What DOESN'T expanding foam stick to? I want to bridge a gap in the apex of
a roof, that foam would droop away from, so need to install a temporary
'shelf' until it has hardened.
(Background: this is a barn with fibre cement roof that I had sprayed with
foam insulation some years ago, but they failed to seal the apex properly
despite claiming that they had. Access is extremely difficult as the barn is
full of immovable objects (large lathes, milling machines etc) and the apex
is about 15 foot up so it will have to be done in short sections - its about
40 foot long)
Idiot boy question: why not accept that expanding foam sticks to most
stuff and use as a "shelf" something that you are happy to leave there
which won't do any damage if they do fall off in time? Eg lengths cut
from polystyrene sheet?
reply-to address is (intended to be) valid
Just cover whatever you use for "shelving" with polythene or
any other thin transparent sheeting as a barrier. Fixed on the
underside with drawing pins etc. To save the pins tearing the
plastic first reinforce the site of the pins with squares of duck
tape or similar.
The worst that can happen is that the barrier doesn't work
and it sticks but after pulling out the pins taking down the board
and trimming all you're left with are strips of transparent
polythene on the foam.
Or it might separate with no problems at all.
As was pointed out in a previous thread all plastics are
different, as in plastic sheeting and knowing the precise chemical
composition of what you have available, and so it may just be a
case of try it and see. ( I could go up in the loft right now and maybe
check out some old carrier bags which had been subject to
"foam abuse" but there would be little point)
Or maybe treating the polythene with a further barrier.
On Sat, 9 Apr 2016 09:11:07 +0100, "Andrew Mawson"
I'd try well-greased bit of shuttering, such as a wooden plank.
Experiment on a small piece first. It would need to be held in place
quite firmly to resist the expansion. Even if it did stick, if it was
a neat piece of wood, it wouldn't look too bad if it remained up
Cling film wrap the shelf - the cling film may or may not stick to the
foam, but that would not matter if it stayed up there presumably?
I used the cling film trick around door threshold oak strips when I
needed to embed the wood onto 3-4 big blobs of isopon to get a level
surface to mount the oak onto.
The oak lifted straight out and the cling film peeled off the isopon
leaving a perfectly moulded set of pads :)
Thanks for all the suggestions :)
I've just worked out roughly that it would take 13 750 mL cans of foam, so
maybe not a practical solution. :(
What I need is something like the foam pipe insulation you can get - ie a
sausage like shape - that I can push into the gap to seal it. But it needs
to be about 6 inch diameter and stiff enough to be poked in and stay with
it's own 'gription'
So where can I get 6" diameter stiff foam - 1 metre lengths would be
convenient, and i'd need a total of 13 metres of them !
On Sat, 9 Apr 2016 15:04:25 +0100, "Andrew Mawson"
Armaflex who make a lot of the pipe insulation also supply the same
material in sheet form .
You could cut sections out of that roll it up and push it in , they
also make a jointing tape and on a clean dry surface that sticks like
shit to blanket.
A tightwads option would be to cut up foam camping mats.
On Saturday, 9 April 2016 09:10:55 UTC+1, Andrew Mawson wrote:
You have another problem too.
Expanding foam turns into one huge hollow bubble if too thick.
ie you can't fill voluminous spaces with it.
It needs moisture to go off too. So wet down slightly in the place you out it in.
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