Best time of day to do a flat roof IR scan?

A guy I know has a few flat commercial roofs he wants courtesy scanned–just curious what would be the optimal time of day to get best results? I was thinking late in the day after the sun had beat on it all day or early morning before sun is up for long?? I’m in Canada and its march so think 30-32F in the morning up to 35F in the afternoon (-2 to +2C) I’m told the flat roof is mod-bit but I’m not 100% sure

The camera is a fluke TiR if that makes a difference…

Need a sunny day then scan about an hour after sunset

This isn’t a good time of year as there isn’t enough heat from the sun to heat up the roof, not to mention snow covering the roof. The best time is during the summer a little after sunset. You can also do it during late spring/early fall but the window is much smaller.

You could try a poor mans thermoscan and show up early in the morning while the frost is still on the roof. It will tend to melt off the wet areas faster.

Jeff, that is one way to do it.

This is going to sound like a smart arse answer, but the actual answer is…when you get the best images.

David Anderson and Charley will be able to give you a better worded answer. You can do flat roofs during the day, night, whenever. It just really depends.

There are other factors involved as well, including, but not limited to; wind, weather, when it rained last or roof was soaked down, what kind of “sky” conditions, objects that can create shade, what time of year…these are just off the top of my head, others will chime in with more I am sure.

Jason Kaylor
AC Tool Supply
Net Zero Tools

Never is a good time for a “courtesy scan”
When is the best time to do a “courtesy home inspection”???
I had a conversation with Dave Anderson the other day regarding doing free inspections. When are these profitable or warranted?

Dear Stuart:

The topic of infrared inspections of flat roofs has been previously covered in several Tips of the Week at our content-based website, IRINFO.ORG. You may find the following Tip of particular interest as it covers required weather conditions as well as appropriate time of day for inspections.

Infrared Inspections of Flat Roofs](

This Tip and hundreds of others like it can be accessed for free.

Hope this helps.

Looks like lots of good info to cherry pick there.

Best tip on is this one: (although I know everyone here already practices this) :twisted:

First Impressions Count
Tip written by: Infraspection Institute

“First impressions count.” This timeless observation underscores the importance of appearances when meeting someone for the first time. This same observation also holds true in the modern, wired world.

Experienced business people know the importance of first impressions. To this end, they do their best to dress, act, and speak appropriately when meeting prospects. Why is it then that so many fail to understand that first impressions on the web are equally important?

The worldwide web and email have greatly expanded the reach of many businesses. No longer are businesses confined to geographic regions; their ability to reach a worldwide audience is limited only by the connectivity of their prospects.

Prospects will form opinions about businesses or individuals through their websites, emails and posts to public message boards. When using any of these resources, keep the following in mind:

• Be courteous and respectful of others
• Never post anything you should not say in public
• Do not make personal attacks on individuals or companies
• The internet crosses international and cultural boundaries. Depending on local customs, people do things differently. This does not make them wrong.

Remember, with every new encounter, others form impressions of you. Because first impressions can be permanent, make certain that your web impressions are always positive.

Very true…we’re bidding a job in South America for an International Gas Manufacturer (medical and industrial gases).

They want four plants inspected in Ecuador, they also have plants in all other counties in South America too.

Jim Seffrin is the epitome of courtesy, decorum and professionalism. I believe that the whole crew at Infraspection Institute present these same values. I know that Jim has an ear to what goes on here. If you look closely, you will often find his IRINFO.ORG tip of the week to be relevant to some contemporary happenings here. The above tip is one of those. Perhaps coincidence, perhaps not, but always relevant.

Here’s the link to go with Jim’s content that has been included in this thread.

I will confess that I often you his tip of the week archive to “brush up” on a topic when I’m preparing a proposal or planning an inspection.

Duffy… Dale Duffy. International Man of Mystery. A martini please, shaken not stirred. :wink:

Great tips! Thanks Jim et al. I may not have access to the site at an optimal time so its good to be able to pass on the various factors that would influence a quality result.

Jason, I know it was only one way but I didn’t want to confuse the issue with all that can go into a roof scan since it is a courtesy scan.

Stuart, I personaly wouldn’t be using a TIR on a commercial roof scan. I’d recommend 320x240 with a better sensitivity minimum on any commercial job. Just a suggestion…

I have a question, and a suggestion;

Seeing as this is a “courtesy scan”, why don’t you get your camera out and go spend the day scanning these roofs?

This will help you understand what you’re seeing, why you’re seeing it, and when you will see it. This will help you understand the question you just posted.

There are numerous opportunities to do roofing scans throughout the day. The results will be different. The most important thing is **not **to know “what time to do it” but what causes the conditions that make it feasible.

I’ve done some roof jobs so big that I’ve had to invert the palette colors so the anomalies all look the same in the report! This is because at one time of the day the wet spots were cold and other times they were hot.

Cameras in the “automatic mode” cannot make the correct assumptions, you have to.

If you do this, by the time you get to infrared training you will have some experience that you can relate to and will help you get more out of the class.

The one hour after sunset time frame is taught in school because it’s the easiest for you to achieve and understand without knowing all of the complexities involved in scanning the roof. Even though this is the best time under that standard, it doesn’t mean it will necessarily work for you.

I have done dozens of thermal scans on buildings when I should not have been doing them according to the schools. I run my camera and take pictures regardless of these “Windows of Opportunity”. By doing this (and following exactly what I’m suggesting you do here) I have learned that what causes exceptions to be observed with thermal imaging is much more complex than we can hope to perceive in all cases. We try to take the most opportune times and control the conditions as much is possible by understanding physics, thermodynamics, fluid dynamics, psychrometrics etc. but things often do not appear as they seem!

Infrared training is a progression. The further you go, the more understanding you will have as to what the camera is registering and what you must do to obtain useful data. Some infrared trainers believe that this information and education is totally unnecessary because were just collecting pretty pictures. Well, pretty pictures show up under different circumstances which may be beyond your control or initial observations.

When you see a spot on your thermal scan, you should always be asking yourself what caused this to appear? If you can’t answer this question than you do not have sufficient information to write a report. Just because there is a warm spot on the roof one hour after sunset, it doesn’t mean you have a leaking roof!

“a warm anomaly was apparent on the roof, recommend further evaluation by a roofer” is insufficient information (even though it seems to be sufficient and home inspections). In commercial/infrared inspections your scope of inspection is not the same nonsensical limited inspection as a home inspection. You cannot drag thermal imaging backwards into the home inspection industry. You’re going beyond the limitations of a home inspection and you are no longer protected by these assumed limitations of liability.

I highly recommend that you discuss what you use your camera for with your insurance provider, because at some point in time they may feel that you are not performing a home inspection and are not covered under your insurance. I have this conversation each year with my provider, and just received an email from them yesterday to discuss it again for this year.

David–thanks for the feedback! I have been experimenting with the camera wherever anyone lets me just to get a feel of the results versus conditions. As you say, there are a ton of factors and it is interesting to see real world variations as those factors change.

Gordy…er…thanks but I’m not up to spending 10’s of thousands of dollars just yet lol…maybe after I have had some training and worked my way up to that…

I enjoy roof scans. They are both challenging and fun, and can provide a very lucrative income with the right equipment, training and experience.

You have received excellent advice and reading from experts in the industry. No better opportunity to learn than to try your hand at it with the roofs you have described!

Post some images after you do them, so we can try to assist you further!

Now these are the threads I enjoy.

Thanks everyone for making the TI section interesting and enjoyable again, great learning experience for all.