For those that might not be aware, there was a code change on the length of dryer exhaust from 2009 and 2012 code cycle.
2009
M1502.4.4.1 Specified length.
The maximum length of
the exhaust duct shall be 25 feet (7620 mm) from the con-
nection to the transition duct from the dryer to the outlet
terminal. Where fittings are used, the maximum length
of the exhaust duct shall be reduced in accordance with
Table M1502.4.4.1.
2012
M1502.4.4.1 Specified length.
The maximum length
of the exhaust duct shall be 35 feet (10 668 mm) from
the connection to the transition duct from the dryer to
the outlet terminal. Where fittings are used, the maxi-
mum length of the exhaust duct shall be reduced in
accordance with Table M1502.4.4.1. The maximum
length of the exhaust duct does not include the transi-
tion duct.