Fixing structural damage costs an average of $85 per hour in labor, plus the cost of replacement materials. When specialty pieces of sheet metal are required for a project, homeowners may pay stamping fees that add an average of $2 per square foot to the cost of sheet metal.
http://www.homeadvisor.com/cost/heating-and-cooling/fabricate-sheet-metal/
Some paints are specifically made for use on metal exposed to the outdoors. If the sheet metal structure is located in a place with significant precipitation, the placement of gutters and downspouts adds an average of $5 per square foot of area.
http://www.homeadvisor.com/cost/heating-and-cooling/fabricate-sheet-metal/
Typical costs: Replacing aging, leaking or inadequate ductwork typically costs about $35-$55 a linear foot for labor and materials, or $1,000-$5,000 or more for a single-family home, depending on the length and type of ducts used (sheet metal, fiberduct or round flexible ductwork) and local rates.
http://home.costhelper.com/duct.html
Because sheet metal is typically used outdoors, it encounters a range of environments and hazardous conditions that cause damage to the material. Exposure to pests like ducks and birds sitting on screens causes corrosion and rust to the metal.
http://www.homeadvisor.com/cost/heating-and-cooling/fabricate-sheet-metal/
Sheet metal is a cost-effective material that is used in a wide variety of purposes including the construction of storage sheds or barns and for use in screens and cages. Over time, exposure to the elements, wear and tear, or other issues may lead to the need for repairs and fabrication of replacement sheet metal.
http://www.homeadvisor.com/cost/heating-and-cooling/fabricate-sheet-metal/
1 Kingspan KoolDuct is 85% less weight than insulated sheet metal ductwork: Easier installation with lower handling costs, ideal for new and refurbished projects.  Thermal properties R-6, 7/8 thickness; R-8, 1 3/16 thickness: Low thermal conductivity allows thinner insulation to achieve required thermal performance.
http://www.speermechanical.com/koolduct/home
If the home's layout makes installation particularly challenging, replacing existing ductwork or adding it to a house that never had ducts can cost $5,000-$15,000 or more.
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Poorly designed or inadequately installed ductwork can decrease the efficiency of the heating or cooling system by as much as 40%. HGTV Pro explains duct system design and installation. The U.S. Department of Energy provides an overview of the best practices for installing duct systems in new and retrofit homes.
http://home.costhelper.com/duct.html
1 KoolDuct’s efficient jointing system and sealed duct seams: Virtually airtight and leak-free, SMACNA Class 3 rating, 79% less air leakage than sheet metal.  Maximum insulating properties, minimal air leakage: Lower energy costs, lower CO2 emissions, significant savings in reduced heating and cooling loads.
http://www.speermechanical.com/koolduct/home
DIY materials can cost $100-$2,000 or more, depending on the type of materials and total length. For example, DIYNetwork estimates it takes a weekend and $100-$250 to replace a section of ductwork with flexible ducting and install a return vent, rating the project difficulty at moderate to hard.
http://home.costhelper.com/duct.html
cost of installation of sheet metal ductwork
The cost of installation of sheet metal Ductwork is between $1,000 to $5,000. The installation cost of sheet metal Ductwork is from $1,000 to $5,000.