Frost King R338H Adhesive-Backed Foam Seal for Residential Energy Savings, Blocks Drafts Around Doors and Basement Windows
Frost King R338H Adhesive-Backed Foam Seal for Residential Energy Savings, Blocks Drafts Around Doors and Basement Windows
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Why you'll love it
- Self-stick backing requires no tools, glue, or professional installation
- Wide range of sizes (11 variants from 3/16" to 9/16" thickness) ensures a fit for nearly any gap
- Rubber foam construction delivers both sealing compression and shock absorption in one product
- Multi-surface versatility works on home, auto, and marine applications from a single roll
- Made in USA manufacturing and limited lifetime warranty signal trusted, long-term quality
- Stretches slightly when laid in place to reach the actual advertised length
- Foam compresses nicely but is thick enough to not be crushed
- Adhesive remains strong even after 4+ years on previously purchased rolls
- Blocks drafts effectively even after a month of regular door opening/closing
- Easy to separate from backing paper
- Significantly dampens outside sound on casement windows
Perfect for
- Seal gaps around windows and exterior doors to block drafts and reduce energy bills
- Weatherstrip vehicle doors and trunks to cut down on road noise and rattles
- Weatherproof boat cabins and hatches against water intrusion in marine environments
- Cushion and stabilize appliances, electronics, or cabinet doors to prevent vibration
- Block dust, insects, and cold air from entering through small structural gaps
- Shimming a permanent A/C home filter that is slightly smaller than needed
- Replacing compromised weatherstrip on a 2005-2007 Mustang to fix water leaking onto floorboard
- Sealing lids on ATV/four-wheeler boxes to keep out moisture and dirt
- Preventing wind noise and air leaks around car windows
- Adding a cushion/protective strip that is sticky enough not to move
- Preventing rattling/noise on a window fan by taping where it contacts the window frame
- Sealing plexi panels over old windows without messy caulking
About us
From your basement to your roof, from the front door to the back, Frost King products are there to save you money and save you energy. Frost King, simply the trusted name in home insulation. It all began nearly a century ago when Frost King introduced the nation’s first do-it-yourself weatherstripping kit. That simple kit, just 17 feet of felt carpet strips and some nails, managed to single handedly ignite America’s “Do-It-Yourself” revolution. Since that time, Frost King has expanded to help you save money and energy in just about every corner of your home. During the winter, Frost King products will keep the cold air out, insulate your pipes and protect your rooftops from freezing snow. In the summer, Frost King keeps gutters clean, protects your home from leaks, and cuts air conditioning costs.
Frost King R338H Self-Stick Rubber Foam Weatherseal, 3/8"W, 3/16"T, Black|Blacks
A tough, durable self-stick tape with minimal compression. Use the Rubber Foam Weatherseal as a weatherstrip, or as a gasket or to cushion and stabilize major appliances. Plus, on cars, trucks and boats, it can help prevent rattles, vibrations and squeaks.
Product Information
The product is 3/8x3/16 BLK Foam Tape Easy and simple use kit The product is manufactured in United States Minimum Compression Superior Shock Absorbing Minimum Compression Superior Shock Absorbing Extra tough and durable Seals around windows and doors Many automotive and marine uses Show more
Brand Frost King Material Rubber Color black|Blacks Product Dimensions 120"L x 0.38"W Item Thickness 0.25 Inches Recommended Uses For Product weatherstripping, sealing gaps in vehicles, cushioning and stabilizing appliances UPC 077578012209 Number of Items 1 Manufacturer Frost King Unit Count 10.0 Feet Part Number R338H Item Weight 0.6 ounces Item model number R338H Is Discontinued By Manufacturer No Size 3/8"W, 3/16"T Style 3/8"W, 3/16"T Item Package Quantity 1 Included Components No Batteries Included? No Batteries Required? No Warranty Description Limited Lifetime Warranty
Frequently Asked Questions
How does the self-stick backing help me seal drafty windows without calling a contractor?
The pressure-sensitive adhesive peels off the backing paper and bonds directly to clean trim, so you can install the foam strip around windows, doors, and garage entryways in minutes with no tools, caulk gun, or professional help.
Will this 3/8" wide foam actually block cold drafts around my exterior door?
Yes, the 3/16" thick closed-cell rubber foam compresses to fill the gap between the door and stop, then rebounds to maintain a tight seal that blocks cold air, dust, and insects from entering your home.
Can I use one 10-foot roll to seal an entire door and a few windows?
A 10-foot roll typically covers a full standard door perimeter (about 17 feet compressed) or multiple windows, so most homeowners complete a draft-proofing project in one or two rolls.
Does the rubber foam hold up to seasonal temperature swings in a residential setting?
The closed-cell foam is designed to resist weather, moisture, and UV exposure, so it maintains its sealing performance through hot summers, cold winters, and humid basement conditions.
Will the black color look out of place on my white door frame or window trim?
The black foam blends discreetly with most door, window, and vehicle trim, and since it sits along the compression edge rather than the visible face, it is barely noticeable once the door or window is closed.
I'm a renter — will this damage my apartment's window frame when I remove it?
The self-stick adhesive is designed for clean removal on most painted surfaces, making it a popular non-permanent insulation fix for renters who want to block drafts without risking their security deposit.
Is this a good last-minute weekend project to lower my energy bill before winter?
Absolutely — most homeowners complete a full-house weatherproofing job in under an hour, and customers report noticeable reductions in drafts and outside sound almost immediately after installation.
Will this work on an old casement window that lets in a lot of road noise?
Yes, customers specifically report that the foam significantly dampens outside sound on casement windows, in addition to blocking air leaks around the sash.
Can I use this to seal around a permanent A/C filter that is slightly smaller than the housing?
Yes, the compressible foam shims nicely around undersized filters to create a tight seal, preventing bypass air and improving HVAC efficiency.
How does rubber foam compare to felt weatherstripping for interior doors?
Rubber foam offers better compression recovery, moisture resistance, and durability than felt, which tends to mat down, absorb humidity, and lose its sealing ability over time.
Rubber foam vs. silicone door sweeps — which is better for a front door?
Door sweeps handle the bottom threshold, while this foam weatherseal handles the side and top gaps around the door stop, so most homes benefit from using both products together for a complete seal.
Is the adhesive strong enough to stay put on a frequently opened front door?
Yes, customers report the adhesive remains strong even after four or more years on previously purchased rolls, and it continues to block drafts effectively after a month of daily door operation.
What if my door gap is bigger than 3/16" — will this thick enough foam still seal it?
Frost King offers 11 size variants from 3/16" up to 9/16" thickness, so you can choose a thicker profile if your gap is wider, or stack two strips for unusually large openings.
Will the foam compress flat and stop sealing after a few months of door use?
No, the closed-cell rubber foam is engineered to rebound after compression, so it maintains a tight seal through years of regular door and window operation.
Does installing this myself void any warranty on my windows or doors?
Because the foam is removable and applies only to the trim, it does not modify the window or door itself, so it will not affect the manufacturer's warranty on those products.
Is the foam safe to handle without gloves, especially around kids helping with the project?
The closed-cell rubber foam is non-toxic and safe to handle with bare hands, and the peel-and-stick installation means no sharp tools, solvents, or chemical adhesives are required.
How do I install the Frost King R338H self-stick foam weatherseal?
Clean the surface where the foam will be applied, making sure it is dry and free of dust or grease. Cut the foam to the desired length with scissors, peel off the release liner, and press the adhesive side firmly into place along the gap. Hold for a few seconds to ensure a strong bond.
Can I cut the foam to size without fraying or losing the seal?
Yes, the closed-cell rubber foam cuts cleanly with scissors or a sharp utility knife, and the adhesive backing remains intact along the cut edge, so you can create custom lengths for any window, door, or compartment.
How long does the adhesive take to fully bond?
The pressure-sensitive adhesive grips immediately on contact, with full bond strength typically developing within 24 hours as it cures against the surface.
Will this foam stick to painted wood, metal, vinyl, and plastic surfaces?
Yes, the adhesive is engineered to bond to a wide range of surfaces including painted wood, aluminum, vinyl, plastic, fiberglass, and glass, making it suitable for home, automotive, and marine applications.
Is this product compatible with my 2005-2007 Mustang door seals?
Yes, customers specifically use this foam to replace compromised weatherstrip on 2005-2007 Mustangs to fix water leaking onto the floorboard, and it also works on many other vehicle door panels, trunk lids, and window frames.
What comes in the box when I order this product?
You receive one 10-foot roll of self-stick rubber foam weatherseal in a 3/8" width and 3/16" thickness, in black, with a release liner protecting the adhesive backing — no additional tools or accessories are required for installation.
Is rubber foam weatherstripping safe to use in homes with allergies or asthma?
Yes, the closed-cell rubber foam does not shed fibers like felt, does not absorb moisture that can harbor mold, and helps seal out dust, pollen, and outdoor allergens, making it a good choice for allergy and asthma sufferers.
Will the foam degrade or lose its seal if exposed to direct sunlight for years?
The closed-cell rubber foam is engineered with UV resistance to maintain its structure and sealing performance under prolonged sun exposure, making it suitable for both indoor and outdoor applications.
What is the difference between rubber foam weatherseal and silicone weatherstripping?
Rubber foam compresses easily to fill variable gaps, absorbs vibration, and is more affordable, while silicone weatherstripping offers higher temperature tolerance and longer UV life but costs more and is less forgiving on uneven surfaces.
