Here is an example of an existing roof system that has been torn off down to the plywood deck. As you can see, the plywood overall is in good shape. That is due to the underlayment which is the felt paper that protects the plywood deck from moisture intrusion. In San Diego, houses that are 25 years old or less, in most cases, have plywood as the roof deck surface. Houses that are over 25 or 30 years old could have plank boards instead of plywood. That was the standard deck surface back 25 – 30 years ago.
A third type of roof system that we tear off is an old wood shingle roof system. These wood shingle roof systems were used over 25 years ago and were known at the time to be an upgraded type of roof system. This wood roof system we have found over time here in San Diego to be highly flammable and are being replaced at a rapid rate. You will find in San Diego there aren’t many wood shingle roofs left and with local fire codes these days, we will no longer find these roofs in existence in the next few years to come.
When these roof systems are torn off, wood slat boards known as “skip sheeting” is found underneath. Back in the day when these wood shingle roofs were installed the ideal way to install the wood shingle was over skip sheeting instead of plywood or plankboard because the premise was that the wood can breath easier with the wood slat spacing and therefore last longer. But, we have found through time and experience that really isn’t the case. When these are torn off, full sheeting, either plywood or known in today’s industry as OSB board is installed on top of the skip sheeting as a wood base onto which we apply the new roofing material.