Message Board Thread - "Air Leaks in Wooden Ceiling????"

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Air Leaks in Wooden Ceiling???? Infraredhitech 12/11/2008
Hey guys,

This image was taken on Dec. 8 2008 at 5:30 p.m. it was 21°F outside and the inside was heated up to 70°F. Above this finished wood is normal joists and batting insultation. This ceiling was done about a year ago. I can see the obvious air leaks but what is the other colder spots from? Is that missing insulation? The air infiltration doesn't appear to be moving but do you think that it's colder air going across the wood?
 
Re:Air Leaks in Wooden Ceiling???? Infraredhitech 12/11/2008
Here is the infrared image.
 
Re:Air Leaks in Wooden Ceiling???? LenMelso 12/18/2008
Yes, air infiltration should be the correct answer. Whether or not insul is missing is anybody's guess. My guess is just a cold air pocket between the face of the insul and the back of the ceiling. Is there a soffit vent outside this rafter bay? One other problem that genius builders forget about when installing recessed lights that close to the eaves is ice damming. The lights give off a ton of heat and can cause melting of snow/ice. When I see areas like this, I always check w/ moisture mtr just to rule out. All that said, it's prob just cold air.
-Len
Infrared Energy Services
 
Re:Air Leaks in Wooden Ceiling???? Infraredhitech 12/31/2008
Thanks, I thought it could be that as well. I have some other images that specifically show hotter square images which show to me missing insulation. This one was tough.
 
Re:Air Leaks in Wooden Ceiling???? WCT 1/7/2009
Any wind? The cold air infiltration patterns would be exaggerated on the windward side of the house and the opposite on the leeward. Definitely check with a moisture meter as Len mentioned.
 
Re:Air Leaks in Wooden Ceiling???? SteinyIR 1/7/2009
If the smaller spots you are referring to are towards the lower edge of the ceiling, they are likely either fasteners or knots in the wood. Knots will show up as warmer or colder, depending on the delta T, because of the difference in thermal mass.

If you check the spots with a non-penetrating moisture meter, they may show up as having higher moisture only because of the conductance. You may have to use a penetrating moisture meter to be 100% sure.

 
Re:Air Leaks in Wooden Ceiling???? Weatherization guy 1/8/2009
The fiberglass batts are probably performing especially poorly at the bottom of the sloped ceiling due to the soffit venting and windwashing through the fiberglass. We see this lack of a continuous air barrier (tongue and groove isn't one) in concert with proper venting/attic ventilation causing alot of poorly performing sloped ceiling assemblies. Fiberglass should never be installed in anything less than an air tight cavity. By the way that is almost impossible to do
 
Re:Air Leaks in Wooden Ceiling???? damodog 1/11/2009
Looks like a roof leak to me. I don't think air behaves the same as water. In the absence of a moisture meter, think like a rain-drop with me: The drip occurs over the beam, then travels downward enlarging the damp spot on the beam, then travels laterally at the first joint in the T&G, then disperses downwards from there.
 
Re:Air Leaks in Wooden Ceiling???? Scott Wood Associates 2/16/2009
damodog wrote:
ike a roof leak to me. I don't think air behaves the same as water. In the absence of a moisture meter, think like a rain-drop with me: The drip occurs over the beam, then travels downward enlarging the damp spot on the beam, then travels laterally at the first joint in the T&G, then disperses downwards from there.
Careful to describe the patterns observed as moisture. Based on what I see, they do not look like mositure patterns, but conductance and convection. However, you are correct to note that a mositure meter will provide conformation and should be used when a "roundy" fairly uniform thermal pattern is observed.
 


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