There are plenty of decisions to make when installing a new roof, but choosing whether to do a complete tear-down may have the most significant impact on your overall costs. For shingle roofs, you can typically opt to install your new roof over the existing shingles. Although this can save you some money on labor, it's not the right option for all situations.
How Does Layering Work?
The name says it all: when you choose to layer your roof, you install the new roofing shingles over the existing ones. Tearing down the old roof represents a significant investment in time and labor, so this can potentially save you several thousand dollars. Installation proceeds as usual, despite the extra layer of shingles underneath.
Layering is a popular option with do-it-yourselfers since demolition and removal of the existing roof can be challenging. However, you cannot safely add more than two layers, so layering will not be an option if you've already undertaken a re-roofing project in the past.
When Is Layering a Bad Idea?
Aside from roofs that have already had a second layer installed, there are many situations where you'll still want to consider a complete tear-down. Layering works best when installing the new shingles over an existing roof that's still in relatively good condition. Although layering over worn shingles is fine (that's the point, after all), your roof decking should be stable and secure.
In many cases, water can infiltrate below the shingles as your roof ages, and this means the failing upper layer may only be the tip of the iceberg. Before deciding to install a second layer of shingles, thoroughly inspect your entire roof. Your contractor should check the condition of your decking both from above and from your attic, if possible.
Note that layering your new roof won't necessarily save you from any demolition or removal work. If you notice significant damage, you'll need to remove those sections to replace the decking and underlayment. You also will not be able to reuse your old flashing. In some cases, these repairs can begin to approach the cost of removing the old roof, in which case layering may be a bad idea and you should choose to install a new roof.
Which Should You Choose?
Roof layering is ultimately about doing the best job possible within your budget. If you can afford to replace your old roof entirely, this is often a superior installation method. On the other hand, layering can be a practical option under the right circumstances. Relying on an experienced contractor to perform a thorough evaluation of your current roof is the best way to make an informed decision.
For more information, contact a company like Roofers of Minnesota Co.