The problems of venting moisture from a bathroom into an attic can be very severe and vast. The venting of bathrooms into attic space has been going on for years now. The code which states this can not be done has been changed many years back. The practice was used all the time. Many older homes did not have venting in them at all. The venting in the older home bathrooms was a window in the bathroom. Let’s face it no one really wants to open a window in the middle of winter to vent the moisture out of the bathroom. I have been in many houses where these windows don’t even open due to moisture problems or have been painted shut.
The bathroom vents have been code for many years now and most are now also vented correctly to the outside of the home. You can still see improper venting when a home owner installs a exhaust fan and does not know where to go with the tube from the fan. I have even seen it just vented directly into the attic space. The amounts of moisture this can put into your attic can vary on how many people live in your home and how many showers are taken daily. I can tell you this even one shower a day and vented directly into the attic space is not good.
I was visiting a client’s home and they had a new roof put on the home, but did not vent the bathroom through the roof at that time. If you have a older home and you have the roof done, this is a great time to spend the extra money and have the company install a roof vent for your bathroom. This is a very easy task for anyone who professionally installs roofs. While I was visiting the clients discussing gutter protection, it was pointed out there was a dip in the roof over the bathroom area. The home owner explained that the person who did the aluminum work on the house said, just get the tube to the overhang area as there is small holes there in the overhang. I explained the the overhang holes are for attic venting and is not able to handle the moisture from the bathroom.
The client then told me they took the tube and just put insulation around it, so it would force the air to the overhand of the house. I explained that by doing this the moist air would then collect on the roof boards causing mold to grow and the boards to rot. This house showed how venting moisture directly into the attic can cause structural defects. The roof above the vent had dipped down almost a half inch or more. It was explained that placing a vent in the overhang would take care of this problem. It is also possible to still put in a roof vent at this time. It takes more time and should be done by a person who installs roofs, when installing a roof vent.
So, you can see venting bathroom moisture into the attic is not good. The vent in a bathroom needs to also be sized to the room to make sure it can get the moisture out of the bathroom also. So, you do need to make sure your bathrooms in your house are vented to the outside of your home. Again, even if you only take one shower a day the moisture can cause mold growth and rot your roof.
As with any home projects safety first.
