Message Board Thread - "Best Conditions Scanning For Water Intrusion"

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Best Conditions Scanning For Water Intrusion Dusty 4/19/2004
I have an opportunity to shoot numerous public housing units for water intrusion that were shoddily built. The units are unoccupied and have power so I can dictate the environmental conditions. Would it be best to run the heat and let cool or run the A/C and let heat up for optimum scanning conditions? The weather forecast is for mid 70°’s in the day and mid 50°’s at night with clear to partly cloudy skies.
Re:Best Conditions Scanning For Water Intrusion scott 5/5/2004
Since the infrared camera "looks" at heat, which is transfered by radiation, convection or conduction and heat flows from hot to cold it is best to be on the cold side. In most cases this will provide the best IR viewing. The conducted heat will flow through the building envelope highlighting the different conductivities of the building materials.
In other words the building materials that conduct the heat best will show warm and the non-heat conductors will be cooler (if you are on the cool side of the building envelop). Turn the HVAC on or observe the walls providing the most exposure to the sun. Additionally heat the building if the outside temperatures are low viewing again from the cold side of the building envelop or the outside in this case. During the day this will change as the earth rotates, which may give you better thermograms depending on the suns exposure. A note; the ducts of the HVAC system will be cooler as well as the air being blown from the vents of the system. Beware, leaky or broken HVAC ducts may create interesting “cool” spots that would not normally be present.
In the IR thermagram the metal framing, which is conductive is hot and the wood framing is cooler. In this example the sun is shining on the wall and has not yet heated the wood framing as well as the metal framing.
Re:Best Conditions Scanning For Water Intrusion Thermasearch 5/15/2004
I assist an engineering firm speciallizing in mold and mildew issues by scanning structures for wet insullation. I recently completed several appartment units that were new and in various stages of completion. I was called on because a wet wall was found in one appartment and their best guess was it was because support beams for stair wells in the open were not sealed properly and water had flowed along the beams and into the wall. They wanted to know how many appartments were affected. after scanning some 73 of the units we were able to identify with a high confidence, all. Of those identified as possible wet to lightly damp, all were correctly identified. Some lessons learned included:
- Get as much delt T between inside and out as possible, 10 C degrees provides some excellent shots.
- The composistion of the wall primarily determines wether best to shoot from inside or out. typically shooting from the inside. Experiment with both points of view before deciding and how to complete the project.
- Wet insullation should have an irregular pattern but will look like a picture frame when viewing non absorbent sheets on walls. These sheets are are among the worst because the water runs an internal path not easily seen from the inside but capable of rotting entire door and window frames in just a few months.

A word of caution, typically you are asked to do these types of scans because of pending or present legal litigation. The requesters may try to hang their hats on what you provide. Include words that cover your(and our professions) rear, As examples; "these results are tentative and may require destructive testing to confirm.", "every attempt to identify a possible fault was made but due to the sometimes subtle nature of water intrusion and environmental factors, not all possible faults may have been observed."

If the intent of your findings is to find mold and mildew you will need to partner with a qualified engineering firm in this area to best cover your rear and provide the most complete answer to your client.

I have been working with Atoka engineering of Little Rock/Hot Springs AR for a few years now.

Good luck with your project.

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