What is the difference between a knocked down frame and a welded frame?
A knocked down (KD) frame ships as three separate pieces (head and two jambs) that are assembled on-site using interlocking tabs and slots. A welded frame ships as a single piece with factory-welded corners. KD frames install after the wall is built and are used in drywall and masonry walls. Welded frames are set before or during masonry wall construction. Welded frames offer higher corner rigidity and are the standard for masonry walls and high-fire-rating applications.
What is a drywall slip-on frame?
A drywall slip-on frame, also called a wrap-around frame, is a three-piece knocked down frame designed to wrap around a finished drywall opening. The frame profile includes backbends that grip both sides of the drywall, creating a finished appearance without exposed fasteners. Slip-on frames install after the drywall is hung and finished, making them the standard choice for commercial interior applications in metal stud walls.
What fire ratings are available for hollow metal door frames?
Hollow metal frames are available in five fire rating levels: 20-minute, 45-minute, 60-minute, 90-minute, and 3-hour (180-minute). Drywall frames (KD and slip-on) can achieve ratings up to 90 minutes. Masonry frames (KD or welded) can achieve the full range up to 3 hours (180 minutes). All components in a fire-rated assembly, including the door, frame, hardware, glass, and louvers, must carry matching fire labels.
What does the throat dimension of a frame mean?
The throat is the opening between the backbends of the frame, and the throat dimension must match the total wall thickness exactly. For example, a wall with 3-5/8” metal studs and 5/8” drywall on each side has a total thickness of 4-7/8”, requiring a frame with a 4-7/8” throat. Ordering a frame with the wrong throat dimension results in a frame that does not fit the wall and cannot be corrected on-site.
What type of anchors are used with masonry door frames?
New masonry walls typically use T-anchors or wire anchors that are factory-attached to the frame and embedded in the mortar joints during wall construction. Existing masonry walls require expansion bolts or tap-in anchors drilled through the frame into the block or concrete. The anchor type must be specified at the time of order because T-anchors and wire anchors are factory-attached before shipping.
What is the difference between single rabbet and double rabbet frames?
A single rabbet frame has one stop and one door-closing surface, designed for a single door leaf. A double rabbet frame has a center stop with rabbets on both sides, designed for a pair of doors. The rabbet configuration is determined by whether the opening has one door or two. Single rabbet frames are used for standard single-door openings; double rabbet frames are required for pairs of doors in corridors, conference rooms, and other wide openings.
How do I determine the correct frame depth for my wall?
Measure the total wall thickness at the door opening, including studs, drywall or plaster on both sides, and any furring strips. The frame depth (jamb depth) must match this total dimension exactly. Common frame depths include 4-3/4” (3-5/8” studs + 1/2” drywall each side), 4-7/8” (3-5/8” studs + 5/8” drywall each side), and 6-3/4” (6” studs + drywall). Measure in at least two places, as walls can vary in thickness due to construction tolerances.
Can a knocked down frame be used in a masonry wall?
Yes. KD frames are available in masonry configurations that install into existing masonry walls using expansion bolts or sleeve anchors. KD masonry frames are commonly used in renovation projects where a new opening is cut into an existing block wall. KD masonry frames can achieve fire ratings up to 3 hours (180 minutes) when properly specified and anchored.
