Message Board Thread - "Regarding detecting moisture"

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Regarding detecting moisture Mobius01 4/23/2011
When doing a thermal scan of a building from inside for moisture intrusion does it matter what the inside temperature is of the house. I am guessing that it doesnt matter and the camera should pick up effected areas because of thermal mass of moist areas, correct?

Also, how can we pick up water damaged areas if the leak is not active?

Thanks
 
Re:Regarding detecting moisture dandersen 4/24/2011
Yes and No:
The camera does not measure thermal mass.
So there must be a temperature difference for the mass to show up. Thermal mass determines the rate of heat transfer. The building envelope must be in thermal transition for the leak to be seen.

Also the relative humidity counts.
If it is at 100% (like a basement) and there is no delta T, you will not see anything. Evaporative cooling does not occur at 100% rh.
If you have no delta-T but there is a large delta-h, you will see the effects of evaporative cooling.

A non-active leak requires a huge delta-T in transition to detect the change in thermal mass caused by water damage.

A good knowledge of psychrometrics and thermodynamics is required in building diagnostics.

Consider the Building Science course if you plan to use this application.
 
Re:Regarding detecting moisture Mobius01 4/24/2011
dandersen wrote:
No:
The camera does not measure thermal mass.
So there must be a temperature difference for the mass to show up. Thermal mass determines the rate of heat transfer. The building envelope must be in thermal transition for the leak to be seen.

Also the relative humidity counts.
If it is at 100% (like a basement) and there is no delta T, you will not see anything. Evaporative cooling does not occur at 100% rh.
If you have no delta-T but there is a large delta-h, you will see the effects of evaporative cooling.

A non-active leak requires a huge delta-T in transition to detect the change in thermal mass caused by water damage.

A good knowledge of psychrometrics and thermodynamics is required in building diagnostics.

Consider the Building Science course if you plan to use this application.
yes, I understand that the camera does not measure thermal mass, it actually measures the effects of thermal and mass thermal conductivity with respect to its surroundings.

When you say, no delta-T and large delta-H, you are referring to delta-H in the basement from inside to the outside of the basement, correct?

Also, are you saying that we wont be able to detect a non-active leak at all that is suspected on an INTERIOR wall in a house where there is never a delat-T? Unless, we do the scan when it is active (during rain etc)?

Thanks for your comments.
 
Re:Regarding detecting moisture Mobius01 4/27/2011
Mobius01 wrote:
yes, I understand that the camera does not measure thermal mass, it actually measures the effects of thermal and mass thermal conductivity with respect to its surroundings.

When you say, no delta-T and large delta-H, you are referring to delta-H in the basement from inside to the outside of the basement, correct?

Also, are you saying that we wont be able to detect a non-active leak at all that is suspected on an INTERIOR wall in a house where there is never a delat-T? Unless, we do the scan when it is active (during rain etc)?

Thanks for your comments.
Care to respond?

 
Re:Regarding detecting moisture ldapkus 4/27/2011
You should be able to detect moisture on interior walls as long as the moisture hasn't evaporated. Here's a few images from sliding glass doors leaking into ceiling areas.
[IMG]http://i1192.photobucket.com/albums/aa330/LinasDapkus/4-25-11017.jpg[/IMG]
[IMG]http://i1192.photobucket.com/albums/aa330/LinasDapkus/4-25-11013.jpg[/IMG]
[IMG]http://i1192.photobucket.com/albums/aa330/LinasDapkus/4-25-11007.jpg[/IMG]
 
Re:Regarding detecting moisture ldapkus 4/27/2011
ldapkus wrote:
uld be able to detect moisture on interior walls as long as the moisture hasn't evaporated. Here's a few images from sliding glass doors leaking into ceiling areas.
[IMG]http://i1192.photobucket.com/albums/aa330/LinasDapkus/4-25-11017.jpg[/IMG]
[IMG]http://i1192.photobucket.com/albums/aa330/LinasDapkus/4-25-11013.jpg[/IMG]
[IMG]http://i1192.photobucket.com/albums/aa330/LinasDapkus/4-25-11007.jpg[/IMG]
Oops, here they are:
 
Re:Regarding detecting moisture ldapkus 4/27/2011
All interior walls/ceilings
 
Re:Regarding detecting moisture bdrogin 5/4/2011
In NYC, it is rare for the indoor and outdoor temperatures to be the same. Just sayin'.
 
Re:Regarding detecting moisture Mobius01 5/4/2011
bdrogin wrote:
it is rare for the indoor and outdoor temperatures to be the same. Just sayin'.
hmm..there has to be a period of time in the year where there is no delta-T.
 
Re:Regarding detecting moisture bdrogin 5/23/2011
Mobius01 wrote:
hmm..there has to be a period of time in the year where there is no delta-T.
More like period of time in the day. Extensive use of HVAC in NYC, to make indoors cooler or hotter. That said, a "large" temperature differential is rare, except on the coldest or hottest days.
 
Re:Regarding detecting moisture Mobius01 5/23/2011
bdrogin wrote:
More like period of time in the day. Extensive use of HVAC in NYC, to make indoors cooler or hotter. That said, a "large" temperature differential is rare, except on the coldest or hottest days.
So you are saying that its summer one minute and the next minute the climate turns to winter?
 
Re:Regarding detecting moisture Scott Wood Associates 5/23/2011
To “view” moisture from an intrusion, no inside to outside temperature difference is necessary. Why, since all conditions for heat transfer require a delta T? For most water intrusions you are looking for evaporative cooling to provide the temperature difference as shown prior in the images by ldapkus.
To get evaporative cooling you need conditions that enhances this as discussed prior by danderson. Energy is required to evaporate water. Lower relative humidity, air movement and higher temperatures all increase evaporative cooling.
Regarding temperatures inside the building; if they are too low, evaporation is limited and may not be visible as a cooler pattern in the imager. No temperature difference is required between the interior or exterior to enhance evaporative cooling.
 
Re:Regarding detecting moisture Wieslaw 5/23/2011
Recently, in order to see moisture intrusions inside of flat, I tried to obtain the Delta-T by thermal stimulation : 20 min heating with thermoblower fan to 30C, then 5min cooling down - and I did see difference between moist and dry stuctures.. In this flat builders did not cover the roof before the autumn rains; and in winter frost bloomed on the walls..
So it is usable to use primitive "active thermography" sometimes - actually it goes about simple heating inside a little...
 
Re:Regarding detecting moisture bdrogin 6/30/2011
Mobius01 wrote:
So you are saying that its summer one minute and the next minute the climate turns to winter?
No, the outdoor temperature usually stays above or below the indoor temperature. Most people set their indoor thermostats to upper 70's, and the exterior temperature is almost never upper 70's. During the cold months, indoor is always heated, and during the hot months, temperature either stays above or swings past thermostat setting around midnight or so.

We typically get one - and I do mean one - day in the spring where the outdoor temperature is upper 70's. Everyone goes outside that day (either lunchtime or all day on the weekend).

I did write that a large temperature differential, such as the 35 to 45 degrees of ASTM C1153, is rare.
 


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