90% Fail To Properly Ventilate.

When I first began my roofing company I looked at the vent that the company I worked for previously used. I knew it was a cheaply made product that had very little flow. I liked vent that was hidden and had good aesthetics. I went looking for something that I wanted to put on my roofs. Here was my list of requirements.

1. Meets code standards, they all do on a ranch house, but not all meet every single manufactures warranty requirements.

2. Long lasting

3. Easy to install correctly

4. Flush design for aesthetics

We ended up using the OWENSCorning VentSure, because it met Code requirements and all the other requirements in my list. After installing this common, code compliant, meets all the specs vent, for a few years, we had a roof that had condensation issues. I had double checked everything and it met the requirements. But it previously had a baffled ridge vent, the only thing different about the roof was the vent. I started looking more into the science of how ventilation works to find the answer. I found it from only one manufacture, They were the only ones teaching about the issues. We replaced the vent on that roof with a Baffled vent, and all the condensation issues went away immediately. What I found was most vent companies do not display their vent actually working. I did find one company, LOMANCO, that demonstrated how the Bernoulli effect works on a baffled design, without this baffle, cross winds turn the air flow system upside down on a non-baffled vent. The building with The OWENS Corning Vent sure was sitting perpendicular to the prevailing Southwest wind, meaning the ridge vent was an INTAKE vent about as often as an exhaust vent. This constant right side up to upside down switch in the system made so that very little air and moisture actually escaped the attic space, causing the condensation. During the demonstration, my LOMANCO rep Rob, took my current ridge vent, put it on a mock roof, added some cross wind, filled the cavity with a smoke generator and we watched the system turn COMPLETELY up side down. With air pushing out the eaves, I was a little skeptical, you know, He was trying to sell his vent. Then he put a hand made baffle on my previous unbaffled vent of choice, while introducing crosswind. The system turned right around and worked properly with a proper vent baffle. It was much slower at venting out since it had a VERY restrictive filter, but I was convinced, since his demonstration was more about baffles, and less about HIS brand. The LOMANCO also does not use any internal snow filter, only internal baffles as well. On one of the first roofs we did after this switch to LOMANCO, we had a cross wind, while the vent was installed. I went into the attic to hook up some vents. When I opened the attic access there was a significant suction from the ridge vent. Quite noticeably more than I had ever encountered before. Below I have a photo demonstrating what happens.

There are many other aspects of ventilation that can cause problems,

1. Ridge vents at different heights, within the same attic space. 36” is the maximum allowed differentiation. If more difference is present, the attic space needs separated.

2. Different types of vent. The more powerful vent will over take the less powerful and it will become an intake. Think of a straw in drinking cup, with a hole part way up. The air will take path of least resistance and will no longer suction from the eaves efficiently.

3. Static vents on multiple sides of the roof. During a slight breeze, the wind side gets air pushed into it, and the off side becomes the exhaust. Again not getting good air flow from the eaves.

4. Many houses with vented soffit have wood soffit underneath, or wood blocking between the rafters, eliminating any air channels, and making ventilation an impossibility. These issues can in most cases be addressed if your roofing contractor actually cares about your home, mold, condensation, heat build up, AND your warranty. Your roof warranty Means NOTHING, worth less then the paper it is printed on, if you have inadequate ventilation. I have run into instances where it was an impossibility to address the issues without doing VERY costly structural changes, like an entire finished upstairs remodel. In these cases we explain the scenario to the homeowner, do everything to get it as good as possible, and also prepare it for any future upgrades that could make it perfect, should the homeowner get in a position financially to do the interior upgrade later.

5. In northern climates, many vents have filters for snow, these filters, especially when warmer moister attic air meets the cold air in winter, the condensation causes dust to collect on the filter, clogging the filter. If you dig far enough, most if not all vent manufactures suggest you clean it regularly, WHEN you DON’T follow the recommendations, why would they warranty the shingles WHEN they fail prematurely. LOMANCO Uses no Filters instead opting for a superiorly designed, internal baffle system. This eliminates a maintenance step, and potential roof issue.

If your Roofer of choice is not addressing at least one issue in the ventilation of your home, according to study's done, you have a statistically propable 90% chance it will be wrong again.