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TOPIC: Ventilation

Mid-roof ventilation

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NEED ventilator other than roof ridge type. I am constructing a large, roughly square foundation house with a hip roof. The peak of the hip roof is a hip roof shaped skylight. Inside the house, a ceiling height well extends from the floor to the skylight. A ridge vent cannot be used on the top ridge of the house. The area between the eves and the skylight needs ventilation; however the only option presented to me by the metal roof salesman is a ridge vent on the corners of the roof, which the salesman admits will not be rain proof. IS THERE ANY manufacturer of metal roofs who makes a low-profile ventilator designed to attach to metal roofing panels, much as two metal roof panels would connect to one another in a long span of roof? I don't want to compromise the longevity of the roof by cutting a hole and caulking with silicon rubber or some such sealing material. A manufactured ventilator section is needed. Do you know of a roofing system from any manufacturer that includes mid-roof ventilators?
Guest User

8/22/2001
I personally do not know of anyone manufacturing a vent that would attach at the vertical seam between two panels. However, that doesn't mean that it couldn't be specially designed and custom fabricated for you. I would bring this up to the manufacturer of the product you choose. Also, there are numerous types of standard vents available, including low profile vents, that could be installed in the field of roofing right below the skylight. That would be easy to accomplish. Todd Miller
Todd Miller
Isaiah Industries, Inc.

8/23/2001
When faced with this situation, we reccommend that the hip framing and trim detail be modified to act similar to a ridge vent. There are a number of mesh type products that can fit under the hip trim to provide the neccessary ventilation and not appear out of place. I would suggest you contact the manufacturer directly.
Allan Reid
Dura-Loc Roofing Systems, Inc.

8/24/2001
I am considering a metal roof on our 1920 farmhouse. The original roof was shakes and there are two layers of asphalt over that. Can the metal roof be installed over the old roof, or will we need to remove the old roofing down to the furring strips. If we install overing furring strips, how would it be insulated?I have been told by one owner of a metal roof that condenstion has been a problem and that items in the attic have been damaged by the dripping moisture. Is there a way to prevent the moisture problem?
Guest User

8/25/2001
Many types of metal roofs are designed for installation over old roofs. From a weight standpoint, metal roofing weighs approximately 1/8 to 1/3 what standard shingles weigh, depending upon the type of metal roofing and the heaviness of the shingles. Therefore, it is not adding much weight to the structure. In fact, it might be adding less than what the old roofs have lost over the years in terms of worn-off granules and evaporated oils. Generally, some of the shake and tile metal profiles are better suited for going over old roofs that are rough or uneven. Once you select a metal roof that you like, inquire with its manufacturer as to its suitability for installation over your old roof. Building codes in many areas call for a maximum of two layers of roofing. In many cases, once you explain to your building inspector the low weight and fastening methods of metal roofing, they will waive this requirement. If not, you might consider having a structural engineer evaluate your exact situation and write up a report on it for presentation to the inspector. Some metal roofs can be installed over furring while others require something solid beneath them such as decking or old roofing. Again, you'd need to choose a product and then discuss this with the manufacturer. Condensation occurs when warm, moist air strikes a cooler surface. In many cases, we have made our houses so "tight" with windows, siding, house wrap, etc., that they can no longer breathe. As a result, all of the moisture that is generated inside the home ends up in the attic and, if it cannot be vented out by positive airflow and ventilation, it condenses when it hits a cool surface. This happens particularly in the "changing" seasons of fall and spring. Condensation is not really a matter of insulation but instead of ventilation. You need to vent out the moisture before it condenses on a cool surface. Also, you certainly don't want to then "trap" that condensation in insulation or some other material where it will cause problems over time. Todd Miller
Todd Miller
Isaiah Industries, Inc.

8/27/2001