs in the near future.
Christopher Eaglin is the owner of Christopher Ross Contracting (CRC). They provide insulation, siding, roofing, gutters, and window services in the Greater Madison area. He has been well received and reviewed by Madison property owners since he incorporated his business in 2009. Before that, he worked in the ventilation field for other companies as a subcontractor, and, before that, as an employee. His various roles in the ventilation industry make for well-rounded experience. Customer names have been changed for privacy purposes.
Christopher Ross Contracting
1310 Mendota Street
Madison, WI 53714