Re: 2X6wall header
Howdy, without knowing what loads that load bearing wall is bearing- no one can tell you what size header. It is much stronger to not sandwich foam between wood members instead consider sistering the wood using pl premium caulk liberally and then bolting, or screwing or ring shank nailing the boards together( note there is proper spacing and fasteners needed to bear the load) then add foam to the interior side of your header to fill out and insulate the wall stud cavity. Also the support of the header to transfer the load is important. So is it a 2by4 wall, one or two story home, roof loading the wall or not such as a hip roof or a gable end?? All this is important not to mention snow loading. Where you buy wood, guys can direct you as too what type of header and support framing- take photos of the house showing the wall and whats above it with you to assist them.
Any an all of my comments are just my opinion and not to be confused with facts.