Hello,
Have a old house.tore off old dolly varden lap siding.the sheeting is 7/8 t@g . I am going to put vinyl siding on house.I was going to put 1/4 inch fanfold insulation and tape joints and then put housewrap and then vinyl siding.someone told me house wrap goes under fanfold and others said it goes over fanfold.others said not to use housewrap at all.everyone has their own opinion.I tore off siding because of rot.I wanted to use fanfold to help level out vinyl siding.wanted to use housewrap to keep air and water out.inside has 4 mil plastic then drywall ceiling and walls and all taped.Thanks in advance.
Joe
Replies
Using both is 'guilding the lily'. Use which ever is less expensive/less labor and do not bother with the other.
Skip the fanfold and just use the housewrap. Fanfold is ONLY used over existing lap to produce a (sorta) flat surface for the vinyl. It is unnecessary/useless if you've stripped off the old siding. (If you need insulation, install insulation -- fanfold is useless as insulation AND as housewrap.)
the sheeting is not flat that is why I was going to use fanfold.does the fanfold do same as house wrap?tyvek told me to install it over the foamboard.I want to protect from water infiltration.Thanks in advance to both replies.
Generally the fanfold is perforated to keep it from becoming a (unwanted) vapor barrier. And the seams are not that tightly sealed.