Question: We will be putting a new roof on soon and it will most likely be a lightweight tile one. We currently have a heavy shake roof. Should we remove the shakes before the tile is put on or should the tile be put over the shakes? I have seen both approaches lately and am not sure which would be better.
Answer: We too have seen both approaches and are even familiar with some firms that, as part of their advertising, tout leaving the existing shakes and installing the new roof over them. They claim that by doing so, the job will go faster and will result in cost savings to the homeowner.
We strongly recommend that all of the existing roofing be removed before a new one is installed. The wood sheathing below the roof is highly susceptible to fungus damage and dry rot that will continue to spread if left untreated. Roof replacement is an excellent time for a thorough inspection of the roof sheathing and to make any needed repairs. This would be impossible if the new roof is installed over the existing one.
True, there is a cost attached to this, but, comparatively speaking, it is only a small part of the price of the roofing job.
Besides, if there is dry rot and it is not dealt with now, it could cost significantly more to make the repairs later.
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