My washer and dryer are on the 2nd floor of my 2 story house. The dryer vent goes into the wall and then straight up into the attic. Once in the attic it tips to maybe 30 degrees from vertical and continues up to a roof vent. I can stand in the attic but it is one which is accessed via a pull down trap door and the "floor" is just some bits of plywood here and there. My problem is where the solid duct meets the roof vent. Basically it is just shoved up in there and there is not an air tight seal. The result is that probably half or more of the moist hot air from the dryer ends up in the attic and not out the roof. Surely this can't be good.
My initial thought had been to take some of that foam insulation that you can buy at walmart intended to be shoved around a window air conditioner. Then I started wondering if maybe that isn't a good idea around a duct which will have some amount of heat being a dryer duct.
It would seem like something which permanently seals off the air may be less than desirable because it will make it harder to periodically clean the duct.
Any suggestions on a good approach here? I'd rather avoid anything which requires being on the roof. The only roof I will go on would be much flatter and closer to the ground so that right away adds the cost of hiring professional help. If it is the only way, I can do that but we already have enough other projects around here that are needing pros....