Message Board Thread - "Thermal annomalies"

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Thermal annomalies dryfix 10/10/2010
Can anyone provide clairty on the following;

You loose heat 25% faster in water than on the surface. If testing for water intrusion internaly this would be represented by cool signiture on a thermograph, due to evaporative cooling.

So why when testing for water damage to a flat roof would this be represented by a warm heat signiture, as apparently the water retains heat? Surely water entering a rooing material would help heat transfer resulting in a cooler surface-T?

Am i being stuid?
 
Re:Thermal annomalies TomC 10/11/2010
In roofing applications the thermal capacity of water is much greater than that of the dry roofing materials as the roof solar loads the water absorbs the radiant energy much more slowly and is much slower to lose that heat back to the environment through radiation heat transfer on a clear cool evening. The water has been in the insulation material for a while and while it does evaporate all that would be seen during the day is a solar loaded roof

In interior wall surfaces there is no solar loading so we rely on the effect of evaporative cooling to locate the moisture laden material. It is possible with great care and a little bit of luck in the morning to see water as a colder spot before the roof solar loads.

It is also possible to see moisture from under the roof deck during the day as a cold spot but that again is due to thermal capacitance and not evaporation.

It is a much simpler process to use the difference in thermal capacities of water and dry roofing material to locate areas of moisture intrusion than to look for evaporative cooling effects.
 


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