That was my answer when a client asked me if a retaining wall was actually doing anything.
Retain - verb 1 continue to have; keep possession of. 2 absorb and continue to hold (a substance). 3 keep in place; hold fixed. ORIGIN Latin retinere - 'hold back'.
Retaining wall - noun a wall that holds back earth or water on one side of it.
Those are my Oxford Dictionary definitions of the two words above.
The retaining wall on the right is 10' high.
It begins at the rear corner of the house, has two corners, and holds back earth to frame a very nice patio outside the rear door. It is made of pressure-treated wood and is properly inclined to hold back weight. It is also anchored here and there with "dead men," which are perpendicular, T-shaped pieces of the same timber, extending 6 or 8' into the soil behind the wall, and which help hold the wall in place.
If it was not there no patio would be possible and the basement door would open to a concrete stair well. While the wall is a bit imposing, I think the patio is much more functional!
So, after asking me if this wall was doing what it is supposed to do, we had a look at it with my thermal camera. The lavender and purple indicate areas cooler than the surrounding wood. This would be where moisture is present. But nothing looked wet on the patio side of the patio. Water was actually retained.
This wall exactly meets the definition Oxford proposed above! So I said, "Yep, it's doing its job!"
My recommendation: retaining walls are integral to the landscape in many yards. Check them out! Make sure they are doing what they are intended to do. If stones or wood or concrete are out of place or cracked, you might have an expert have a look to make sure it's doing the job intended.
Jay Markanich Real Estate Inspections, LLC 
Based in Bristow, serving all of Northern Virginia.
Office (703) 330-6388 Cell (703) 585-7560
We have an exposed lower level....and the caution i would give anyone considering building/doing the retaining wall thing is to know a good contractor AND be aware of the price...not burying the first course of block...taking shortcuts with fill....will leave a wobbly outcome...ask our neighbors the diy kings...who said we paid too much...oh not...
Fer sher S&D! If it ain't done right, it ain't done! And doing it right the first time never costs more...
Don't forget it may need weep holes in the appropriate places.
They are at the very bottom Alan, but not in this image. I could not get the moisture and the holes in the same shot!
I like the thermal image. I really need to get me a infrared camera.
You have a thermal camera? Awesome!! I'm glad the wall was doing its job.
Well, Randy, they are about 1/2 the price now than when I bought mine 6 years ago, and much better, with better software. Mine was state of the art at the time!
Weber Team - of course! About six years now. I have many thermal image blogs on this site - just go to my blog and tags and you will find them. My camera is the sharpest and straightest arrow in my quiver.
Jay, very informative information -- thanks for the images and the explanations!
Tish - thermal imaging is very informative, to us inspectors and to those with little experience with the technology. I think it is a a great addition to home inspection abilities.
My son is at Camp LeJeune right now. Just got back from his third tour and will be leaving again in December.
Glad to hear the wall is performing as expected, but the homeowners sense of color is a little wacky. ;)
Those weren't favorite colors of mine either, Jim, but hey, to each his own... ;)
Jay...your posts do bring out the 'nutty and fun' in comments; those colors are interesting, but if anyone watches "Ghost Hunters" on SyFy, the thermal camera is used all the time.. Were this a ghost hunter episode, I would have to say that you captured some 'live--warm' entities on that screen shot. LOL
Actually, I find your posts very informative, bot your post, the comments & your answers to said comments [please be gentle with this one]
Barb & Sal
Barb and Sal - well, I didn't want to frighten anyone, but that really is a lavender ghost running to the right from the darker, cooler corner! OK, maybe not... I have not watched that Ghost Hunters show yet, but have seen the commercials. I tease my wife all the time that we should go around the house with my camera and see if we can find "entities..." She really hates that, I don't know why!
Perhaps you had seen my ghostly friend on other posts - I call him Mosby.
This was the second time I met him, and he has followed me ever since:
http://activerain.com/blogsview/1647522/ever-feel-like-you-are-being-followed-
Thermal imaging is fantastic. Thanks for sharing this story!
It is definitely important for retaining walls to be checked out!
Hi Jay, Great illustration, love the thermal camera, I'm sure your client did too. jay
Jason - it is a great tool that can reveal things otherwise not even thought about. I am glad to have a thermal camera, and have had one for many years.
Damon - I have to admit, this was my first retaining wall of this size. And made of wood... It framed the house and patio, so we thought it important to check out.
Jay - never to date have I had a client dissatisfied with what the camera can do. It's kind of fun too!