bathroom exhaust venting

He vented it through an existing attic vent?
Losing 1 attic vent likely won't change anything.

Soffit vents are a no no. The issue is that warm moist air rises so it is likely to get sucked into the attic through the gaps in the soffit that normally provide ventilation to the attic introducing moist air.

As for using a roof vent, this is also a no no. The issue again is that you are hoping all the moist air from the fan is forced out of the vent. This will not happen completely and some of the moist air will instead get redirected into the attic. Even worse if it's a windy day where the pressure of the wind on the outside of the vent will not let the passive moist air to get out.

Ideally you want a sealed vent on the roof where the pipe from the fan attached and seals to it. This ensures that all the moist air from the bathroom goes outside and doesn't potentially end up in the attic. You're probably ok for now but should get it redone in the spring/summer if possible.

Something like this is what you want. Just get one for the size of vent pipe you have coming off the fan.

Shaner wrote: ↑ He vented it through an existing attic vent?
Losing 1 attic vent likely won't change anything.

yes existing roof vent for one of the washroom

RCLapCar wrote: ↑ Soffit vents are a no no. The issue is that warm moist air rises so it is likely to get sucked into the attic through the gaps in the soffit that normally provide ventilation to the attic introducing moist air.

As for using a roof vent, this is also a no no. The issue again is that you are hoping all the moist air from the fan is forced out of the vent. This will not happen completely and some of the moist air will instead get redirected into the attic. Even worse if it's a windy day where the pressure of the wind on the outside of the vent will not let the passive moist air to get out.

Ideally you want a sealed vent on the roof where the pipe from the fan attached and seals to it. This ensures that all the moist air from the bathroom goes outside and doesn't potentially end up in the attic. You're probably ok for now but should get it redone in the spring/summer if possible.

Something like this is what you want. Just get one for the size of vent pipe you have coming off the fan.

not 100% certain but he vented it though what looks like this in that one washroom
https://www.homedepot.ca/product/gaf-ma ... lsrc=aw.ds

for the washroom that has the vent coming out of the soffit - can i drill say a hole and pass some kind of piping through it (with a flapper) and an elbow to direct it away from the house?

roosters6879 wrote: ↑ for the washroom that has the vent coming out of the soffit - can i drill say a hole and pass some kind of piping through it (with a flapper) and an elbow to direct it away from the house?

Soffit vents aren't ideal but it might be installed so humid air isn't backdrafting into the attic. If there is no insulation baffle for air entry on adjoining rafter bays on either side of the soffit vent you should be ok.

Soffit vents can work depending on the volume of air being moved. Go fill your bathroom with steam, turn your fan on and go look at the vent. See where the air is going. If it all appears to be going up around the roof, then you're good. If it sees to be going right back up into the soffit, then yes, you'll want to address that. The sheathing will end up rotting in that area.

RCLapCar posted excellent advice, follow what they post. A video might help it be explained

User452441 wrote: ↑ RCLapCar posted excellent advice, follow what they post. A video might help it be explained

RCLapCar isn't wrong, but it is possible for soffit vents to not pump our humid exhaust where it will get sucked into the attic. IF there is no soffit vent/insulation baffle on adjoining rafter bays the soffit vents can work without issue. OP needs to take a look into the attic, see where the baffles are allowing intake air into the attic.
If the intakes aren't close to the exhaust vent location OP can do a smoke test on the exhaust fan for peace of mind, do that under different wind conditions. I have seen soffit vents that were operating without issue, I don't like them so always check them out thoroughly if doing a reno with one present.

Zamboni wrote: ↑ RCLapCar isn't wrong, but it is possible for soffit vents to not pump our humid exhaust where it will get sucked into the attic. IF there is no soffit vent/insulation baffle on adjoining rafter bays the soffit vents can work without issue.

If they didn't do the other vent properly, I seriously doubt they blocked the soffit around the exhaust, which is more of a pain to do and requires outside access and messing around with thin aluminum in lots of cases. I hope I'm wrong, but I'd bet on short cuts being taken.

Did he actually change the vent on the roof? Or just he just run insulated duct up to an existing roof vent?

If he used the existing vent - it likely is just one that let's the attic breath... so the duct wouldn't be "sealed" to it?

The proper technique is to install a dedicated vent that the duct is attached to (a vent intended for venting a bathroom fan). Dropped into the soffit is garbage...

Something like this: https://www.homedepot.ca/product/gaf-ma ... 1001090038
I also had a plastic one that worked great too... don't see it on the HD site currently. I actually had them replaced with fancy taller ones when I re-shingled, and I like these Broan and even the plastic one better...

I had to put 4 vents on the roof of my house when I moved in due to the builder just dropped the duct into the soffit. I will also point out that the insulation was SOAKED and I had to replace it all when I vented them properly through the roof. Because the ends were "open" in the soffit, I guess they just sponged up moisture - it was ridiculous. There also was water in the duct itself because it was laying flat and didn't have a slope...