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