After many false trails I have narrowed down the cause of wet carpets in
our cars to rain leakage past the plastic membrane between the door trim
panel and the door metalwork. I have to confess that for years I thought
the membrane was for keeping out draughts, but I know see it forms a
critical part of a cunning water drainage system. There is actually a
shallow vertical channel pressed along the bottom of the door inner skin
with a drain slot through the skin (see below in fixed font).

The idea is that any water running down the compartment side of the door
inner skin is supposed to run along this channel to the drain slot/s
thence to the door innards, and then finally drain out through a hole in
the very bottom of the door. This lower drain hole is outside of the
main door weather seal. Any water that runs down the surface next to the
door trim will drip out on the interior side of the weather seal and
finish up on the carpet. The plastic membrane forms completes the
channel in the door skin, and without the membrane being glued to the
door below the indented channel the whole scheme fails and wet carpets
are the result.

Now the membrane is relatively delicate and has to be removed for
several kinds of repair inside the door; e.g. central locking motors,
electric window winders, door lock etc, so the original is stuck on with
a tacky tape that allows several removal/refit operations while
retaining a waterproof seal of membrane to the door skin.

So at last my question: What is this adhesive and where can I get some?
It needs to stick permanently to the metal door skin and be tacky to
plastic sheeting, and impervious to water. A double-sided tape would be
ideal, but a caulk, or adhesive would also be suitable.

As you may guess the membranes in our cars have exhausted the tackiness
and are now leaking, as evidenced by wet carpets and steamed up windows.


t m r| |
t m r| |
t m r| Door |
t m r| Section|
t m r| |
t m r| | Outside
t m r| |
Car t m r) == Channel | = door skin
Interior t m rrr== Drain hole t = Trim Panel
t m LX|r | m = Membrane
t m LX|r | X = Adhesive
LLLLLW|r | W = Weather seal
L --- W|r | r = rain water intended path
Carpet L/ |W\rrrrrrr / L = Leakage path
______L/ \W\_____ r == Lower drain hole
Sill \_ r
r
Road


--
Phil
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