Pemko 255A Half Saddle Thresho...
IN STOCK (leaves warehouse same day if ordered before 3pm ET)
$134.72
Pemko 255A Half Saddle Threshold cross-section drawing showing 1/2" height and 5" width dimensions, mill aluminum, fire rated

Pemko 255A Half Saddle Threshold 1/2" x 5" Mill Aluminum Fire Rated

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Model: 255D-36
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In Stock (leaves warehouse same day if ordered before 3pm ET)

$134.72
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Pemko 255A Half Saddle Threshold - 1/2" x 5" Mill Aluminum, Fire Rated

The Pemko 255A is a half saddle threshold in mill finish aluminum, rated for UL 10C positive pressure fire doors and cUL Listed 4L10. At 1/2" height and 5" width, it fills offset floors and creates a flush transition between different floor surfaces. ADA compliant when butted to a 1/2" offset. BHMA certified to ANSI/BHMA A117.1 and A156.21. Available in Mill Finish Aluminum and Dark Bronze Anodized Aluminum; standard lengths are 36", 42", 48", 72", 80", and 84".

Key Features

  • Dimensions: 1/2" height x 5" width
  • Fire Rating: UL 10C Positive Pressure; cUL Listed 4L10
  • Certifications: BHMA Certified, ANSI/BHMA A117.1, ANSI/BHMA A156.21
  • ADA Compliance: Meets ADA requirements when butted to a 1/2" offset
  • Material: Aluminum
  • Fasteners: Standard #10 x 1.5" wood screws; additional fastener options available
  • Thermal Key Channel: Built-in channel for connecting thermal keys
  • Combination Use: Can be paired with other half saddles to build custom-width configurations

Typical Applications

  • Commercial office and institutional entrances requiring fire-rated door assemblies
  • Healthcare, education, and government facilities with ADA-accessible thresholds
  • Multi-family and mixed-use properties with offset floor transitions
  • Retail and industrial doorways requiring code-compliant saddle thresholds

Product Specs

Subcategory:
Thresholds
Product Group:
Door Trim and Accessories
Product Subgroup:
Door Thresholds
Product Type:
Half Saddle Thresholds
ANSI/BHMA:
BHMA Certified, Fire Rated UL10C Positive Pressure, cUL Listed 4L10
Commercial/Residential:
Commercial
Product Model:
255
Product Dimension:
W: 5", H: 1/2"
Product Substrate:
Aluminum
Product Category:
Door Trim and Accessories
Department:
Door Hardware

Pemko 255D-36 – Frequently Asked Questions

1) Will the Pemko 255A threshold work on a fire rated door opening?
Yes. The 255A half saddle is rated for UL 10C positive pressure fire doors and is cUL Listed 4L10, so it can go under a fire rated assembly in a commercial building. It is also BHMA certified to ANSI/BHMA A117.1 and A156.21. That combination is what an inspector on a healthcare, school, or government job will be looking for at the sill.
2) Is a 1/2 inch high threshold ADA compliant?
The 255A stands 1/2 inch high and meets ADA requirements when it is butted to a 1/2 inch offset, meaning the saddle bridges the height difference rather than adding a 1/2 inch step on top of a level floor. If your floors are already flush, a half inch tall saddle sitting proud of both sides is not the right approach for an accessible route.
3) What length Pemko 255A do I order for a 36 inch door?
Order the 36 inch length for a standard 3-0 door. The 255A comes in 36, 42, 48, 72, 80, and 84 inches. The 72 to 84 inch lengths are there for pairs of doors and wide openings, and aluminum thresholds are routinely cut down on site, so the usual practice is to buy the next length up and trim to the frame.
4) What is a half saddle threshold and when do I use one instead of a full saddle?
A half saddle covers one side of the opening rather than spanning the full door sill. The Pemko 255A is 5 inches wide and 1/2 inch high, so it fills an offset floor and makes a flush transition where two floor surfaces meet at different heights, carpet to tile, or slab to finished floor. A full saddle is the choice when you need to cover the whole sill under the door and both sides of the frame. Two half saddles can also be combined to build a custom overall width if the offset is wider than 5 inches.
5) What screws do I need to install a Pemko 255A threshold?
Standard fastening is #10 x 1-1/2 inch wood screws, and other fastener options are available for substrates that will not take a wood screw. Anchoring into a concrete slab means drilling and setting anchors instead, so plan for that if the opening is not over a wood sub-sill.
6) Can I run a thermal break or thermal key with the Pemko 255A?
The 255A has a built-in thermal key channel, so thermal keys can be connected into the extrusion. That matters on exterior openings where an uninterrupted aluminum path from outside to inside would otherwise conduct cold and sweat at the sill.
7) My floor offset is wider than 5 inches. Can I still use the Pemko 255A?
Yes, by combining it. The 255A is 5 inches wide, and half saddles can be paired with other half saddles to build a custom overall width, so a wider offset gets covered by two pieces rather than one. What it will not do on its own is bridge more than 5 inches of transition.
8) What finishes does the Pemko 255A half saddle come in?
Two: mill finish aluminum, which is the raw silver aluminum look, and dark bronze anodized aluminum for openings with bronze or dark storefront and hardware. Both finishes are offered in all six lengths, so you can match a 36 inch single door and an 84 inch pair on the same job.
9) Is the Pemko 255A rated for commercial traffic or is it a residential threshold?
This is a commercial specification threshold, aluminum extrusion with a ribbed top surface for traction, certified to BHMA and carrying a UL 10C fire rating. It is what gets specified on office, retail, industrial, multi-family, and institutional entrances, not a light residential saddle.
10) Will the same threshold work if I am standardizing sills across a whole building?
The 255A is a single profile, 1/2 inch by 5 inches, offered in six lengths and two finishes, which is what makes it workable as a facility standard. One part number covers single doors and pairs, and the fire rating and BHMA certification hold across the range, so an MRO buyer can carry one saddle for both rated and non-rated openings instead of stocking two.
How fast can I get the Pemko 255D-36 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 255D-36 come with a warranty?
Absolutely. The Pemko 255D-36 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 255D-36?
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 255D-36 from ZenSupply?
ZenSupply makes it easy to get the commercial door hardware you need—fast shipping, expert support, and rewards on every order. Our team is always ready to help you choose the right product for your project.
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