We suspect we are getting wind driven rain in through our soffit vents. Additional leakage is also evident on the North facing sheathing seams. The house is ~4 years old, and has developed several water stains near the north facing walls. Stains appeared most commonly during storms with relatively high winds. The stains are fairly evenly spaced, and most noticable in the Master bedroom. The house has no wind protection as there is a farm to our north, with very few trees, or any other structure to provide any wind breaks, and fairly high winds are common. The soffit is covered with perferated aluminum which is mounted at the lowest point of the soffit, so there is no wind break. The attic is insulated heavily with blown insulation. Styrofoam baffles ensure unblocked area for venting, and are mounted every four feet (every other rafter), accept in the area of the Master Bedroom, where the baffles are mounted in each rafter space (2′ Centers). Mold is growing on the OSB by the baffle space.
There is a continuous Roof vent on top of the house, but there was no sign of leakage from this area.
There is evidence of additional leakage on the north facing roof, where the OSB seams are. There is a distinct “Line” in the blown insulation directly under the seam which appears to be from dripping water.
We have had a few of the North facing FG Shingles replaced due to the wind tearing them off, and I noticed the seal never seemed to set up properly on these shingles. Some of the other shingles lift up easily, and appear to have never sealed.
We do not believe the moisture is a result of wet basement air or other house moisture intrusion, as the basement is normally dry, and the problem areas are in direct alignment with the vent baffles, and OSB seams. I also checked the bathroom vents, and they are all sealed well and vented to the south soffits. There is no sign of any mold in these areas.
The house is in Northern Illinois, so climate ranges from Cold to hot and humid, and we have seen Temps fom -20F to 105F since the house was built.
Does anyone have any ideas on what else may be happening or suggestions on remedies?
Replies
Well, as a temporary measure I'd suggest that you tape plastic over the soffit vents. If that seems to do the trick then you need to invent a sort of baffle system that will prevent the rain entry.
Since I can't fully visualize your situation (many different ways to do a soffit) I can't be too specific, but probably the "ultimate solution" is an essentially horizontal baffel above the vent opening that is closed on the house end and forces air to reverse direction towards the fascia after it goes through the vent.
DanH,
Thanks for the feed back.
I am hesitant to block the Soffit vents as I do not want to create a new problem with inadequate ventilation. I am looking at different soffit vent styles, and any feed back from anyone who has ever seen a similar problem. I think your idea of a baffle is what I will most likely try.
We will most likely replace the shingles also, since there is also evidence of leaks and several shingles have blown off. Many of them seem to have never formed a "Seal" the way they should have. Any suggestions on shingles which perform well in high winds?
Peter
Here on the PNW coast, in high wind areas, I use Malarkey laminated shingles, designed for high wind (extra seal down tabs, etc.).
It costs a bit more than the competition ($67 per sq. for 50 year) but. because it's quite flexible, is a joy to use (if roofing can be enjoyable).
We use a 6 nail pattern, and if the roof is applied during colder weather, especially in very exposed areas, a little mastic under the lower edge of the shingles doesn't hurt (with any asphaltic shingles, for that matter).
Thanks for the info on Malarkey! I see they also have a high impact product to resist Hail damage. Hail is another problem we ran into here, so maybe this roof will actually work. This house will be on its third roof in only 4 years, so I am researching as much as possible before anything gets done. A few extra $/square is a lot cheaper than having to do this again.
I have already found several shingles with only 3 nails, and poorly spaced at that, so I am sure 6 nails/shingle will go a long way. I plan to install in the upcoming warm season, so hopefully we will get a good seal this time around.
Any info on soffit venting for high wind areas?
Peter
Glad the Malarkey looks promising for you...I find it a little frustrating sometimes to try to get people to consider a better quality roof. The roof on the home we're just finishing is just over 50 sq. Given that the underlayment, ice and water, flashings, labor, etc. are the same, the diff is about $1500 between a 30 yr. mid-quality roof and the 50 yr. Malarkey. (In my situation, a 12% upgrade).
I mostly use the Hardy F/C soffet....when doing t&g cedar soffets, we inlay strips of the plastic continous vents. Using the dark brown and set flush with the bottom of the cedar, it makes a nice, clean detail (requires a really straight layout with the cedar).
Peter, I'm in NW Illinois farm country and our house is also very exposed to the wind and whatever mother nature has to offer. The roof over a the farm is even more vulnerable. Even though cyclonic storms come thru several times a year, it's a rare thing to see a house around these parts that has lost asphalt shingles...... provided the shingles aren't ancient and out of useful life, they weren't poorly installed, they weren't laid when it was zero outside and that they aren't the cheapest shingles that Menard's had to offer. Even those will last ten or more without failure.Some pics of your soffits and some of the roof in general would be mighty helpful here if you could post those. If you do, try to keep each one around or under 100 kb for those of us on dial-up.Even before seeing pics, I gotta say that I'm questioning the soffit vent suspicions. You're about to put on the third new roof in 4 years? Yikes! Something wrong. "Over powered" venting wouldn't cause total roof failure in my mind. You say you've lost shingles, many aren't sealed down and you've seen shingles with three nails in them. This all sounds to me like a poor product and/or poor installation or both. If you're got shingles with three nails in 'em, I'm thinking the roofer also cheaped out and didn't lay paper either........and that there's a good chance that the water you see dripping from those OSB sheet edges is water being driven under the shingles and then running down the OSB till it finds a point of exit; the seams. If such poor installation practices were employed, I'd hate to see what goes on in the valleys and such where detailing is ever more critical. Knowledge is power, but only if applied in a timely fashion.