Without proper ventilation you can easily turn a 30 year shingle into a 15 year shingle. I’ve seen decent quality architectural shingles curl and crack because the installer didn’t provide proper ventilation.
Ventilation requires intake and exhaust. Think of proper attic ventilation like a chimney. A chimney has an opening at the top and an opening at the bottom. To work properly, the openings must be equal. Unfortunately that’s not always possible and because todays soffit material is often covered (clad) in either aluminum or vinyl, you can’t tell how much space is open in the soffit. Even if the soffit venting is visible, sometimes it is clogged by insulation in the attic.
So what is the solution? It is two-fold.
EXHAUST through Roof venting: Make sure that your roof follows at least the 1/300 rule. That means that for every 300 square feet of attic space, you should have at least 1 (full) square foot of ventilation. Optimally this would be in one contiguous vent. Some ridge vents give maximum ventilation. For instance, the GAF Snowcountry vent allows you to have a smaller amount of linear footage of venting making it optimal for hip style roofs with limited peak space.
INTAKE through Soffit venting: You really can’t go wrong by maximizing the amount of soffit venting you put in. Even if you have more intake than exhaust, if your exhaust is continuous it will draw up from the soffit venting. If you want to maximize the amount of air flow you get from your soffit, but still want the benefit of it being maintenance free, hidden vent soffits like the Quality Edge hidden vent (aluminum) or Alside’s Charter Oak hidden vent (vinyl) are the best options in the market today. As a side note, today’s high end vinyl can lay nicer and is more forgiving for older homes where fascia boards may no longer be as true as they day the house was built.
Jim McGuigan is a GAF Certified Roofing Contractor and owner of Energy Masters, LLC. He has helped hundreds of homeowners diagnose their ventilation needs and understand now only how to save money on their energy bills, but to extend the life of their roof and reduce ice damming. He can be reached through his webpage at https://www.wisconsinenergymasters.com