Pemko 321 Fire-Rated Door Bott...
IN STOCK (leaves warehouse same day if ordered before 3pm ET)
$35.28
$31.50
Pemko 321 door bottom sweep cross-section diagram showing 3/16" face depth, 1" overall height, and 15/16" drop leg dimension

Pemko 321 Fire-Rated Door Bottom Sweep with EPDM Neoprene Insert - 36"-48" UL10C Certified

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Model: 321CN 48
$35.28
$31.50
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In Stock (leaves warehouse same day if ordered before 3pm ET)

$35.28
$31.50
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Pemko 321 Fire-Rated Door Bottom Sweep with EPDM Neoprene Insert

The Pemko 321 is an aluminum door bottom sweep with an EPDM neoprene insert, rated for fire-rated commercial door assemblies. Available in 36" and 48" lengths in Clear Anodized and Dark Bronze Anodized aluminum. UL10C positive pressure fire rated, UL1784 smoke tested, cUL Listed 4L10, and BHMA certified for air infiltration control.

Certifications and Ratings

  • Fire Rating: UL10C Positive Pressure
  • Smoke Rating: UL1784 Smoke Tested
  • cUL Listed: 4L10
  • BHMA: Air Infiltration Tested, BHMA Certified

Technical Specifications

  • Model: 321
  • Insert Type: EPDM (Neoprene)
  • Substrate: Aluminum
  • Available Lengths: 36", 48"
  • Finishes: Clear Anodized Aluminum, Dark Bronze Anodized Aluminum
  • Application: Commercial
  • Warranty: 5 Year

Typical Applications

  • Fire-rated door assemblies in commercial office buildings
  • Educational facilities and healthcare institutions
  • Government and municipal buildings
  • Multi-family residential and hospitality properties
  • Industrial and warehouse facilities requiring smoke and air infiltration control

Product Specs

Insert Type:
EPDM (Neoprene) Insert
Warranty:
5 Year
Subcategory:
Door Sweeps
Product Group:
Door Trim and Accessories
Product Subgroup:
Door Bottom Sweeps and Door Shoes
Product Type:
Door Sweeps and Bottoms
ANSI/BHMA:
Air Infiltration Tested, BHMA Certified, Smoke Tested UL1784, Fire Rated UL10C Positive Pressure, cUL Listed 4L10
Commercial/Residential:
Commercial
Product Model:
321
Product Length:
36", 48"
Product Dimension:
H: 1-15/16", W: 3/16"
Product Category:
Door Trim and Accessories
Product Substrate:
Aluminum
Department:
Door Hardware

Pemko 321CN 48 – Frequently Asked Questions

1) Can the Pemko 321 door sweep be used on a fire-rated door?
UL10C positive pressure fire rated and cUL Listed 4L10, so the Pemko 321 sweep is built for fire-rated door assemblies rather than plain weather sealing. It is also UL1784 smoke tested and BHMA certified with air infiltration testing, which is the combination an inspector looks for on a rated opening in a school, hospital, or municipal building. The aluminum retainer holds an EPDM neoprene insert that makes the seal at the floor.
2) My commercial doors are 3 foot wide leafs. Which length of the Pemko 321 sweep do I order?
The 321 comes in 36 inch and 48 inch lengths. A 3'0" leaf is 36 inches wide, so the 36 inch sweep matches it; the 48 inch is for a 4'0" leaf. On a pair of doors you need one sweep per leaf, not one across the opening. Both lengths are offered in Clear Anodized and Dark Bronze Anodized aluminum, so a mixed building of 3'0" and 4'0" openings can still be finished the same way throughout.
3) What is the closest equivalent to the Pemko 321 door bottom sweep from another manufacturer?
On construction, the nearest match is the NGP 197NA, a neoprene door sweep with an anodized aluminum housing. That is the same pairing the Pemko 321 uses: an EPDM neoprene insert carried in an aluminum extrusion, offered in Clear Anodized and Dark Bronze Anodized aluminum. The Cal-Royal BTN-112 is built the same way, a neoprene insert in an extruded aluminum retainer. Where the 321 stands apart is its certification package: UL10C positive pressure fire rated, UL1784 smoke tested, cUL Listed 4L10, and BHMA certified with air infiltration testing. On a fire-rated door assembly, specify the 321 and not a look-alike neoprene sweep, because the rating follows the tested product and not the material.
4) What door sweep should I use on a boiler room or commercial kitchen door where the seal sees high heat in normal service?
When the opening needs a published operating temperature range, the NGP 200SA is the silicone door sweep with an anodized aluminum housing rated -100 F to 500 F. The Pemko 321 carries an EPDM neoprene insert in an aluminum extrusion and is certified on the fire and smoke side, UL10C positive pressure, UL1784 smoke tested, and cUL Listed 4L10. Those are two different questions: continuous service temperature at the seal versus performance of the door assembly in a fire event. If the mechanical room door is also a rated assembly, the 321 is the one that carries the UL10C listing; if the deciding factor is sustained heat exposure at the sweep itself, the 200SA is the one that publishes a temperature range.
5) How much does the Pemko 321 sweep stick out from the face of the door?
The extruded aluminum profile measures 1-15/16 inches high by 3/16 inch wide, so it only adds 3/16 inch to the door face at the bottom. That matters where the door swings past a wall return, a jamb condition, or an adjacent leaf on a pair, and it matters for the 1-15/16 inches of face height the sweep needs below any existing bottom rail hardware or vision kit.
6) Will a door bottom sweep help with drafts and energy loss on exterior commercial doors?
Air infiltration is exactly what the 321 is tested for. It is BHMA certified and air infiltration tested, with an EPDM neoprene insert running the full length of the aluminum retainer to close the gap between the door bottom and the threshold or floor. EPDM holds up to weather and UV exposure better than vinyl, which is why it shows up on exterior commercial openings. It is rated for commercial use, not a residential-grade seal.
7) I need to replace worn door sweeps across a building. Is the Pemko 321 the same part on both fire doors and regular doors?
One part number covers both. Model 321 in the 36 inch or 48 inch length is fire rated to UL10C positive pressure and cUL 4L10, so it is legal on the rated stairwell and corridor doors, and nothing stops you running the same sweep on the non-rated openings for a consistent look. Order by leaf width and finish, then standardize on Clear Anodized or Dark Bronze Anodized across the whole property.
8) What does UL10C positive pressure mean on a door sweep, and why does the spec call for it?
UL10C is the positive pressure fire test, which pressurizes the fire side of the assembly so hot gases push out through gaps rather than being drawn in. Seals at the perimeter and the door bottom are what get tested under it, which is why the sweep itself has to carry the rating and not just the door. The Pemko 321 is UL10C positive pressure rated and cUL Listed 4L10 for Canadian work, and it is separately UL1784 smoke tested for air leakage under the smoke standard.
9) Do all the doors in a building need the Pemko 321, or only the fire-rated openings?
The certification is what drives the decision. The Pemko 321 is UL10C positive pressure fire rated, UL1784 smoke tested, cUL Listed 4L10, and BHMA certified for air infiltration, which is what a rated corridor, stair, or fire-separation door needs, and it is a commercial-duty sweep offered in 36 inch and 48 inch lengths. On openings with no rating requirement, an office or storage door where the goal is simply keeping out drafts and dust, a Cal-Royal BTN-112 neoprene insert with extruded aluminum retainer or an NGP 197NA neoprene sweep with anodized aluminum housing gives the same neoprene-on-aluminum construction. Many facilities standardize the 321 across the whole building anyway so maintenance stocks one part, which is a stocking decision rather than a code one.
10) How does the Cal-Royal BTN-112 differ from the Pemko 321 door bottom sweep?
Both are surface-applied bottom sweeps that carry a neoprene sealing element in an aluminum carrier: the Cal-Royal BTN-112 pairs a neoprene insert with an extruded aluminum retainer, and the Pemko 321 is an aluminum extrusion with an EPDM neoprene insert, 1-15/16 inch profile height by 3/16 inch profile width, in Clear Anodized and Dark Bronze Anodized aluminum. Two things separate them for a spec writer. The BTN-112 sits in Cal-Royal's Brush Weatherstrips Series, so confirm the exact sealing element on the order line before it ships. And the 321 is the one carrying UL10C positive pressure, UL1784 smoke testing, and cUL Listed 4L10, which is what an inspector looks for on a rated door.
11) Does the Pemko 321 come in dark bronze to match the rest of my door hardware?
Both finishes are Clear Anodized Aluminum and Dark Bronze Anodized Aluminum, and both are offered in the 36 inch and the 48 inch length, so you are not forced into a finish by the size of the opening. Dark bronze anodized is the one that disappears against bronze or dark aluminum storefront and entrance hardware; clear anodized reads as mill aluminum.
12) Is there a vinyl door sweep option instead of a neoprene insert like the Pemko 321 uses?
Yes. The NGP 101V is a vinyl door sweep with an aluminum alloy housing, so the sealing element is vinyl rather than neoprene while the carrier is still aluminum. The Pemko 321 uses an EPDM neoprene insert in an aluminum extrusion with a 1-15/16 inch profile height and 3/16 inch profile width, in 36 inch and 48 inch lengths. Insert material is the main difference to weigh against the door and the environment; where the 321 differs beyond material is that it is UL10C positive pressure fire rated and UL1784 smoke tested, so a fire-rated opening should stay with the 321.
How fast can I get the Pemko 321CN 48 delivered?
Most orders ship the same day from our distribution partners, with quick delivery throughout the continental U.S. Need it urgently? Contact Us for expedited shipping options.
Can I return it if it doesn’t work for me?
Yes—ZenSupply offers a hassle-free return policy. If the product isn’t the right fit, reach out to our support team for a return authorization or setup a return by following our return instructions.
Does the Pemko 321CN 48 come with a warranty?
Absolutely. The Pemko 321CN 48 is backed by a manufacturer’s warranty. For full warranty terms, check the product documentation or Contact Us.
How do I get technical support or installation help for the Pemko 321CN 48?
You can call, text, or email our expert support team for fast answers. We’re here to help with product selection, installation tips, and troubleshooting. Contact Us
Why buy the Pemko 321CN 48 from ZenSupply?
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Product Reviews

  • 5
    removable mullion

    Posted by Shane McCoy on Nov 20th 2025

    prefer the neoprene over brush. shipped fast

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