Time for a new roof? Getting bids from multiple roofing contractors is always good to compare value and performance but may also raise questions for the property owner. Some roofing contractors may be quoting a complete roof replacement or reroof (tear off existing roofing down to the structural deck), and others may quote a recover or layover (install new roofing over the existing). So what is the difference and what should you do?
In most cases a complete tear off reroof is only necessary when there are multiple layers of roofing, or when there has been a history of ponding water, leaks and other issues. Most state building codes require roofs to be replaced when there is 2 or more layers of roofing on a building. A roofing contractor should always take a core sample to determine how many layers of roofing are on a building. It is always a good idea to check your local building codes requirements. Ponding water and leaks that have been a constant issue can cause damage to the insulation and the structural deck. Having a history of leaks means there is a greater chance for that damage and the roof should be torn off and any damaged decking will need to be replaced.
A complete tear off reroof will most likely always be more expensive, but there is another option – a recover. This option is more budget friendly and can still achieve a manufacturer’s warranty. A roof recover or roof repair is a good option when there is only 1 layer of existing roofing, there has been minimal leaks, and the insulation and structural decking is in good shape. One way to determine if the insulation is reusable would be to take a few core samples. Also, if the roof has positive slope with minimal signs of ponding water issues, it’s likely that the insulation has not been damaged. Another moisture detection method that may be used, or required by some manufacturer’s, is a thermal scan. Some roofing materials are not compatible to be installed directly on top of each other, so it’s always a good idea to install a separator such as a coverboard. A roofing contractor should always consult the manufacturer before recover a roof.
So, what should you do? While budget is always a concern, the most important thing is to install the best roof possible for the existing conditions. Whether it’s a reroof or a recover, always ensure that there is positive drainage. If the roof is not structurally slope, tapered insulation panels should be installed to achieve positive drainage. Tapered insulation will add more to the cost but can save much more in the long run. Ponding water is the achilles heel of any roof system. Having a manufacturer’s warranty on any roof system ensures that the roof is being installed by a trusted, insured, and bonded roofing contractor and will be inspected by the manufacturer’s technical representative. And as always, make sure to contact licensed and certified roofing contractors for any roofing needs.