way out I know but ......

we have a small crawl space of around 22x8 with a varied depth of 6" to 18".
It's in the south end of the house and is quite cold in winter.
I'm thinking about blow in cellulose or Cementitious foam/Air Krete.
The floor is old hardwood that I'm quite reluctant to pull up to build a "contained" space in between the joists.
Has anyone any ideas for a very partial pull up that might allow the building of a such a "contained" space for the Air Krete or cellulose to fill?

I'm confused about what you're trying to insulate. It sounds like you have a room with a hardwood floor that has 6" to 18" clearance below it. Does the floor have joists? Is the 6" to 18" the distance from the joists to the dirt?

I have air krete throughout the house. One of the places it did not work well was insulating between the joists in the crawl space because the contractor used stapled Tyvec to hold it up (which eventually fell down).

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"In science it often happens that scientists say, 'You know that's a really good argument; my position is mistaken,' and then they would actually change their minds and you never hear that old view from them again. They really do it. It doesn't happen as often as it should, because scientists are human and change is sometimes painful. But it happens every day. I cannot recall the last time something like that happened in politics or religion." (1987) -- Carl Sagan

Yes there are joists.
The joists to the ground (which is surfaced with something, though I'm not sure what).
I've seen Air Krete contained with mesh rather than Tyvec as it spreads the weight rather than concentrate it.
Tyvek does tear, and without a pantload of staples, I could see the method easily failing.

The problem here is that in some parts, there isn't enough space for a member of the lollipop guild to crawl in.

Can you get into said crawlspace? Even if you have to dig out in some areas, once in there, it would be relatively easy to add insulation between the joists, around the perimeter walls and even pipe wrap. I was surprised how easy it was to break through a red brick foundation to access the crawlspace in one area I needed to access. Once done, you'll have better ventilation in that area in warm weather.

In that case, airkrete or some other cementicious product) would be good. One thought is to somehow use rigid foam insulation under the joists and then fill the cavity above with airkrete or similar. I'm pretty happy with the airkrete though it really needs to be installed in a place where its strength (which is approximately zero) doesn't become a liability. Cellulose would probably be cheaper but then you have to deal with settling which could create a gap above the insulation, thus rendering the cellulose useless. You need to make sure that whatever you use stays up tight against the floor boards.

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"In science it often happens that scientists say, 'You know that's a really good argument; my position is mistaken,' and then they would actually change their minds and you never hear that old view from them again. They really do it. It doesn't happen as often as it should, because scientists are human and change is sometimes painful. But it happens every day. I cannot recall the last time something like that happened in politics or religion." (1987) -- Carl Sagan



Edited 1 time(s). Last edit at 12/08/2009 10:05PM by davester.

I can get in, but the dirt has something on it. Could be fiberglass or concrete, dunno.
We'll see what the AirKrete rep says when I finally contact one.

If you are having someone else do it, you may consider using a spray foam insulation (reference Holmes on Homes).