30 / FRAME BUILDER - VOL7 NO3
BUILDING LOADS IMPOSED 
BY MONO AND BI-FOLD DOORS
P
ost-frame buildings are 
frequently used to store 
and maintain equipment 
of various types. The size of 
post-frame buildings and the 
openings in those buildings have 
increased as the articles and 
equipment housed in post-frame 
structures has increased in size. 
Heated structures demanded 
doors that can be insulated and 
properly sealed to minimize 
heat loss. Finally, our customers 
are demanding the convenience 
provided by automated doors. 
Bi-fold and the newer hydraulic 
mono-fold doors address the need 
for large, insulated, automated 
doors in post-frame structures.
Mono and bi-fold doors load 
post-frame structures in unique 
ways. Wind pressure 
flows both vertically 
and horizontally. 
Gravity acting on the 
open door induces 
a couple in the jamb 
columns. The door’s large size 
results in large forces imposed on 
the building into which they are 
installed. The quick start and stop 
Paul Boor, PE
Lester Building Systems
RESEARCH & TECHNOLOGY
THE OFFICIAL NFBA MAGAZINE
Photos Courtesy of  Midland Doors 
Bi-Fold Door

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