We were called out to a customer's house the other day because their dryer was taking up to 4 cycle to dry a load of laundry. The homeowner was the original owner of a 20 year old house and never had the dryer vent cleaned. She and her husband had three kids and a handful of dogs, needless to say this vent was totally packed with lint. They had purchased a new dryer on Black Friday and had been using it for around 6 weeks before calling us.
As we often see during the winter, the dryer was producing a lot of condensation inside of the pipe. Newer dryers get extremely hot and some even produce steam which will build up a significant amount of water over a short period of time if the vent is clogged. Running the new dryer for six weeks caused the lint inside the 20 foot pipe to soak up the condensation like a sponge. As in the diagram to the right, the pipe routed above the ceiling of the laundry room inside the attic. When the customer's husband went into the attic to check out the pipe he walked on the beams and plywood inside above the laundry room which had also soaked up a lot of water. This caused the water held inside to flood down into the ceiling of the laundry room! When I inspected the damage I could tell the pipe had been dripping onto the laundry room ceiling for several weeks! Not only does wet lint make it nearly impossible for your dryer to work properly it can leak out from the joints of the pipe and into the surrounding area. After we finished removing all of the lint I advised the homeowner to call a contractor to replace the damaged ceiling in the laundry room and possible wood beams or plywood in the attic. She also told me she had called a plumber a couple weeks earlier when she had noticed the leak but he couldn't track down the source of it. All together she may end up spending close to $600 or more to repair the damage which could have been avoided with a simple cleaning!