suspect leak in roof

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Old 02-04-14, 04:03 PM
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Question suspect leak in roof

Hello,

Recently went into attic of my home built 2012. Attic seems to be moist. Plywood sheathing under roof is damp and dark discolored in spots. Centerline of roof I see line of ice with in 1/2 gap in between roof sheathings. I originally suspected moisture from bathroom as the most dampness is on that side of house ran shower for 20 minutes didn't notice steam leaks. I am not sure whether gap is sheathings is supposed to be there at centerline of roof where the only ice is don't know if I can get attic dry and then seal this with foam insulate or whether this is a good idea. I am going to buy dehumidifier and have been running fan. There are few spots of dampness in insulation on floor level of attic no soaked areas.

Any help would be appretiated

Thanks,
Jason
 
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Old 02-04-14, 04:22 PM
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"Centerline of roof I see line of ice with in 1/2 gap in between roof sheathings."
I'm not quite sure what I'm looking at, but the peak of the roof could gave a ridge vent. Normally the sheathing stops on each side leaving a 2 or 3" gap. The top is then covered with one of several different vent arrangements. If this is a roof vent, don't block it.

In fact, more venting may be needed to eliminate the moisture.

Where does the bath fan exhaust to, attic or outside. Be sure it hasn't become disconnected and is dumping into the attic.

Does your house have venting in the soffits, the overhang in front and back?

Bud
 
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Old 02-05-14, 12:02 AM
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First pic is of roof plywood sheathing darker areas in plywood are damp or wet.

Second pic is of one point in peak of roof, has ice running all the way down the peak in between sheathing, was unsure whether gap in between sheathing was supposed to be there running all the way down the peak.

House has three vents on roof, need to find out whether roof is leaking or bathroom exhaust is problem. Would smoke pen help trace leak.
 
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Old 02-05-14, 03:33 AM
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Is there currently snow on the roof?

A water leak can be due to an ice dam where melted snow has frozen and now blocks additional water from flowing under the snow to the edge of the roof and draining harmlessly.

The other source of moisture is from condensation from warm inside air which holds a lot of moisture entering the attic and condensing on the bottom of the cold roof deck.

Ice at the ridge may be a result of that condensation as the warm moist air exits and hits the cold.

Where do the bath and kitchen fans exit the house. When they are running can you see from the outside that they are working?

Are you running a humidifier inside the home?
Do you know what the relative humidity (RH) is inside?
Are the windows getting wet from condensation.
A lot of questions I know, but it helps from where I'm sitting.
Bud
 
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Old 02-05-14, 07:19 AM
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There is no plywood on that roof, it's OSB.
There is no ridge vent because what your seeing is the bottom side of the shingle.
Hard to see in that picture but it looks like there's insulation blocking the soffit vents if there even is any.
Even if the bathroom was just venting into the attic there's just no way that amount of mold and that large an area would be effected from just that.
Roof leaks can not be sealed from the attic.
You have mold all the way from the soffits to the ridge so I'd doubt it ice dams.
Looks like more lack of ventilation to me.
Some of that OSB looks like it's behind saving with a simple mold abatement treatment and will need to be replaced.
I'm also not seeing any H clips between the trusses to support the OSB.
 
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Old 02-06-14, 12:30 AM
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I do no yet know rh of home not sure yet on kitchen vent. Bathroom vent is on that side near damage no steam leaking. I do notice ice around bath exhaust has melted Attic is now frozen where you can see wet in pic the mold spots I can wipe off with glove almost like a powder. Is there any way to dry sheathings. It doesn't look as tho they are soaked thru at the peak of roof on edge of board. Will running fans help I plan to run a dehumidifier in attic. No humidifier is being used. Also no mass amounts of water are being leaked on insulation. So Am I understanding that much moisture can only be caused by leak?
 
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Old 02-06-14, 05:16 AM
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Don't try running a dehumidifier in the attic. They are temperature sensitive and likely will not operate properly in the attic. The fans will do more to help the issue.

Make sure that you are reviewing air leakage paths from the living space to the attic. You will most likely have to do this from the attic by lifting insulation and looking for any wiring and plumbing stack holes. Check the area of any ceiling light fixtures and seal or box around those as well. Also observe the top plates of any interior partitions and look for shrinkage gaps between the framing and drywall finish. Those gaps should be sealed as well.

Over the bathroom area look for evidence of drop soffits that are open to the attic. They are also directing warm air with moisture to the attic. You can cover those open soffits with a piece of rigid foam or any other rigid material and seal the edges with foam or an elastomeric caulk.

You mentioned a few times that you don't see steam rising to the attic. The moisture in the air does not have to show up as steam.

In your original picture the back of the osb appears to be wet/frosty/moldy in the area of the picture but is it as bad in bay's adjacent to that area?

I believe someone has mentioned blocking off the eave vents that are adjacent to where the bath vent exits the eave. I would second that opinion or if you can....re-route the vent to a gable end wall and vent it through that wall. Be sure to insulate over the vent line so that you minimize the chance of condensation in the vent as moist air exits through a cold exhaust line. If the line is the flexible PVC you should get rid of that as well and replace it with a hard line.
 
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Old 02-06-14, 06:20 AM
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"I do notice ice around bath exhaust has melted"

Where is this, in the attic, on the side of the house, on the roof? Assuming it's in the attic, then I think it is the source of the moisture. I had a similar experience with a bathroom vent exhausting in the attic and ruining plywood sheathing. I've subsequently vented it outside.

Also, the picture of the shingle (as joecaption1 so expertly pointed out), and the large gap between the OSB sheets at the ridge tells me that you need to have a ridge vent installed. It looks to me like the gap was cut for a ridge vent, then they just shingled over it.
 
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Old 02-06-14, 04:13 PM
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Ok so RH in house is 38% to 40% higher on second floor, still higher in attic 45%.
Bathroom vent runs from fan above bathroom in attic thru aluminum duct that isn't insulated which runs straight up thru roof and out. I checked to make sure it was secure and it is, I can also see steam or exhaust from this outside exiting from this vent. There is also no insulation within this hole in sheathing corresponding to the bathroom exhaust. This is the area where the frost has thawed/melted around the hole of exit in sheathing for the bathroom exhaust. Sheathing Adjacent to pics in post are also frosted with not as much dark spoting, actually a majority of roof is frosted on either side, but with most of dark spotting on the northwest face of house same side as bathroom.

As I understand it I need to cover up eave vents adjacent to water affected areas, but with what and for what duration? Also near eaves there is card board what is its purpose. I also need to insulate any areas that are points of entry into attic from house either from within attic or from bathroom. What about other areas gaps where light from the outside of house can been. Can this be sealed or will it not help at this point. I also need ridge vents what quantity. Continuing to run the fans will also help.

My last question is in relation to thawing and repair it is so cold that the dampness seen in original posted pictures is not present everything is frosted. After sealing everything and excluding moisture from bathroom. What should be next steps.
 
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Old 02-06-14, 05:37 PM
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Jason,there seems to be some confusion. The eave ventilation you apparently have is designed to work in conjunction with the ridge vent that you don't yet have. You don't want to block off any of the eave vents.

The suggestions to close up eave vents were based on contributors' assumption that your bath fan was venting across the ceiling and into the eave. If it were being done that way you would want to prevent warm, moist air from rising back up the eave vents and entering the attic where it could be contributing to your problem. You would have only blocked them in the vicinity of the bath vent pipe opening.

The relative humidity you have is not extraordinarily high. The 45% reading in the attic doesn't mean a lot to me since you are not giving me the temperature that the recording was made at....all relatively unimportant as we KNOW you have an issue based on the fact that the roof is frosty/icy.

The sooner you are able to get a ridge vent in place, the better off you will be.

The cardboard that you see in the area of the top plate of the exterior walls near the eave is more than likely installed there to prevent insulation from touching the back of the roof deck and closing off your air flow from the eaves to the attic.

If you see any holes in the ceiling plane for wires, pipes, drop soffits, you want to seal these to prevent air flow from the house but you must do that with products that are going to create an absolute air barrier. Fibrous insulation is not the product to use for that as it is air porous. Foam sealants, caulking compounds for small gaps and holes, rigid foam or other sheet goods for large holes such as soffits and then seal the edges with the caulk or foam sealant.

You may not get a real good resolution to this until you have a ridge vent and that vent should run the length of the attic ...assuming you have a gable roof as opposed to a hip design.

Please keep in mind that even with everything done as it should be you may get some frostiness on the back of the roof depending on a variety of factors. The ventilation may not always prevent the condensation but the airflow will assist in drying it out when it does occur.
 
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