I cant get a straight answer from the building inspectors around here (Louisville, KY) regarding the allowable span of a sistered 2 x 6 joist. I have done many attic renovations and I have spanned up to 13' with out a problem. The allowable span for a reg 2 x 6 by itself is 9'. There is a new kid at the inspectors office and he's giving me the run around on a attic renovation. Any help or websites you all could direct me to would be great. Thanks in advance.