KS Hardware , Patent Pending, Adjustable Double Bubble Door Sweep, Draft Stopper, Under Door Seal for Exterior Doors, 1 3/4" x 36", White

A stubborn draft under my garage side door was making the space noticeably colder than the rest of the house. I swapped in KS Hardware’s adjustable door sweep, and the difference was immediate and measurable by feel: no more cold plume rolling across the floor, and the door now closes with a snug, weather-tight finish rather than a thud and a whoosh.

What it is and how it’s built

This is a 36-inch, under-door sweep with a two-lip “double bubble” gasket and an external drip cap. The body is rigid, heavy-gauge plastic rather than aluminum, which matters more than you might think. Plastic won’t get painfully hot or cold to the touch, and it avoids the thermal bridging you get from metal sweeps. For exterior doors, that helps prevent the sweep itself from becoming a tiny radiator of outside temperatures. The finish is clean (white or black), and it looks like part of the door rather than an add-on.

The heart of the design is the dual-seal profile. Instead of a single fin, the two rounded contact points create more continuous contact across typical thresholds, especially the slightly crowned or worn ones you see on older sills. The sweep mounts to the door with included screws, and KS Hardware adds a full-length screw cover that slides over the interior face for a neat, finished look. An exterior drip cap kicks water away from the threshold so it doesn’t wick under the seal.

The adjustment range is 3/8 to 7/8 inch—enough to cover the majority of exterior door gaps I encounter. If your gap is outside that range, you’ll want a different solution.

Installation: straightforward with a couple of tricks

The manufacturer says you can install without removing the door. That’s true. I did the job with the door on its hinges using a couple of shims under the door to keep it steady. That said, if you’re working solo and your door is steel, popping the hinge pins and laying the door on sawhorses can speed things up and make screw driving easier.

My process, and what I recommend:

• Measure your gap in several spots. Aim to compress the seals slightly across the entire threshold without dragging.
• Dry-fit the sweep and set it flush to the bottom of the door. Make sure the drip cap clears the jamb weatherstripping and doesn’t interfere with the latch side.
• Start your screws at the two ends first. That lets you micro-adjust the height so the bubbles just kiss the threshold.
• Don’t overtighten. Overdriving can bow the body and create high/low spots in the seal.
• Slide the screw cover on from the end of the door—don’t try to “snap” it over the track. A little wax, bar soap, or silicone on the cover’s track helps it glide. Once the cover is on, it looks factory.

On a steel door, I needed to lean into the first turn of each screw to get the threads started. A small pilot punch or a 1/16-inch pilot hole makes this painless. Plan on 15–30 minutes if you’ve done a sweep before; under an hour even if you haven’t.

Performance and day-to-day use

Once dialed in, the seal is excellent. With my original 3/4-inch gap, I could feel cold air streaming in at ankle level. After installation, that draft disappeared. Temperature equalized with the rest of the house much better, and the garage no longer smelled faintly of dust after windy days.

The double-bubble profile is the difference. A single fin often seals well on one side of a slightly uneven threshold but lifts on the other. Here, the two contact points maintain pressure as the sill height changes across the span. I set mine so there’s light resistance when closing the door and zero scraping on the floor—just a gentle compression that keeps air and pests out.

Noise reduction is modest but noticeable; road noise and leaf blowers sound a bit more distant. More importantly, the tight seal has kept out insects that used to find their way under the door, and seasonal pollen no longer accumulates just inside the threshold.

Weather control and water management

The integrated drip cap does its job. Rain now sheds forward off the door edge instead of clinging and migrating under. If your door faces driving rain, that cap is worth having; it reduces the chance of water pooling right at the gasket line. The plastic body has no corrosion risk, and after months in the sun the white finish on my sweep remains consistent with no chalking.

Adjustability and fit

The 3/8–7/8-inch adjustment range is accurate. I set mine near the high end and still had play to fine-tune. If your threshold is crowned or slightly out of level, take time to balance compression across the span. A helpful approach is to close the door on a slip of paper at three points (hinge side, center, latch side). You should feel equal drag pulling the paper out at each point. If one area binds, raise/lower that side by loosening the nearby screws and nudging the sweep.

Compatibility notes

• Works best with typical exterior thresholds, including adjustable ones. If yours is severely cupped or dented, fix the threshold first.
• If your door is badly out of square, you may need to split the difference so the door closes smoothly. This is a seal, not a carpentry fix.
• If you’ve relied on the exact screw pattern of a previous sweep, expect to drive new holes; this is normal for under-door sweeps.

Durability and maintenance

The rubber on this sweep is thicker and more resilient than bargain options. After daily use, I see no nicks or set-in flat spots. A quick wipe now and then keeps grit from abrading the seal. If your door is sticking on a humid day, a swipe of silicone spray or a dab of petroleum jelly across the rubber makes it glide without squeak. Because the body is plastic, it won’t ding or dent like aluminum if you bump it with a boot or a box.

Shortcomings to know about

• The screw cover channel is tight. If you try to snap it on after the screws are set, you’ll struggle. Always slide it from the end, and lubricate the track. Once on, it looks great, but this step trips up first-time installers.
• If you set the sweep too low, the doubled seals can make the door feel “sticky.” Err on the side of light compression and adjust the threshold if you have one, rather than forcing the sweep to do all the work.
• Very large gaps (over 7/8 inch) are beyond its range. In those cases, look at a combination of threshold adjustment and a different profile sweep.
• On some jambs, the drip cap can highlight how out-of-true the frame is. It’s not a flaw in the sweep, but you’ll notice misalignment more because the edges are crisp.

Value

This isn’t the cheapest sweep, but the performance-to-hassle ratio is excellent. The dual-seal design simply works better on imperfect thresholds, the plastic body avoids thermal bridging and corrosion, and the finished appearance is clean thanks to the screw cover. If you’re tired of trial-and-error with single-fin sweeps or stick-on skirts, this is a meaningful upgrade.

Who it’s for

• Homeowners with 3/8–7/8-inch door gaps who want a dependable air and pest seal.
• Exterior doors that see rain; the drip cap adds real water management.
• Garages, utility rooms, and entry doors where temperature control matters.
• Anyone who prefers a non-metal sweep to avoid heat/cold transfer and corrosion.

Recommendation

I recommend this sweep for most exterior doors with standard gaps and thresholds. It seals better than single-lip designs, installs with basic tools, and the plastic body avoids the thermal and corrosion downsides of aluminum. The screw cover requires a light touch—slide, don’t snap—but that’s a solvable quirk. If your door is wildly out of square or your gap exceeds 7/8 inch, address the carpentry or choose a different profile. Otherwise, this is a smart, durable, and low-maintenance way to stop drafts, keep pests out, and improve comfort with a neat, finished look.