Replies

1. 
   fortdh | Jan 19, 2004 11:05pm | #1

   I think you will condense moisture right into the roof sheathing, which will begin rot under the roofing.

   Now this is a possibility for you to try. No guarantee, and you need to check on it frequently for potential moisture. Seal the edges of the plywood with something like aluminum mastic backed duct tape for the entire distance between two roof rafters.(ridge board as well if you have one).This is not cheap tape. Has a heavy grey mastic on one side. You may have to heat the ridge vent material with a hair dryer, but once the tape sticks, it's pretty solid. Wrap/stick it from inside of the ridge vent to the under side of the plywood or osb... and staple it in place to the plywood(and ridge board). Block the two ends of your ridge vent chamber(14 1/2 " if rafters on 16' centers) so that all of the bath air has to leave the ridge vent in that immediate area, and not travel to the sides and condense downstream. You want a water proof membrane from the ridge vent material to well inside the under side of the sheathing. Then box the chamber with something like foil foam board, well sealed so that all interior surfaces are water proof. ( you are making a custom fit hvac boot to fit you situation.) Then connect the bath vent to the "box". I would connect from a side,between the rafters, not the face, so that you can remove the face "plate" to inspect inside the box. I do not know the vent sq. in. opening of free air space vs the cfm you will be blowing, but there is a chance this inexpensive experiment will work if the bulk of the moist air is blown clear of the interior, and only minor condensation occurs. You could leave a small sponge inside the box, and check it after a few rounds of venting to see if soggy. If not too wet, it may hold the water long enough to evaporate before the next shower.

   Other than that, its through the roof or wall. When the others who read this stop laughing, maybe they will have some improvements to offer.

   Hope this helps, Paul

   Energy Consultant and author of Practical Energy Cost Reduction for the Home
1. 
   johnnyd | Jan 19, 2004 11:10pm | #2

   OK, I get your drift.  Think I'll just run the flex or maybe rigid up the truss...note the measurements and go up and do it right from the top this spring when it's once again civilized outside and well before the first shower.

1. 
   fortdh | Jan 20, 2004 03:05am | #13

   Well johnnyd, the votes are in, and the guys didn't think my suggested non-certified, non-guaranteed, shot in the dark, temp box would work. Too bad you can't vent through a wall. I don't like any extra holes in roofs any more than you do. PaulEnergy Consultant and author of Practical Energy Cost Reduction for the Home

1. 
   gatno | Jan 20, 2004 05:01am | #14

   One plus to stickin it up at the ridge, specially on a metal roof, is that a thru the roof vent is so much easier to install if ya can just stick it underneath the ridge.  (but yeah, what happens to the condensate when down is just back to the fan...?)

   rod in quebec

1. 
   HeavyDuty | Jan 20, 2004 05:38am | #15

   What about terminating a bathroom vent just behind a gable vent? I'll try to face it to the down wind side.

   Any thoughts anybody?

2. 
   gatno | Jan 20, 2004 06:01am | #16

   yeah, done that--seemed to work fine--just find a way to let condensated drain outside. 

2. 
   johnnyd | Jan 20, 2004 04:43pm | #17

   Or I could stop taking showers

2. 
   rjw | Jan 19, 2004 11:15pm | #3

   I don't see enough ridge venting and bath fan venting by the ridge to draw any conclusions, but in my climate, it almost always works to nail off a bath vent next to a thru roof vent

   Personally, I would try it with the ridge vent but would monitor closely for awhile for condenstion

   _______________________

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3. 
   BossHog | Jan 19, 2004 11:20pm | #4

   Sounds like a REALLY bad idea to me.

   It might work temporarily. But temporary things have a way of becoming permenant when we don't get around to fixing them. (Or forget them)

   I suspect you'll get all kinds of ice and moisture problems if you leave it like that.

   Lettin' the cat outta the bag is a whole lot easier 'n puttin' it back. [Will Rodgers]

1. 
   davidmeiland | Jan 19, 2004 11:27pm | #5

   Agree with the Boss. If I were doing it I would not terminate it near the roof, I would terminate it maybe a foot above the insulation. That would let the moisture spread out a bit rather than hitting one small part of the sheathing and rotting it out. As soon as it's spring you need to punch a hole through the roof and get it outta there.

2. 
   johnnyd | Jan 19, 2004 11:27pm | #6

   I'm 100% with you after giving it some thought.  You tend to think differently, however, when standing there at about 0 F and going through the mental punch list of what needs to be done before the temp furnace can even make a dent.

   Guess I'll get the carharts out.

1. 
   BossHog | Jan 20, 2004 12:11am | #9

   "You tend to think differently, however, when standing there at about 0 F and going through the mental punch list of what needs to be done before the temp furnace can even make a dent."

   Believe me, I understand - I've been out in weather like that too. (Taking care of livestock and such)

   But I've also put things off and know how hard it is to get back in the mood to work on them again when other things pop up that need done.

   Like the temporary light I wired outside the back of the house figuring I would straighten it out later. It's been there 9 years......................(-:ADAM TO EVE: Hey! I wear the plants in this family!

1. 
   johnnyd | Jan 20, 2004 12:19am | #10

   Probably would be a good thread, especially when procrastination ended up biting you in the ***.

   Like a neighbor I had told me a sob story about why his house was totaled by a fire...luckily no one injured or killed.  Seems a few years ago he had "temporarily" run an extension cord under the carpet...you know the rest,

   I tell that story everytime someone asks why I'm putting so many outlets in... 

3. 
   rjw | Jan 19, 2004 11:42pm | #7

   I agree that it _sounds_ like a bad idea; and I certainly agree about temp solutions often becoming permanent.

   OTOH, I see bath vents nailed off next to through roofs a lot (which also sounds like a bad idea to me!) and they almost always work fine. (out of probably a couple thousand such onstrallations, I can only think of 1 or 2 which have had condensation problems.)

   I don't know it the air movement through a ridge will be different enough to affect the result.

   _______________________

   Tool Donations Sought

   I'm matching tool donors to a church mission to Haiti - we're shipping a bus converted to a medical facility in (now it looks like) April and can fill it with clothes, tools and all sorts of stuff needed in that poorest of all countries. A few hand tools or power tools can provide a livelihood for an otherwise destitute family. Please email me if you have tools to donate.

   Thanks to Jeff and David and Jim and Rich and Steven and Mark and Jason and Shep and Jen and Mike and Joe for their offers!

   The first donation just arrived! Thanks and God bless!

   "You can safely assume that you've created God in your own image, when it turns out that God hates all the same people you do." Anne Lamott

1. 
   brownbagg | Jan 19, 2004 11:58pm | #8

   I did this to mine about a year ago and within months the plywood under was covered in mold, I did not want to cut the roof either because I have a metal roof. No choice just do it.

   nuthing but happy thought.

1. 
   rjw | Jan 20, 2004 12:22am | #11

   BB - by a ridge vent or through-roof vent?

   _______________________

   Tool Donations Sought

   I'm matching tool donors to a church mission to Haiti - we're shipping a bus converted to a medical facility in (now it looks like) April and can fill it with clothes, tools and all sorts of stuff needed in that poorest of all countries. A few hand tools or power tools can provide a livelihood for an otherwise destitute family. Please email me if you have tools to donate.

   Thanks to Jeff and David and Jim and Rich and Steven and Mark and Jason and Shep and Jen and Mike and Joe for their offers!

   The first donation just arrived! Thanks and God bless!

   "You can safely assume that you've created God in your own image, when it turns out that God hates all the same people you do." Anne Lamott

1. 
   brownbagg | Jan 20, 2004 01:34am | #12

   Started out just under the ridge vent. did not work so I had to go throught the roof just lower than ridge vent

   nuthing but happy thought.