It is very important to remove all of the old roofing materials and make sure that your roof decking is in good shape before installing a new roof. Back in the day, it was common practice to install a second lay-over on top of the first or second layer. Shingle manufacturers have changed a lot over the years & will no longer warranty shingles if that is done. There are a slew of negative issues with installing multiple layers & they do not out-weighs the low cost of doing the “lay-over”. We always strip all of the old felt & shingles off before installing the new roof. In addition, we take plenty of pics for the homeowner to see the condition of the wooden roof decking & replace any rotted or bad wood. Here are a few pics of rot that we frequently encounter. If we just did a lay-over, the nails would not anchor into the rotted wood. Contact us for a free estimate.
Remove all old roofing materials before the new roof is installed. Re-nail loose wood & replace any bad or rotted wood for a solid sound deck.