Envelope General Requirements

All of the applicable general requirements from the 2000 International Energy Conservation Code must be met regardless of which compliance method is chosen.

Moisture Control

Non-vented framed cavities (walls, floors, and ceilings) need an approved vapor retarder with a maximum perm rating of 1.0. Non-vented areas are framed cavities without vents or other openings allowing the free movement of air. The ability of a material to retard the diffusion of water vapor is measured by units knows as "perms" or permeability. The lower the perm rating, the better the vapor retarder. Vapor retarders help control the amount of moisture that gets through the insulation and are typically installed on the "warm-in-winter" side of the insulation.

Exceptions

Where moisture or its freezing will not damage the materials
Hot and humid climates
Where other approved means to avoid condensation are provided (must be approved by the jurisdiction)

Types of products that may meet the perm requirement:

Polyethylene sheeting over unfinished batts
Foil and kraft-backed insulation
Some blown-in insulations (check with the manufacturer)
Certain paints (check with the manufacturer)

The importance of Vapor Retarders in Certain Climates
Installed Vapor Retarder Photos

Masonry Veneer

When insulation is placed on the outside of a foundation supporting a masonry veneer exterior, the horizontal foundation surface supporting the veneer isn't required to be insulated to satisfy any foundation insulation requirement. A masonry veneer is a thin layer of stone or masonry on the outside of a standard framed wall that replaces standard siding. A common example is a brick face on a framed wall.

Recessed Lighting Fixtures

Recessed lighting fixtures must meet ONE of the following requirements, IC is insulation contact:

Type IC rated, with no penetration between the inside of the recessed fixture and ceiling cavity (sealed and caulked)
Type IC or non-IC rated, installed inside an appropriate air-tight assembly with a 0.5" clearance from combustible materials. If non-IC rated, the fixture must be installed with a 3" clearance from insulation.

See examples of installed recessed lighting fixtures

Air Leakage

Manufactured window and door assemblies (in the building envelope) have the following maximum allowable infiltration rates (and most windows and doors are labeled and meet this certification). If in doubt (or if there is no label), ask the manufacturer for product literature.

Windows (cfm per square foot of window area)	Sliding Doors (cfm per square foot of door area)	Swinging Doors (cfm per square foot of door area)
0.3	0.3	0.5

Exception: Site-constructed windows and doors (need to be sealed properly)

Caulking and sealants
Joints, penetrations, and all other such openings in the building envelope must be sealed, caulked, gasketed, weatherstripped or covered with moisture vapor-impermeable house-wrap

Why is proper sealing important?

Sealing the building properly reduces air movement into and out of the building. Uncontrolled air movement nagatively impacts the heating and cooling systems, resulting in higher initial and on-going maintenance costs.

Get more details on potential areas of air leakage

Fenestration Solar Heat Gain Coefficient

In locations with heating degree days (HDD) < 3500, the combined solar heat gain coefficient (SHGC) of all windows, glazed doors, and skylights must be < 0.4. Note: The combined SHGC is the weighted average of all glazed fenestration products (including the effects of any permanent exterior solar shading devices).

Find out if your location has HDD < 3500
Get more details on SHGC

Materials and Equipment Information

Show sufficient detail on building plans or specifications to indicate conformance with the requirements of the code.
Materials and equipment must be installed in accordance with the manufacturer's installation instructions, and must be identified so that compliance can be determined.
Manufacturer manuals for all installed heating and cooling equipment and service water heating equipment must be provided.

For example, call out the following information on the plans or specifications:

envelope insulation levels
duct insulation levels
high-efficiency heating equipment (especially if credit is taken for high-efficiency equipment - include the equipment efficiency, make, and model number on the plans or specifications)

Other information that should be included:

U-factors of fenestration products
size and type of apparatus and equipment, and
equipment and systems controls.

For blown or sprayed insulation, the initial installed thickness, the settled thickness, the coverage area, and the number of bags must be clearly posted at the job site. In attics, thickness markers must be placed at least once every 300 square feet.

Example of a thickness marker in an attic

MECcheck Energy Label

Materials and equipment can be identified on an optional MECcheck Energy Label which can then be posted at the residence (e.g., on the main fuse box, on a garage wall, in the utility room).

Summary

Vapor retarders are required in certain climate locations
Recessed lighting fixtures must be IC rated and sealed and caulked appropriately or be IC or non-IC rated and in an air-tight assembly with 1/2" clearance from combustible materials and a 3" clearance from insulation
Joints, penetrations, and all other such openings in the building envelope must be sealed, caulked, gasketed, weatherstripped, or covered with moisture vapor-impermeable house wrap
In locations with HDD < 3500, the combined SHGC of all windows, glazed doors, and skylights must be < 0.4
Show sufficient details on the building plans or specifications to indicate conformance with the requirements of the code

Test your knowledge:

The "warm-in-winter" side is typically between the insulation and the conditioned space.

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