Sonotube is a cellulose/cardboard based material with a mylar coating which was used in many floor duct systems throughout the Albuquerque market. In a perfect installation, Sonotube is incased in concrete when the slab is poured. However this type of product has been susceptible to damage through water infiltration likely due to inadequate drainage conditions, overwatering of irrigation and evaporative cooler operation and leaks) and installation problems as well. Furthermore, due to its cellulose make-up, this product has also been prone to damage from termites.

Since the majority of the ducting system is not accessible or visible, and because damage to the in-floor ducting system can in some cases be an expensive repair, having the ducts scoped/inspected by a qualified professional with a fiber-optic camera is always advised

***Obviously the picture is of a toilet paper roll and this is because I like to think of sonotube ducting as a bigger thicker toilet paper roll lined on the inside with aluminum foil.