Crawl Space ventilation

[mathew stouffer]

What year did the IRC require insulation in the ceiling of the crawl space when the crawl space is vented with passive wall vents. Was it 06 or 09

[Bruce King]

What year did the IRC require insulation in the ceiling of the crawl space when the crawl space is vented with passive wall vents. Was it 06 or 09

I think it was way before that, the NC building code started requiring floor insulation in april 1982.

[H.G. Watson, Sr.]

What year did the IRC require insulation in the ceiling of the crawl space when the crawl space is vented with passive wall vents. Was it 06 or 09

Mat,

The 2000 IRC. (first IRC). All references below are 2000 IRC with the exception of the final one, otherwise attributed to 2006 IRC.

It (insulation, thermal performance, building envelope protection) has been required since the inception of the unammended IRC (2000), regarding building/thermal envelope, and thermal performance criteria, for vented to the outdoors, crawl space ceiling insulation (floor/ceiling assemblies above vented crawl spaces).

See Chapter 11, Energy Efficiency:




N1102, Building Envelope,
N1102.1 Thermal Performance Criteria
see Table 1102.1 for "Ceilings"


N1102.1.2 Ceilings.


See also:


N1102.1.4 Floors which cross references to requirements and table for ceilings when 25% or more of the Floor exposed directly to outside air which takes you back to meeting the R-value for "ceilings"


and See also:


N1102.1.10 Air leakage., esp. "...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."See also N1102.1.7 and while doing so note the condition where insulating crawl space walls and not insulating crawl space ceilings (floor/ceiling assembly above crawlspace) applies (not vented) below:



N1102.1.7 Crawl space walls. (2000 IRC)


Where the floor above the crawl space is uninsulated, insulation shall be installed on crawl space walls when the crawl space is not vented to outside air. The required R-value in Table N1102.1 shall be applied inside of the crawl space wall, downward from the sill plate to the exterior finished grade level and then vertically and/or horizontally for at least an additional 24 inches (610 mm). The exposed earth in all crawl space foundations shall be covered with a continuous vapor retarder having a maximum permeance rating of 1.0 perm [(57 mg)/(s · m2 · Pa)], when tested in accordance with ASTM E 96.

Here is the corresponding reference in the 2006 IRC:

N1102.2.8 Crawl space walls. (2006 IRC)

As an alternative to insulating floors over crawl spaces, insulation of crawl space walls when the crawl space is not vented to the outside is permitted. Crawl space wall insulation shall be permanently fastened to the wall and extend downward from the floor to the finished grade level and then vertically and/or horizontally for at least an additional 24 inches (610 mm). Exposed earth in unvented crawl space foundations shall be covered with a continuous vapor retarder. All joints of the vapor retarder shall overlap by 6 inches (152 mm) and be sealed or taped. The edges of the vapor retarder shall extend at least 6 inches (152 mm) up the stem wall and shall be attached to the stem wall.


The floor-ceiling assembly over the crawl space may have additional requirements in the event that mechanicals are present in the crawl space itself, exposed floor or earth in crawlspace, what building system componants may be present in same (floor-ceiling assembly) such as electrical, DWV plumbing system, potable plumbing system, HVAC ducting, hydronic heating, etc.

Further, what comprises the assembly, such as TJIs, sawn lumber, open trusses, etc. Most engineered lumber and/or lumber or engineered wood trusses require moisture content and RH and absolute humidity exposure to be stablized prior to installation, and maintained within ranges while in-use/installed with limited (over) exposure exceptions during construction prior to loading.

Here is a free (clickable) link to the unammended 2000 IRC's Chapter (N) 11: Chapter 11 - Energy Efficiency (http://publicecodes.citation.com/icod/irc/2000/icod_irc_2000_11_section.htm)



HTH.

[Matt Fellman]

In my neighborhood (Oregon) it was around the early 90s. Maybe even 1990. I owned an 89 house that had perimeter wall bats but can't recall seeing many houses after 1990 w/o underfloor.

[mathew stouffer]

Thank you