If you have water making its way inside your 996, often you will find the carpet and the bottom of the cards wet. This is more often than not due to the failure of the plastic membrane that lives behind the door card – if not the plastic itself, the adhesive that fixes and seal it to the steelwork of the door.
This is quite a common problem in many cars, not just Porsches. (You might be surprised by just how much water passes down into the door shell past the window’s waist seal. This is perfectly normal – and is the reason why there are substantial drain holes at the bottom of the panel.) To stand any chance of fixing this problem you need to remove the door card and see what’s what. That sounds daunting, but it’s actually quite straightforward once you know where all the fixings are (see pictures). Do be careful, though not to damage either the card or the shell as you pull one away from the other, preferably by using a ‘trim’ tool or strong spatula to ease the plastic clips out of their holes. Personally, I would be inclined simply to buy a new membrane before you even start. They are not hugely expensive – typically about £50 including VAT per side. If you want to try sticking your car’s membrane back into position, use either thin double-sided adhesive tape, or perhaps some DIY-style silicone sealant.
Removal of the door cards is described in the thumbnails below: