PipeDown wrote:
I want to insulate the bottom of the floor (inside crawlspace). The problem
is the floor joists are nowhere near 16" on center. My single story 1000SF
house is built on a deck like subfloor. It is made up of 4x8 beams running
the length of the house set 4 feet apart with 2x8 tongue and grooved planks
set perpendicular. The result is a thick solid floor with few beams
underneith.

To put it another way, the floor joists are 4 feet apart and the crawlspace
access is a 2'x2" hole in the closet floor.

I was considering 4x8 sheets of solid core insulating panels cut in half the
long way but this would be expensive and would not have as good R value as
fiberglass. I would need to double or triple up on them to get the same R

Has anyone seen a product that sounds like it would work well here or am I
stuck using 16" wide rolls and stapling in strips to the underside of the
subfloor instead of the joists. This is not ideal because it would compress
the edges of the insulation.

Do you think installing paper faced insulation with the paper up so I can
staple through it is a good solution?

Fortunately, I am in northern CA and the climate is mild.



That type of construction is a standard type
called post and beam. I would consider insulating
the walls of the crawl space rather than the floor.

The paper should be toward the warm side, i.e. for
the floor it would be directly against the
subfloor. I would use 24" wide fiberglass so two
widths would fit between the beams and just staple
it to the floor. You might need to compress the
sides a bit that is ok. It will be a messy job,
but with the paper facing against the floor it
should go up fairly well.

However, you will still need some type of material
to support the fiberglass as it would eventually
pull away from the paper. A very wide mesh or
netting with holes at least 1" square and better
2" square could be used. Nylon might be preferred
but most anything will do. Check what is
available and cheapest in your area. Don't forget
to cover the dirt floor of the crawlspace with 4-6
mil plastic if not already covered.