Cedar Shake Roof Installed Under Asphalt Shingles

What Should You Do with a Roof that Doesn't Have Plywood?

We have worked on many multi-family homes. The common characteristic we find with these homes is 1-2 layers of asphalt shingles on top of Cedar Shake roofing. Under the Cedar Shakes are furring strips. Furring strips are 4” wide boards that are spaced apart several inches, to hold up cedar shakes while allowing them to breathe. This does not work well with asphalt shingles because asphalt shingles are designed to go into plywood, which has no gaps. The gaps in a furring strip roof mean that many of the nails in an asphalt roof will not be anchored to any wood. Also, asphalt shingles that are put on top of a Cedar roof do not last very long. The extra weight on the roof and heat trapped in the attic causes the asphalt shingles to start decaying prematurely.  

Having your contractor install a second or third layer on a roof will only push out the problem a few more years without solving the core issue. Whenever we come across a multi-layered roof such as this, we tear off all the layers and get down to the furring strips. Once we have reached the furring strips, we install a 1/2” CDX plywood deck over the furring strips. Why do we use plywood? Plywood does two things for us: Plywood fills the gaps that are left by the furring strips. Also, the 1/2” plywood is stronger and is designed to hold up the heavy asphalt shingles. 

Once the plywood is down, this allows us to install all the proper underlayments and flashing. Now I know you might be thinking: Isn’t all that extra plywood going to make the roof replacement more expensive? Yes and no. Yes, it will add to the cost of the replacement but it will fix the bigger problem and allow your roof to live out its full life. If you leave the underlying problem unattended, then any other fixes or new layers of shingles will be short-lived.

If you go the extra mile and get the foundation of your roof set, then the rest of the roof can last and give you a worry-free roof. Working with IKO, we are able to give our customers a 50-year full warranty on a full roof replacement. This warranty covers the shingles themselves but also guarantees our workmanship. Feel free to look at the multi-family roofs we have installed in your area!