Flat Roof Furring Strips

Bob Jennette
10/31/2016
I built a 12'x20 flat roof shed for storage. I put 2'x4' furring strips on the rafters to hold down cost. No sheathing. Someone told me that I had to put felt paper on the furring strips to hold down condensation and that it was also required. Do I need to do this.
Todd Miller
Classic Products, Inc.
10/31/2016
Assuming this is not a conditioned space, you may get by without an major considerations to avoid condensation. I am more concerned though about your reference to a "flat" roof -- I assume you mean very low pitch. What is the roof pitch? Is the metal panel you plan to use approved for this pitch?
Guest User
10/31/2016
Sorry. Should have given more info. The roof pitch is 4/12 and yes the panel is approved for this pitch. The space is just for lawnmowers and other outdoor equipment. It is based on the run in shed for horses or cattle in the field. Nothing fancy, just something to get my things out of the weather. I just find it hard to think that I have to put felt paper on the 2x4 grid but maybe I do. Just want to make sure befoe I go to that expense. Thanks so much for your help.
Todd Miller
Classic Products, Inc.
11/1/2016
Thanks for the additional info. First of all, always adhere to manufacturer instructions for the product you're installing. This would include things like decking or lathe boards, spacing of lathe boards, fasteners, underlayment, etc. Not adhering to manufacturer specifications will likely void your product warranty. From a practical standpoint, underlayment probably will not avoid condensation ... unless you went to a fancy underlayment designed to hold condensation and release it gradually. It sounds like this building will not be heated and also that it will have a lot of air exchanges. Those will work in your favor. If this building will have animal confinement, though, that will work against you and could encourage condensation.

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