Sigh. Having sanded and varnished most of my downstairs floors
(suspended over a space too small to access), fitted new skirtings, a
hearth and a fireplace (which seemed like quite enough work at the
time), I'm now wishing that I'd really bitten the bullet, taken up the
floorboards and insulated underneath. Even if I'd demolished most of
the tongues in the process, I could have ripped them into straight-
I have one room to go, and might go the whole hog there (ironically
it's a spare room). But for the rest of the ground floor, the idea of
pulling off all the skirtings (how else to remove the T&G boards whose
ends go under them, and are fixed with brads an inch from the wall?),
and doing the floors again, is heartbreaking, though I might just bite
the bullet when I've completed all the other jobs. Or I'll content
myself with lots of rugs.
Which leaves the Holy Grail, discussed on here before - how to
insulate under a suspended timber floor, with no access from
underneath, without removing the floor.
Even if I did cut such an access, there's not enough room for anyone
other than an unskilled very small child, and the dwarf walls that
support the joists at intervals would necessitate many such holes.
Helium-based squirty foam,that would rise and stick to the underside
of the floorboards?
Oh come on, there must be a way we haven't thought of.
On Mon, 04 Oct 2010 03:51:37 -0700, geraldthehamster wrote:
How much space are we talking about? It's surprising how small a space a
human can fit into. Insulating probably doesn't need a lot of clearance,
either - no messing with power tools, no need to swing a hammer etc.
Flat panel insulation needs a big hole in the floor to fit if there is no
depth, particularly if thick. Flexible insulation is generally an irritant, I
don't like getting too close.
I'm toying with pulling through spaceblanket (mineral wool (or is it
recycled bottles) wrapped in a plastic film, much less irritating than bare
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.
On Wed, 06 Oct 2010 01:54:46 -0700, geraldthehamster wrote:
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
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?
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.
Otherwise, I like idea of the the radio-controlled car ;-)
We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember geraldthehamster
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.
On Thu, 07 Oct 2010 01:12:58 +0100, Grimly Curmudgeon wrote:
:-) 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.
Rats; mice; and wasps seem to be pretty good at filling up under floors with
Otherwise: foam through the knotholes. The cavity wall insulation people
very quickly filled up the walls in my old house. Sure they could quote for
floors if you asked.
Filling the entire void is not an option, unless you want your joists to rot
away within a few short years.
You can't get access under the floor and you don't want to take the entire
floor up? - then it cannot be insulated, end of story.
You could insulate above the existing floor, with 75mm celotex or similar,
then put a floating floor above that, but then you'd lose about 90mm of room
height (and your internal doors would be 90mm shorter too) plus you'd have
to put new skirtings all the way around
These have been my conclusions, every time I've thought about it :-(
I can only see two ways to make the floor warmer, short of a detested
fitted carpet, with its propensity to collect dust, and stains from
coffee, wine and mouse blood. Or ripping the lot out and replacing
with concrete, which would be stupid and unnecessary ;-)
One is to remove my skirtings, prise up the floorboards, insulate,
tidy up the boards on a table saw, refit, fit new skirtings and
decorate. In three rooms and a hallway.
The other is to continue to collect relatively inexpensive Persian
rugs, and attach Tri-Iso insulation to the backs of them. That way
much of the heat loss would be eliminated.
Hence my reference to the Holy Grail - don't bring me common sense,
bring me solutions ;-)
Surely only one or two long boards removed would provide access to
blow insulation under?
Even if you wanted to remove ALL the boards, sawing through the tongue
on one with <insert favourite sawing device here> would release them
all (once skirtings off).
Do wonder about insulating under floor voids, roof voids have air and
draughts deliberately introduced to stop rot, concerned that creating
static air under floor timbers might introduce a rot encouraging
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