Crawl Space Insulation

[Jimmy_B]

Hi Jerry,

I could use your help with a project I'm working on in the crawl space of our home. The home is located in Westchester County, New York. The crawl space is under an addition that was added to the house in 1970. The space is currently enclosed on three sides with the fourth side an open area that goes out under a deck in the rear of the home. The "ceiling" of the crawl space was covered with 1/4" plywood that was covering fiberglass batt insulation. One of the walls is the concrete slab from the original build and the other two walls are stucco. The ground is currently dirt and has never been covered.

I ended up removing all of the plywood and batt after I opened up a section to try and find the source of a draft in one of the rooms above. I found copper piping that I have insulated and also a junction box that I have now made accessible.

Where I need your help is with the code for re-insulating the space. First, I'm going to put a 6 mil vapor barrier on the ground. I would also like to close off the fourth wall leaving an ample access door to get in. I'm not sure if I should use the batt insulation again or go with pink or silver foil lined foam boards to insulate the floor boards above. I'm also considering using batt between the joists and covering it with silver lined foam boards.

What is the code in my area for installing insulation in this crawl space? Do I need a fire blocking of some kind to cover any insulation that I put in, either on the ceiling or walls? Can I just cover the entire area (walls, floors) in rigid foam boad? The area will not be used for anything. I am trying to keep the rooms up above as warm as possible.

Thanks for your help,
Jimmy

[Jerry Peck - Codeman]

Westchester County, New York, is Climate Zone 4 in the New York State Residential Code.

Climate Zone 4 requires the following:
NYRC Climate Zone insulation table.jpg

The minimum floor insulation R-value is R-19. I would use faced batt insulation, the facing is required to be substantially in contact with the underside of the floor above as the facing can burn (there will be a warning on each batt stating the same thing).
- From the NYS Residential Code:
- - N1102.2.6 Floors. Floor insulation shall be installed to maintain permanent contact with the underside of the subfloor decking.
- - N1102.2.9 Crawl space walls. 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 Class I 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.

If the copper water piping is in the floor joists spaces at the right height to allow the copper piping to be within the insulated thermal envelope, then no additional freeze protection is required, however, if the water piping is not fully within the insulated thermal envelope then you will need to insulate and protect the pipes from freezing, which is sounds like you either already did or at least already started to do.

You could insulate the floor above the crawl space with R-19 in accordance with N1102.2.6 Floors, then additionally insulate the crawl space walls in accordance with N1102.2.9 Crawl space walls, that would help the greatest as insulating the crawl space walls would keep the temperature within the crawl space more consist throughout the year (heat or cold), and then the floor insulation would only be keeping the difference between the conditioned (heated and cooled) living space and the crawl space instead of trying to keep the difference between the conditioned space and the outdoor temperatures (hot or cold).

[Jimmy_B]

Thanks Jerry. You have helped me yet again.

I am going to install the faced batts up between the floor joists. Does the code state anything about covering the joists? I'm thinking of using foil lined foam board to cover both the ceiling and the walls. Does code call for any kind of fire protection to cover this insulation?

I also just picked up an automatic foundation vent at Home Depot that I am planning on installing through the new wall that I am putting up. I thought this would help with air ventilation in the warmer weather when the vent opens.

Thanks again,
Jimmy

[Jerry Peck - Codeman]

The code does not address covering the floor joists.

Foam plastic insulation, such as the foam board you are considering, requires an ignition barrier - unless the product is listed as having been tested and passed to the appropriate tests listed in R314.6.
- R314.5.4 Crawl spaces. The thermal barrier specified in Section R314.4 is not required where crawlspace access is required by Section R408.3 and where entry is made only for service of utilities and the foam plastic insulation is protected against ignition using one of the following ignition barrier materials:
- - 1. 1.5-inch-thick (38 mm) mineral fiber insulation;
- - 2. 0.25-inch-thick (6.4 mm) wood structural panels;
- - 3. 0.375-inch (9.5 mm) particleboard;
- - 4. 0.25-inch (6.4 mm) hardboard;
- - 5. 0.375-inch (9.5 mm) gypsum board; or
- - 6. Corrosion-resistant steel having a base metal thickness of 0.016 inch (0.41 mm).
- - The above ignition barrier is not required where the foam plastic insulation has been tested in accordance with Section R314.6.

- R314.6 Alternate approval. Assemblies containing plastic foam not meeting the requirements of Sections R314.3 through R314.5 shall be approved on the basis of one of the following tests: FM 4880, UL 1040, NFPA 286, ASTM E 152, or UL 1715, or fire tests related to actual end-use configurations.

I believe you will be defeating your intended purpose of insulating the crawl space when you install the automatic vent which will open during the warmer months.

Keep in mind that crawl spaces are required to meet specified minimum required ventilation, unless the crawl space is a sealed crawl space; however, it sounds like you are trying to combine the two different types of crawl spaces. This could lead to moisture problems.

[Jimmy_B]

Good point on the vent installation. I was not aware that this could possibly cause a problem.

Thanks for all of the helpful information and the very quick responses. I really appreciate it.

Jimmy