Message Board Thread - "ghosting between trusses"

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ghosting between trusses joma2299 7/18/2007
I have a great room with a vaulted ceiling,and during the last couple years large grey sections have appeared between the trusses.there is a large area between the insulation and the roof and i have an enclosed soffit that is vented.the house is only 3 years old.I have been told that the insulation is not on the sheetrock and it creates cold areas and airborn dust particales cling to these spots. i had it re painted and the installer of the insulation soid everything is fine. can you help me?
 
Re:ghosting between trusses JNTOOLS 7/19/2007
Do you have any images to post? Also when you say large gray sections have appeared, are you talking about cool spots showing up on a gray tone pallet on your thermal imager? If insulation is not in thermal contact with the gypsum ceiling, it is not effective in those areas. I am not sure about the airborn dust particle thing. If you have areas that are not insulated well they can in extreme cold weather reach the dew point and moisture will condensate on these points. I see all kinds of thermal issues with vaulted ceilings. I have also seen outlet cover plates dripping with water from condensation from the same issue.
 
Re:ghosting between trusses doctorleak 8/2/2007
You say that you have vented soffits but do you aslo have other vents or a vented ridge cap? An image would possibly assist in finding the solution to your problem. Regards:

Jim Jennings
Manager
Canadian Acdemy of Building Sciences
 
Re:ghosting between trusses Alaskan Lady 8/2/2007
Is this an air conditioned house. It could be that there is candle smoke clinging to the cooler area between the trusses. The wood of the trusses would conduct any heat. Smokeless candles are a common source of grey discoloration.
 
Re:ghosting between trusses lmcfarla 8/2/2007
joma2299 wrote:
a great room with a vaulted ceiling,and during the last couple years large grey sections have appeared between the trusses.there is a large area between the insulation and the roof and i have an enclosed soffit that is vented.the house is only 3 years old.I have been told that the insulation is not on the sheetrock and it creates cold areas and airborn dust particales cling to these spots. i had it re painted and the installer of the insulation soid everything is fine. can you help me?
I have had mold that has shown up between the studs on the outside of my house. It showed up as a gray color with stripes. I think the material on my house held moisture well, and caused the issue, and the temperature differences between the studs caused the stripes. You might have high moisture in your room. If not, you might try adding a mold inhibitor to your paint (double the recommendation). It solved my problem.
 
Re:ghosting between trusses dandersen 8/18/2007
Ghosting generally occurs at the studs where thermal conductivity is higher.

Ghosting occurs from airborne particulate matter that is accelerated from a molecular activity due to the thermal differences.

I would recommend an energy audit to determine the effectiveness/existence of insulation in the ceiling.
The "R value" can be determined with an infrared camera and a little bit of math.

In my area, 80% of vaulted /cathedral ceilings have significant insulation deficiencies which is accentuated by the small distance between the roof and the ceiling.
 
Re:ghosting between trusses DMcGiffin 1/23/2008
In my experience ghosting is caused by high humidity levels in the home, low dew point and CANDLES. The ghosting comes from the soot in the candles and the condensation at the areas of low insulation.
 


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