Message Board Thread - "Metal over Asphalt roof"

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Metal over Asphalt roof gzuni51 8/5/2009
I am trying to shoot an aluminium roof that has been installed over a asphalt shingle roof. I have taken photos at night and during the day for comparison. I am not able to get consistant readings with my BCAM-SD and wonder if there is an adjustment I need to make for conditions other than dewpoint and general weather conditions.Will the airflow between the two systems cause any unusual issues?
 
Re:Metal over Asphalt roof ron lucier 8/11/2009
A metal roof is too reflective in the longwave (8 to 12 micrometers) and there are no settings in the camera that can help this. Changing emissivity only changes the temperature.

Pretty much the same results for aluminized elastomeric coatings - longwave emissivity is too low to see the thermal patterns. A midwave (3 to 5 micrometer) camera works well on the coatings but I am not sure what you mean by "aluminum" roof - coating or standing seam? If there is an air gap between the two the chances of you detecting moisture approach zero due to convection.

Contact me at ron.lucier@flir.com or 978-764-7020 if I can help further.
 
Re:Metal over Asphalt roof gzuni51 8/12/2009
ron lucier wrote:
roof is too reflective in the longwave (8 to 12 micrometers) and there are no settings in the camera that can help this. Changing emissivity only changes the temperature.

Pretty much the same results for aluminized elastomeric coatings - longwave emissivity is too low to see the thermal patterns. A midwave (3 to 5 micrometer) camera works well on the coatings but I am not sure what you mean by "aluminum" roof - coating or standing seam? If there is an air gap between the two the chances of you detecting moisture approach zero due to convection.

Contact me at ron.lucier@flir.com or 978-764-7020 if I can help further.
Ron, Thanks for the reply and you have confirmed what I suspected.
I should have indicated athat the roof is AEC,sorry for that. Any ideas on how I can use the camera to help determine if the roof is failing? This will go to litigation so I need to be accurate with any inspections methods. I would appreciate any input so expect a call.Thanks
G. Wellborn
 
Re:Metal over Asphalt roof StecGuy 9/8/2009
I know that i am a little late here, but hey. It can be scanned using your camera (i do it on a regular basis), but i use additional equipment. First you need to know the underlying construction of the built-up roof (fiberglass insulation, wood fiber insulation). This will help you identify the type of moisture patterns you are looking for in the camera (ie. wood fiber coverboards typically absorb in very noticeable board patterns). Second, i highly recommend the use of an electrical capacitance meter (Tramex) to provide confirmation that you are picking up on the patterns. It is, however, very time consuming, as you have to check the roof very carefully and very thorough.

Matt
 
Re:Metal over Asphalt roof StecGuy 9/8/2009
StecGuy wrote:
that i am a little late here, but hey. It can be scanned using your camera (i do it on a regular basis), but i use additional equipment. First you need to know the underlying construction of the built-up roof (fiberglass insulation, wood fiber insulation). This will help you identify the type of moisture patterns you are looking for in the camera (ie. wood fiber coverboards typically absorb in very noticeable board patterns). Second, i highly recommend the use of an electrical capacitance meter (Tramex) to provide confirmation that you are picking up on the patterns. It is, however, very time consuming, as you have to check the roof very carefully and very thorough.

Matt
In addition, ron is right that the roof will be very reflective, but the heat load in any entrapped moisture is still conducting through, given there is not air space. Move around, look from all angles. Adjust your temp ranges, most times you can adjust the temp of the reflections to be in a different scale than the wet insulation anomalies.
 


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