Do you have ice dams? If you have insulation pushing up against your roof deck, you have a hot roof. You can place these tubes between the baffles or insulation and the roof deck to improve air flow. The attic must be ventilated! Insert the tubes from inside the attic, or maybe from the outside. Give this a try before ripping off your whole roof?! These PVC pipe sections are each about 30” long. 1-1/2” inside diameter pipe. I have 46 or 47 of them. Asking $40.00 for all of them. I CAN DELIVER in Anchorage. Make offer. Reduce the need for heat tapes, heat trace, stop condensation, roof leaks, leaking ceiling.