Dear Guru: Do I Need Vapor Barrier Under Insulation?

Welcome to Ask the Pole Barn Guru – where you can ask questions about building topics, with answers posted on Mondays.  With many questions to answer, please be patient to watch for yours to come up on a future Monday segment.  If you want a quick answer, please be sure to answer with a “reply-able” email address.

Email all questions to: PoleBarnGuru@HansenPoleBuildings.com

DEAR POLE BARN GURU: Is it a huge mistake to go without a vapor barrier on the walls?  How about Tyvek on the walls during construction?  I was thinking of doing Tyvek between the metal siding and the purlins to at least get that vapor barrier in there, just in case I decide to put insulation in my walls later when the budget allows.  Thoughts? CONTEMPLATING IN KANSAS CITY

DEAR CONTEMPLATING: If you EVER think you or the person(s) who own your pole building after you, will ever apply insulation to the walls of a building – then placing a quality house wrap between the wall girts and the siding (whether it be steel or any other material) is an excellent idea for a vapor barrier. At time of construction is the one single time in which it will be extremely easy to add.

To learn more about house wrap: https://www.hansenpolebuildings.com/blog/2012/11/house-wrap/

 

DEAR POLE BARN GURU Insulation – I read your warning about the steel skin acting like “unibody” construction, so it should be applied directly to framing. What is a good way to use foil-faced foam board for putting insulation on a roof? I want to avoid using the large rolls of insulation that will sag in 6-8 years? LEARY IN LOUISIANA

DEAR LEARY: I am glad you have been reading and paying attention.  Your new building will be well planned, with pleasing results. I just am seeing no way for foil-faced foam board to be a practical and economical solution for roof insulation. Here is a link to an article I wrote which might give you some further food for thought:

https://www.hansenpolebuildings.com/blog/2013/07/insulation-6/

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