leaking roof vents

[beer batter]

We have some roof vents that face north. In strong wind conditions from the north, we'll find moisture on our bathroom floor that leaked in from the fan/vent tube that runs up to a roof vent.

Now it appears to be getting snow blown inside the vent tube, and when it melts it makes water spots on the bathroom ceiling, and drips in through the fan housing itself.

Crawled in to the attic and found snow patches on top of our insulation under areas with other roof vents, and when I raised up our ventilation tube that runs from the bathroom fan to the roof vent, more water rant out in to the bathroom.

Roof was replaced about 4 years ago, so the vents should all be up to code (I hope). How does one stop moisture from getting in those vents with horizontal winds?

[dillon]

Beer Batter, I have water dripping from my bath fan vent also. I initially thought that the moisture was coming from outside in the form of rain/snow, but I am now fairly sure that it is melting condensation from the vent tube. This only happens in the winter.

Last week my roof vent was frozen shut so it didn't allow the air to escape. I opened the vent and shortened the tube length, but the problem showed up again today. I think that I might try putting insulation around the tube.

We seem to have the same problem, but I am not sure if it is being caused by the same thing. Do you get water dripping in the summer from wind driven rains or is it only in the winter?

[Surface Tension]

Use an insulted flex duct. The warm moist air won't condense inside the duct as much.

[Tom7227]

Two possiblities - the flapper jobberdo on the vent isn't closing properly and/or you don't have insulated duct work and it's condensing in the tube. Tough to tell this time of year whether the flapper is boogered up but if you took the ducting off you may be able to see. Tougher to do anything about it not unless it's something simple like a wasps nest or something you can clear from the inside. No matter what if the duct isn't insulated replace it with a piece of insulated ducting. Fairly reasonably priced at the box stores.

[soldoncass]

just had a long post wiped out ....at MY typing speed that is NOT GOOD

SHORT VERSION- need insulated 4" pipe from fan out the gable end siding, with flappers on the outlet. Blown insulation over pipe doesn't hurt either. When we started doing that, it eliminated problems going out the roof, snow covering etc.

Snow coming in roof vents can only be controlled by great ventilation system (soffit,proper vent chutes, roof vents). With air moving up and out, it is hard for snow to blow in.

[beer batter]

We have an insullated flex tube running from the fan to the roof vent. We've been seeing it (water) more requently since winter has hit, but we have seen water/moisture damage to the sheet rock around the fan housing in other times of the year.

When it's windy out, you can hear the flapper on the roof blowing open and closed quite often. Is it perhaps a faulty flapper? Should they not blow open and closed when the bathroom fan is not running?

[soldoncass]

BB,

I'm a little confused about what you have... years ago people used to run a pipe from a fan up "near" a roof vent, and call it good. They never worked well...it should be connected to an outlet (roof or wall) with its own flapper. Then it has 2 flappers on the system(one in the fan and one at the outlet). Keeps the brutely cold air away from the warm 70degree inside air at the fan flapper. The huge temp difference (with humidity diff) is what condenses, and you see the moisture created. Flapper outlet out the gable end wall is the way to go.(unless you have a hip roof, then you have to go out the roof)