Anon if i understand your original question you have a bath exhaust that is discharging into a roof cavity or space not to outside.
Exhaust fan into roof cavity.
Hot air exhaust vents located at the peak of the roof allow hot air to escape.
It needs to exhaust to the exterior.
The master flow erv5 power roof vent is the master flow erv5 power roof vent is a great overall investment in attic ventilation.
This includes two bathroom exhaust fans and the range hood in the kitchen.
I m no master builder but i do not see any signs of mold or rotting in the ceiling at all and when we purchased the property 3 years ago the building inspector explicitly stated that.
A ceiling exhaust fan is one of the most popular methods of ventilating a room.
These fans expel air upwards through the ceiling and can be exhausted into the roof cavity or ducted to be exhausted outside.
This in turn can help save money on your heating and cooling costs.
Those ceiling vents are fine to vent off into the roof space i think the recommendations for a bathroom is 50litres per sec which u will roughly get from a ceiling fan.
A ceiling exhaust fan as the name suggests is an exhaust fan that is mounted on a ceiling.
The bath exhaust vent duct is routed through the ceiling between i trusses used to support the roof over the wall top to the building exterior into the soffit cavity.
The location of bathroom exhaust fans can also determine how effectively the fan operates.
Intake vents located at the lowest part of the roof under the eaves allow cool air to enter the attic.
The metal visible below the exhaust duct was put in place to reinforce the supporting web between the i trusses.
Am i missunderstanding that you are thinking of blowing the exhaust air into a 100mm cavity between the ceiling and the roof.
It could also lead to problems with moisture in the roof cavity.
When connecting a bathroom fans to ducting consideration needs to be given as the length of duct will sometimes impact air capacity especially on bathroom exhaust fans with smaller capacities.
It s important to make a thorough assessment of the existing spaces where air may enter and exit the roof cavity.
Inline fans are like anything else spend good money on them and you will get a quality fan eg less noise and vibration.
Of course it s unusual for a roof to have no existing ventilation.
This means that there s been 40 years of venting into the ceiling cavity.
In no case is it acceptable to just dump any exhaust fan directly into an attic.
The fan draws in fresh air from the lower vents pushing the warmest air highest in the roof out through the high vents.
On 2020 02 26 by anonymous.
The rangehood is perhaps only 5 7 years old.
I would say that the bathroom exhaust fans are original or close to original to the house which is mid 1970 s.