We often have customers come into our offices to discuss their metal roofing project and when we get to the subject of venting their attic, they either choose to do nothing or use foam closures to prevent water from coming underneath the ridge cap. Even though the later makes sense, the thing they forgot to think about was what are they preventing from getting out of their attic; air. The thing with all metal roofs are that they aren't flat. Each profile has some kind of rib in it and when you install a ridge cap at the peak of the roof, that ridge cap is going to stick up the height of the rib of the panel profile. The question is what do you do with the gap created by the bottom of the ridge cap and the flat of the metal roofing panel.
You really have three options;
1) option 1 is to do nothing
2) option 2 is to install foam closures and
3) option 3 is to install some kind of ventilation material.
Option 1 is good for letting air out of the attic but not very good from letting undesirable things from getting into your attic; like water, wasps, squirrels, or even bats. Option 2 stops all the undesirables from getting into your attic but doesn't allow your attic to breath. An attic needs to have a continuous cycle of fresh air flowing through it and since hot air is lighter than cold air, it tends to rise. If hot air doesn't have an outlet to escape, which would from underneath the ridge cap or possibly gable vents, then hot air continues to build up. What ends up happening is that hot air has to go somewhere so it decides to creep into your living spaces, making your home get hotter and if you have air conditioning, then it has to work harder and stay on longer. An air conditioner that works harder and longer means more energy being used which we all know what that means, an undesirable electric bill. Option 3 makes the most sense from the perspective of accomplishing both letting your attic breath and preventing your attic from becoming a bat hotel. There are many different kinds of ventilation products on the market place that you can use for under a metal roof. To me most of them are the same. Each product might come packaged a little differently or look a little different but for the most part they all function the same. We actually carry three different kinds to give our customers a little variety to choose from. You can check them out in our product guide or call and we would be more than happy to answer any questions you might have.