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Knock Down vs. Welded Frames

Architects specify the type of frame for every job with openings – there isn’t a standard frame. Therefore, design professionals often have to decide which type of frame is best-suited for their project.

The two types of frames and elevations are knock down (KD) and welded. This article covers the most popular types of KD and welded frame constructions, along with the pros and cons of each.


KD Drywall Frame

Also called KD pressure-fit or slip-on drywall frames, these frames are specified for installation in existing drywall openings. They are shipped disassembled, use compression anchors, and have interlocking tabs and slots in the corners.


Standard KD Frame

Standard KD frames are specified for new wall construction. They generally have slots and tabs, but use standard anchors instead of compression anchors.


Face Welded Frame

The most common type of welded frame. The joints between the head and jamb faces have a continuous weld on the visible side of both faces only. Frames are shipped assembled.


Continuously Welded Frame

Also called full profile welded or fully welded. The comer/perimeter joints have all elements of the frame member continuously welded including soffits, stops, rabbet, faces, and returns.

The specification of frames and elevations is a combination of application and preference. The cost, performance, and aesthetics for these frame types are covered below.

KD Frames

KD frames are the least expensive because they are shipped disassembled, allowing them to be tightly packed for shipping and jobsite storage. As a general example, a truck might be able to hold 1,000 KD frames or 300 welded frames.

KD drywall frames allow for assembly into the drywall opening after wall construction. Their design has visible seams and screws because they are not welded. Standard KD frames are assembled in the field and installed in new wall construction. Unlike KD drywall frames, they do not typically have visible screws.

Both types of KD frames are capable of meeting some fire ratings. Field welding of standard KD frames may be possible for new wall construction or existing walls at butted applications. However, field welding is usually not required and may void the fire rating, if any.

Welded Frames

Welded frames and elevations are commonly specified for their seamless appearance and additional strength. They are particularly well-suited for exterior openings and masonry walls.

Costs are higher for welded frames than KD frames. However, in addition to their superior appearance and strength, they can also achieve higher performance capabilities (fire rating, tornado, etc.) and help maintain the square and width of the opening.

Face Welded vs. Continuously Welded

Continuously welded frames are the most costly due to the additional welding and hand grinding that is required.

In the past, continuously welded frames were specified to provide a seamless appearance. Today, frames are mitered on precision dies and can be face welded by SDI members to provide an appearance similar to continuously welded frames. Most applications do not require continuous welding of frames and your client can achieve a high degree of aesthetics while spending less.

Proper Installation is Essential

Installation is critical to the longevity and appearance of all types of frames. The videos below can be referenced to ensure they are installed the right way.

Prep and Installation Videos:
How to Install Frames in Steel Stud Construction
How to Install Frames in Masonry Construction

Troubleshooting Videos:
Fixing Uneven Gaps Between a Door and Frame
Fixing Frames that are Twisted or Out of Square

Frame Specification Tip for Drywall

Except for slip-on construction, frames overlapping walls should have a throat dimension 1/8 inch (3.1 mm) greater than the dimensioned wall thickness to accommodate for irregularities in wall construction.

Choosing Quality Frames

Always specify from SDI member manufacturers for frames that look good and are built to last. They are the only manufacturers who have proved that their products and processes meet our standards.

It’s their consistency that sets them apart from the rest — whether ordering five frames or 500, they will be true to spec.