The thermostat was the easy thing to blame.

When a room feels cold, more heat seems like the answer. It's the thing you can change without moving furniture or opening a toolbox.

But a warmer thermostat setting can't tell you why that one corner feels different from the rest of the house.

Try this before buying anything: go back to the spot that bothers you. Around the window, is the surface cold, or can you actually feel air moving?

Those are different clues. And that small distinction can change what you do next.

The cold spot may start below your feet.

The place you feel a draft isn't always where it enters.

If there's an unfinished basement or an accessible crawl space below the room, you may be able to see what the finished floor hides. Along the outside edge, the floor framing meets the foundation. That's the rim-joist area.

Look for accessible gaps around those connections and service openings. Suddenly, the question gets more specific: could air be getting through here?

Leave required vents and openings clear. Dampness, damaged wood or uncertain clearances need sorting out before any foam comes out.

Now there's a job you can actually picture.

A room that never feels right can sound like a whole-house project. An exposed section you can inspect and measure is easier to get your head around.

This is where BEEST FullStop can fit. It's a spray foam for air sealing and insulation on suitable exposed surfaces. The can-and-gun format lets you work through the sections you've planned.

You can see where the foam is going. You're not guessing behind a finished wall.

First, though, there's a question worth answering while the wall is still bare: how much of it are you actually going to spray?

The room size isn't the number you need.

It's tempting to say, 'It's a small room. One kit should do it.'

But you might only be treating a few exposed sections underneath it. Or you might be insulating several open walls. The same room can lead to very different orders.

Measure the surfaces you've chosen, then decide the thickness your job needs. A 12-can kit is rated for up to 240 sq ft at 1 inch, or 120 sq ft at 2 inches.

Those are rated figures. Leave room for practice and awkward gaps, too. Finding that out now is much better than finding it out with half a wall left.

The first can can wait a little longer.

Once you've found the job, it's natural to want to get on with it.

This is the part where a little patience pays off. Clear the work area. Cover the finishes you want to keep clean. Watch the tutorial before you're standing there with the gun in your hand.

Follow the current guide for surfaces, temperatures, ventilation and re-entry. Wear a suitable respirator, gloves, goggles and a coverall. The respirator is separate from the kit.

Keep ignition sources away during use and until vapors clear. Then make your practice pass before moving to the wall.

Read the application and safety guide

What you want back is an ordinary room.

You probably didn't start thinking about insulation because you wanted to spend more time thinking about insulation.

You wanted to sit down without fetching another blanket. Walk across the room without noticing the floor. Use the corner you keep avoiding.

A published BEEST garage review describes fewer cold drafts and a warmer garage after application. That's one customer's experience, but it speaks to the kind of change that matters day to day.

Once your work has cured and the room can be used again, go back to the places you checked first. Comfort is the goal. Results depend on the home, weather and installation; there's no promised bill reduction.

And if that window still lets air through?

You haven't failed. You've found the next part of the job.

A worn door seal, a drafty window and an exposed gap below the floor may each need a different fix. Foam belongs on suitable gaps and surfaces. Weatherstripping or a window repair may still be needed elsewhere.

That's why it helps to remember where this started. Which spot felt cold? Where could you feel moving air?

Now you can go back and check, instead of turning the thermostat up and hoping.

Start with the corner you're tired of avoiding.

You don't need to guess at the whole house today.

Find the accessible section that needs attention. Take its measurements. Work out the thickness, and use the calculator to see how many cans the job calls for.

If the surface or clearance leaves you unsure, ask BEEST before ordering. A quick conversation is easier than trying to undo the wrong application.

Then you can choose a kit for a job you understand, with a clear reason for doing it: you'd like that room to feel like part of your home again.

Use the project calculator Call BEEST

FullStop foam includes a 1-year limited warranty. Register within 30 days of purchase for a free extension to 10 years. The extension covers the foam; the gun has a 1-year limited warranty. Read the warranty terms.

See the current kit options for your project.