Ridge vent leaking? Or what?

Whatever1 · 09-24-2008, 01:41 AM

We had a new roof put on 17 months ago. It is a low pitch roof (2-12). A continuous ridge vent was installed that runs the length of the 50' 6" roof. Not long after the job was finished I called the roofer back to point out to him what looked like a couple of small yellowish drip stains running down (maybe 6" long) from near the exposed center beam in the living room's 12' wide cathedral ceiling. Without getting on a ladder, he looked at it and said it probably was condensation. We decided to monitor the situation. After a time, the stains disappeared and we assumed he had been correct.

During the past 17 months though we would occasionally discover spots on our living room furniture and floor. My wife thinks these usually appeared a few days after a rain. We would examine the ceiling, but could see no stains on the ceiling, so were at a loss as to what was causing this. I believe I did stick my head up in the crawl space during one storm and could see no dripping anywhere, but don't remember if there were subsequent spots on the living room floor.

We even thought that it might be something in the leather furniture "expressing" moisture (or some sort of oil/resin) outward. Since there was no ceiling damage, we did nothing.

About 6 weeks ago, after over 2 years in the house, we discovered what appeared to be evidence of mold on the east side of the beam (the side where the stains were appearing below) and some dark spots on the ceiling. A mold technician advised using Spirocidin to deal with the suspected mold. We did and thought the problem solved, but recently noticed more spots on the floor. Inspecting from a ladder today I was amazed to find numerous droplets along the bottom/east edge of the beam. Running my hand over one area of that side of the beam, I found it to be quite wet. There are also now more black dots on the ceiling extending out about 18" from the center on that side. We had a mild rain 3 days ago, but don't remember any wind.

I began to wonder if the ridge vent could be the culprit and got up on the roof and took the attached photo.

I don't know what the ridge vent looked like right after installation, or if there is a problem with this, but I am wondering if the waviness evident is problematic or normal after 17 months exposure to sun and weather. After searching the web a bit tonight, I am beginning to wonder if the ridge vent should be removed and some other form of venting installed. What do you think?

johnk · 09-24-2008, 02:26 AM

Looks to me it is coming from your ridgevent.Replace it with a ridgid ridgevent.Shinglevent 2 or Cobravent is what I'd choose if its available to you.

jayp · 09-24-2008, 05:37 AM

First of all, that ridge vent looks like it's probably about as effective as having nothing at all. Your roof pitch seems kinda slight so I wouldn't be surprised if water was backing up in there. I've seen that stuff at Home Depot I think -- I wouldn't have put that up there when there are so many other ridge venting systems that are superior. What you have there is pretty much the cheapest thing made. Looks like your contractor either took you for a ride or doesn't know much about venting.

buletbob · 09-24-2008, 05:45 AM

another thing I can see, is that the plumbing flange is installed back wards, you could have rain water backing up under the vent from that location also. BOB.

jayp · 09-24-2008, 09:33 AM

Good eye Bob -- yeah, if your moisture is coming from that side, you might have found the problem.

johnk · 09-24-2008, 10:33 AM

I seemed to have missed the 2/12 part.The pitch is too low for a standard ridgevent.I have used it on low slopes without problems,but not that cheap rolled ridgevent,like you have.I just figured because it was shingled it had more of a slope than a 2/12.Do you know what kind of underlayment they used?

**Ed the Roofer** · 09-24-2008, 11:58 AM

See my 2 answers so far on the other roofing site you posted this on, if you have not checked it out yet.

Ed

Whatever1 · 09-24-2008, 09:59 PM

Going over previous ground and adding some
Returning from trip, we were told that, when the remnants of Hurricane Ike came through (Sept. 13-14) there were 60 MPH winds with a little rain. We did not note anything unusual inside the house.

Saturday, Sept. 20: We believe there was a light rain on/off, with no wind. No rain the next 2 days.

Tuesday, Sept. 23: We had an east window, south French doors, and west entrance door open most of the day. The inside temperature rose to 78°. The inside relative humidity was 71%, and 68 a little later. We started the air conditioner. The house cooled down later in the day. We kept the doors closed.

We noticed spots on living room floor and the west side of the main ceiling beam in the living room was very wet. We could see vertical drip lines on the beam, and drops on the floor. There were also some black (mold?) spots on the ceiling near the east side of the beam, over an area not more than 18 inches from the beam.

Opened a bedroom French door slightly around 10 and closed it around 4 AM.

Wednesday, Sept. 24: It was cool. May have opened a south French door a little for a short time in early morning. In mid-late morning, climbed up to check the beam. It felt dry, but a little cool. Went out and left the house closed. Returned after 2 PM, the sun was out (partially cloudy) and it was warm outside, but only around 74-75° / 68-70% inside. We opened the studio window, carport door, and front deck door. Climbed up ladder: west side of beam was damp with a few drops of water on bottom edge. By then the inside temp was 76°. Closed the doors and put the air conditioner down to 75. A little while later, turned on the house fan so there would be constant circulation even when the air conditioner isn't running. 7PM: beam is dry.

Replies to some posters; thanks to all:
"what can happen: cloudy day / roof doesn't heat much / beam stays near interior temperature. Night / turn off any heat / beam cools from the interior, also cools significantly from cool air drawn over it via ridge vent. beam cools to 55 degrees or colder... morning, you cook or turn on an unvented gas heater, open to bathroom - just took a shower. hot moist air rises to ceiling, encounters cold surface of beam. If the dew point of the hot air, say 65 degrees, is higher than the temperature of the beam, moisture will condense on the beam, and the air around it will be supersaturated with moisture. Sometimes more/less - don't notice it. Sometimes beam warms quickly enough that it evaporates. Other times, it drips. At other times, there is no notnoticeablendensation, but your beam is living in a rainforest environment...
If you didn't notice any significant decrease in cooling costs after the new roof was installed, I'd leave the roof unvented. If I did use vents, I'd use roof turbines at least five feet from the ridge beam." (harry chickpea)

We don't know if we have saved money, but my wife belies the AC is coming on less frequently this year.
Are you suggesting turbines in addition to the ridge vent? How many?
We find harry chickpea's condensation theory compelling, but the suggestion to "unvent" seems radical and doubt we would find many local builders in agreement. Complicating matters is the fact that we are in the process of moving out, having sold this house about 3 weeks ago. We'd like to discover some reasonable suggestions for action, but the decision will not be ours.

"Is the leak/stain anywhere near the plumbing vents? Did you happen to look at the flashing around them?"
Not really near plumbing. See photo of pipes.

"The other argument against the condensation idea is it should occur in more than one spot, maybe all along that ridge."
The moisture does seem to extend over much of the west side of the beam, though not evenly.

"Do you know what kind of underlayment they used?"
The contract (my stipulation) called for:
Install 2 layers [req by Tamko warranty for low roof] water resistant 15# felt to decking.
This was supposedly complied with.

"What about the continuous Intake Ventilation? Was that addressed?"
Not sure exactly what is meant, but the house has wide overhangs all around and vents in soffits. From outside, they appear unblocked.

Close-up of ridge vent mid-Cathedral ceiling

longer shot of present roof

close-up of plumbing vents

floorplan

Even more images - http://s462.photobucket.com/albums/qq345/hopnort/roof/

tinner666 · 09-24-2008, 10:38 PM

The vent collars are all correct. Turned right way and good amount exposed. No problems there.

jayp · 09-25-2008, 03:25 PM

Were there any rafter baffles installed to move air from the soffit to the ridge vent? If not, there could be a lot of moisture buildup in there especially if the rafter channel is blocked by insulation or something else.

Whatever1 · 09-25-2008, 07:24 PM

Quote:

Originally Posted by jayp

Were there any rafter baffles installed to move air from the soffit to the ridge vent? If not, there could be a lot of moisture buildup in there especially if the rafter channel is blocked by insulation or something else.

I don't know what is in there... have only lived in this 1970 house for the past 2-1/2 years.
Latest data - To increase circulation, turned on house fan Wednesday, Sept. 24 approx 2pm.
Thur Sep 25 fan off at 5AM; 7AM beam dry (room: 70°/71% humidity).
10:30AM turned on house fan.
Thur Sep 25 1PM beam dry (74°/76% humidity).