I was called to do a One Year Inspection prior to the expiration of the builder's warranty. I do a lot of them.
Looking at this deck and door from the rear yard everything seemed normal enough.
Until I got closer.
You might not notice it from this photo.
I'm talking about what you see in the photo below.
That's it, right there. Water.
Now, it had not rained in the past month. There is a bedroom window above this door, but it could not have been opened during a recent rain storm. There is no plumbing in the wall, service or drain. There is a typical soffit overhang with a gutter, but all that was dry.
Coming inside, the floor around the door was dry according to my moisture meter. I had my IR camera with me and looked at the wall above and around the door inside and out. Nothing visible. Similarly, inside, nothing thermal was visible in the floor or ceiling above.
Neither upstairs bathroom is anywhere nearby. The closest, the Jack and Jill bath, is 20 feet above and to the left of this photo. I had not tested the bathroom yet, it was dry, and this water is fresh, the puddle even growing slightly during the inspection. The plumbing penetration to vent the kitchen and that bathroom is 30 feet or so to the left of this photo. He had not used the hose or watered the lawn that day.
I have to admit, I was stumped.
I NEVER DID FIGURE IT OUT!
My client had never noticed this puddle before. I advised him to call me if it continued or grew. He never did.
Sometimes things remain a mystery. Any ideas as to this water's source?
My recommendation: when you notice something out of the ordinary, and you cannot figure out a reason, watch it to see if it changes. Maybe then you will find a change that leads you to the cause. And then maybe you won't...

If the walls arent wet then that is a mystery. Maybe its condensation from the doors and heavy HVAC use?
I would suggest that the owner has a garden hose and uses it generously.
Laura - nothing was wet except for the little puddle! I don't know!!
Lenn - I asked, he had not used the hose that day. The inspection was late afternoon...
Is the house near a lake? It could be the sea water level during high tide.
Rosalinda - not near a lake but it is near the ocean -- about 125 miles. It is a bit closer to the Potomac River, about 5 miles, but the river is at least 100 feet below this house... (;>)
Wow this is a stretch and I'm pretty sure anything I can think of you already did, but is there any possibility that this unexplained puddle is being caused by condensation?
Jay--maybe it was a dog marking their territory?:)
Mr Jay,
Had I been there, had I caused that, I would have fessed up.
Nutsy
Sue - I don't think so or it would have shown up on IR. But you could be right...
Charlie - perhaps! It was something that happened prior to my arrival, though I discovered it within minutes of getting there. He had marked it before - see the paint missing from the lower nail head? It was not stained however.
Nutsy - I am glad to hear that. It doesn't look like a location you would find too appealing for that sort of thing... if I understand what you meant by "caused that."
Jay, I recommend the "Scratch & Sniff" test:)
Charlie - now why didn't I think of that!? Tried and true.
Jay,
You did not have a big scare or something, right before that?
Steve - I have big scares every time I turn on the radio and hear a politician speak. But at the moment I saw this my radio was turned off.
Jay,
At least we are able to eliminate one source of the water....that is a start.
I still have not heard from the client and told him to call me if it mysteriously reappeared and/or grew larger.
We had a strange puddle on a house once...the home inspector, plumber couldn't figure it out...had a wise old handy man who diagnosed and fixed the problem..many eyes make for great solutions.
And many hands make light work.