Skylight Repair & New Install Blog (Toronto)
This is something that we see quite often. The homeowner got his roofer to upgrade his vents at the same time as he was re-roofing the house. The roofer installed the large 14" turbine vent. Unfortunately, he put it on top of the old small hole (for the old passive vent that was there before), rather than cutting the hole to the size of the new vent. As you can imagine even though the new vent is much larger, it still doesn’tt draw much air as it has to draw through a small hole.
When installing new, more efficient venting systems, the hole in the plywood has to be cut to match the size of the new vent, for the new vent to be effective.