I work for a Cost Consultant and recently came upon a rather interesting and indeed tricky situation.
I usually find that my estimate on the total duct weight is more conservative than the contractor's but in this instance it was the other way round.
As an example, for a 7 feet long Galvanized duct of size 74"x54", I came up with a weight of 247 Lbs. (assuming 0% wastage).
The contractor on the other hand came up with 95.57 Lbs. which he confirmed included some wastage.
Can someone comment on the above calculations as to which is more correct.
what gauge? smacna standard? pressure class?
22g = approx. 225#
20g = approx. 266#
no droppage figured
Last edited by zzonko; 05-02-2008 at 12:25 PM.
Thank you Zzonko for your reply.
The duct is Low Pressure. My calculation is based on 20 gauge duct.
From your reply, I see that the contractor is wrong in his calculation.