i am doing a remodel and thinking of using TITANIUM-UDL underlayment because we won’t be able to shingle immediately.  This is a “warm” roof with 3″ of foam against the underside of the sheathing (plusfiberglass or cellulose to reach approx. R38) .  Will the vapor barrier qualities of this product create problems?  We are in a relatively dry climate (western MT).  Also, installation instructions state that staples cannot be used?  Does this also mean that the shingles can’t be put down with staples? This appears to be a new porduct in this area and dealers don’t seem too familiar with it yet.  Thanks for any help/advice.