saw thread recently on expanding faom and thought this might be of interest.
I have a new Alkathene pipe (or MDPE to give factual type) bringing mains
water into the build, this come sin via a PVC conduit.
The water board want the conduit filled with insulation - I asked about
expanding foam - and they advised that under no circumstances muct expanding
foam come into contact with MDPE pipe - it eats it away.
Anybody else come across this, I would like to follow up and see if true.
I've heard of the foam eating into plastics and things, but I've never read
anywhere that it does. We use polyurethane guns to inject the foam into
gaps and things, so I would have thought that if it did eat into plastics,
they would sell you a plastic gun to use as the application method. I've
never read on the instructions that is has any adverse effects on the things
around it and it only says that it is flammable will still in the container,
and that you should wear protective gear in case it gets in your eyes or on
your skin. But that's just because of the propellant that's used to blow it
out the tin.
Some foams are now resistive to UV in the sunlight and some are even being
used as water repellents on or under other surfaces. All this stuff is on
the tin when you look, so I would have thought the makers would have made
anything about it ruining other materials more apparent in their guide on
Hmmm - perhaps time to own up to a little DIY "mishap" shall we say ;-)
Some time ago we had a problem with, as it transpired, a mouse and a rat
that had somehow got under the bathroom floor. Not sure how they go
there, but they made a hell of a racket for a few weeks as we tried
various ways of trapping / disposing of the blighters.
Anyway to cut a long story short, ratty decided to eat his way through
the kitchen ceiling next to where the central heating pipes come up into
the bathroom, and promptly found himself sat on top of one of the
kitchen cupboards now unable to return "home". A phone call from SWMBO
informed me of this, as I was on a clients site working late one
evening. Having considered this method of escape a possibility, I had
taken the precaution of placing a "humane" trap on top of said cupboard
in advance. So said to SWMBO "does it look like he will go in the
trap?". She replied "no.... he is BIGGER than the trap!". Anyway I asked
her to keep him talking, and said that if he was there when I arrived
home I would attend to the situation. Needless to say he was still
sitting there when I got home. It looked like he was in a pretty poor
state (having had nothing but mouse poison to eat for weeks!) and was
not keen on moving. Needless to say I was not that keen on getting that
close to him as he was a big bugger with long teeth! I decided the most
expedient method of disposal was the addition of a small lead weight to
the forehead... with the help of my trusty .22 air rifle! I hope ratties
departure from this world was swift and painless - he certainly seemed
co-operative enough by keeping perfectly still as I offered the barrel
to his head! SWMBO was a little less impressed when he decided to bleed
all over the top of the cupboard - but the up side is I was allowed to
claim said cupboard as my own thereafter! ;-)
Mousy decided a few days later to escape from the tiled and boxed
sections of the bathroom to go for a wee walk round the perimeter of the
room as I lay there having a soak. He then made a small tactical error
by climbing up the back of the pedestal bin and promptly falling in it
instead of returning to his former hiding place. After my bath I decided
that he and I would take a short walk to the woods where he could claim
This then left the question of sealing up some of the small holes round
the pipework to close off some possible entry and exit points. Expanding
Poly Foam was (it seemed) the ideal solution. Did a fine job of the
kitchen ceiling by the pipes. I then added some to where the pipes exit
the boxed in section of the bathroom to go to the sink; since it looked
like this was how mousy made his escape. Job done.
A few hours later I noticed that there were some traces of water on the
kitchen tiles - much as if some water had been trickling down them from
the ceiling level... seemed at bit odd. The only possible source was
from the bathroom above. Went upstairs - it all looked ok - ran the taps
- still ok. Flushed the loo.... oh dear (for want of a better
expression!) a little cascade of water running down the kitchen wall
with a slight disinfectant smell! Blurch!
A quick investigation with a torch and a mirror revealed that when the
bathroom had been re-done (prior to our ownership) the loo must have
been re-sited a couple of feet to the right. Hence its trap fed a pipe
which had a right angle bend followed by a short run of pipe before
turning the corner again to re-attach to the soil pipe in its original
location - just under the sink in the boxed in section. These joints
seemingly made water tight by the flexible soft plastic shroud that
encased them and incorporated the rubber seals at the ends. The one
under the sink now had a large lump of foam embedded in it where it had
completely dissolved said shroud! Needless to say the shroud was no
longer quite up to the job it was designed for, and the contents of the
loo were being flushed into the ceiling void!
The plumber (I will DIY most plumbing jobs - but am not so keen on ones
involving the output of toilets! - and anyway I had to deal with
aformetioned client the next day) was amused!
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