MH Belly Repair - Rigid Bottom Replacement

Detail ID 3.0102.8
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

Install support material for spans wider than 24", except when air barrier material is rated to span greater distance under load (e.g., wind, insulation)

Support material will support applied loads without sagging, bending, or failure

Ensure sealing materials remain in place and support applied loads

  • MH
Specification Objective

Cover entire area with as few pieces of rigid material as possible

Avoid unnecessary seams

  • MH
Specification Objective

Attach rigid belly material to sub-framing every 6" where possible with mechanical fasteners that penetrate sub-framing a minimum of 1-1/2"

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

Durable attachment

  • 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