Rain screen really necessary with vinyl siding ?
Climate zone 4 ( Western NC mountains ) Prospective wall — 2×6 24″ OC, 7/16″ – 1/2″ sheeting only as required for bracing. Thermoply or similar with taped seams for one air barrier. 2″ to 4″ rigid foam in several layers with taped/sealed staggered seams(with adjustments for the bracing to give a even outer wall) 1″x4″ strapping for siding attachment. Vinly siding. Minimum 5′ roof over hang ( porch completely around house ). I’m thinking that I would be better off to fit foam in between the 1″x4″ strapping and put the housewrap WRB as the last thing before the vinyl siding rather than keep the rain screen. I believe that vinyl siding acts as it’s own rain screen and with the large overhang the value of a rain screen is marginal and I’d be better off with the additional R value.
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Replies
Roy,
Vinyl siding is a well-ventilated cladding. You don't need any additional rainscreen gap.
For more information, see All About Rainscreens.
In climates where the main benefit of installing a rain screen is to provide additional ventilation you probably don't need it behind vinyl. In climates where water infiltration from the exterior is a problem, like the PNW, rain screen is a must as vinyl siding, especially at openings, is very poor at keeping water out.