Condensation and Ice Damming on a Metal Roof
Condensation on the Metal Roof
Absolute Steel periodically receives panic calls from homeowners who have experienced roof condensation. Often this is during the fall season when it first begins to get cold and warm air that contains moisture meets up with cooler air resulting in condensation.
Sometimes the homeowner will assume this drip to be a roof leak; but this is far from that. Similar to a glass appearing to “sweat” when a cold drink is poured in it and moisture accumulates on the outside, the same thing tends to occur with metal roofs. This is also more noticeable with metal roofs because they conduct heat much faster than other roofing materials such as wood. Also, because wood can absorb some of the moisture, it will appear more obvious on a metal roof.
Warm air is more capable of holding moisture than cold air. For this reason, your home remains warmer in the hotter months than in the colder, winter months. Other activities and sources bring added moisture to your air such as cooking, doing laundry or taking a hot shower. And, those who wear eyeglasses are quite familiar with the “fog up” they experience when going from the cold outdoors into a warm space. Similar to a drinking glass, the moisture is building up on your cold lenses. Along with showers and washing machines, other appliances in the house can also aid in building moisture in your home. And problems with moisture in the basement or plumbing leaks can further put moisture in the air which later appears as condensation on your metal roof.
An important step in alleviating this problem is to eliminate or minimize condensation in your attic space. Obviously your attic along with your metal roof will become cold in the winter months – there is no way to avoid this. However, you can work on preventing moisture from getting into or onto these cold spaces.
Begin by installing a vapor barrier in the openings around the ceiling insulation and between the attic and the interior of the house. Along with minimizing condensation, good insulation will also keep warmth in the home. And along with insulation, you can further add a drywall ceiling with taped and sealed joints covered by a quality coat of paint. Another option is a plastic film which is ideal when the ceiling is made of tongue and groove wood.
Secondly, you can minimize moisture building on your metal roof by eliminating spaces that may serve as a cold air entryway. This includes light fixtures and ceiling fans that are unsealed as well as items that actually put moisture directly in the air such as exhaust fans and dryer vents. Often these are vented into the attic but should actually be vented outdoors.Proper attic ventilation is also crucial to allow for air to be evenly distributed around the space and for your colder, outdoor air to be replaced by warmer air from inside the house. For this to properly be done, you’ll have to make sure ventilation does not hinder a clear path for air to enter at the soffit and move around the ridge area. If you find it difficult to get quality insulation, consider a power vent to properly move the air.
And last but perhaps most importantly, in the installation of your roof, you’ll want to be sure to begin with a strong, solid deck underneath. This is possibly the most important step to avoid problems with moisture building and condensation accumulating on your metal roof. One reason is that when you have a strong foundation, condensation will build on the underside where the wood will absorb much of the moisture.
Ice Damming on the Metal Roof
In colder climates, ice damming can also potentially be a problem. This event happens when it is cold outside and snow melts in spots on the roof where it is warmer. As the water tries to flow down the overhang which is slightly colder, it will refreeze and as it builds up, will hang over the eave. Later in the season or on warmer days, the ice will then melt and gather at the eave and under the roof panels resulting in leaks. And in the valley, “ice damming” can become even larger and more of a problem.
Ice damming, like condensation, is avoidable. Many methods for solving the problem of ice damming is also similar to the solutions for condensation. This includes ensuring you have both adequate attic insulation and ventilation. Quality insulation will keep the cold air outside ensuring the snow does not melt while ventilation will eliminate the problem of heat build-up in the attic which also contributes to melting snow followed by refreezing.
One problem you may encounter however is that of cathedral ceilings. This is because these are more difficult to insulate or ventilate because of the limited amount of insulation materials you can use with these designs. With poor insulation and ventilation, you are bound to have moisture problems resulting in both condensation and ice damming. If you do have cathedral ceilings in your home, there are special products available to help provide your home with better insulation. Additionally, you will need to make sure there is proper ventilation as well as a tight seal around all of your recessed lighting fixtures.