I came across Harry's article about vapor barrier and would like to ask for advice about my problem. At each spring thaw-out (late March), I usually found some water at the bottom of the walls in our bedrooms (these are exterior walls & the bedrooms are upstairs of a 2-story 4-year old house). At the same instance, there were also 3 or 4 streaks of water dripping down on the outside of the vinyl sidings; the streaks started in the region between the windows of two bathrooms (bathrooms are also on 2nd floor, separated by a walk-in closet); a small water stain mark (1-inch long) was also found at the bottom of a wall in one bathroom, (I could not inspect the exterior wall of the other bathroom because it is behind the shower stall & bath tub).
When the inside wall was removed in one bedroom, I found two tears (4-5 ft long) in the vapor barrier near the location where water was observed. It seems the tear caused condensation behind the vapour barrier, which then caused water to appear at the bottom of the walls in the bedrooms.
I wonder what could cause the water streaks seen on the sidings, and the stain mark in the wall of one bathroom ? How can I inspect the vapor barrier in the bathrooms (without ripping apart the ceramic work, the mirrors, the tub, the counter top carpentry, etc.. attached to the exterior wall ?). Can I get to the vapor barrier in this area from the outside (i.e. removing sidings, OSB sheathing & insulation) to see if the barrier is damaged or not ? How the vapor barrier should be sealed around window rough-in wood frame, and to the bottom plank of the wall ?(Is sound insulation sealant required for that? I did not find sound insulant put around window opening and at bottom plank). The more general question is what could cause the outside water streaks/icicles and how to fix it. (The attic was checked OK (dry), the hole for vent piping was properly sealed in the bathroom). Any thought and help you provide is greatly appreciated; please ask me if questions. (I already talked to the builder, but am not too sure how much help I will get). Thanks.
TranMcT

How old is your home and what area of the country are you located?
There could be a number of reasons for the water damage.
I'm going to ask you a bunch of questions to see if I can determine the main water damage cause. Answer what you can and ask questions yourself for details you might not understand.
1. Do you live in an area with large amounts of snow accumulation along with fluctuating outdoor temperatures?
2. If the answer to the above is yes, then have you ever noticed ice accumulation forming at the eave area on the roof?
3. Do you have a bath fan that's equal to a minimum of 1 CFM per sq ft of room size?
4. Does your home have an air to air exchanger?
We'll start with these for now and progress depending on the resulting answers.

Vapor permeance of the wall structure materials and thermal characteristics of the assembly all contribute to the amount of resistance to water vapor entry or vapor/condensation accumulation on certain parts of the structure. There are many factors involved in determining the cause of the problem IE: exterior temperature,temperature of the individual wall components from the outside to inside, type of exterior cladding,building paper or air barriers etc.
So you may already see this is not an easy process without a lot of detailed information from your end.

As for investigating a vapor barrier, that will be impossible to do from the outside efficiently. You need to do all tear outs from the inside, starting with the drywall and if need be all tile and backer in the bath area.

Air movement from exterior to interior or reverse is the major cause of waterdamage from water vapor and worst case, water penetration from the exterior. This is why you may have noticed the water pooling where the vapor barrier was torn. It forms condensation just like a cold beverage on a hot day. The rip in the poly is the pathway for cold air to meet warm air, thus forming condensation if all the criteria is met.

The best you can hope for is to seal all penetrations in the wall cavity to stop or reduce as much air flow as possible. This means poly, electrical boxes on exterior walls, plumbing penetrations within the wall cavity(ABS vent pipes)and electrical wire runs.

Thanks, Randall, for looking into this issue. Please find some quick answers below and I'll continue tomorrow evening (I work tomorrow).
1) Our home is 4 year old, built at end of 2006. We live in the Northern Alberta region, winter is long & cold but ouside temperature seems to steady, -25C to -35C in Dec to Feb. And yes there is about a foot of snow on the roof. In early April, there usually is a one or two week warm spell where temperature may get up to 15C in day time and -5C at night. It was at these periods that the water problem was observed, probably as it is the 1st time the outside temperature goes above 0.
2) I did not see any icycles forming underneath the eaves (soffit) area. This year, we climbed into the attic to check for water stain underneath the roof plywood but did not find any. We came in the attic one or two weeks after the temperature had warmed up, so I am not sure if the water marks might have already dried up ? For the coming winter, what symptoms should I check ?
3) I'll check the fan tomorrow
4) Could you please explain what the air to air exchanger is ?
Thanks

Your weather conditions are similar to those here in Ontario, however your average winter temperatures are much colder.
Extreme cold to warm temperature fluctuations are the main ingredient for forming ice dams.
These ice dams start forming under the layer of shingles and eventually the melt water ends up somewhere in the house. You normally will not see any ice forming under the eaves. The first tell tale sign is what would appear to be ice in the snow pack on top of the roof just above the eaves trough. Ice dam formation also need the warm air which leaks out of the house at the top of the wall. This area is normally a poorly insulated section of the building envelope allowing a fair amount of heat loss.
You may or may not see any actual ice on the underside of the roof sheating nor any watermarks. Once the ice starts to melt it drips down into the insulation and then on to the top of the vapor barrier. The water will eventually find an open seam or penetration to run thru and then down the wall.

I have seen ice dam water travel up to twenty feet along a ceiling before making its way inside an interior wall cavity.

My hunch right away is you have an ice dam issue due to the pooling your seeing at the bottom of walls and surface staining of your siding.
It takes huge amounts of moisture vapor to even come close to what your describing. Even without a bath fan you should not see any pooling from normal bathroom use.

An air to air exchanger is an appliance that continually changes the air in your home. It takes air from outside and mixes it with air from inside the home. This mixing is somewhat similar to what an air conditioner does, it helps remove excess moisture from the air in the home along with an exchange of air in the home. These units are part of the mandatory building code here in Ontario for new home construction.

1) Thanks, Randall, ice dam is a good lead. I wonder if there are other symptoms that I should look for if this were due to ice dam ? Should I sweep the attic at end of winter and check the underside of the roof sheating to try locate where the ice drips down, especially in area around exterior wall ? I can also get snow removed from roof to see if this would solve the problem ? (The roof is kind of high so I will have to call a professional).
I also like to describe the snow condition on the roof in more details to see if this resembles the ice dam condition. As viewed from the front of the house or away from a distance, the typical build up of snow seems fairly gradual, about 1 foot hick at the bottom edge of the roof, thinning out gradually to about 6" at the top of the roof. As temperature warms up, the entire snow buildup thins out fairly uniformily from top to bottom edge of the roof. I don't recall seeing a flat spot region on the snow surface near the eaves area where melted water may accumulate. But I should also say I don't really know what an ice dam would look like either: need more help and visual cues here. The builder did inspected the attic insulation (1 ft of blown fiberglass) and it seemed to be OK.
On this east-facing roof and halfway from the edge of the roof, there are two goose neck vents from the two bathroom fans. The snow there is as thick as the top of the goose necks (8" high I think), so the vented air from the goose necks usually creates a depression in the snow around the goosenecks. In the first winter, melted water was leaking down through this cutout. But the gap between the gooseneck base and the roof cutout has been repaired and no water seemed to leak down since. I am always concerned about the gooseneck being buried in snow and about the depression the warm air creates, so I am thinking about replacing them by a 14" high gooseneck. Is this a good idea at all ?
The reason the goosenecks were mentioned was, in the 1st winter, there was condensation found on the underside of the roof sheating. The builder thought the goosenecks were buried in snow and vented gas blew back into attic through gap between goosenck base and cutout hole. The gap was sealed and a turbine vent installed the 3rd year. No condensation was observed last winter after these fixes.
2) The fan in the large bathroom is equivalent to 0.4 cfm per sq ft, whereas the fan in the smaller bathroom is 1.6 cfm. I guess I should replace the fan in the large bathroom ?
3) Besides ice dam, could there be other possible reasons and what are the symptoms so that I can look for them in my place to establish a match ? Since rips were found on the vapor barrier in one wall, I naturally become more leery about this possiblity. However, I like to be open and hear about other suggestions too. Thanks.

The time frame to inspect the attic area is when the first warm spell arrives or when the temperature fluctuations start reaching near the freezing point(32F or above). That is, if there is snow on the roof.
The only real clue that an ice dam is forming may be right at the edge of the roof just above the trough. At its worst, you would see a layer of ice in the snow. There are no depressions unless its from the exhaust of a fan. Roof mounted fans are the worst culprit for starting the ice dam. They start melting the snow and as soon as the melt water gets moving down the roof and reaches a colder area it starts to freeze. I had that exact problem in my own house. Once I removed the bath fan roof vents, no more ice problems. I now install all exhaust fan vents in the underside of the soffit. The right type of grille must be used so it directs the exhaust air away from the house.

I'm not sure what your describing when you are talking about the goose neck vents. Are they the plumbing vents or the attic vents? We run all straight pipe thru the roof here for plumbing vents. Attic vents are either the whirlybird style or static vents.

When you look in the attic where the top of the outside wall is, what do you see there?

Can you post any photos of your roof and the area where the water is pooling?

From the amount of water that you describe as pooling it's either an ice dam issue or an actual roof leak from the plumbing or venting penetrations on the roof.

Yes, I would replace that small bath fan.

Thanks, Randall, for continuing to look into this. It is much appreciated.
1) The gooseneck vent is actually the exhaust oulet of the bathroom fan (this oultet is mounted on the roof and connected to the bathroom fan exhaust via an insulated hose). I like the idea of routing the bathroom vent air through the underside of soffit. Is there a special name for this type of venting and which type of professional can do this work (roofing, heating/ventilation, etc..)? (the soffit is quite high that I don't think I can do it).
2) Right above the top of the exterior wall, there are pieces of cardboard, each cardboard is lodged between two roof trusses and leaves an open gap about 3"-4" from the roof for air circulation. Underneath the cardboard is blown fireberglass.
3) In the next few days I will include photos of the roof, pooling water area (stain on wood panel at bottom of wall), drips of water on outside siding and some issues with vapor barrier (rips and incompletely sealed). Thanks. TMcT.

You could try a heating contractor or a renovation contractor that specializes in bath renos.
The duct work used is the insulated flex duct and the exhaust grille for the soffit is actually the grille from a fresh air intake. It is an open louver style with a wire mesh screen in it to keep the critters out. If you want, I can e-mail you a photo of the grille I use.

I have tried other soffit grilles that have the self closing louver but I found they didn't function all that well. They would get stuck in the closed position once the fan was turned off and the residual moisture began to freeze.

Your attic ventilation sounds good.
If those fan gooseneck vents are in line with where you see the water pooling then I would say that's where your problem is.

Randall, sorry that I was a bit busy the past few days to follow-up on this issue until today. Please find below additional info on this subject.
a) Could you please email the type of grille you used (open louver type)
b) Attached is a photo of a small water stain pooling at the bottom of the drywall in one bathroom. On the exterior surface of the vinyl sidings near the stain area, a few water streaks on the sidenings were observed. I will try to attach some photos here. (Another water streak was observed on this same wall (east facing) but in different room. I did not check at the time to see if the interior area has water pooling or not).
c) Next time, I will include photos showing "darkened studs" probably due to two 4-5ft long rips on the vapor barrier. Thanks. TMcT

To post photos on the web site go to the Ceramic Tile forum and under subforums there is a section called http://www.backyardforums.com/forums/ubbthreads.php/forums/17/1/Post_PHOTOS_of_the_project_you. Click on that and go to New Image. This is where you will add the photos. Image manager is the section you place the photo links in.