Expert: Dave Johnson - 12/4/2008

Question
I recently purchased a single-story home on a crawl space. the original home was built in the 50's and is about 900 sq ft on a concrete block crawl space about 4ft high with a dirt floor. there are also two 300 sq ft additions built in the early 80's on concrete block crawl spaces that are just deep enough to crawl into (24 inches maybe...true crawl spaces), also with dirt floors. The home is in central NJ just a mile from the ocean on a very sandy soil base. There are no radon problems at all within 15-20 miles of this location.
the crawl space has no insulation evident anywhere. all of the pipes, including the hot water baseboard heating system, are not insulated at all.
There are hardwood floors throughout the home and the floors already feel cold and we're just getting to December.
What would you recommend as far as insulation goes for this space? Some people have told me to just insulate the box, others say hang the insulation around from the box all the way to the ground, and yet others think I should insulate the floor between the joists.
Also, what would you recommend as far as insulating the pipes? Should they all be done? Hot, cold and the baseboard system?
Do I need any kind of vapor barrier for the dirt floor of the crawl?
I greatly appreciate any input you might have.

Mike

Answer
Hi Mike,
First the heat; insulate with pipe insulation thoroughly. Even if there is no chance of freezing, you will save a lot of heat.

Vapor barrier; if there is any moisture at all, after all other work is done lay poly on the ground.

I would insulate at the "box header" (over the block wall between the joists against the outside) and then use rigid foam between the joists leaving a space between the foam and sub-floor. If the foam is not tight, use spray foam insulation to seal the cracks.

Also, go into the crawl spaces in the daytime and close yourself in, wait til you have adjusted to the dark and see if there is any light coming through, seal these places. ( any crawl space that is reasonably air tight will not get below 40 degrees.

Best of luck,
Dave