On Wed, 06 Oct 2010 01:54:46 -0700, geraldthehamster wrote:
PROGRESS! There's a solution here, it just needs a bit of fine tuning.

To lay the access thing to bed - I haven't measured the depth of my void
(so to speak), but it's no more than 18 inches.

If that's 18 inches below the joists, you have no problem. If it's 18
inches including joist depth then it's tight, but probably still do-able.
People often under-estimate how small a space they can squeeze into - but
I note your point about not liking small spaces :-)

We did a partial house rewire the other week and that was around 9" of
void below the joists - but the horizontal space was larger (around 4'
between supporting structure). The major pain with that one was the
discarded lumps of jagged concrete from some previous structure which
were littered around on the ground. Oh, and getting in's a lot easier
than getting back out :-)

re. spaceblankets, maybe you need a couple of metal straps holding the
blanket tight against the joists? Couple of nails/screws on the side
faces of the end joists would do it I'd think - if it's a big room then
it might still sag an inch or two in the middle, but I wouldn't expect
that to be a problem as the insulation layer would still be tight against
the joists at the ends, so heat would still be retained above the blanket
layer.

In my own case, I would also need to feed each run of space blanket
through the four-inch gaps where the joists sit on the dwarf walls. This
might be doable with stick and bits of wire, but again, needs a bit of
finesse.

Is the ground below reasonably flat? If so, small RC car to pull a rope
or two through, then tie the rope to the blanket to pull that through?

cheers

Jules