Putting shingles on a flat roof is probably not the best way to go, but in the event you decide you want shingles on your flat roof instead of shakes, tile or metal here are a few good pointers to follow. But remember, the lowest pitch accepted by most cities and counties for applying basic asphalt shingles is a 3 inch rise to a 12 inch run. Read on to learn how to shingle a flat roof.
Know that there are a number of cities that will allow for composition asphalt roof shingles at a two to 12 pitch. However, because of the lower pitch they may require double the amount of paper, and instead of a standard 5 inch reveal, they will ask you to overlap your shingles with a 3 inch reveal. In doing so, you are doubling the amount of material per square foot of roof and doubling the weight being put on your roof.
Understand that most contractors prefer using a roll-out roofing as opposed to shingles when roofing low pitch roofs, such as patio awnings and sheds. Basic standard roll out roofing is called 90lb. mineral spirit. It is a fibrous asphalt impregnated with granules. It comes in several basic colours such as white, brown and black. The roll-out is placed over a 30lb. felt. One roll covering 100 sq. ft. weighs about 13.6kg (30lbs) thus the reason for the name, 13.6kg. felt.
Keep in mind that another method for roofing a low pitch or flat roof is called torch down roofing. This method looks the same as the 40.8kg. mineral spirit, but it has a different composition. It requires a 2000-degree torch to heat it as it is being laid down. The torch down roofing material melts together as it overlaps. This method does not require a 13.6kg. felt base because it catches fire. A fibreglass felt base is the standard base. Metal cap nails are used instead of staples for securing the fibreglass base.
Remember the best way to roof a flat roof or low pitch roof is to use a modified self-adhesive roll out roofing material. Much like torch down with a fibrous base, nailed rather than stapled, this roof material is laid out in lengths and has a self-adhesive backing for securing it in place. This material adheres to the fibreglass backing and eliminates the torch. Adhesive roll out roofing might cost more up front, but the long lifespan will save money over time.
The number one purpose of a roof is to prevent leaking. Following directions completely is imperative. Be sure to allow for adequate ventilation and flashing. Low cost is great, but good weather resistance is better. Although shingles might have higher appearance standards, shingling a flat roof can lead to problems down the road. Make sure to thoroughly discuss all options with a professional before attempting any roofing job.
Unfortunately, shingles for a flat roof are not advised. Roof shingles are not sealed in any way and will leak. If you have a low pitched or flat roof, tar, bitumen, rolled, or rubber roofing material is recommended. If shingles are your hearts desire and no other method will do, put down a rolled or rubber roofing material first for protection. Shingles can then be laid over top for aesthetics.