1. Remove & replace unusable material

• Replace or remove deteriorated materials that are rusted, torn, or unrepairable. 

• If materials cannot support the weight of connections, they should be replaced with fabricated metal duct.

2. Secure connections

• Attach and secure connections. 

• Rectangular duct shall be connected with s-cleats and enclosed with end caps. 

• Round duct should overlap approximately 1" and screwed with at least 3 sheet metal screws, evenly spaced. 

3. Support ductwork 

• Flexible ducts and plenums shall be supported every 4 feet with material that is a minimum of 1 1/2" wide

• Metal ducts will be supported by 1/2" wide eighteen gauge metal straps or 12-gauge galvanized wire at intervals not exceeding 10' 

4. Secure duct boots 

• Duct boots shall be connected to supply lines and secured with a minimum of three sheet metal screws, spaced evenly around duct. 

• Duct boot shall meet the surface of the conditioned area without any gaps and secured to surface with nails or screws 

5. (Mobile homes) Install scoops 

• When no end cap is installed at the far end  of the main trunk install and air seal a "scoop" at the last register take off.

6. (Mobile homes) Secure and seal cross overs and plenums 

• On Mobile Homes remove plenum access and secure and seal drop duct and the crossover if applicable 

7. Repair small gaps 

• Seal gaps and seams less than 1/4" width with a combination of mesh tape and UL 181 duct mastic. 

• Mastic alone is acceptable for seams and holes less than 1/8" 

8. Repair medium gaps

• Seal leaks between 1/4" and 3/4" using a two stage process

• Install temporary tape as a backing material

• Seal with fiberglass mesh and mastic that extends at least 1" past the temporary tape on all sides

9. Repair large gaps 

• Repair leaks larger than 3/4" using a rigid duct patch

• Mechanically fasten patch before applying mastic

• Install fiberglass mesh and mastic over the seam, overlapping repair joint by at least 1" on all sides

10. Mastic all seams

• Seal all seams with mastic or similar adhesive. 

• Mastic covering seams must be a minimum of a "nickel-thick" 

11. Duct board

• Existing duct board can be repaired

• New duct board should not be installed.

12. Worst case draft test 

• Conduct a Worst Case Draft Test to verify Category I, II and III appliances are venting safely before leaving home for the day. 

• Testing shall be recorded using the WAP Worst Case Draft Test from.