I have said it before; your home is not a submarine… and even subs leak!
Fiberglass – asphalt and other types of roof shingles, such as tiles, shakes, slate, are not water proof. They are designed to shed water on a pitched or sloped surface. Steeper surfaces shed water faster and dry faster.
You can’t put shingles on a pitch lower than 2 in 12″ [roof rises 2″ in 12″]. We do not recommend it on slopes below a 4-12 pitch without special conditions. Roofs lower than a 2-12 need a roof system designed for “low slope roofs.” These are single – ply membrane roofs such as TPO , E.P.D.M. , P.V.C. , or modified bitumen . And just because shingles are on it now does not mean you should replace that roof area with the same thing. Even if it doesn’t leak now, it may in the future.
No responsible roofer would use the wrong type of material. A good roofer looks at every roof on a case by case basis. For example: A low pitch or low slope roof in a heavily populated suburban area not near large open spaces of land or water is not the same as one facing north on the river in Hampton Roads, Virginia cities such as Portsmouth, Norfolk, Virginia Beach, Chesapeake, Suffolk, Smithfield, York Town ,Hampton, or Newport News.
I might nail a shingle roof on a 3-12 pitch on the first roof described above, but not on the second. On the second I might recommend a low slope roof system or maybe install ice and water shield under the shingles in case wind driven rain forces itself in. And I might even use stainless steel roof nails so they won’t rust out by being wet too often for too long. #15 or #30 pound double layer asphalt saturated felt paper or “tar paper” roof underlayment might be an option as well.
Our roofers have been doing at this for a while so we have the ability to consult with you in these matters. We have seen all kinds of roof leaks and all kinds of roofs leak! We also listen to what the manufacturers say about how and where to install their roofing products. We are always sure to meet building codes.
We recommend the use of CertainTeed Landmark and other models of shingles made by CT because of their #1 rank on consumer reports and because of our experience over the years using all name brands. We took years to pick the horse we would race so you don’t have to worry about it!
So please remember: No matter how good the roofing material is, it must be installed in the right place and in the right manner to perform and do so for a long time. Ask the roofer and find out how much he knows before you hire him. The right decision in picking a roofing contractor or company is very important.