The Holy Grail

[Jules Richardson]

If only you can get in there, you could probably attach some form of fine netting to the underside of the joists and then use blown-in insulation to fill the gaps between the joists.

cheers

Jules

[geraldthehamster]

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. Joists are 4x2 at

16 in. centres. Every couple of feet or so is a block dwarf wall which supports the joists, and therefore runs parallel to the boards. You'd have to do so much taking up to get in there, that you might as well take up the whole floor. There is negligible height to work in, and I don't do confined spaces.

Now then - yes, you could pull through spaceblanket, and you'd only need to take up maybe four boards across the room. I like this. However - without taking up numerous boards, how are you going to eliminate sagging, and ensure that it's tight up between the joists?

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.

I can't help thinking that a very small child is part of the solution. I never thought to fabricate any.

Cheers Richard

Cheers Richard

[Jules Richardson]

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.

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

[geraldthehamster]

Thanks Jules. I was thinking along the lines of a couple of straps running longitudinally each side of the batt of encapsulated space blanket, which could be pulled tight and fixed at each end. If the space blanket were quite thick, and slightly wider than the gap between joists, that might pull it in nicely. I'd maybe aim to remove a board every 3 feet or so, and do it in 3 foot chunks.

I'll measure the depth of the void tonight, just for interest. You won't catch me trying to get in and out of it; besides which I'd need to take up more adjacent boards to get in, than I would separate boards to try the thing with the batts. And you're right about the getting out; I'm not as limber as once I was, though I have lost a fair amount of weight lately.

Cheers Richard

Otherwise, I like idea of the the radio-controlled car ;-)

[<me9]

I had thought of using tile lath to lay over te dwarf walls to support the spaceblanket

I have used that method in the past.

Mine are now much larger than me.

[Grimly Curmudgeon]

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember geraldthehamster saying something like:

Easy - peasy.

Flood the underfloor space with wotter and on it float a carpet of sticky foam pellets that will stick to the underside of the joists and floorboards. Drain away the moisture, and there y'go.

It's so good I might just patent it - or I might not bother.

[Grimly Curmudgeon]

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember geraldthehamster saying something like:

You'd be surprised at the perceived difference to the tootsies that a simple 12mm layer of Celotex topped with hardboard makes. Wouldn't cost much to find out in one room.

[Jules Richardson]

:-) Oddly enough, I almost suggested the same approach, but with expanding foam - but then I got to wondering if that stuff actually floats in water before it's done its expanding and set, and I didn't have any around to test with. Didn't want to give poor advice, so kept quiet.

;-)