Replace MH Duct Boots

Detail ID 5.0105.5
Forced Air
Duct Repair
Desired Outcome

Durable duct boot installation that prevents duct leakage @ 25 Pascals

SF Single Family Site-Built Housing
MH Manufactured Housing
MF Multifamily Housing


  • MH
Specification Objective

Use a minimum of 28 gauge galvanized or aluminum sheet metal to build new boots

Durable material selected

  • MH
Specification Objective

Build boot 1/8" smaller in width than the opening in the main duct trunk and a minimum of 2" longer than the distance between the top of the duct trunk and the top of the subfloor

Bend a 1/2" wide outward facing lip on all sides of the top facing end of the boot

Cut 1" wide tabs in the bottom 1-1/2" of the sheet metal boot that will fold under into the duct trunk

Boot fits in trunk and allows firm connection to both subfloor and trunk line

  • MH
Specification Objective

Install boot into subfloor register hole aligning sheetmetal tabs with the interior of the duct trunk register hole until the outward facing lip on the top of the boot is firmly in contact with the subfloor surface

Fold all tabs up into the duct trunk so that the boot is firmly in contact on both the top of the subfloor and the inside top of the duct trunk line

Secure and snug boot installation

  • MH
Specification Objective

Attach all four sides of the boot to the subfloor using galvanized or stainless steel fasteners

Prevent excessive duct boot movement

  • MH
Specification Objective

Seal the boot to the interior of the trunk line using UL 181 approved mesh tape and mastic

Seal the seam, joints, and any gaps in the boot using UL 181 approved mesh tape and mastic

Sealant will not be visible beyond edges of the register cover

Tightly sealed boot to trunk connection

  • MH
Specification Objective

Allow sealing materials to dry before replacing register cover

Register must be easily removable by the occupant

Occupant accessible boots that are aesthetically pleasing