Hi to all,
This is my first time posting to this forum; my older brother suggested I connect with the best of the best. So here is my problem,
I live in Bothell <!—-><!—-> <!—->Washington<!—-><!—-> and in the last few weeks we had some cold weather where we got about 2-4 inches of snow. One night I started hearing a dripping sound that till now I can’t find where it is coming from, when I went to the attic to check it out, I noticed several things:
1. 85% of the roof deck area, which is made of OSB with 3 tab composite shingles on top, is moist and very wet and cold to the touch.
2. I noticed that some of the areas where I had some repair done by 2 different roofers had some rotting one was black plywood between the rafters where he put a new roof/fan vent and the other I saw on the lower part of the hip by the gutter area has some white residue building, looks like rot, I didn’t go there as it is deep in the roof and in a tight area. One roofer added more vents he said that would help in ventilation; the other roofer he put a flashing in a valley section.
3. I saw some droplets of water forming on the tip of the nails that are protruding from the roof (i.e, shingles nails)
4. Today it was a cold and frosty temp below freezing, when I went and checked on the attic to locate that irritating dripping sound again I noticed that the decking has some frost building from the cold air coming through the vents that are placed between the rafters (1.5 inch circular hole). Is that normal?
5. The collapsible ducting from my toilet room to the roof vent had about ½ a gallon of water in it. This is the one where the plywood around had turned black. Is this possibly coming from condensation?
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The house is only 10 years old with a cap type one and one gable roof, I am thinking of replacing the roof, but my question is it okay to leave the OSB as sheathing? Or should I replace all with plywood?
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There are about13 roof vents right now so where is the moisture coming from, is there something I need to be aware off?
Also that dripping sound occurs off an on, with different frequencies, even when there is no rain
Sorry for the long question.
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Thank you all for any inputs.
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Replies
The problem is condensation. Which isn't to say that you might not also have a roof leak, but there is no point in worrying about that until you correct the condensation.
The condensation occurs when warm, moist air comes into contact with a cold surface which in your case is the bottom of the roof.
The first problem is the bathroom vent pipe.
"The collapsible ducting from my toilet room to the roof vent had about ½ a gallon of water in it."
Get rid of the collapsible ducting and run solid metal duct with no dips to collect water.
That should be fairly straight forward.
And it probably won't solve the problem.
The warm, moist air is almost certainly coming from the living area of the house, although it is not impossible that it is going to the attic from the basement/crawl through a wall without ever going through the living area.
So, are you on a crawlspace? A slab? A basement? Does the basement have a concrete floor?
What is the humidity in the living area?
You need to address the humidity issue and then address the issue of opennings in the attic floor that allow air into the attic from the living area/crawl/basement.
Rich Beckman
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Dear <!----><!----><!----><!---->Mr.<!----> <!---->Beckman<!----><!---->,<!----><!----><!---->
Thank you for your response and your input.<!----><!---->
I really do not know what is the moisture content of my living space or the living room, how do I measure it? The house is a 3 story house situated on a sloped property with 2 stories above street level and one below with a finished day light basement on a concrete slab (no crawl space under it)<!----><!---->
There is no soffit around the house, but there are those circular 1.5 inch holes (don't know their trade names) that are situated between every other rafters. The attic has blown in insulation with the access to it inside a walking closet, and that cover is always closed. and it is insulated so there shouldn't be any heat escaping from the house or the bathrooms. All bathrooms vents are ducted outside none to the inside of the attic. <!----><!---->
Thank you for the recommendation about changing the collapsible pipe to a solid pipe I will do that. There are 3 such pipes in the attic now from 2 bathrooms on that 2nd floor<!----><!---->
Your primary problem is condensation from warm moist air inside the living space somehow getting into the attic. To find out how will take some investigation. It could be a combination of factors....
Are you leaving the attic access door open?
Do you run a humidifier?
Do you have a dampcrawl space?
You have upper vents, but do you have soffit vents?
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In addition to Piffen's suggestions, check to be sure any baths are not vented to the attic. I had a client last winter with the same problem in a 3 yr old house. Upon inspection, I discovered the baths were vented directly into the attic, the exhaust ducts were simply pointed in the direction of the soffit vents.
Actually, I haven't made any suggestions yet. I'll need answers to questions to fill in the empty spots in my head on this one first.
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Thank you for your reply.
To answer to your questions:
Are you leaving the attic access door open? NO neverDo you run a humidifier? NoDo you have a dampcrawl space? My basement is on a slab no crawl space 3 story houseYou have upper vents, but do you have soffit vents? Only the ones between the rafters (1.5" circular holes 3 of them every other rafter) The attic has blown in insulation and tehy have cardboard set on top to keep the vents open or so the insulation does not block the air.
Thanks
Jeremy
OK, then, here is the problem, as I see it. There could be additional factors other too...But there is no-where near enough ventilation at the soffits. A general rule of thumb is that you should have one sq ft of vent for every 100 to 150 sq ft of living space.
That means one foot in and one foot out to maintain full flow venting.You have far more vent at top sucking out than you have at soffit flowing in.With out being balanced, this means that when the wind blows especially, the top vents create a negative pressure in your attic. Since the sofit vents are so small, the replacement air haas to come from somewhere. The attic is finding a way to suck it out of the house, around fixtures, through sheet rock, at the access, in framed walls, at plumbing stacks, etc. You would multiply your air flow at the soffits by more than ten if you either used a 4" popin vent at every rafter space or if you let in a 2" continuous soffit vent. That way, you'd be more balanced and the house would hold onto more of its heat and moisture.to prove all that, you'd have to have an energy consultant do a blower door test, but I have seen this a dozen times, so I feel confident this is what you need to correct the problem.
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Not to disagree with your diagnosis but I have several points.
OP states that he has 3-1 1/2" diam. holes every other rafter bay at the eaves/soffits. That is 5.3 sq. in. of vent every other rafter bay (not deducting for the loss to mesh sq. in.) , he doesn't say how many over all. It is quite possible he does have adequate soffit venting depending on the configuration of his roof.
OP states he has 13 high vents but doesn't say what size (sq. in free air passage) the vents are.
Code in, Ore. at least, applies the 1/150 rule (cross ventilated) to the sq. ft. of the ventilated space, ie.: attic area, not total living space. Soffit Venting may be reduced to 1/300 if at least 50% but not more than 80% is located high in the attic space.
Reduction to 1/300 is also allowed if a 1 perm vapor barrier is applied to the warm side . (Believe it or not PVA paint primer applied to manufactures specs actually meets that criteria here!!)
No question he has excessive humidity in the attic space.
No argument with solutions.
I lay awake some nights thinking about all the houses I built as a young builder and wondering about the way I vented things back then (among many other issues) .. all to the then current code and usually above code minimums, but so much has been learned.
I would lean towards the theory that he has very leaky and inadequate venting of the shower/bath fans, range hood, etc.
I also wonder just how much the Pac. N.W. general high humidity followed by a sudden well below freezing cycle plays into this scenario. I have several small outbuildings that have no heat /humidity sources in them that will show frozen condensation on the underside of the roofs for the first few days after we get these weather cycles. This inspite of the fact they have continious soffit vents and oversized high gable vents.
Edited 1/29/2007 3:22 pm ET by dovetail97128
We are in agreement that someplace in his system his Vbarrier is very leaky.But from what he presents, I am sure he has more sucking out than following in so that negative pressure in the atic is making the leaky VB worse.Most hat vents range from about 65 to 144 sq in.I realize that we don't have all the specifics as to size of house, but he would have to have a small hip house for those soffit vents to come close to having half enough ventilation in to balance.Not arguing - just explaining my thinking.
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The balance issue makes sense.
Wow I am very impressed by all these theories. I am honored by this Thanks.
Just to add some more info on my house. The house is 3 story house, total footage is 3000 sqft. So each floor is about 1000 sq ft. The roof pitch is unknown to me, but in the attic below the hip area there is more than 8 ft (estimate). The size of these 13 roof vents looks about 8x8 inch cut out in the OSB.
One roofer who came to give me an estimate to replace my roof said that my ventilation looks excellent. He also looked into my attic and said that I have enough ventialtion. He is coming back tonight to meet with me to discuss the issue I learned from here and that is the moisture content in my attic where is it coming from.
Thank you all for all the feed back.
You might also ask over at http://www.inspectorsjournal.com/
Several of the home inspectors who hang out there are in your general area, and 'local' knowledge is key
As several have noted, a damp crawl is one of the more common causes of excessive condensation in the attic.
Also, I'm guessing you don't often get freezes.
In areas with actual winters, there tends to be a lot of condensation at and following the first freeze, while the house is still relative "damp" before the heating season begins.
So perhaps that has added to the amount of condensation
Talking with an experienced local home inspector who is looking in attics in your area day in and day out can be valuable.
>>I saw some droplets of water forming on the tip of the nails that are protruding from the roof (i.e., shingles nails)
A common event with a damp crawl (or cellar) during very cold weather.
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from Jesus: The Compassion of God (The Liturgical Press, 1983)
My experience with houses that have a compromised ventilation syustem is that the colder it gets outside, the worse the condensation problem is.
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I just re-read your original post and seem to have missed your 5th bullet. Assuming you don't have any roof leaks that are compounding your condensation problem, I'd reckon that the on-off nature of your drips is caused by the freeze-thaw cycles in the attic. When it's below freezing up there, the condensation is in the form of frost, when it warms up, the frost on the nail tips melts and drips.
Regarding possible sources for the moisture, you mentioned a bunch of water in an exhaust duct. The water inside the duct is obviously from condensation that occurs when you are blowing warm, moist air from the bathroom into the cold ducts. This is a common problem. I've seen cases where the flexible duct will fill up with enough water to create a sag in the duct. The sag will occur where the duct can settle down between hangers, or down between ceiling joists if the duct is simply laid on top of the loose fill insulation. If the sagged part of the duct fills with enough water, it can act like a P-trap under your sink, basically blocking the duct from being able to serve as a conduit for moisture out of the building. The fan will force moist air elsewhere, usually through the seams in the sheet metal housing of the fan unit and eventually into the attic. I've seen ducts filled with so much water that it was literally running back into the bathroom. This will only be noticable in the winter when the duct in the attic is cold enough to condense the moist air.
To fix, you need to insulate the ductwork in the attic. Alternately, or in addition, you can replace the flex duct with ridgid and pitch it so that any condensate can drain out of the building. Until you can properly fix, you might try running the fan for a few minutes BEFORE running the shower. This will warm up the duct a little bit before it gets slammed with the moisture from the shower. Also, run the fan for a good 15 minutes or so AFTER each shower in an effort to vent the majority of moisture laden air out of the duct. Running the fans before and after using the shower are not permanent solutions but may help you get the space dried out until you can rectify the failing duct.
In the event that the duct is not completely blocked, check to see if it exhausts at a soffit. If so, moist air exiting the building via the duct can get pulled right back into the attic through nearby soffits. Moving the duct so that it vents at a gable wall is far preferable.
Good observation. I wonder if this problem is worse in the 8-10 feet nearest that duct
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Well when the weather was a bit warmer last week (after all the snow had melted) I noticed the moisture was concentrated more around the bottom skirt of the roof, closer to teh suffits opening. While the area in the center or where the vents are located towards the HIP were dry.
Thanks
Jeremy
Perhaps, but I believe that water vapor will diffuse itself evenly in an unbstructed space. You will only observe condensation/frost/and to a lesser extent, any resultant mold, where the surfaces are cold enough for the vapor to condense (unless it's bulk water from a leak of some sort). For example, I have an unheated barn connected to my house. Some moisture from the house migrates into there because the door to the barn gets opened and closed about 20 times a day. Every once in a while, I'll see frost on the undersides of the roofing nails, but on a sunny day, it is only evident on the north side that doesn't gets any direct sun. I am sure the RH up in the loft is the same throughout the space, but I only see the condensation and subsequent frost on the underside of the colder north facing roof deck.
Just like the mossy side of a tree, if you ever get lost in the attic of a McMansion, you can find north by looking for the blackened underside of the roof deck. Works especially well in hip roofed goliaths that are almost impossible vent anyway.
I'm remembering an attic where I was called to fix what they thought was a roof leak.
The dryer vent was totally disconnected, and within that 8-10 foot circle, everything was a very nasty stringy mold
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It sounds like you have excess moisture comes into the attic from the interior of the home. Is the attic insulated? It sounds as if the warm air from the house is condensing on the roof osb and the nails. With the cold weather it is freezing and then thawing. You need to insulate and ventilate the attic. The black and white you see sounds like mold or fungus growth.
The water in the bath vent is the hot air condensing as it cools and is creating water in the duct. Replace duct with an insulted duct to outside vent.
Deryl
HI Deryl,
Thanks for your response.
The attic is insulated with blown in insulation about 10-12 inch thick, The cover to the attic has a pad of R30 or R24 insulation and it is always closed. There are 13 roof vents on this cap roof and there are suffits opening beween every other rafter. The attic feels so cold because of all that cold air blowing from these holes and openning.
Thank you
Jeremy