One of the common misperceptions out there about metal roofing is that it increases the need for ventilation in the home. That really is not true. However, is the need for ventilation in the home greater than it’s been in the past? Absolutely, and I’ll tell you why.
The reason is – that homes are so much tighter than they used to be. It used to be that we’d have leaky windows and doors, and even walls in our house, so the moisture that we generated inside of our house from things like cooking, and laundry, and showers, and houseplants, all that moisture just ended up going out through the walls and windows of our house. Well now that we’ve made the walls and windows tighter, you know where that moisture goes? It goes up into your attic.
Metal roofing does not give you a greater chance of having problems with that moisture Any type of roofing product… if you get too much moisture in your attic… that roofing will eventually hit the dew point someplace, and it will condense. So the need is for ventilation. You’ve got to properly ventilate your attic… make sure that any moisture that does end in your attic is properly vented out.
What’s the best way to do that? With most roof systems, the best way is to have soffit vents in the eaves of your of your attic that act as intake air (that’s where the air comes in the overhangs of your of your attic). And then that air actually flows up through your attic, and the best way to exhaust that air is with a ridge vent with your roof system. And if you’re choosing a metal roof, you’ll find that most metal roofs are available with a matching ridge vent system that can that can be coordinated with the roof, or you can use other types of vents on the roof as well. But that combination of soffit vents and then either ridge vents or other types of vents near the ridge of the roof is the best way to get really good airflow through your roof to ventilate that moisture out.
So what happens if you don’t ventilate that moisture out? A lot of bad things can happen. The worst thing that can happen is you have more have mold or mildew start in your attic. But even aside from that, an attic with high moisture content also ends up being a very inefficient attic, because once your insulation becomes laden with moisture, your insulation is no longer as effective as it was when it was dry, and light, and fluffy.
So you want to keep that attic well-ventilated. It doesn’t make any difference what type of roof is on top of it. You want to have good airflow inside the attic so that you’re constantly creating air exchanges, and as much as possible, keep in that attic dry and as close as possible to the outside temperature.