Sometimes we see roofs that have two layers of shingles. Not completely a huge deal other than tearing off two layers of shingles will raise a new roof price, but having four or maybe even more layers is just plain crazy. Some building codes do not allow more than one layer of shingles and some allow up to two,
contact your local building code office for requirements in your area. When you put extra protection for the underlayment like doing 30# felt instead of 15#, there is really no need for another layer. There are many reasons why it is not a good idea to keep adding layers. There are some that do not care what building codes there are and do not follow them and sadly sometimes it is the same for a building owner as it is a contractor. Always make sure to do your research and if suggested by a contractor to just roof over top of what you have, make sure to contact another professional roofing contractor to get a second opinion. In most cases with the new advances of shingles and other roofing system products, there really is no need to have a second
layer. Topics: Commercial Roof
How Many Layers of Shingles Can Be on a Roof?
When faced with the perceived cost or inconvenience of replacing a roof, some homeowners may consider “re-covering,” or adding a new layer of shingles as an alternative. While re-covering may save some money, mess, and the hassle of removing old shingles, there are considerations that you must weigh. For instance, building codes in your area will limit the total number of acceptable layers of shingles on your roof. Additionally, you will need to consider the type of roof you have and its structural soundness when deciding whether to re-roof or add to your existing roof.
How Many Layers Is “Too Many?”
There are a variety of factors that determine how many layers of shingles a homeowner can have on a roof, including:
- Local building codes: Checking building codes in your area is an important first step. Depending on climate and weather, some areas may only allow one layer. Also, building codes are subject to change frequently, so it’s important that you know what current local codes allow.
- Roofing materials: In the Portland area, as of 2018, the current code allows up to three layers if the current layer is in good condition. However, this depends upon the roof materials. For example, cedar or tile roofs are only allowed one layer.
- Structural soundness: The soundness of the building you’re re-roofing is another consideration. Adding a second or third layer of shingles adds significant weight to the structure. If the current roof is in poor shape, re-covering may not be a sound choice.
Other Factors to Consider
If local building codes allow for an additional layer of shingles, you’re adding composition shingles over composition shingles, and your structure is sound, there are other considerations to examine before moving ahead with re-roofing:
- No mixed mediums: Not only can you not add a second layer to cedar or tile roofs, you cannot put composition shingles over them as a second layer. Neither cedar nor tile are flat enough to put composition shingles on them and damage or defects to existing shingles will transfer through to the new layer.
- Voided warranty: You want your roof to last for several years, but if there’s an issue, you want to be able to recoup loss and pay for repairs using your warranty. Unfortunately, most manufacture warranties are either voided or significantly reduced for re-covering composition shingles with new shingles.
- Soft spots: Roof replacement requires an inspection to determine if there are soft spots on the wood sheathing which can indicate a need for repairs. Because a re-cover does not involve a tear off, soft spots may go undiscovered and unaddressed, leaving your home vulnerable to damage from wind, rain, ice dams and more.
- Flashing replacement: Flashing prevents water from penetrating your roof and should be replaced if you’re adding additional layers.
Thinking Long-Term
While re-covering may seem like a less expensive fix, it may only serve as a temporary band-aid, covering over potentially serious defects and damaging your roof even more. If you are considering re-covering, you should research all options available to you and consider the long-term impact versus the short-term savings.
Questions about re-covering or roof replacement in the Portland area? Contact All Surface Roofing to schedule a roof inspection and free estimate. Call us at 503-570-7663 or contact us online today.
Related Posts
All Surface Roofing and Construction is licensed, bonded and insured.
We’re Currently Open and Operating Prudently During the COVID-19 Pandemic
Ask about our financing options which can help in these trying times. Our focus is exclusively on exterior work so there is no need for direct contact with our estimators or crew. We can text, email, call you or talk with you from at least six feet away about your project.
Awesome!Start My Free Quote.
No thanks,
I'll pass for now.