The Thermal Camera Test: How Much Heat Escapes Under an Unsealed Door?
We pointed a $2,500 FLIR thermal imaging camera at a standard front door during a cold snap. The bright purple-and-black heat map revealed a hidden, costly truth most homeowners and renters never notice.
The Invisible Leak Draining Your Bank Account
When you look at your front or patio door, it probably looks completely fine. It shuts tightly, the lock turns, and everything appears sealed.
However, when our thermal camera scanned the entryway, a stark story emerged: while the wall held steady at 71°F, the bottom edge of the door plummeted to a freezing 48°F.
That tiny 0.5-inch gap beneath the door was acting like a continuous, invisible exhaust pipe, letting climate-controlled air escape while pulling freezing drafts across the floor.
According to energy auditors, an unsealed door bottom gap can account for up to 15% to 20% of a home’s total HVAC energy loss. You aren't just losing heat. You are paying double to keep your home warm.
Traditional Fixes Fail Over Time
To solve the heat loss revealed by our thermal camera, we tested the three most common DIY draft solutions. While a few offered temporary relief, none provided a durable, long-term fix and each came with major flaws:
- Foam Slide Tubes: They blocked some air for the first week, but quickly dragged on rugs, collected dust and pet hair like a broom, and tore at the seam within 14 days.
- Rolled-Up Towels: A temporary band-aid. They shifted out of place every time the door opened, looked unsightly, and offered zero barrier against crawling pests.
- Screw-In Metal Sweeps: Effective at blocking air, but required power drills, left permanent screw holes in the frame, and scraped ugly scratches across hardwood floors.
Long-Term Durability
Engineered from high-density polymer that won't rip, fray, or collect dirt like cheap foam tubes.
Friction-Free Floor Glide
Moves smoothly over hardwood, tile, and rugs without sticking, catching, or leaving ugly scratches.
Damage-Free Install
Attaches securely in under 2 minutes and peels off cleanly with a hairdryer when it's time to move.
Long-Term Durability
Engineered from high-density polymer that won't rip, fray, or collect dirt like cheap foam tubes.
Friction-Free Floor Glide
Moves smoothly over hardwood, tile, and rugs without sticking, catching, or leaving ugly scratches.
Damage-Free Install
Attaches securely in under 2 minutes and peels off cleanly with a hairdryer when it's time to move.
What Our Customers Are Saying
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"Seals Really Well"
"I mean, look at that difference! It took me so long to find something that doesn't mess my floors, but it also seals the gap. I'm really glad I finally found this!"
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"Fixed My Outside Door"
"Our hallway always felt weirdly cold, especially by this door. Added the seal and it made a noticeable difference. Might do the same to the other doors just in case."
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"Works Really Nice"
"Honestly didn’t expect much from a door strip, but this actually seals the gap really well! No more dust collecting underneath either. I'm glad I've got less to clean now."
