Cribbing is essential during rescue operations.  In fact, cribbing is one of the most frequently used tools during vehicle rescue operations.  Gravity is inescapable; thus cribbing is used to redistribute the weight of objects into a ‘footprint’. Cribbing provides a temporary support during rescue operations.

Wooden cribbing pieces seem to be the most commonly used with softwood a popular choice.  The softwoods most frequently used are Southern Yellow Pine and Douglas Fir.  Advantages of softwood cribbing pieces include being lighter in weight compared to hardwood, and most importantly providing warnings of failure.  These warnings include visible cracking of the wood, and sounds produced by such cracking.  The properties of wood allowing the noticeable signs of failure result from the two primary growing seasons spring and summer.  Spring growth produces softer fibers while summer growth produces harder fibers.  The softer fibers of spring growth produce the noise of cracking and the evident physical cracks during crossgrain loading.  When building box cribbing the load is perpendicular to the wood grain producing a slow, noisy, and visible warning of failure.  Axial loading, such as in shoring operations relies upon the crushing failure of the summer growth.

In some instances fifty pieces or more may be needed to stabilize an upright school bus.  If your primary response vehicle doesn’t carry this amount, is it easily obtainable?  In not, consider establishing a quantity to be stored at your agency.  Pack this cribbing according to dimension or primary purpose into open mesh crates.  These crates can be easily handled.  Consider storing a hand truck with the cribbing to transport a large quantity quickly using minimal personnel.

Wooden cribbing should be left unfinished and unpainted.  Cribbing pieces rely on gravity and friction between bearing points for stability.  Painted surfaces become slippery when wet and may hide damage or defects of the pieces.  Colored handles of rope or webbing may be attached near the ends of cribbing to separate the types and sizes.  The ends of cribbing may be painted or labeled to identify various types and sizes as well.

Cribbing should be inspected frequently for physical and chemical damage, or other deterioration.  Cracks are obviously indicative of physical damage.  If cribbing is found to be damaged it should be removed from service.

Varied lengths of cribbing may be used, however an accepted value is that the height of a stack crib shouldn’t exceed three times its width (footprint).  For example, if the footprint of a stack crib is 24”, the height shouldn’t exceed 72” (3:1).  Therefore rescuers may gain insight into cribbing length based upon this value, especially if considerable height is anticipated.  Although shorter lengths are most commonly used, longer cribbing pieces should be in a rescue tool inventory.

Stack crib height should not exceed
three times its "footprint if all
contact points are covered.

REFERENCE INFORMATION  

(All contact points covered)

Weight Bearing Capacity/Stack Cribbing Height

(Less than 4 contact points)