Ridge vent causing leak over cathedral ceiling? (floor, shingles, Air Conditioner)

[Whatever1]

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?

[Cosmic]

That ridge vent is put on after about a 2-3 inch gap is left open right at the peak. Usually a gap is left on both sides of the ridge beam. It usually runs all the way across the roof. Gaps run parallel to the beam. There is no roof wood decking or shingles in that area, that gap is completely open to allow air to flow under the roof and out the vent.

Three possible factors could be involved.

1. He made the gaps too wide

2. Your roof slope is too flat

3. He made a splice in the ridge cover and didn't get it quite right.

Crawl up there and inspect it again. Ensure a spice is not made in the cover, about right where you are getting the leak. Especially just a butt type splice where a gap could be available that water can leak thru, if there is a splice should be 6 inches or so overlap. I don't remember exactly how long those covers are, it may have needed a splice. Some provision should have been made if there is a splice. There is some black sticky tar stuff that looks like thick tape, sticky both side, that or something should have been used under a splice area if that cover can't be overlapped due to appearance.

That ridge cover should overlap the gap underneath by something like a couple inches. What can happen is the water dripping down off the cover can get blown back thru the filter material underneath by wind during a rainstorm. Not that uncommon for it to happen. Usually in a house with attic volume, you just put some sheet poly under that area and arrange it so the sides are dished to hold the water that might leak, it just evaporates out.

In your case it might be far tricky. You probably don't have any area or access to attempt that solution. Might attempt to slip some sort of shim materials under the cover both sides to further extend the area before it drips. Your slope could also be a factor. Water can get blown back up that roof area by very strong wind.

Seeing as how it is a wee, wee bit. I would start with the searching for the splice and try to locate the exact spot in the ridge vent where the leak is. See if the splice (if there is one) matches with the location of the leak. Also inspect the filter material underneath and ensure there is not a splice in it at that location, maybe leaving a gap that wind could blow water thru. I also see lil lbump areas under the filter, ensure there is not a big one that you can see back thru. In general that type system works pretty good, the filter material catches most dirt, water, big bugs but leaks can happen in bad storms. Some covers and the filter materials are made as one piece, depends on what you got.

Anywho, I would start by measuring or whatever to get the exact spot in the house, then check that location on the roof and see what can be determined.

[Cosmic]

I didn't see your last comment.

It does look a bit wavy but that is sort of normal. Wondered did he just cut normal shingles to make the cover.

[harry chickpea]

"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."

You just answered your question in the first paragraph.

Consider the dynamics. You have a ridge vent that allows air to pass from interior to exterior of the tiny attic space, and in some conditions, in the other direction. You have a cathedral ceiling and an exposed (to the interior) ridge beam. Ridge beams by definition are not insulative material like an air space or fiberglass. By installing a ridge vent, you have one side of the beam much closer to the exterior temperature, and the interior of the beam at the peak indoor air temperature.

Here is an example of what can happen:

You have a cloudy day when the roof doesn't heat much. The ridge beam stays near interior temperature. Night comes and you turn off any heat source. The ridge beam starts to cool from the interior, but also now cools significantly from the cool air being drawn over it because of the ridge vent. The beam cools to 55 degrees, or colder in winter depending on the various factors.

In the morning, you come in to the space and cook hot oatmeal, or turn on an unvented gas heater, or open the door to the bathroom where you just took a shower. The hot moist air rises to the ceiling, and encounters the cold surface of the ridge 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 it will be a small enough amount of condensation that you don't notice it. Sometimes the surface of the beam will warm quickly enough that it evaporates. Other times, it drips. At other times, there is no noticable condensation, but your beam is living in a rainforest environment. The same thing can happen at night when you sleep, as the humid air from the day cools, or on a windy cold day, when the beam is cooled more than normal.

IMO, the roof vent needs to be removed, the opening in the deck closed, and area re-shingled. 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.

[Barking Spider]

Since the roof is such a low slope, it is not likely you can get into the attic above the stain (there might not even be an attic).

The wavy look, may just be the way it is. This type of ridge vent is covered with shingles, so looking for a butt joint may be difficult. Butt joints usually have a transition piece, but this vent is covered with shingles.

Is the leak/stain anywhere near the plumbing vents? Did you happen to look at the flashing around them?

Harry may be on to something though.

[Cosmic]

Been a while since I have done a roof. That didn't look right to me. Was out riding around, looked at roof's.

He has apparently cut shingles like in the old dazes, to make the roof peak cap. How he nailed them your guess.

Those covers if custom; snap in, they set up higher and are far neater. Probably far less chances of getting back leakage. That is why that looks so sloppy. Some are the same color as the shingles, some are like a grey or black. So not the best in any case.

I don't know about the condensation argument, can see it both ways. If that vent is done right the air can not get in contact with the beam to see the temperature difference. With that design only the volume of the rafter bays are probably being used for both under roof air flow and insulation difficult to say, exactly what they did.

It might be condensation, it might be leakage from rain. Can you relate the incidents to a rainstorm?

The other argument against the condensation idea is it should occur in more than one spot, maybe all along that ridge. Should be far more common in other houses. I got a roof vent, zero condensation AFAIK.

Anywho, I rethought the entire process. Not a good installation, he went on the cheap. Left lots of possibly paths for problems. Yeah, I would be tending to ripping it out, might inspect it first as I said in the first post. Verify they really are cut shingles.

See what type of traction I could get with the roofer guy. Probably get the typical run around.

[DanBev]

I do not understand why an aluminum ridge cap was not used,looks cheap and sloppy.Mine has been on for 30 years fastened down with 1 1/4 screws.Been thru very heavy wind.Friend 's was mailed down and wind lifted it.Has never leaked.

[Whatever1]

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 believes 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.jpg


longer shot of present roof


close-up of plumbing vents


floorplan

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

[MikeJaquish]

1. Your roof slope is too low for ridge vent. Ridge vent is specified for a minimum of 3/12 pitch.
http://www.airvent.com/pdf/installat...nt-install.pdf

http://www.airvent.com/pdf/installat...II-install.pdf

2. That minimum pitch is needed to allow convection currents to build and to move air from the soffit vents to the ridge. Low slope does not create adequate convection current.

3. I bet a jelly donut (and that is HIGH stakes for me ) that the insulation in your cathedral area fills the rafter cavity, blocking ALL air movement from soffit to ridge. In a blowing rain, the wind passing over downwind side of the ridge sucks air out of the vent and creates a vacuum that draws rain-laden make-up air into the upwind side of the ridge vent and staining the ceiling.

You probably need to eliminate the ridge vent.

[harry chickpea]

You are on with that jelly donut bet. (yumm ) However, looking at the additional photos and hearing the descriptions, I'm about 99.9% positive that we are both right on the need to remove the ridge vent. It simply does not fit the application. The exact method of failure is less an issue than finding the solution.

FWIW, looking at the roof, I would not put in the roof turbines I considered earlier.