Is it OK to still install a soffit vent with an unvented spray foam attic?
I realize that a soffit vent is not really required as part of the roof system but was thinking that we should think twice before removing it – it may allow moisture to escape from the overhang if any gets in.
Last time I did a foam roof I asked the installer this and he told me no – that they filled the entire soffit full with foam and that venting defeated the purpose of an unvented attic which I of course understand the theory behind an unvented roof assembly. But when it was time to install the foam, the boxing was not installed yet, so the cavity was not completely filled with foam (not that that really matters). I recently asked the technical support at Icynene the same question and he explained to me why you do not vent an unvented roof assembly – he obviously did not get my point nor understand my question.
I am thinking it is better to be safe than sorry in this instance. I am planning on blocking between the rafters to give something for the foam to back up to. I am worried that if moisture ever gets into my soffit/overhang through solar vapor drive or a clogged gutter that overflows that there will not be any way for it to escape if there is not a vent there. I do not think I am hurting anything by venting this small space. Any thoughts?
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