View Full Version : IRC codes for sealing sills, doors, windows

Ken Larson
10-08-2008, 03:50 PM
Does anyone happen to know off hand the IRC requirements for sealing the sill plate to the slab foundation and sealing around interior rough framing at doors and/or windows? Using a low expansion type sealant the sill plates were all sealed with some gaps noted, all door framings were sealed, but no windows were sealed. Out of the last 50 or so pre-sheetrock inspections I've done all windows were usually sealed with foam. This was the first one not to seal the windows. Builder stated it would void the manufacturers warranty. I read over the installation instructions and found no such disclaimer.

IRC N1102.1.10 states: Air Leakage: All joints, seams, penetrations, site built windows, doors, and skylights; openings between window and door assemblies and their respective jambs and framing; and other sources of air leakage (infiltration and exfiltration) through the building thermal envelope shall be caulked, gasketed, weatherstripped, wrapped, or otherwise sealed to limit uncontrolled air movement.

Wouldn't then IRC N1102.1.10 apply to these 3 photos?




Ted Menelly
10-08-2008, 03:57 PM
You know. I don't have a book in front of me right now or a cd on the computer. I will tell you this. If a manufacturer stated that you can not insulate around there window then they are going out of business. I never heard of such a thing. I have never inspected a home or built a home or addition where the windows and doors were not stuffed with fiberglass or filled with low expansion foam.

Jerry Peck
10-08-2008, 05:32 PM
From the 2006 IRC. (underlining is mine)
- - - N1102.1 Insulation and fenestration criteria.The building thermal envelope shall meet the requirements of Table N1102.1 based on the climate zone specified in Table N1101.2.

The area around the window is part of the wall, thus, that space is required to meet the 'Wood Frame Wall R-Value' column for your climate zone - Zone 2 R 13.

Then (to continue with the 2006 IRC).

- N1102.4 Air leakage.
- - N1102.4.1 Building thermal envelope. The building thermal envelope shall be durably sealed to limit infiltration. The sealing methods between dissimilar materials shall allow for differential expansion and contraction. The following shall be caulked, gasketed, weatherstripped or otherwise sealed with an air barrier material, suitable film or solid material.
- - - 1. All joints, seams and penetrations.
- - - 2. Site-built windows, doors and skylights.
- - - 3. Openings between window and door assemblies and their respective jambs and framing.
- - - 4. Utility penetrations.
- - - 5. Dropped ceilings or chases adjacent to the thermal envelope.
- - - 6. Knee walls.
- - - 7. Walls and ceilings separating the garage from conditioned spaces.
- - - 8. Behind tubs and showers on exterior walls.
- - - 9. Common walls between dwelling units.
- - - 10. Other sources of infiltration.

Your reference N1102.1.10 is in the 2003 IRC, so the 2003 reference for the above thermal envelope wall insulation is:

- N1102.1.1 Exterior walls. The minimum required R-value in Table N1102.1 shall be met by the sum of the R-values of the insulation materials installed in framing cavities and/or insulating sheathing applied, and not by framing, drywall, structural sheathing, or exterior siding materials. Insulation separated from the conditioned space by a vented space shall not be counted towards the required R-value.

Simple answer - Yes, those cavities are required to be insulated *for both* thermal insulation and air infiltration and exfiltration reasons.

Jim Luttrall
10-08-2008, 10:09 PM
One thing to note, standard expanding foam should not be used around aluminum frame windows. The foam expands and puts too much pressure on the frame causing the window to be hard to operate. I know I had at least one window rep. caution me about that on a job. I don't remember seeing it in written instructions, but I do remember the verbal warning.
Low expansion foam is OK though.

Darren Miller
10-09-2008, 06:29 AM

When you read Jerry's reply, pay attention to item #4 Utility penetrations.
If you want to bust the builders balls, I would check all the outlets, switches etc on the exterior wall; nobody does it.

Jerry Peck
10-09-2008, 08:40 AM

When you read Jerry's reply, pay attention to item #4 Utility penetrations.
If you want to bust the builders balls, I would check all the outlets, switches etc on the exterior wall; nobody does it.

That part is addressing all penetrations by: gas lines, electrical lines, plumbing lines, cable TV lines, phone lines, any and all "utility" penetrations.

Also remember that there are two type of "penetrations":

1) Through penetrations, i.e., where something, such as a gas line, penetrates "through" the wall, entering the exterior side and exiting the interior side.

2) Membrane penetrations, i.e., where something, such as an electrical outlet boxes, penetrates "through" the exterior wall surface without going "through" the wall. They only penetrate 'one side' of the wall.

Both types of penetrations are required to be sealed at both the exterior wall surface and the interior wall surface. Yep, "all" "membrane penetrations" into the interior side of the exterior walls are required to be sealed, not just all membrane penetrations into the exterior membrane side of the exterior wall.