MH Belly Repair - Rigid Bottom Patching

Detail ID 3.0102.7
General Pressure Boundary
Specific Air Sealing
Desired Outcome

Minimize air leakage and keep insulation in place

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


  • MH
Specification Objective

Select sealants that:

are compatible with their intended surfaces,

allow for differential expansion and contraction between dissimilar materials,

meet the requirements of the applicable fire safety code (e.g. thermal or ignition barriers), and

for use inside the pressure boundary select low volatile organic compound (VOC) sealants that meet independent testing and verification protocols

Select effective sealants

  • MH
Specification Objective

Select materials that:

meet the requirements of the applicable fire safety code (e.g., thermal or ignition barriers),

create a continuous insulation layer when possible (i.e., rigid insulation board), and

rigid materials that adequately support applied load and are permanent air barriers

Select effective materials

  • MH
Specification Objective

Remove any material from the sealing and patching area that will prevent full adhesion of the selected sealant and patch material

Surface is clean and ready to accept sealant

  • MH
Specification Objective

Patch any hole larger than 1 square foot with patch material that laps over the sub-framing on at least two edges

Sealing materials remain in place and support applied loads

  • MH
Specification Objective

Install rigid patching material over all holes lapping a minimum of 3" over the surrounding material

Apply a continuous bead of sealant under the patch that creates an airtight seal

Airtight permanent repairs

  • MH
Specification Objective

Attach patches using mechanical fasteners spaced no more than 6" apart

Use mechanical fasteners that incorporate washers/caps that prevent fasteners from being pulled through belly material

Durable repair

  • MH
Specification Objective

Install only noncombustible materials and sealants with an ASTM E136 listing in contact with any device producing 200 degrees F or more (chimneys, vents, flues, etc.)

Prevent a fire hazard