TECHNICAL TIPS

How to Connect Door Jambs to the Frame
By MarkWesterfield, P.E.
Application Engineering Manager, Clopay Building Products

It has become an old joke about wind load-rated garage doors: the door is so strong that it still stands while the building around the door falls down. The truth is, without the building, the garage door would fall down, no matter how strong the door.

The loads that wind exerts on the garage door are ultimately transferred into the building via the door jambs. And since the door jambs are the transition points between the door and the building, the jamb attachments are of critical importance.

Transferring the Load

Take, for example, a 16' x 7' garage door with design wind load pressures of +20/-20 PSF. This door will transfer 1,120 lbs. of load to each jamb (assuming no vertical post or latches are used to reinforce the door).

Garage doors in hurricane-prone regions can have design wind load pressures up to 50 PSF or more. At 50 PSF, a 16' x 7' garage door will transfer 2,800 lb. of load to each jamb when the door reaches its design wind load. That’s more than one ton per side! Hammering a few 10d nails into each jamb to attach it into the door frame will not transfer this load.

Free Advice

For this reason, the DASMA Commercial & Residential Garage Door Technical Committee authorized a project to create a Technical Data Sheet on connecting garage door jambs to building frames. DASMA Technical Data Sheet TDS #161 is the result.

Building frames are not all constructed from the same materials. Many buildings are wood frame, some are concrete block or concrete column, and a lot of commercial applications are framed in steel. In each case, the jamb attachment method options differ.

Different Strokes …

For example, lag screws are an acceptable attachment for wood frame buildings, but lag screws are not an option for concrete or steel frame buildings. Conversely, an installer would not weld garage door track to a wood frame home.

Therefore, TDS #161 discusses several different fastener types, including:

• 1/4" self-tapping anchors into concrete block or concrete column
• 3/8" sleeve anchors into concrete column
• 3/8" expansion anchors into concrete column
• 7/16" “L-bolt” anchors into concrete block or concrete column
• 3/8" lag screws into wood
• 16d common wire nails into wood
• 1" long fillet welds into steel
• 1/4" x 3/4" self-tapping screws into steel

The notes listed for each fastener in TDS #161 are important, too. These notes describe the conditions or limitations for each fastener, including minimum distances, positioning of lowest and highest anchor, and any special preparation needed (predrilled holes, washers, allowable counterbore, etc.).

Pullout Loads

The allowable pullout loads for each fastener type were calculated with a safety factor recommended by the manufacturer or a nationally recognized structural design publication. For example, a 4:1 factor of safety is specified by the manufacturers of self-tapping concrete anchors, sleeve anchors, and expansion anchors.

The safety factor is important; it accounts for variations in assembly techniques, differences in materials, and changes in environmental conditions.

For Example …

TDS #161e demonstrates the difference between attaching jambs to wood frames of Southern Yellow Pine (SYP) and Spruce-Pine-Fir (SPF). Compared to SPF, SYP is a denser and stronger lumber and has higher allowable pullout loads.

As TDS #161e shows, a 16'-wide door with a design wind load of 30 PSF requires that 3/8" x 3" lag screws must be spaced a maximum distance of 24" for SYP and 19" for SPF.

The Last Word?

TDS #161 is not meant to be the only word regarding jamb attachment methods or fasteners. The number of possible combinations is virtually endless.

For other fastener options, consult a professional engineer or an architect. All DASMA Technical Data Sheets can be found at www.dasma.com.