Corpus sync: neutrality remakes, note hygiene, datasheet relocation, transformer-split cross-refs
---
title: Hollow Metal Doors and Frames
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## Doors and frames shall be fabricated by a single source so that components of each opening are mutually compatible in gauge, reinforcement, and label.
−## Fire-rated assemblies shall be labeled by a nationally recognized testing laboratory and shall bear a permanent label identifying the rating and the test standard. {note}
+## Fire-rated assemblies shall be labeled by a nationally recognized testing laboratory and shall bear a permanent label identifying the rating and the test standard.
## The label is the only field-verifiable evidence that the assembly was tested as a unit. Any field modification that is not within the listing — drilling for unlisted hardware, enlarging a lite, or cutting the door height beyond the listed allowance — voids the label and requires re-listing or replacement of the opening. {note}
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## ANSI/SDI A250.8 defines four Levels, and ANSI/SDI A250.4 prescribes the physical-abuse and cycle-endurance test that substantiates a Level claim. Specifying a Level without requiring the A250.4 basis invites under-built submittals that nominally cite the Level but were never tested to it. {note}
+## The door duty grade shall be specified as an ANSI/SDI A250.8 Level, substantiated by ANSI/SDI A250.4 physical-abuse and cycle-endurance test data for the traffic and abuse conditions of each opening.
+
```datasheet
label: Door duty grade (ANSI/SDI A250.8 Level)
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# Environmental and Service Conditions {toc}
−## The steel substrate and coating shall be selected for the service environment of each opening, not assumed uniform across the project. {note}
+## The steel substrate and coating shall be selected for the service environment of each opening, not assumed uniform across the project.
## Interior dry openings can use cold-rolled steel; interior humid or wet areas and any painted frame benefit from galvannealed steel, which holds paint better and resists corrosion at cut edges; exterior and corrosive-environment openings require hot-dip galvanized steel. Choosing a single substrate for the whole project either over-spends on interior doors or under-protects exterior ones. {note}
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```
−## Thermal performance shall be specified for exterior openings in heating-dominated climates. {note}
+## Thermal performance shall be specified for exterior openings in heating-dominated climates.
## A standard honeycomb-core door provides little thermal resistance. Polystyrene and polyurethane cores raise the assembly U-factor into the 0.35-0.59 BTU/hr·ft²·°F range and are appropriate for exterior openings in climate zones 4 and colder. If a core type is not called out, the fabricator will default to the least costly honeycomb core, and the thermal or acoustic intent is silently lost. {note}
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# Materials and Substrate {toc}
−## Face-sheet thickness shall be specified as a minimum decimal thickness, not as a gauge number. {note}
+## Face-sheet thickness shall be specified as a minimum decimal thickness, not as a gauge number.
## Gauge designations are nominal and vary between manufacturers; a "18-gauge" sheet from one mill may be thinner than another's. ANSI/SDI A250.8 and the HMMA standards now express requirements as minimum decimal inch thickness for exactly this reason. Specifying by gauge alone allows an under-thickness substitution to pass review. {note}
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## Stainless face sheets are used for hospitals, food service, and exposed coastal exteriors where galvanized steel is insufficient. Type 316 is specified where chloride exposure is severe. {note}
+## The door face material shall be specified for each opening, with a corrosion-resistant material selected where hygienic conditions or chloride exposure warrant it.
+
```datasheet
label: Door face material
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# Door Construction {toc}
−## Doors shall be 1-3/4 in (44 mm) nominal thickness unless an acoustic, security, or other assembly requires a different thickness. {note}
+## Doors shall be 1-3/4 in (44 mm) nominal thickness unless an acoustic, security, or other assembly requires a different thickness.
## The 1-3/4 in door is the commercial standard for the overwhelming majority of openings. The 1-3/8 in door is a light residential or closet leaf rarely seen in commercial work; 2 in doors appear in acoustic and high-security assemblies. Selecting a non-standard thickness drives custom frame profiles and longer lead times, so it should be a deliberate choice. {note}
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## ANSI/SDI A250.8 defines three Models. Model 1 is full flush, a smooth face with no visible seam. Model 2 is seamless or center-seam, with the face sheets joined at a concealed seam for improved appearance. Model 3 is a stile-and-rail or embossed panel door, with pressed-in profiles that simulate a wood-panel door and is common in schools and public buildings. {note}
+## The door model shall be specified as an ANSI/SDI A250.8 Model for each opening, based on the required appearance and end use.
+
```datasheet
label: Door model (ANSI/SDI A250.8)
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## Exterior doors shall have a flush top closure to shed water.
−## Core type shall be specified explicitly for every door, since it governs thermal, acoustic, and fire behavior. {note}
+## Core type shall be specified explicitly for every door, since it governs thermal, acoustic, and fire behavior.
−## Honeycomb kraft-paper core is the standard interior filler. Polystyrene and polyurethane cores add thermal resistance, and polyurethane also adds structural stiffness. Temperature-rise cores limit the heat transmitted through a stairwell door during a fire. Fiberglass and mineral-wool cores provide acoustic mass. Because the fabricator defaults to honeycomb when no core is named, omitting the core selection is a common and costly error. {note}
−
```datasheet
label: Door core
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```
−## Vision lites and louvers shall be located and sized on the shop drawings and shall not exceed the maximum permitted by the assembly's fire listing. {note}
+## Honeycomb kraft-paper core is the standard interior filler. Polystyrene and polyurethane cores add thermal resistance, and polyurethane also adds structural stiffness. Temperature-rise cores limit the heat transmitted through a stairwell door during a fire. Fiberglass and mineral-wool cores provide acoustic mass. Because the fabricator defaults to honeycomb when no core is named, omitting the core selection is a common and costly error. {note}
+## Vision lites and louvers shall be located and sized on the shop drawings and shall not exceed the maximum permitted by the assembly's fire listing.
+
## For rated openings, the UL listing caps the maximum lite area and dictates the glazing product. An oversized lite voids the label. Louvers are generally not permitted in fire-rated doors except where specifically listed. Glass for rated lites is specified in [[sync/fire-rated-glazing]]. {note}
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# Frame Construction {toc}
−## Frame type shall be matched to the wall construction, since anchorage and assembly method differ by substrate. {note}
+## Frame type shall be matched to the wall construction, since anchorage and assembly method differ by substrate.
−## A knocked-down (KD) three-piece frame is field-assembled and is the common choice for new drywall partitions. A shop-welded one-piece frame, with corners welded, ground, and filled, is specified for masonry, concrete, and high-abuse openings. A slip-on drywall frame is applied over finished drywall without rough-in and suits retrofit and light commercial work. Selecting a slip-on or KD frame for a masonry opening, or vice versa, produces anchorage that does not suit the wall. {note}
−
```datasheet
label: Frame type
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```
+## A knocked-down (KD) three-piece frame is field-assembled and is the common choice for new drywall partitions. A shop-welded one-piece frame, with corners welded, ground, and filled, is specified for masonry, concrete, and high-abuse openings. A slip-on drywall frame is applied over finished drywall without rough-in and suits retrofit and light commercial work. Selecting a slip-on or KD frame for a masonry opening, or vice versa, produces anchorage that does not suit the wall. {note}
+
## Welded frames shall have corners mitered or coped, continuously welded on the contact surfaces, ground smooth, and filled so that no joint is visible after finishing.
−## Frame throat dimension shall be verified against the actual wall assembly thickness, including finishes, before fabrication. {note}
+## Frame throat dimension shall be verified against the actual wall assembly thickness, including finishes, before fabrication.
## The throat is the dimension across the back of the frame that straddles the wall. A nominal 4-7/8 in frame profile will not fit a 6 in CMU wall, and a single project commonly has several wall thicknesses; verify each condition separately. {note}
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```
−## Frames installed in masonry shall be grouted solid at hinge and strike locations, at minimum, to resist deflection under hardware and lateral loads. {note}
+## Frames installed in masonry shall be grouted solid at hinge and strike locations, at minimum, to resist deflection under hardware and lateral loads.
## An un-grouted masonry frame deflects under wall load and door operation, causing the door to bind and the latch to misalign. HMMA 840 requires grout fill at least at the reinforced hardware locations. A high-water structural grout can bow the frame faces. {note}
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### Hardware preparation shall be coordinated with the hardware schedule of [[sync/door-hardware]] before fabrication.
−## Electrified hardware rough-in shall be provided in the hollow metal at the factory, never created by field drilling of a finished or labeled assembly. {note}
+## Electrified hardware rough-in shall be provided in the hollow metal at the factory, never created by field drilling of a finished or labeled assembly.
## Electric strikes, maglocks, electrified hinges, and access-control devices require conduit knockouts, raceways, junction boxes, and through-bolt preparation built into the door and frame. Drilling these in the field after delivery — especially into a labeled assembly — voids the UL listing and damages the finish. {note}
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# Fire-Rated Assemblies {toc}
−## Fire-protection ratings shall be provided where the International Building Code requires opening protectives, and the required rating follows the rating of the wall. {note}
+## Fire-protection ratings shall be provided where the International Building Code requires opening protectives, and the required rating follows the rating of the wall.
−## IBC Section 716 prescribes the opening-protective rating for each rated wall or partition. Ratings range from a 20-minute corridor protective, through 45-, 60-, and 90-minute labels, to the 3-hour label required at a fire wall — a rating only hollow metal achieves. A 20-minute assembly is not the same as a fully listed fire door: under NFPA 80 it has different hardware and glazing allowances; treat each rating class as a distinct assembly type. {note}
−
```datasheet
label: Fire-protection rating (IBC Section 716)
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```
+## IBC Section 716 prescribes the opening-protective rating for each rated wall or partition. Ratings range from a 20-minute corridor protective, through 45-, 60-, and 90-minute labels, to the 3-hour label required at a fire wall — a rating only hollow metal achieves. A 20-minute assembly is not the same as a fully listed fire door: under NFPA 80 it has different hardware and glazing allowances; treat each rating class as a distinct assembly type. {note}
+
## Fire-rated door assemblies shall be tested and labeled to UL 10C positive-pressure criteria where required by the IBC. {note}
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# Acoustic Assemblies {toc}
−## Sound-rated openings shall be furnished as a complete listed assembly — door, gasketed frame, and seals — because the rating is a property of the assembly, not the door alone. {note}
+## Sound-rated openings shall be furnished as a complete listed assembly — door, gasketed frame, and seals — because the rating is a property of the assembly, not the door alone.
## A bare flush door carries an STC of roughly 28 to 32. An acoustic assembly reaches STC 38 to 42 with a continuous gasketed frame, automatic drop seal, and a mineral-wool or dense core; high-acoustic specialty assemblies reach STC 44 to 48. Specifying an "STC-rated door" without the gasketing and seals delivers none of the rated performance. {note}
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## Standard door sizes shall be used wherever possible, and oversized leaves shall be flagged as custom. {note}
−## A 3 ft 0 in (914 mm) wide single leaf at 7 ft 0 in (2134 mm) height is the commercial 80% case. Heights of 8 ft 0 in (2438 mm) are common; anything taller than 9 ft or wider than 4 ft triggers custom fabrication and engineering review, with longer lead times and reinforcement implications. Pairs run 5 ft 0 in to 6 ft 0 in overall. Treating an oversized opening as standard leads to schedule and structural surprises. {note}
+## A 3 ft 0 in (914 mm) wide single leaf at 7 ft 0 in (2134 mm) height is the commercial norm. Heights of 8 ft 0 in (2438 mm) are common; anything taller than 9 ft or wider than 4 ft triggers custom fabrication and engineering review, with longer lead times and reinforcement implications. Pairs run 5 ft 0 in to 6 ft 0 in overall. Treating an oversized opening as standard leads to schedule and structural surprises. {note}
### Doors wider than 4 ft 0 in (1219 mm) or taller than 9 ft 0 in (2743 mm) shall be furnished as engineered custom assemblies with reinforcement reviewed for the size.
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# Finish {toc}
−## Doors and frames shall receive a factory finish appropriate to the substrate and the field finishing intent. {note}
+## Doors and frames shall receive a factory finish appropriate to the substrate and the field finishing intent.
## Most commercial hollow metal ships factory-primed for field painting. Where a durable factory finish is wanted, a powder coat or baked enamel is applied. Galvanized exterior assemblies may be primed over the coating or left for a galvanized-compatible field system. The prime coat itself is a tested product, not just paint. {note}
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# Testing {toc}
−## Manufacturer's physical-endurance testing shall substantiate the specified duty Level. {note}
+## Manufacturer's physical-endurance testing shall substantiate the specified duty Level.
## ANSI/SDI A250.4 is the abuse and cycle-endurance test that backs a Level claim. The certification submitted under Quality Assurance is the project's evidence that the furnished product was actually tested to the Level specified, not merely cataloged at it. {note}
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## Field modifications that would void a fire label, including cutting, drilling, or welding outside the listing, are prohibited. {note}
−## Installed openings shall be adjusted so the door latches and operates without binding, sticking, or excessive force. {note}
+## Installed openings shall be adjusted so the door latches and operates without binding, sticking, or excessive force.
## HMMA 840 Section 7 sets the operational acceptance: a properly installed door swings freely through its full arc with hardware engaged. Binding usually traces back to an out-of-plumb or un-grouted frame. {note}
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- Touch-up paint (each factory finish)
```