MH - Blown Insulation for Flat, Bowed, or Vaulted Ceilings (via Roof Top Access)

Detail ID 4.0103.11
Attic Floors - Unconditioned Attics
Desired Outcome

Continuous, contiguous, safe, and compliant thermal barrier installation that protects integrity of roof

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

uncovered electrical junctions

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

insulation escape openings

Verify that installation area:

is intact, able to support insulation weight, and air sealed

Ensure space can be safely insulated

  • MH
Specification Objective

Select loose fill fiberglass 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 fire safe insulation

  • 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)

Select safe, durable, and effective sealants

  • MH
Specification Objective

Create a horizontal opening the full length of the attic by slicing the roof open at the peak allowing no more room than is necessary for access to the entire attic cavity using a fill tube, OR

Drill or cut uniform holes in the roof adequately spaced to access the entire roof cavity to be insulated

Create safe access to entire cavity

  • MH
Specification Objective

Fill entire attic to prescribed R-value

If existing insulation is roof-mounted, insulation will be blown below

If existing insulation is ceiling-mounted, insulation will be blown above

If existing insulation is mounted at both locations, insulation will be blown in between

Continuous thermal barrier of consistent R-value

  • MH
Specification Objective

If the roof is sliced open:

Install a solid metal ridge cap centered over the slice that overlaps each side of the roof by a minimum of 2"

Install a continuous, permanently flexible and durable sealant between the roof and the entire perimeter of the ridge cap

Install mechanical fasteners along the perimeter of the ridge cap every 6" or less that do not enter any framing material, prevent wrinkles and create a permanent seal

Apply a durable and flexible final roof coating over the screws and edge of the ridge cap to create a continuous seal between the roof and the perimeter of the ridge cap

For holes that are drilled or cut:

Prepare at least 6" of surface surrounding the opening by removing any material that will interfere with sealant adhesion

Install a durable metal patch of equal or greater gauge than the roof material that overlaps the opening by a minimum of 2" on all sides

Install a continuous bead of flexible and durable all-weather adhesive between the roof patch and the roof

Mechanically fasten patch along the perimeter every 2" without entering any framing material to prevent wrinkles and create a permanent seal

Install a durable and flexible 45 mil minimum adhesive roof patch in accordance with manufacturer specifications over the initial patch that overlaps the initial patch by a minimum of 2" on all sides ensuring surface temperatures are within manufacturer's guidelines for installation

Adhesive patch must meet the following minimum standards: Tensile strength of 640g, elongation of 380%, service temperature between -25 and 150 degrees F.

Apply a durable and flexible final coating (e.g., elastomeric paint) over the adhesive patch that laps at least 6" over the patch on all sides to create a continuous seal between the roof and the perimeter of the patch

Durable and weathertight roof closure

  • MH
Specification Objective

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

Comply with 16 CFR 460.17 and document contract compliance