Best way to add/retrofit ventillation to an existing roof?

How best to add/retrofit ventillation to an existing roof?

We’ve got humidity & some mold in the attic.
Attic ventillation consists of two gable vents (maybe 12"x18") on a 28 x 32 roof.

The humidity level in the attic ranges between 70-90%, little changed a few days after cutting the humidifier and sealing air leaks.

The roof doesn’t appear to leak. I’m pretty sure about this – I got a good look around while cleaning mold.

The eaves have vinyl-covered soffits, though apparently no holes through the plywood underneath, and the vinyl is only 1/3rd vented.

If this was your roof, what would you do?

Is adding soffit vents even feasible, given the vinyl soffit covering?

Is adding a ridge vent when roof is near end-of-life cost-effective, or would it need to be torn out during re-roofing?

Check for the leaks and check the garage. It is possible that there is accumulation of ice in the soffit. It may be necessary to insulate the attic,especially the first 3 feet of the wall. Attic pictures might help.

If it was my house I would add ridge vent or power vent with humidity thermostat and cover gable vents.

+1: No ridge vent. add a power vent with a thermostat and humidistat. buy a good one from ABC Supply or your local distributor, not HD or Lowe’s. They are quiet. Lomanco is what we use. Ridge vent and power fan = no no. All you are going to do is suck the air from ridge vent right back out. Instructions even tell you this. Go with the fan and some box vents located atleast 10ft from fan.

PTroofing. “ridge vent OR power vent” i mean.Ridge vent and Power vent- it will create turbulence in the attic.It knows even student.

You can add the Vents.To install the vents, holes will need to be cut into the soffit. When cutting the holes that will allow ventilation, it’s critical to make certain that you don’t cut into the roof rafters. Cutting the rafters could weaken the structure of the roof. Use a stud-finder to help determine where the rafters are located before cutting the vent holes.

Dear Dan,

The combination of intake vents at the soffits and ridge vents at the peak are perhaps the best idea ever invented for ventilating attics. Ridge vents come in various types, but I like the aluminum ones in 10 foot lengths, overlapped 5" and screwed down with corrosion-resistant screws and shielded grommets. I would also take down the vinyl soffits, remove the old plywood and reinstall the soffit vents, replacing the non-vented panels with vented ones. It’s a bit of a job, but it should cure the condensation problem, make your roofing last longer and possible reduce your energy costs.

John C Bishop

If the new roof installers are careful, it can be re used.
I recommend soffit vents and any, or all, of the above( ridge, gable, power fan) vents. Depending on your location and situation.
For an explanation of that see the link below.