MH Belly Repair - Soft Bottom Replacement

Detail ID 3.0102.6
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:

adequately support applied load and are permanent air barriers, and

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

Select effective materials

  • MH
Specification Objective

Span each belly section with an uninterrupted section of belly material creating as few seams as possible

Complete and durable coverage

  • MH
Specification Objective

Lap any seams in the belly material a minimum of 6", seal with a continuous bead of sealant, and mechanically fastened every 2"

Airtight seams that prevent insulation loss

  • MH
Specification Objective

Attach belly material at opposite ends of spanned section using rigid support material (i.e., wooden furring strips)

Attach belly material to rigid support material by wrapping it around the rigid support material a minimum of 2 times and mechanically fastening every 6"

Attach rigid support material to belly at every joist or at a maximum of every 2' with mechanical fasteners that penetrate the substrate a minimum of 1-1/2"

Durable repair

  • MH
Specification Objective

Apply a continuous seal at all seams, cracks, joints, edges, penetrations, and connections of the belly material while applying sufficient pressure to push sealant into any gaps or cracks and contact any backing or infill material required

Airtight belly 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