I can't see it as being a problem. Even the local building code only
specifies a 1/8 inch expansion gap between sheets of exterior grade plywood
on a roof. Would 1/8 inch in 4 ft be too much?

There are a lots of plywood boats which took longer than a year to build.
As one young woman of my aquaintence said about childbirth, "a lot of
other people have done is successfully".


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