Exceeding the duct run length is dangerous. The code is in place for safety reasons. If you exceed the length, you run the risk of a fire.
DryerPlacard is a permanent solution to provide an indication for future repairs/replacements to the dryer ducts. Made of an extra thick 3” X 4” Lexan® velvet textured polycarnonate, this is designed to last the lifetime of your home. It's the same material used to create bullet proof windows! Permanent marker is accepted very well, so forget having to scrape in your numbers.
High quality 3M®467 pressure sensitive adhesive sticks permanently to a wide variety of surfaces, including your ductwork. Check it out on DryerPlacard.com!