6 Best UV Resistant Sealants for Apartments That Slash Utility Costs
Boost your apartment’s energy efficiency. Our guide reviews the top 6 UV-resistant sealants that prevent drafts and sun damage, cutting utility costs.
That mystery draft you feel by the living room window isn’t just a minor annoyance; it’s money literally flying out of your apartment. Every month, unsealed gaps around windows, doors, and vents force your heating and cooling systems to work overtime. Sealing these air leaks is one of the highest-impact, lowest-cost upgrades you can make, and choosing the right UV-resistant sealant ensures the fix lasts for years.
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Slash Your Utility Bills by Sealing Air Leaks
Before you can pick a sealant, you have to play detective. The biggest energy thieves in any apartment are the tiny, unsealed gaps that let conditioned air escape and outside air creep in. Your prime suspects are window frames, door casings, and any penetration through an exterior wall, like the exhaust for a dryer or a portable A/C unit hose.
Run your hand along the edges of your windows on a windy day. Feel that? That’s an air leak. These gaps might seem small, but added together, they can be equivalent to leaving a window open all year round. Sealing them stabilizes your indoor temperature, meaning your HVAC system doesn’t have to kick on as often.
This isn’t just about saving money, it’s about comfort. Sealing leaks reduces drafts, keeps out dust and pollen, and can even dampen outside noise. For a few dollars and an afternoon of work, you gain a quieter, cleaner, and more comfortable space that costs less to maintain. It’s the ultimate small-living win.
GE Silicone 2+ for Lasting Weatherproofing
When you need a seal to last against sun, rain, and snow, GE Silicone 2+ is a workhorse. This is a 100% silicone sealant, which means it doesn’t shrink or crack over time and remains permanently flexible. Its excellent UV resistance makes it the top choice for sealing the exterior side of window frames that get blasted by direct sunlight.
I’ve used this on everything from van conversions to apartment windows, and its longevity is impressive. Because it’s 100% silicone, it’s also 100% waterproof and ready for rain exposure in just 30 minutes. The major tradeoff? You cannot paint it. Paint simply won’t stick to its surface. So, if you need a perfect color match with your trim, you’ll need to look elsewhere.
DAP Dynaflex 230: The Paintable Sealant
Get a durable, crack-proof seal with DAP Dynaflex 230. This paintable, waterproof sealant offers superior flexibility and adheres to various building materials.
What if the gap you’re sealing is highly visible on an interior wall? That’s where DAP Dynaflex 230 shines. This is a "siliconized" acrylic latex sealant, which gives you the best of both worlds: the flexibility and durability of silicone with the easy cleanup and paintability of an acrylic.
Think of the trim around your windows or patio door. You want a sealant that moves with the building but can be painted to blend in seamlessly. Dynaflex 230 is formulated for this exact scenario. It provides a strong, weatherproof seal that stretches without cracking and is ready for paint in just a couple of hours. While not quite as durable as a 100% silicone for harsh exterior applications, it’s the perfect choice for any job where aesthetics are a top priority.
Loctite PL Polyurethane for Maximum Durability
Sometimes you need a sealant that’s just plain tough. Loctite PL Polyurethane Window, Door & Siding Sealant is the product for those jobs. Polyurethane is a different chemical class entirely; it creates an incredibly strong, tenacious bond that’s also highly resistant to abrasion and UV degradation.
This is my go-to for sealing gaps between two different materials, like a metal window frame set into a brick or concrete wall. Its powerful adhesion prevents it from pulling away as the materials expand and contract at different rates. The downside is that it can be messy to work with and has a stronger odor during curing. But for a high-stress joint that needs to last a decade or more, nothing beats the durability of a quality polyurethane.
Gorilla 100% Silicone for Tough Sealing Jobs
Gorilla has built its brand on strength, and their 100% Silicone Sealant lives up to the name. Like the GE product, it offers fantastic UV resistance and permanent flexibility, making it a great all-around choice for exterior sealing. It won’t yellow, shrink, or crack, even in direct sun.
Where Gorilla often stands out is in its aggressive adhesion and mold/mildew resistance. If you’re sealing a window in a bathroom or a humid climate, this sealant’s formulation helps keep the seal clean and free of ugly black spots. It’s a reliable, tough-as-nails option for creating a long-lasting, waterproof barrier against the elements. Just remember, like other 100% silicones, it is not paintable.
Sashco Big Stretch for High-Movement Gaps
Seal gaps up to 2" wide with Big Stretch sealant. This high-performance, elastomeric formula offers powerful adhesion and stretches over 500% without cracking, making it ideal for interior and exterior applications.
Have you ever sealed a gap perfectly, only to see the caulk crack a year later? You likely have a high-movement joint, and that’s a job for Sashco Big Stretch. This is an elastomeric, co-polymer sealant designed to stretch and compress with temperature swings without tearing.
I recommend Big Stretch for older apartments with wooden window frames or for gaps wider than a quarter-inch. Wood expands and contracts significantly, and standard caulk just can’t keep up. Big Stretch can handle that movement, stretching up to 500% of its original size. It’s a specialty product that solves a very common and frustrating problem, ensuring your seal holds even when the building shifts.
Lexel Clear Sealant: The Invisible Solution
Seal leaks and bond materials with Lexel Adhesive Caulk. This clear, paintable sealant sticks to wet surfaces for a durable, waterproof bond.
Sometimes, the best sealant is the one you can’t see. Lexel is a co-polymer rubber-based sealant that is famously "clearer than silicone." When applied, it’s a true, crystal-clear bead that won’t yellow over time from sun exposure. This makes it perfect for sealing around glass or on unique surfaces where a white or colored caulk line would be an eyesore.
Lexel is also known for sticking to almost anything—even wet surfaces. This makes it incredibly versatile. The main tradeoff is that it can be a little more difficult to "tool," or smooth out, than silicone. It’s stickier and less forgiving. But if you need a truly invisible, waterproof, and UV-stable seal, the extra effort is well worth the flawless result.
Applying Sealant for an Airtight Apartment
The best sealant in the world will fail if the surface isn’t prepared properly. This is the most important step. You must remove all the old, cracked caulk. A utility knife and a putty knife are your best friends here. Once the old stuff is gone, clean the surface thoroughly with rubbing alcohol to remove any dust, grease, or soap residue.
Next, cut the tip of the sealant tube at a 45-degree angle. The opening should be just slightly larger than the gap you’re filling—start small, you can always cut more. Apply steady, even pressure to the caulk gun and move at a consistent speed to lay down a uniform "bead" of sealant.
Dispense materials precisely with the Bates Caulking Gun. Its 10:1 thrust ratio provides smooth, consistent flow, while the ergonomic design ensures comfortable, fatigue-free use.
Don’t skip the final step: tooling. Immediately after applying the bead, wet your finger or a caulk finishing tool and run it smoothly along the seam. This presses the sealant into the gap for a strong bond and creates a clean, professional-looking concave finish. Wipe away any excess with a damp rag (for latex) or a dry paper towel (for silicone) before it starts to cure. A little prep and a steady hand are all it takes to create a perfect, energy-saving seal.
A few tubes of the right sealant and a Saturday afternoon can do more for your comfort and utility bills than you might think. By identifying your apartment’s specific needs—paintability, flexibility, or sheer durability—you can choose the perfect product to stop leaks in their tracks. It’s a small project with a huge return, proving that smart, simple fixes are the cornerstone of efficient small-space living.
