A. Wood technologist Paul Fisette responds: Many builders and material suppliers think that using housewrap under vinyl siding is a waste of money. I disagree. Housewrap is cheap insurance, for two reasons: It protects the building shell from the weather and it helps save energy.
Vinyl siding is a good siding material, but it is loose fitting and somewhat permeable to weather. Wind-driven rain can penetrate at overlapping ends, around windows at J-channels, at corner posts, at the intersections between siding and rake trim, and any other places where joints are involved. A smart installer should expect water to penetrate...
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