Proper maintenance of dryer vents prevents an excess build up of lint that can decrease the efficiency of your dryer as well as being a fire hazard in your home or business. According to the National Fire Protection Association, nearly 17,000 home clothes dryer fires are reported each year. Some newer dryers have sensors that detect inadequate air flow due to plugged dryer vents and will shut down the dryer completely. So how often should you have your dryer vents cleaned? The answer to this question will depend on multiple factors: The type of material or fabric being dried, the frequency of use and the type and length of the dryer vent. Certain materials and fabrics produce more lint that others. Cotton bath towels are probably some of the highest lint producing items you can put in your clothes dryer, and this should be obvious to most as the lint trap in your clothes dryer becomes full after doing a load of cotton towels. The lint trap captures some but not all the lint. The remaining moist lint travels down and over time accumulates on the dryer vent walls. The heavier the usage of the dryer the quicker the lint accumulates on the dryer vent walls. Dryer vent duct material that is flexible or ribbed will also accumulate lint much faster than smooth, rigid ducting. Sometimes sections of ducting are improperly joined together with screws rather than heat-resistant foil tape, and these screws quickly become a place of accumulation of lint. The final determining factor of how often you should have your dryer vent cleaned is the length of the ducting until it reaches its exhaust point on the outer wall or roof of the building. The longer the dryer vent is, the slower the velocity of the air at its exhaust point which allows the lint to more easily attach to the vent walls. In determining how often you should clean your dryer vent all these factors need to be considered, but as a general rule if your dryer vent is 20 to 30 feet or longer you should consider having it cleaned every year or two, but if it is connected to an outside wall or under 10 feet in length you may be able to go multiple years without any issues. You will want to be observant of the drying time for your dryer as it will increase as the venting becomes plugged. Commercial usage dryers may need to be cleaned every few months or so to avoid fire hazards. Ultimately, it is better to be safe than sorry. If you haven’t had your dryer vent cleaned in some time, have a professional clean it out and take note of how much material is removed as this will be a good indication of how often you should have it cleaned in the future.