Excess Moisture on the Walls


  #1  
Old 12-27-06, 06:44 PM
P
Member
Thread Starter
Join Date: Jan 2006
Location: Pittsburgh
Posts: 80
Upvotes: 0
Received 0 Upvotes on 0 Posts
Excess Moisture on the Walls

I have an 8 x 6 bathroom and huge amounts of moisture collects on the walls after showers. We have had to repaint once already (after one year) and the paint is getting weak again.

There is a fan, but I suspect that it may be part of the problem. It is rated for 45 square feet and the bathroom is 48 square feet. It also discharges into the attic. So, not only was the contractor nice enough to use the wrong fan, they also didn't vent it properly. However, the bathroom isn't much bigger than the fan's rating and the attic space is pretty large.

So, should I get a new/bigger fan and/or vent it out the roof asap. Or, could there be another problem I am not thinking of? The house isn't insulated, but the moisture collects on both the interior and exterior walls.

(For those of you who recognize me, this is a different bathroom than the one I have been discussing here over the last couple weeks. Lucky me)
 
  #2  
Old 12-28-06, 04:23 AM
J
Member
Join Date: Oct 2006
Location: Wilmington
Posts: 3,994
Upvotes: 0
Received 0 Upvotes on 0 Posts
The fan is not that far out of size, but it certainly not doing the job. A bath fan should be about 1.5 times the area, 45 sq ft should have a fan of about 60CFM. It should vent to the outside, and don't use flex corrrugated ducts, they severely restrict air flow. And every elbow reduces the effective size of the fan. Venting it into the attic won't cause the problems you describe, but it is still not a good idea. It can cause mold and rot in the attic.
 
  #3  
Old 12-28-06, 07:08 AM
P
Member
Thread Starter
Join Date: Jan 2006
Location: Pittsburgh
Posts: 80
Upvotes: 0
Received 0 Upvotes on 0 Posts
I plan to fix the venting into the attic problem... I actually just discovered it.

I actaully have to use the flex pipe in order to get to a good spot to vent
 
  #4  
Old 12-28-06, 04:11 PM
J
Member
Join Date: Oct 2006
Location: Wilmington
Posts: 3,994
Upvotes: 0
Received 0 Upvotes on 0 Posts
If you must use flex pipe, use the aluminum pipe that has much smaller corrugations. But I have done a lot of fans over the years, and in most circumstances, I can avoid flex pipe.
 
  #5  
Old 12-28-06, 05:06 PM
T
Member
Join Date: Aug 2000
Location: USA
Posts: 15,047
Upvotes: 0
Received 2 Upvotes on 2 Posts
"Huge amounts of moisture collects on the walls.." In addition to a properly sized vent with adequate CFMs that is vented to the outdoors, insulation is a consideration. Warm, moist air that encounters cold surfaces will condense, just like it does on the outside of an ice tea glass in the summer. If properly insulated, wall surfaces tend not to be so cold that "huge amounts of moisture collects on the walls."

In the meantime, run fan to improve air and heat circulation. A dehumidifier can be run to remove excess humidity. Leaving bathroom door open during and after bathing is also helpful. Running vent/fan unit during and after bathing/showering for 20 minutes will help exhaust humidity.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: