Does your home have asphalt shingles? What many homeowners are surprised to learn when it comes time for a roof replacement is that their asphalt shingles are actually installed over cedar shingles/shake.

While today’s roofs in Upstate New York are most commonly asphalt, that was not always the case. Many older homes used cedar shake/shingles as their roofing material. As time went on and these roofs needed to be replaced, asphalt shingles were sometimes installed directly on top of the cedar. Once installation was completed, it was almost impossible to detect the cedar at all.

This can be a problem for a variety of reasons.


Every kind of roof that is installed requires decking. Without decking, there is just a frame with empty spaces in between. Roof decking fills in those spaces, attaches to the trusses and joists (the basic framework and support of your roof), and adds protection between your roof and home. It is also what the roofing materials attach to.

When a cedar roof is installed, it uses step sheathing as its base. Step sheathing consists of boards that run perpendicular with space in between (varying, but typically several inches). Cedar shingles are then nailed to the boards.

Asphalt roofs, however, use OSB sheathing as their base. This decking consists of sheets of wood that leave no space in between.

When asphalt roofs are installed over cedar roofs the asphalt is often nailed directly to the cedar—which may or may not be directly above the decking. This means that there are places on the roof where the asphalt shingle is only nailed to the wood shingle, and not to any decking—meaning that the asphalt shingle is not secure.

Underlying issues

Typically, when a homeowner replaces a roof, it is because there is a problem. Maybe the roof is old, maybe it is experiencing leaks. Whatever the issue, simply putting another layer of shingles on often does not correct the problem. Additionally, putting another layer on makes it difficult, if not impossible, to put down underlayment (protecting your decking from water damage).

It is also important to keep in mind that asphalt shingles need a flat surface to install correctly. On an older cedar roof, you are likely to have some curling of shingles—not allowing for a flat surface. This can make the new installation prone to leaks and water damage.


Most homes are not designed to hold multiple layers of shingles in addition to the weight of snow, etc. Keep in mind, asphalt shingles often weigh more than 350lbs per 100 sq feet of roofing. Adding this to an existing cedar roof can compromise the roof structure.

Code violations

Currently, in New York State, homes are only allowed a maximum of two layers of shingles. If your home has cedar shingles, with asphalt over them, you could not add another asphalt layer, and it would be virtually impossible to remove the existing asphalt layer without damaging the cedar.

Code also states that contractors may not roof over existing cedar shingles/shake.

If you currently have a roof with cedar underneath asphalt, when you do need a repair/replacement, a full tear off will be necessary.

So…how do you know if your current asphalt roof has cedar underneath? If you have access to an attic or crawl space, you can often look there. Is there space between the boards? If so, there is a good chance there is cedar there, and often you can see the cedar shingles through the gaps. If you don’t have access to an attic/crawl space, a roofing professional can evaluate for you.

While certainly not every home has hidden cedar shingles, it does happen, especially in older homes. When you are getting estimates for repair/replacement, don’t let a contractor tell you that they will avoid a tear-off, or that they will simply add another layer to save you money. This is a code violation, it can cause you to lose your homeowner’s insurance, and it can lead to a host of problems with your roof that will cause you more money in the long run. Also, be sure that your contractor is actually going on the roof to inspect it, and looking in the attic/crawl space, if possible. This will give them the greatest chance of detecting cedar shingles/shake to ensure an appropriate estimate.

If you are thinking about a new roof, contact us at anytime, 585-400-7663 or