Thread: Baffles have a baffling problem

There is old black stain on the OSB sheathing of this 20 year old 2 storey house.
There are 2 small patches of actively growing white mould (mold) behind the soffit vent baffles on the northfacing side of the attic. The OSB is damp in these spots. The rest of the sheathing looks not bad, see the last pic facing south.

You guys with all the answers - Why is this happening and what's the repair?

Don't tell me it might not be mold, that it needs to be tested, or that there is ice damming. Outside temp was about 40 degrees F.

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Ice damming. If there's snow on the roof the leaks will get worse when the temperature gets above freezing. That is, until all the snow and ice has melted.

Ken, there's no ice damming. There's no snow. But yes, it could be leaky shingles, but why only wet behind the baffles?

Could be that there is an issue with the roof covering itself - and the baffles are, to some extent, a coincidence. Their presence, however at the same location as the roof leak is exacerbating the mold growth. Note the sheathing discoloration extends beyond the baffles but does appaer to be more concentrated under the baffles. Any pics of the roof / eaves at this point from the outside?

Is there a bathroom exhaust fan in the area that could be ducted to the soffit?

John, could you see daylight coming through between the baffles and roof decking? I saw an attic in a newer construction house where despite the baffles, the person who blew in the insulation blew it into the space between the baffles and roof deck. I guess they didn't understand what purpose the baffles served.

Any chance the soffit vents really aren't open at all? Did the roof have a ridge vent?

Originally Posted by John Kogel

Ken, there's no ice damming. There's no snow. But yes, it could be leaky shingles, but why only wet behind the baffles?

John, in my experience the location of the wet sheeting indicates a previous ice dam leak. The stain is within a couple feet of the exterior wall and on the north side of the home. You stated it is currently wet. Unless there is some major problem that would be evident by looking at the shingles, ie. they are missing, and its recently been raining heavily enough to soak through the osb, it's a previous ice dam leak.

Is it possible that there was snow and ice on the roof a couple weeks prior to the inspection? Could there have been an ice dam leak and recently it's been warm enough to melt the snow and ice from the roof? If so, it's most likely a recent leak due to ice dams.

Originally Posted by Nick Ostrowski

John, could you see daylight coming through between the baffles and roof decking? I saw an attic in a newer construction house where despite the baffles, the person who blew in the insulation blew it into the space between the baffles and roof deck. I guess they didn't understand what purpose the baffles served.

Any chance the soffit vents really aren't open at all? Did the roof have a ridge vent?

There was no insulation blown over the baffles, but I could not see light either. Perforated soffit covers on the outside, but could be blocked off soffits, not visible.
No ridge vent, four roof vents near the peak, typical.

Originally Posted by Ken Rowe

John, in my experience the location of the wet sheeting indicates a previous ice dam leak. The stain is within a couple feet of the exterior wall and on the north side of the home. You stated it is currently wet. Unless there is some major problem that would be evident by looking at the shingles, ie. they are missing, and its recently been raining heavily enough to soak through the osb, it's a previous ice dam leak.

Is it possible that there was snow and ice on the roof a couple weeks prior to the inspection? Could there have been an ice dam leak and recently it's been warm enough to melt the snow and ice from the roof? If so, it's most likely a recent leak due to ice dams.

No, they had some wet snow a couple of weeks ago, cold for 2-3 days, but then it warmed up above freezing. No ice buildup.

Bathvents may have leaked in the past, possibly causing the black stain. Exhaust vents are all piped out thru gable ends now.

Shingles are fiberglass impregnated asphalt, some granule loss and a lot of moss growth on the north side. Could it be moss damming? No.

The OSB is damp but not dripping. I believe there is condensation moisture getting trapped by the baffles. Plugged soffits seems to be a reasonable explanation for the mould growth.

I've posted a weather map. That's me on the upper left. sun, then cold rain. Sorry about that, you guys in the East are getting hammered this year.

Originally Posted by John Kogel

There is old black stain on the OSB sheathing of this 20 year old 2 storey house.
There are 2 small patches of actively growing white mould (mold) behind the soffit vent baffles on the northfacing side of the attic. The OSB is damp in these spots. The rest of the sheathing looks not bad, see the last pic facing south.

You guys with all the answers - Why is this happening and what's the repair?

Don't tell me it might not be mold, that it needs to be tested, or that there is ice damming. Outside temp was about 40 degrees F.

There is not enough ventilation. It is obvious.
Condensation. High humidity.
There should be a baffle every joist and the saw-fit looks like it is covered over with insulation in my books.
Is it a mansard roof system?
Are you there to report on a fix, or report the defects?

!: Yes you call out defect. If you wish recomend roofer does a report. I am that roofer.
2: No mention of mold unless you have that cert. , testing-kit and written report that has been handed back to you from the lab..
I do not see photos of exterior saw-fittings. I would need all angles to give you a fix. Again we are nit here to mention the fix.
Just to report on the defect.

Actively growing may imply a knowledge you don't have. Did you get to it and stab it with a moisture meter?
Is the house brick creating a stack effect from the crawl space via the "dead air space" that is never really dead?
JLMathis

Originally Posted by Jeffrey L. Mathis

Actively growing may imply a knowledge you don't have. Did you get to it and stab it with a moisture meter?
Is the house brick creating a stack effect from the crawl space via the "dead air space" that is never really dead?
JLMathis

I know it's mould. This is the land of mould. If it is 3 dimensional and wipes off, I know it is not dried out and dead, hence, alive. I got to it and felt the OSB with my hand, and it was damp. Yes I have a Surveymaster MM, didn't need it.

No bricks, it's all wood frame here, 2X6 walls with a double top plate, sheathed in plywood or OSB, drywall. Not much air movement there. But the wall/ceiling junction could very well be leaking there.

Originally Posted by John Kogel

I know it's mould. This is the land of mould. If it is 3 dimensional and wipes off, I know it is not dried out and dead, hence, alive. I got to it and felt the OSB with my hand, and it was damp. Yes I have a Surveymaster MM, didn't need it.

No bricks, it's all wood frame here, 2X6 walls with a double top plate, sheathed in plywood or OSB, drywall. Not much air movement there. But the wall/ceiling junction could very well be leaking there.

I'm not saying what you see is NOT mold but I have seen a white substance on OSB on subflooring above a basement, took tape slides and sent them in for analysis. Came back as not mold. I don't know what is was but it was white, 3 dimensional, and would wipe off.

Originally Posted by Stuart Brooks

I'm not saying what you see is NOT mold but I have seen a white substance on OSB on subflooring above a basement, took tape slides and sent them in for analysis. Came back as not mold. I don't know what is was but it was white, 3 dimensional, and would wipe off.

Well, Stuart, thanks, but you had to be there to see what I saw.

Originally Posted by Stuart Brooks

I'm not saying what you see is NOT mold but I have seen a white substance on OSB on subflooring above a basement, took tape slides and sent them in for analysis. Came back as not mold. I don't know what is was but it was white, 3 dimensional, and would wipe off.

Well, Stuart, thanks, but you had to be there to see what I saw.

True enough, other white powders are drywall dust, efflorescence, chalk, etc.

Originally Posted by John Kogel

Shingles are fiberglass impregnated asphalt, some granule loss and a lot of moss growth on the north side. Could it be moss damming? No.

That very well could be exactly what's happening.

Meantime moss also holds moisture and prevents the roof from drying. Where it is present on 3-tabs also can prevent drainage causing even pools of water. The moss itself brings the moisture under the tabs, lifting and dammed up water easily gets in.

Moisture is likely wicking through the OSB and barely drying with minimal yet humid, tropical/sub-tropical air flow through the minimal attic venting in what is likely a warmer environment than the outside for the majority of the year, daylight hours, so those roof vents are doing double duty, wouldn't be surprised if where the baffles are, also cools first in the evening or when temperatures drop - so you've got dew point at the wick point - effective terarium type "rain" added goodies of OSB decomp, broken down granuels, secretions/salts from the moss breaking down organic material.

20 yr old roof with a lot of moss growth.

Failed roof, decomposing wet/damp OSB. Moss very destructive to compo shingle roof life.

Cut back the overhang, remove collections of organic matter, adjust planes so not to be a catch-all especially of windborne debris, correct slope if necessary, keep gutters clean, and use a bio-resistant roof media, moss on roof not a good thing, esp. compo shingles in a tropic zone.

Originally Posted by H.G. Watson, Sr.

That very well could be exactly what's happening.

Meantime moss also holds moisture and prevents the roof from drying. Where it is present on 3-tabs also can prevent drainage causing even pools of water. The moss itself brings the moisture under the tabs, lifting and dammed up water easily gets in.

Moisture is likely wicking through the OSB

Show me some wicking. I don't see it. Show me water-soaked OSB.

Originally Posted by H.G. Watson, Sr.

and barely drying with minimal yet humid, tropical/sub-tropical air flow through the minimal attic venting in what is likely a warmer environment than the outside for the majority of the year, daylight hours, so those roof vents are doing double duty, wouldn't be surprised if where the baffles are, also cools first in the evening or when temperatures drop - so you've got dew point at the wick point - effective terarium type "rain" added goodies of OSB decomp, broken down granuels, secretions/salts from the moss breaking down organic material.

Condensation on the inner surface? Sure, I'll buy that.

Originally Posted by H.G. Watson, Sr.

20 yr old roof with a lot of moss growth.

Failed roof, decomposing wet/damp OSB. Moss very destructive to compo shingle roof life.

Cut back the overhang, remove collections of organic matter, adjust planes so not to be a catch-all especially of windborne debris, correct slope if necessary, keep gutters clean, and use a bio-resistant roof media, moss on roof not a good thing, esp. compo shingles in a tropic zone.

I need to be careful posting pics of a home in transition. But I can say the drip edge, lacking in flashing, yes yes, there's no drip edge flashing, is dry.

Cut back the overhang was referring to the overhanging trees, branches, etc. depositing organic matter and keeping the roof from drying, not cutting back the roof overhang.

Moss, its decaying matter, trapped dirt etc. seep back up under shingles and lift them just as ice and water do.

The white residue and wet osb is evidence of wet osb roof deck.

Point was when you sarcastically responded to K.R. that it couldn't be ice damming and that moss couldn't cause a similar problem, especially profilic unchecked MOSS on a 20 year old roof, was entirely wrong, even in your milder winter wet year-round climate. It can and does.

Won't get far with you when you sport an opinion that an every third truss bay with a chute less than half its OC with obstructed intake and high hats adjacent is sufficient venting for your climate zone anyway.

You have styrene chutes one sporting two nested, too small and wet osb with a moss farm on the north side of attic. Figure it out - the deck is wet and insulated, insufficiently ventillated and a wet roof, kept wet by the moss carpet.

If you throw a tarp up and nail down straps on a saturated roof for an emergency roof covering and don't remove it and get the remainder of the roof dryed out in sufficient time, you'd see the same right quick in a sub-tropic or tropic zone as well. That moss does all that and more.

Moss destroys composition roofs. Keeps the roof from drying out, and retains water, organic and decaying matter, and dirt, which gets under and backs up.

You go on some sort of defensive rant including photos. You seem to think that wicking and moisuture entry is like a direct water leak via a hole. It is not. Neither, I might add, is tracking down a direct water leak from damming - ice OR moss related. Tracking the wicking process of moisture through engineered wood products is not the same as following flowing water.

Its a process and your seeing the evidence at the styrene chutes/baffles. You have a poorly maintained, deteriorated, moss infested, failing 20 year old roof over an inadequately ventillated attic with OSB decking.

Its (the roof covering) is toast. Those unfamiliar with the experiences of history are doomed to repeat it, or something to that effect.

Of course the improperly flashed exposed edge of the OSB roof deck is dry, that's the only place it is exposed to the atmosphere and can dry.

The exposed edge of a wick is DRY too - that's how wicking works!?!

Styrene not vapor perm, and insulating.

OK. I post these questions so we can all learn. There are mysteries at work here. I know perfectly well that moss growth is detrimental to the shingles and that it is retaining moisture to some extent on the roof.
However, I do not believe water is soaking through the deck. I can dig up pictures of water-soaked OSB if need be. This decking is stained and has two damp spots. The cold wet moss layer can very well be the cause for moisture to condense in those spots, protected by the poorly installed baffles and perhaps plugged soffits.

I suggest that a dam made of moss would have to form a solid line across the roof to hold water back the way ice does. I just don't see it here.
The stains stop short of the trusses. Why?

Did you answer my original question? If so, I missed it. Is it a brick house?

JLMathis

Originally Posted by Jeffrey L. Mathis

Did you answer my original question? If so, I missed it. Is it a brick house?

JLMathis

Post #11.

John
As far as the white stuff goes you can call it as possible microbial action, needs further investigation.

Those baffles are a joke. It appears that more and larger baffles are needed. Baffles should provided 1.5-2 inches of air space and should spance the entire cavitiy. I would also say there should be baffles in every other cavity and many will tell you every cavity.

Originally Posted by John Kogel

I suggest that a dam made of moss would have to form a solid line across the roof to hold water back the way ice does. I just don't see it here.

Your suggestion incorrect. You have moss growth pictured which creates side walls and can easily contain water/moisture collections, in essence a multitude of moss/dirt "dead valleys" on your roofing surface, just as any similar projection or obstruction to drainage on a slopped surface may. You also photograph curled/cupped lifted shingle just above edge. Dirt, dead moss, organic material, etc. and water = "mud". Essential component of "mud" = water. Between can prevent sealing/resealing and hold as well as wick moisture. Water expands from its liquid state when BOTH heated (steam - gas state) or frozen (solid state). Organic materials +decay/moisture = molds, fungus, bacteria, lichens, etc. Lots of things going on here and potentially going on here.

Shouldn't have to debate the obvious when you submit photo which clearly demonstrates the ability to retain/hold/restrict/obstruct drainage and even POOL water along the roofing surface in various areas despite the slope, and prevents, slows or impedes the rapid shedding/evaculation of liquid water off the roof.

Originally Posted by John Kogel

The stains stop short of the trusses. Why?

There is no isolation thermal or moisture/vapor between osb and top chord of roofing truss. Likewise neither the osb nor the top chord is insulated, nor interior surfaces coated or obstructed via vapor or moisture barrier, nor is airflow drastically obstructed by styrene or otherwise to the remainder of the attic. Hence warmer materials, transfering conducting temperature and conveying moisture. Greater overall surface area.

Convection currents, draft, density, absolute moisture content, relative humidity, get a handle on it. Location of exterior wall relative to span, chutes are short and incorrect on several levels; and run limited air flow (cu.in) a host of considerations.

Consider also the multi-directional chips/chunks of wood glued together at a cellular structural level as engineered OSB compared to sawn lumber or engineered plywood. Again, dry "edges" are further meaningless. Consider also the surfaces of same relative to flow, gravity, and surface tension of accumulated liquid water, even condensation of less than smooth surfaces.

Plastic spiral wire duct above insulation, to the left as you indicated exhausting gable wall, many twists and turns, ineffective and incorrect venting/ducting material for this application; and as installed subject to eddys, drag, condensation, negligable effectiveness and exposure to damage/deterioration - of further issue, and has no place as pictured, in this attic. Upwind low gable wall moisture ladden exhaust easily returned into building via limited soffit intakes immediately down wind/around the corner, for example, at cooler eave, osb surface isolated from air flow from attic and insulated by baffle material.

Originally Posted by Robert Hronek

Those baffles are a joke. It appears that more and larger baffles are needed. Baffles should provided 1.5-2 inches of air space and should spance the entire cavitiy. I would also say there should be baffles in every other cavity and many will tell you every cavity.

I suspect the lower ends of those baffles were crushed flat, pushed down against the soffit cover. They are lacking the dimples in the center which would help to prevent that.

Originally Posted by H.G. Watson, Sr.

Your suggestion incorrect. You have moss growth pictured which creates side walls and can easily contain water/moisture collections, in essence a multitude of moss/dirt "dead valleys" on your roofing surface, just as any similar projection or obstruction to drainage on a slopped surface may. You also photograph curled/cupped lifted shingle just above edge. Dirt, dead moss, organic material, etc. and water = "mud". Essential component of "mud" = water. Between can prevent sealing/resealing and hold as well as wick moisture. Water expands from its liquid state when BOTH heated (steam - gas state) or frozen (solid state). Organic materials +decay/moisture = molds, fungus, bacteria, lichens, etc. Lots of things going on here and potentially going on here.

Shouldn't have to debate the obvious when you submit photo which clearly demonstrates the ability to retain/hold/restrict/obstruct drainage and even POOL water along the roofing surface in various areas despite the slope, and prevents, slows or impedes the rapid shedding/evaculation of liquid water off the roof.



There is no isolation thermal or moisture/vapor between osb and top chord of roofing truss. Likewise neither the osb nor the top chord is insulated, nor interior surfaces coated or obstructed via vapor or moisture barrier, nor is airflow drastically obstructed by styrene or otherwise to the remainder of the attic. Hence warmer materials, transfering conducting temperature and conveying moisture. Greater overall surface area.

Convection currents, draft, density, absolute moisture content, relative humidity, get a handle on it. Location of exterior wall relative to span, chutes are short and incorrect on several levels; and run limited air flow (cu.in) a host of considerations.

Consider also the multi-directional chips/chunks of wood glued together at a cellular structural level as engineered OSB compared to sawn lumber or engineered plywood. Again, dry "edges" are further meaningless. Consider also the surfaces of same relative to flow, gravity, and surface tension of accumulated liquid water, even condensation of less than smooth surfaces.

Plastic spiral wire duct above insulation, to the left as you indicated exhausting gable wall, many twists and turns, ineffective and incorrect venting/ducting material for this application; and as installed subject to eddys, drag, condensation, negligable effectiveness and exposure to damage/deterioration - of further issue, and has no place as pictured, in this attic. Upwind low gable wall moisture ladden exhaust easily returned into building via limited soffit intakes immediately down wind/around the corner, for example, at cooler eave, osb surface isolated from air flow from attic and insulated by baffle material.

Thanks, HG. There are a lot of factors at play, as I acknowledged above.
The slope of this roof is something like 8 in 12. I didn't see any pools, and saw no drips or water stains.
When the end of the wick goes dry, it is time to blow out the light.

Originally Posted by John Kogel

Ken, there's no ice damming. There's no snow. But yes, it could be leaky shingles, but why only wet behind the baffles?

I just noticed your location. I assume that even though it is cool/cold the air is still pretty moist. Are these pictures on the north side of the house or an area that doesnt get much sun? At night a roof can cool below outdoor temps through radiant heat loss. The vent chute protect that part of the roof from heat leaking out of the attic allowing it to cool more and stay cool. Outdoor air flowing through the chute might be accumulating moisture in that spot. Given as far north as you are the winter would not have much sun and what sun would be low intensity. May not dry off the roof if there was soprtion on the sheathing.

Originally Posted by John Kogel

I suspect the lower ends of those baffles were crushed flat, pushed down against the soffit cover.

That's a common situation - the baffles are jammed too tight against the backside of the fascia. I also often find the baffles are not in the same rafter/truss cavity as the soffit vents. John you also mentioned that you could not see light - do you mean daylight in the attic from the soffit vents?

Let me go one step further. For wood soffits wrapped with aluminum panels with punched grills you can't necessarily confirm that the wood itself has openings for air flow. Add to the mix the possibility that the grills are not lined up with potential cutouts in the wood soffits boards.

If I don't see daylight in the attic at the soffits I raise a question as to the effectiveness of the ventilation. I'm neither condemning it or approving it while at the same time recommending further evaluation.

Originally Posted by Eric Barker

That's a common situation - the baffles are jammed too tight against the backside of the fascia. I also often find the baffles are not in the same rafter/truss cavity as the soffit vents. John you also mentioned that you could not see light - do you mean daylight in the attic from the soffit vents?

Yes, at those two mold spots.

Originally Posted by Eric Barker

If I don't see daylight in the attic at the soffits I raise a question as to the effectiveness of the ventilation. I'm neither condemning it or approving it while at the same time recommending further evaluation.

Thanks for the reinforcement.

My first thought is the intake area of the soffit is being fed moisture from the bath vent hose which is partially seen in one of the photo's exhausting into the soffit. I have also seen a dryer duct venting outside close by and the soffit vent sucking the moisture into the attic. You might also check for a furnace vent piping on same outside wall. Either way, the damage is isolated due to the rafter bay where the moisture is coming in. With improper ventilation in the attic the problem would be more widespread.

Originally Posted by Jeff Gainey

My first thought is the intake area of the soffit is being fed moisture from the bath vent hose which is partially seen in one of the photo's exhausting into the soffit. I have also seen a dryer duct venting outside close by and the soffit vent sucking the moisture into the attic. You might also check for a furnace vent piping on same outside wall. Either way, the damage is isolated due to the rafter bay where the moisture is coming in. With improper ventilation in the attic the problem would be more widespread.

Thanks, Jeff. The bath fan hose is about 20 ft long , but it runs off to a vent in the gable. The dryer vent is on that side alright, but it's down at ground level. No furnace, electric baseboard heat, cheap hydroelectric.

John, Attic ventilation is inadequate (ineffective). Trapped moisture inside the attic condenses on the back side of the roof sheathing the same way it does on window glass in poorly ventilated conditioned space. Improved (increased) ventilation is needed. Have seen this very same condition in several homes in the Santa Cruz county, a center for mold propagation. Your description fits the model.

The vent/insulation baffles in the photos look sort of wimpy.

Electric attic fans may be needed. Have you seen the solar power type ?

Does not strike me as a roof or flashing issue, but how did the roof look ?

Originally Posted by robt moore

John, Attic ventilation is inadequate (ineffective). Trapped moisture inside the attic condenses on the back side of the roof sheathing the same way it does on window glass in poorly ventilated conditioned space. Improved (increased) ventilation is needed. Have seen this very same condition in several homes in the Santa Cruz county, a center for mold propagation. Your description fits the model.

The vent/insulation baffles in the photos look sort of wimpy.

Electric attic fans may be needed. Have you seen the solar power type ?

Does not strike me as a roof or flashing issue, but how did the roof look ?

Look to me its simple issues.
! old roof and shaded.
2 inside attic. Not proper venting. Baffles are the cheapest and poorly setup.
Inexperience and tight with the pocket book to get the proper tradesman.
I can not see everything I would like to and do not judge words to describe.
A picture says a thousand words.

"The exposed edge of a wick is DRY too - that's how wicking works!?!" Quoth HG.

Wow..thanks HG. All this time I thought that a wick transfers moisture from a wet area to a dryer area by becoming a transfer medium for the moisture. I didn't know it works by magic! It can move moisture and stay dry the whole time! I wish I was as smart as you then maybe I could understand that process. I could also make fun of other people on the board and lord my knowledge over them. Maybe someday if I keep reading your posts I can reach up on my tippy toes and touch the hem of your beautiful new imperial suit! There's always hope.

Seems like the reason is from the inside, not the roof.
Probably ventilation is not efficient, Due to condensation the OSB is damped, the colder side where would be the most condensation is damped, warmer side is not affected. It may be close to baffles where cold air intake is more, on the colder side. I think it is a pure condensation problem, i guess attic is getting too much vapor from somewhere, possibly from inside, but surely the ventilation is poor. Problem may be due to exhaust vents rather than soffit baffles.
Need to look more carefully what comes from down...Even the vapor barrier may be the cause of this