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    Our kitchen extractor is ducted through the eaves to a roof cowl through cheap flexible PVC spiral duct, installed by kitchen company.

    A mouse has nibbled holes through the duct. So the extractor is now blowing damp kitchen smells into the roof space.

    Probably been several years like this, fortunately no obvious condensation damage. Mice also had a go at the foam insulation on adjacent pipe.

    Not sure if I am most angry with a) the mouse b) the kitchen fitters c) myself for hiring the kitchen co!!

    Any recommendations for vermin-proof ducting?
    There is also a huge gap where the duct passes through the kitchen ceiling plasterboard/insulation. Definitely blame the kitchen co for that as it is too neat to have been made by the mouse, and artfully disguised by panelling. I could seal it with squirty foam but mice chew that too :cry:
    Spiral-wound steel ducting - it'll blunt their teeth a bit.
    • CommentTimeFeb 20th 2017
    What Nick said for the duct, plus mouse traps!

    Maybe aluminium-faced pipe insulation? I don't know about mice, but aluminium on my teeth is horrible, although I have to say that our cats like carrying scrunched up aluminium foil around in their mouths (sweet wrappers).
    • CommentAuthorskyewright
    • CommentTimeFeb 21st 2017
    Posted By: WillInAberdeenA mouse has nibbled holes through the duct. So the extractor is now blowing damp kitchen smells into the roof space.

    I made a very similar discover a few years ago on the ducting from our bathroom fan. I'd often been puzzled by the amount of evidence of condensation drips in the loft even though it was well ventilated. If I'd been up there just after someone had had a shower I might have realised...
    What did I do?
    a) Replaced the plastic coil pipe with aluminium coil pipe.
    b) Put a condensation trap right above the fan (harder to chew, and to deal with back flowing condensate resulting from the next measure).
    c) Arranged a steady upward slope on the pipe by hanging it from the roof timbers, till just before the exit, at which point it drops steeply down to 'exhaust' level.
    d) Made serious attempts to reduce potential access for vermin (e.g. stainless steel mesh over air bricks).

    So far so good. Fingers crossed...
    • CommentAuthorSprocket
    • CommentTimeFeb 23rd 2017 edited
    Yeah, we have insulated flexible ducting in the loft from our bathroom extracts and mice have chewed through the outer foil layer in places and chewed up and removed some of the mineral wool insulation from underneath. They have not yet easten their way right through but it's surely only a matter of time.
    It's not an easy spot for me to use rigid ducting. I figured I just have to put up with it and replace it when they finally damage it badly enough :-/
    • CommentTimeFeb 23rd 2017
    Perhaps you could sell pieces of the old duct as bait for mousetraps, instead of cheese?
    Thanks all! I like the idea of steel duct but needed to route between some pipes. So I went with alu semirigid.

    Mice seem quite happy to munch through alu foil to get at nesting material, well at least they have removed small patches of the foil facing from some PIR in my roof.

    When the semirigid aluminium duct is stretched out round bends it doesn't seem much thicker than foil, so time will tell how it lasts.

    Replacing the duct, I was pleasantly surprised how little gunge had deposited after 10 years without grease filters.

    I found that the 'back draft' flap at the fan outlet had broken off and could have been letting in cold draughts when the fan was stopped, if I hadn't modified the extractor housing to positively seal shut when not being used.There was also quite noticeable 'chimney effect' with warm kitchen air flowing upwards through the duct even without the fan running.
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