Sometimes you can spend a whole lot of money improving your home, only to discover you've made something worse.

And sometimes the people you paid to do the work are the reason.

This particular home had some beautiful new flooring. Professionally installed, nicely finished, and nothing obviously wrong.

At least, that's what it looked like.

It was a hot day, and I was carrying out a home inspection when something unusual appeared on my infrared camera.

Right there on the surface of the newly installed flooring was a remarkably clear rectangular shape.

And it was cold.

Now, I've seen plenty of interesting things through an infrared camera over the years, but this one made me smile. I recognized the shape almost immediately.

Looking at the floor without the camera, there was absolutely nothing unusual. Just a nice, clean surface.

But the infrared camera was telling a completely different story.

🎥See the video in the section below.

That cold rectangle in the photo above was the outline of an air supply vent!

The flooring installers had laid the new flooring directly over the existing vent and forgotten to cut out the opening.

I have to admit, they did a beautiful job of hiding it.

Unfortunately, hiding it wasn't part of the renovation plan.

When I showed the seller what I'd discovered, everything suddenly clicked.

They'd been wondering why that part of the room was so much hotter ever since the new flooring had been installed.

Well, there's your answer!

There was a perfectly good air supply duct beneath the floor, but the cool air couldn't get into the room through its intended opening.

And here's the irony. On that hot day, my infrared camera was showing a cold spot on the floor, while the covered vent was helping explain why that part of the room felt so warm.

Imagine spending good money on professionally installed flooring, only to spend the summer wondering why part of your house had suddenly become so uncomfortable.

And the answer was right under your feet the whole time.

You really can't make some of this stuff up.

The funny thing about this discovery is that the infrared camera wasn't actually seeing through the floor. It was detecting a temperature difference on the surface caused by the cooler duct underneath.

That's how thermal imaging works, and it's one of the reasons I find the technology so useful during inspections.

Ever wondered whether an infrared camera can see through walls, find hidden pipes, or detect something in complete darkness? FLIR explains what these cameras can really see, and some of the answers might surprise you.

As for the missing vent, the correction was pretty straightforward. The flooring installer needed to return, locate the original duct opening, carefully cut and finish the flooring, and reinstall the floor register.

No new air conditioner. No tearing up the entire floor.

Just finish the job that should have been finished in the first place.

If you're having new flooring installed, here's one simple thing I'd recommend.

Take a few pictures of your rooms before the old flooring comes out, making sure all the floor vents are visible.

Once the job is finished, check that every opening is still there and that air is flowing when your heating or cooling system is running.

And if a room suddenly becomes harder to heat or cool after a renovation, don't automatically blame the furnace or air conditioner.

There are several reasons one room might feel different from the rest. This Old House explains how heating systems work and what can affect comfort throughout your home.

Sometimes, though, the problem is much simpler.

Someone forgot to make a hole.

▶ Watch on YouTube

Ever wonder what else might be hiding in a perfectly ordinary-looking house?

After 18 years doing home inspections, I can tell you there's no shortage of surprises.

If this week's infrared discovery made you smile, share the video with someone who's recently renovated.

They might want to count their vents!