The osb treatment that doesn t mean that an unexpected rain or drizzle as you indicated won t occur during the roof replacement.
Roof with rain.
It is not the fault of your contractor and while the delays can certainly be frustrating a contractor who attempts to install a new roof in the rain is going to be compromising the overall integrity of the installation.
Automatic overflow control directs water back to downspout when barrel is full.
If it starts to rain or drizzle the roofers should act quickly to cover your osb most likely with a tarp.
If you get about 10 inches of rain over the course of the spring and summer an average 1 360 square foot roof would yield 8 160 gallons of rainwater.
Relax and enjoy this very heavy rainstorm on a tin roof with thunder.
A wet roofing deck can grow mold and mildew which could cause the wood to change shape or rot leading to failure of your new roof.
Droplets from rain condensation dew or even high humidity could all cause roofing materials to swell or wrinkle leading to buckled rippled or misshapen roofs.