I need some advice diagnosing the cause and remedying water stains appearing on my ceiling. Today I noticed a water stain on the stairway ceiling right along the corner where the ceiling begins a 45 degree slope. I am not sure if the cause is condensation or a roof leak. The stain is a uniform light brown largely confined to the joint tape.
The house is a two level balloon frame built in 1905 which I have fully gutted and remodeled. Thirteen years ago, I removed the plaster and lathe ceilings and walls of the house. I installed ridged foam between the wall studs and a vapor barrier. There is 2″ foam and a vapor barrier in the sloping ceiling immediately above the stain though I regret that I did not then know enough to install vapor barriers above the horizontal ceilings. Still, the ceilings and walls are now sheet rocked and painted. In the attic there is horsehair and loose cellulose insulation about 16″ which I know is not enough for our Minnesota climate. I noticed that the loose fill partially blocked the air passage between the joists for the sloping section of the roof that drops below the floor level of the attic. The stain has appeared right at this intersection.
Three years ago I replaced the roof. This involved stripping off two layers of wood shingles and one layer of asphalt. The sub-roof was rough sawn lumber which I decided not to sheath, but repaired all rotten parts. The boards of the first 4 feet of the sub-roof were spaced very wide apart (purlins) which I closed up. I’m now thinking this open setting of the boards was perhaps done to aid in bottom venting since it is otherwise impossible to provide venting to the attic from the soffits. Where the roof overhang reaches the walls, the original builder installed blocking between the roof joists so even if strip venting were now to be installed under the soffits the air could not flow up into the attic.
During the roofing project, I busted out some of these blocks thinking that this would prevent a ‘hot roof”. After doing this for about 20% of the soffit line, I stopped thinking that these might be barriers to animals. The current water stain is about 5 feet above where I removed these blocks and no stains appear anywhere else in the house. There is also a valley 5 feet right of the stain and a plumbing vent 6 feet higher up on the roof from the point where the stain appears. As for the rest of the roofing, I installed a layer of bitathain along the roof edges and in the valleys which I also lined with metal flashing. I used 35 year architectural shingles and I am confident that I installed these properly. I also installed ridge vents, though I realize the absence of air circulation through the soffits remains a problem and I now see might even cause warm air to be sucked through the ceiling. As I said, the stain is above the stairway where there is a lot of warm air rising.
I inspected the attic this cold morning and saw no frost on nails etc. The insulation was dry as a chip as was the stained area (which for all know may have appeared months ago ). I notice that the frost on the exterior of the roof melts first above the stain area.
I’m not sure why after three winters I’m just now seeing leaks or condensation problems with my roof. I’m certain the problem is not ice dams and I doubt the problem is with the valley or the plumbing vent though we have had a spring melt. I will get a garden hose up there in a few weeks. I had no leaks for 10 years with the old roof. My theory is that now that my kids are taking more and longer showers (no bath fan which I now plan to install) humidity is building up in the house.
Here’s what I want to know:
1. Has my removal of the soffit blocking contributed to the problem as cold air is convecting into these roof cells? If anything, I would think that the air flow here would be more and therefore the chance of condensation be less. I have thought about installing baffling inserts to maintain air flow up past the loose fill in the attic.
2. Should I even try to drill holes in the other blocks with a hole saw on 6′ extensions? I’m not sure if this could be done. Any suggestion how to improve lower air flow in the attic given the blocking above the soffits?
3. Will adding insulation on the attic floor help?
4. Is it worth repainting the upstairs ceilings with vapor barrier paint?
I don’t think an attic fan or heat exchanger are viable solutions.
Any thoughts?
Replies
Just a few questions that might help someone make a diagnosis:
"Today I noticed a water stain on the stairway ceiling right along the corner where the ceiling begins a 45 degree slope."
The stain is at the intersection of the wall and the sloped ceiling? Or at the intersection of the sloped ceiling and the flat ceiling?
"There is 2" foam and a vapor barrier in the sloping ceiling immediately above the stain ..."
"The insulation was dry as a chip as was the stained area ..."
You were able to access the backside (topside) of the ceiling drywall? It's completely dry? Did you have to remove the vapor barrier and foam to check for dampness?
Allen
The stain is at the intersection of the sloped ceiling and the flat ceiling. From the attic I was able to access the top of the drywall save for the vapor barrier, but the vapor barrier was dry and the drywall underneath felt dry and solid. The foam and the loose fill next to it was very dry. From the inside of the house the area of the stain was dry and solid as well.
I checked my attic again this morning. Even though we have frost on the cars, there's no frost in the attic.
Thanks for your interest, Allen
I'm not a roofing expert. In fact I've been trying to solve a leak problem in my own attic for weeks now.
It seems to me that flowing water (a tiny bit, anyway) would have to be seeping down into the drywall seam to cause that discoloration.
If it's truly dry in the attic (check after a heavy rain), then I'd be inclined to just prime the ceiling with shellac-based primer and repaint. But sometimes I can be half-azzed like that.
Hopefully someone with a better idea will chime in.
Allen
Vinyl wallpaper works for me.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
Short of testing with a garden hose (it's still too cold here) I am ready to say there is no observable cause for this stain. In fact I am ready to say that in theory the stain does not exist. I've thought about just shellacking and daring the stain to return. I would, however, sleep more soundly if I could at least attempt some corrective measure so that I can delude myself into thinking the problem has been fixed (at least until the stain returns. Hopefully I will have sold the place by then.
How about a blue FEMA tarp on the roof?
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
I think there are probably five different possibilities as to the cause:
1) Plain old roof leak.
2) Roof leak due to ice damming.
3) Condensation in the insulation, due to too much warm, moist air working its way up from inside the house.
4) Condensation on the INSIDE of the drywall -- basically from frost forming there during a severe cold snap.
5) Some other sort of stain (smoke, pre-existing contamination in the mud, etc) that has somehow made itself more obvious.