New Attic Insulation Causing BIG Problem


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Old 12-23-07, 01:19 PM
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New Attic Insulation Causing BIG Problem

We have an old 1968 Ranch home that had minimal loose rock wook insulation with no vapor barrier under it. We just had loose fill cellulous blown in ontop of it professionally a few months ago. We are in No. Calif. Mild Weather, now that Winter has arrived, New BIG PROBLEM. On winter days when outside cars collect dew/condensation overnight so does my stucco EXTERIOR on a few Shaded Stucco Walls. The condensation burns off after a few hours in the morning but stays longer on the exterior stucco near the roof overhang, so much so, that there is a light stain along the stucco up near the shaded overhang. The stucco walls that collect dew/condensate feel much colder to the touch than other stucco walls that do not condensate on warmer sides of the home, due to the insulation making the exterior stucco colder. We have attic ventilation (ridge, gable and soffit and some added eyebrows), do we need more ventilation? or is it because in the attic they blew the insulation up against the building paper?, should we move the insulation in the attic a few inches away from the building paper so as not to make the exterior stucco so cold that it condensates? Outside Winter temperature only ranges from 30-50degrees and the condensation only happens on winter nights when other outside items naturally condensate/collect dew. INSIDE Winter RH is only 37-44 and we have new strong bathroom and kitchen fans, no condensation inside at all, not even on our windows NONE. The stains do not look good, but more so, I am worried about the exterior condensation causing a problem, so I want to FIX this problem asap. Please advise how. Thanks
 
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Old 12-23-07, 03:12 PM
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Maybe I don't quite understand the problem, but frost is a normal occurance. If you never got frost on the house before, it was because the walls were so inefficiently insulated that you were losing enough heat to melt the frost. Not wanting frost on the house is kind of like not expecting frost on the car when it sits outside.

I can't envision this "stain" you're talking about unless your house is dirty and just needs to be powerwashed.
 
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Old 12-23-07, 05:07 PM
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Hmm...

It is not frost, just wet dew/condensation. We have lived in home 17 yrs and it is something brand new after insulating attic. We have NOT added insulation to walls, it has the old rock wool from 1968 in the walls. So are you saying, just by insulating the attic that it is expected that the shaded stucco walls condensate on winter days? None of my neighbors have any condensation on their stucco (but they have not added additional attic insulation that I know of, however, a neighbor down the street did add attic insulation but theirs was fiberglass batts and their stucco does not condensate). The stain is just a slightly darker color, where the condensation does not burn off from the sun, the house was painted a few months ago, so the stain is new and from the condensation. The condensation looks like patches and it is evident where the studs are because the condensation does not form where the studs are. So this is not a problem?
 
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Old 12-23-07, 06:34 PM
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I see. For some reason I was picturing added insulation in the walls as well. Guess I should read more closely!

So before your home was painted, was your stucco unpainted? Stucco tends to absorb moisture, while condensation tends to build up on some painted surfaces.

I'm wondering if you are noticing a difference because of the recent paint job, not because of the added insulation? Added insulation would help keep the top plate warmer, but I can't see how attic insulation would affect the stucco exterior of a home at all.

Whether this is a problem or not probably depends on the type of paint that was used, so this might be a question for your painter to answer. I wouldn't get overly concerned about it until warmer weather arrives and you see if this "stain" disappears or not.
 
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Old 12-23-07, 07:30 PM
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I agree with X.
 
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Old 12-23-07, 10:38 PM
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Painted before

Stucco had been painted before many times since 1968. This was just added paint. 100% Kelly Moore Exterior Acrylic. My worry would be if moisture that is traveling from interior to exterior is getting trapped because of the many layers of paint (however, the condensation is EXTERIOR so it can't be trapped right???????? or could it possibly be from within that travels to outside and sits on the exterior?) I've been monitoring my interior RH which is only 37 to 47 on winter days. One thing I'll reiterate is that we have normal "in"ternal RH and NO condensation inside at all that I can see anywhere including on windows. Either way, if it is not good to put moisture from sprinklers on exterior stucco, why would exteral condensation be good? It is moisture either way that degrades the moisture barrier more rapidly because it is more constantly wet - yes? no? I'm a newby to learning about wall moisture but know from research we do not want it to be inside the wall, or sit on the outside regularly to degrade the 2 layers of building paper. Frustrated, because I know there is an answer, if this is a new phenonmenon then what caused it that I can reverse?
 
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Old 12-24-07, 04:50 AM
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Two things that may have changed:

1) Unless the insulation installers carefully installed baffles the blown in insulation may have obstructed the soffit vents.

2) In many older homes there is a considerable amount of air movement through the stud cavities and into the attic - the builders did intend this, but it happens and helps to reduce condensation problems. The blown in insulation may now be preventing this.
 
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Old 12-24-07, 09:19 AM
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Where does your bathroom and kitchen exhaust terminate?
 
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Old 12-24-07, 10:58 AM
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So should I....

We are overly careful with indoor venting stove/bathrooms all have strong fans that duct up to attic and vent out the roof properly, all ducts very well sealed and do NOT terminate in attic. However, that wall does have a remodeled kitchen and there is a stove and oven and kitchen cabinets against the inside of that wall. Again INSIDE RH is low (winter 37to45) and well vented. Are stoves and ovens suppose to be located on external walls? (God I hope so, kitchen remodel cost a fortune). We not only use strong stove fan when cooking but have 2 kitchen Velux skylights that are remote controlled and open them an inch while cooking for additional venting in kitchen.

So XSleeper, the wall the is collecting external nighttime condensation is on pitched side so in attic no soffits on that wall, however, the company who blew the insulation put a piece of fiberglass batt a foot away from the soffits they blew in the cellulous as not to obstruct soffit vents. The blown in insulation lays in attic including ontop of wall cavitys and up against the building paper. Should I move the loose fill off the top of the wall cavity and away from the building paper?
 
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Old 12-26-07, 09:34 AM
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We are overly careful with indoor venting stove/bathrooms all have strong fans that duct up to attic and vent out the roof properly, all ducts very well sealed and do NOT terminate in attic. However, that wall does have a remodeled kitchen and there is a stove and oven and kitchen cabinets against the inside of that wall. Again INSIDE RH is low (winter 37to45) and well vented. Are stoves and ovens suppose to be located on external walls? (God I hope so, kitchen remodel cost a fortune). We not only use strong stove fan when cooking but have 2 kitchen Velux skylights that are remote controlled and open them an inch while cooking for additional venting in kitchen.

So Michael Thomas, the wall is collecting external nighttime condensation is on pitched side so in attic no soffits on that wall, however, the company who blew the insulation put a piece of fiberglass batt a foot away from the soffits they blew in the cellulous as not to obstruct soffit vents, however I did not check to see if any blew past the batts. The blown in insulation does lay in attic ontop of wall cavitys including that particular exterior wall cavity and right up against the exterior building paper. Are you suggesting to move the loose fill off the top of the wall cavity and away from the building paper?[/QUOTE]
 
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Old 12-26-07, 10:07 AM
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I'm not quite sure why you keep mentioning "building paper" in your comments... you seem to be describing a type of construction that I'm not familiar with. I've NEVER seen building paper from the inside of an attic before. A digital picture showing the insulation that is blown up against this pitched roof, and against the "building paper" might help us picture what you're trying to describe.

But I think what Michael is saying is a valid point. If they plugged up the space between your rafters with fiberglass insulation and did not leave a space (usually a styrofoam baffle is installed against the roof sheathing which leaves an air space into the soffit and over the top of the insulation) then you would likely want to pull the fiberglass out, install the baffle, and push the fiberglass back in underneath the baffle.

I've never seen a wall system that breathes into the attic, but perhaps if the stucco has been installed on top of a rainscreen type system, there is a space between the sheathing and the stucco that has been plugged by the fiberglass or cellulose. A little investigating would prove whether this is true, and if so... reopening those passageways might help. I don't think this problem has anything to do with the humidity of the home, either inside or in the attic. Condensation on the exterior of the home has more to do with the temperature of the stucco and the RH outdoors.

I still don't see how a little condensation on a paint job is anthing to worry about. You must not get much rain where you live either?
 
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Old 01-16-08, 01:17 PM
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RE-VISITING with NEW INFORMATION.......

Okay, I have kept a log each day for a month to see what is the cause of this new "exterior stucco condensation". I think I have figured it out, but would like to know would be the best thing to do to correct it.

Log shows: There is NO connection with the exterior condensating when we cook or No connection with outdoor temps/humidity, but possibly outside dewpoint because of inside cold wall/cabinets.......

This is what I now believe is the cause: Exterior wall has new kitchen cabinets up against it that have plywood veneer backs up against the walls. Old cabinets had open backs and old kitchen had heater vent. Log shows: The "inside" of the cabinets are very noticably cold on winter days. We used to have a heater vent along that exterior wall but had to remove it when renovating the kitchen because we added additional cabinets. The ouside of the stucco on that wall is much colder than another stucco wall on the same side of the house that has no cabinets and does not condensate on stucco. Insulation inside that wall was NOT upgraded when new kitchen cabinets with back were installed, plus heater vent was removed, so that wall is much colder than any exterior wall of the house. I believe that the stucco on that exterior wall reaches dew point on certain winter days because it has cold cabinets on the inside and no heater vent.

Concern: if the outside is reaching a dew point what about inside the wall cavity? Do you think that this might also be causing wall cavity condensation? Besides that stucco wall recently forming winter dew, that same wall makes loud popping sounds in the hottest time of Spring around 4-6pm, these Spring popping sounds are also something new. What can I do,,, can't remove the cabinets with the granite counters,,,, don't want to remove the stucco to add better insulation.

If COLD WALL SYNDROME is the answer than: Should I add a heater vent in kitchen to warm the room, which hopefully will warm the wall? and drill a few holes in the cabinet sides and bottoms to allow heated room air to enter the cabinets?
Problem is that the stucco only condensates/dew in early morning and we don't keep the heater on at night, but might the warming during the day keep it warmer at night?

Maybe the cabinet backs if possible could be carefully cut and most removed to allow the wall more warmth?

If I shouldn't worry about if it is causing cavity problems then the winter stucco condensation is just unslightly and the spring popping sounds annoying but can be lived with. Please let me know what you think now. Thank you in advance.
 
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Old 01-16-08, 08:00 PM
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Well that explains it then. That would have been a useful bit of information to include from the start.

>>No connection with outdoor temps/humidity, but possibly outside dewpoint because of inside cold wall/cabinets.......

The dewpoint is directly related to the outdoor temps/humidity. The two are undeniably connected.

>>what about inside the wall cavity? Do you think that this might also be causing wall cavity condensation?

No. Provided you don't have massive air leaks around outlets or other wall penetrations that would allow warm humid air inside the home to enter the wall cavity, the inner wall should experience no problems.

>>Should I add a heater vent in kitchen to warm the room, which hopefully will warm the wall?

It couldn't hurt. An electric wall heater w/ its own thermostat might help. But don't be suprised if the problem remains. Your cabinets are blocking heat from exiting (and warming) the interior and exterior wall. Like I mentioned in my initial reply, "If you never got frost on the house before, it was because the walls were so inefficiently insulated that you were losing enough heat to melt the frost." Your cabinets are now blocking this heat loss. By adding heat to this area, you're basically throwing money at the problem. A better solution would be to insulate the wall. You could contact an insulation specialist and see if they have any way to insulate that wall without disturbing the cabinets or stucco.

>>and drill a few holes in the cabinet sides and bottoms to allow heated room air to enter the cabinets?

No. Air currents do not naturally move through small openings like holes.

>>Maybe the cabinet backs if possible could be carefully cut and most removed to allow the wall more warmth?

Also a bad idea. It could compromise the strength of the cabinet and would be useless unless the cabinet doors were also removed.

Have you experimented with leaving the cabinet doors open at night? Using a space heater? Running a fan to circulate air in the room? Or all three at the same time?

As I mentioned previously, I don't see how a little condensation on a paint job is anthing to worry about, other than it being the current focus of your attention.
 
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Old 01-16-08, 08:34 PM
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Thank you

Excellent thorough explanation, thank you and I appreciate you re-visiting my updated post, I hope this will help others, it clears things up for me and re-assures me that I have my answer. Thank you.
 
 

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