Replies

1. 
   mark122 | Jun 09, 2015 12:58pm | #1

   how far along on the repair are you? has the roof been replaced yet? have you pulled the sheetrock off? there are ways to vent but you are very limited with 2x6 rafters

1. 
   Workles | Jun 10, 2015 12:20pm | #2

   I'm in the planning stage and interviewing local contractors. Some of the roof was replaced some time ago and no sheetrock has been removed or compromised.

   Well it s taken 20 years to get to this point and realizing that its condensation from not venting at the top of the joists. Roughly, 8-10 years ago, i had warped 3/4 plywood replaced above some sections of the cathedral ceiling. That section of the roof had the shingles, paper and thermal sheild replaced. I thought the problem was from "wind driven rain" since that section of the house faces the NW which is the direction of most of the weather here. I also initially had some water come in through the end of the ridge vent during a storm and had the ridge vent moved back further from that end of the house and the ridge vent's end covered better.

   One of the possiblities I've been exploring is to put ridge vents along the angled peaks of the hip roof section. But others warn against this.

1. 
   catmandeux | Jun 10, 2015 06:54pm | #4

   There are special hip vent for just the situation you describe. I have not used them  it so I cannot provide any recomendation, but they seems like a good idea in theory.  They have directional venting to  control rain / snow infiltration, so it would be better than regular ridge vents for the hip installation.  A couple of links that I am aware of, there may be more:

   http://www.gaf.com/Roofing/Residential/Products/Roof_Vents/Cobra_Hip_Vent

   http://www.airvent.com/professional/products/ridgeVents-hipridge.shtml

2. 
   mark122 | Jun 11, 2015 06:08pm | #7

   just knowing what we know from your description I would be inclined to advise against the hip venting as well. if you know you are getting condensation in the rafter cavitiy this could just make it worse.

   can you describe the 3/4 ply warping a little more? how long are your rafters spanning and whats the spacing?

   with the plywood, where was the warping more evident and what side showed signs of damage?

1. 
   Workles | Jun 12, 2015 12:37pm | #8

   The plywood warped in the middle of each of the cathedral areas. The ends of the plywood curled up which you could see from the shingles. The shingles were well fastened prior to the warpage. It was'nt the hole cathedral ceiling area, but it was directly above where the drywall had swelled during the spring and thenshrunk during the summer as it dried and there were cracks at the tape.

   The width of the great room is 32' and depth is 16' on 16" centers.

   Not sure about the side the damage was on as my contractor removed the sections that were replaced.

2. 
   AndyEngel | Jun 10, 2015 02:21pm | #3

   Venting may not do it

   Couple of questions to help us out. Where are you located? Do you have penetrations in the ceiling such as recessed lights? And maybe most importantly, believe it or not, is what the foundation is like. Do you have any moisture issues there? I've looked at a lot of houses over the years, and I've hardly every seen a damp roof that wasn't coupled to a damp foundation, unless the roof itself leaked. 

1. 
   Workles | Jun 11, 2015 12:36pm | #6

   Western PA. One penetration for a hanging light over the pooltable, but nothing recessed. Foundation is solid, with a vapor barrier under the poured concrete floor, wolmanized cap on top of block, brick exterior. No leaks or standing water. The issue with the roof or drywall usually occurs in the early spring when there are many nights of freezing temperatures at night and temperatures in the mid 40's. It seems that this cycle is followed by some swelling of the drywall (wetted) and then contraction once summer hits and then the tape line crack. It is strange becasue this appears about halfway down each ceiling section for the drywall and plywood warping on the roof side. IT took almost 10 years for the roof plywood to warp.

1. 
   AndyEngel | Jun 15, 2015 10:13am | #9

   Well, I'm puzzled

   Before you tackle this, I suggest heading over to our sister site, greenbuildingadvisor.com, and asking there. Those gurus are likely to have more insight than I do. Could it be that condensation builds up as ice when it's colder and melts in the spring? What's the source of the moisture? It sounds like a significant amount of moisture, and I wonder if venting would be effective. 

3. 
   Workles | Jun 11, 2015 12:18pm | #5

   This really provides a lot of information. I review these with the contractor to pick one. The GAF appears to have a better warranty.

   Thanks!