MH - Fiberglass Batts

Detail ID 4.0202.3
Enclosed Walls
Desired Outcome

Continuous, contiguous, and safe thermal boundary and vapor retarder

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


  • MH
Specification Objective

Verify that installation area is free of:

active water leaks, fuel leaks (i.e., gas, oil, propane), and pest intrusions

improperly terminated devices (ventilation fans, dryers, plumbing stacks, condensate lines, combustion appliance flues/chimneys, etc.)

unshielded high-temperature devices (non-IC rated recessed lights, chimneys, flues, vents, etc.) unless they are zero clearance devices

Verify that installation area is:

intact, able to support insulation weight, and air sealed

Ensure space can be safely insulated

  • MH
Specification Objective

Select insulation that has a flame spread and smoke development index of 25/450 or less when tested in accordance with ASTM E84 or UL 723

Select a poly-encased fiberglass batt or an unfaced fiberglass batt and a flexible class 1 vapor retarder membrane

Select correct and fire safe materials

  • MH
Specification Objective

Remove objects from the interior surfaces of the walls being insulated

Repair or reattach interior paneling as necessary

Protect occupant belongings and prevent interior paneling failure

  • MH
Specification Objective

Remove skirting if it overlaps the siding

Remove fasteners from the bottom of the siding, working upward until the siding can be pulled away from the framing approximately 6" without damaging the siding

Install temporary fasteners at the seams near the bottom of the siding panels to prevent separation

Cut access through sheathing if present

Access cavities without damaging the siding or compromising the interior wall surface

  • MH
Specification Objective

Insert fiberglass batts that fill entire cavity all the way to the top of the cavity without deforming siding or damaging structure

If using a flexible membrane, cut it 2" wider than the cavity and approximately 1' longer than the batt and install together with the batt in the climate correct orientation

Fill entire cavity with insulation and vapor retarder

  • MH
Specification Objective

Patch or repair sub sheathing as necessary

If skirting was removed, reinstall it to shed water to the outside of the skirting

Reattach siding with new fasteners and without bulges or wrinkles

Weathertight exterior cavity closure

  • MH
Specification Objective

Post a dated receipt signed by the installer that minimally includes: Installed insulation type, coverage area, installed thickness, and installed R-value

Comply with 16 CFR 460.17 and document contract compliance

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