Closed Crawlspace - Rigid Foam Insulation

Detail ID
4.0402.2
Topic
Conditioned Subspaces
SubTopic
Walls
Desired Outcome

Continuous, contiguous, pest and moisture resistant, and safe thermal boundary that prevents air movement @ 50 Pascals

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

Specifications

  • SF
  • MF
Specification Objective

Verify that installation area is free of:

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

energized or undammed knob and tube wiring

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

has a sealed class I vapor retarder installed over all bare earth

has all bulk sources of moisture directed away from the subspace walls (i.e. gutters, flashing, grading, drainage)

Ensure space can be safely insulated

  • SF
  • MF
Specification Objective

Select foam insulation that:

has a flame spread/smoke development index of 75/450 or less when tested in accordance with ASTM E 84 or UL 723

is, or include a facing that is, a class II vapor retarder

is non-absorbent

Select fire safe and moisture resistant materials

  • SF
  • MF
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)

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

Select safe and effective sealants

  • SF
  • MF
Specification Objective

Ensure wall vapor retarder will lap underneath the ground vapor retarder connection to the foundation wall

Remove any incomplete or unsealed vapor barrier from the foundation wall

Keep bulk water below vapor retarder and prevent condensation

  • SF
  • MF
Specification Objective

Remove any protrusions or impediments from the installation area that prevent full contact of insulation with foundation wall surface

Properly bonded rigid foam installation

  • SF
  • MF
Specification Objective

Install insulation to prescribed R-value in a continuous layer in full contact with the foundation wall from ceiling to floor

If installing multiple layers, offset seams by a minimum of 12" and seal the seams and joints of each layer before installing the next layer

Contiguous and continuous thermal barrier

  • SF
  • MF
Specification Objective

Attach insulation with mechanical fasteners

Insulation remains in place

  • SF
  • MF
Specification Objective

Seal all seams, joints, connections, etc. of insulation and vapor retarder layer with compatible sealant (i.e., tape, mastic, adhesive)

Seal ground vapor retarder to the insulation vapor retarder with the foundation vapor retarder lapped under the ground vapor retarder

Airtight and vapor controlled installation

  • SF
  • MF
Specification Objective

If termite pressure exists, maintain a 3" inspection gap from the top of the insulation to the bottom of any wood

Allow for termite detection

  • SF
  • MF
Specification Objective

Separate all foam products from living space with a thermal barrier material (e.g., 1/2" gypsum wallboard) as specified by applicable building code

If space is used only for the service of utilities, foam will be separated from the space using a suitable ignition barrier covering or coating according to manufacturer's specifications and the applicable building code

If space is used for storage or occupancy, foam will be separated from the space using a thermal barrier material (e.g., 1/2" gypsum wallboard) as specified by applicable building code and manufacturer specifications

If code requirements are unclear, consult local code officials for clarification

Minimize ignition and combustion potential

  • SF
  • MF
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