What is Cribbing in Construction?

cribbing constructionCribbing (also called a “box crib”) is a popular practice among aerial lift operators, construction foreman, and other job site workers, and it is used in a variety of work situations. Cribbing construction techniques can be both incredibly effective and incredibly dangerous if the necessary safety precautions aren’t taken.

What is Cribbing in Construction?

Cribbing, also known as falsework, is a temporary structure used to support heavy loads during construction. It is typically made from wooden beams or concrete blocks and is not meant to be a permanent fixture. Cribbing is commonly used in the construction of bridges, roads, and buildings. 

There are two types of cribbing: horizontal cribbing and vertical cribbing. Horizontal cribbing is used to support heavy loads from above, while vertical cribbing is used to support loads from the side. Box cribbing is a type of horizontal cribbing that is particularly well-suited for supporting very heavy loads. 

Box cribbing gets its name from its box-like shape. It consists of interlocking cribs that are stacked on top of each other to create a stable, rectangular shape. The boxes can be filled with sand, gravel, or concrete to add additional weight and stability. Because of its box-like shape, box cribbing is particularly adept at bearing loads from multiple directions simultaneously.

How to Build a Box Crib 

Building a box crib is relatively simple and only requires a few materials. You will need 4×4 lumber, 2×4 lumber, deck screws, drill, tape measure, saw horses (optional), level (optional), and stakes (optional). 

#4 deck screws should be used for fastening the 4×4 lumber together because they are big enough to go through the lumber without splitting it but small enough so that they can be driven in by hand. A drill can be used for pilot holes and driving in the screws but isn’t necessary. If you don’t have a saw horses or level handy, you can use stakes and string to keep your lumber level and in place while you work. 

Treat all lumber before beginning assembly by cutting the 4×4 lumber into 8 pieces that are 3 feet long and 8 pieces that are 2 feet long. These will be your upright posts. Cut the 2×4 lumber into 16 pieces that are 2 feet long and 32 pieces that are 1 foot long. These will be your horizontal crosspieces..   Lay out 4 of the 3 foot long 4×4 pieces in a square on level ground and attach them together at the corners using #8 deck screws driven every 6 inches along the seams.. Repeat this process with the remaining 3 foot long 4×4 pieces to make a second square.. Now you will start attaching the 2 foot long 4×4 pieces between the uprights of each square. Start by attaching one 2 foot piece between 2 uprights on one side of each square using #8 deck screws driven every 6 inches along the seams.. With all of the sides now attached except for the top and bottom, lay out your crosspieces on top of the frame making sure they’re evenly spaced out..  Once you have them positioned where you want them, use #8 deck screws driven every 6 inches along the seams to attach them into place.. Attach remaining 2 foot long 4×4 pieces between corresponding uprights on each side of both squares.. Lastly, cut 4 more 2 foot long crosspieces and attach them along the very top of your structure using #8 deck screws driven every 6 inches along the seams.. Your box crib is now complete!. If desired, fill each box with sand, gravel, or concrete for added stability..  That’s it! You’ve now built yourself a sturdy box crib that can be used to support heavy loads during construction projects..  

Cribbing is an essential tool for any construction project involving heavy loads. While there are many types of cribbing available, box cribbing is particularly well-suited for supporting very heavy loads thanks to its robust rectangular shape. Building a box crib is relatively simple and only requires a few materials; most notably 4×4 lumber, 2×4 lumber, and deck screws. With these steps in mind, you’ll be able to build your own box crib in no time!

Cribbing Construction Materials

Wood is the preferred cribbing construction material, but plastic is also popular. Wood cribbing blocks often consist of softwoods like Douglas Fir or Southern Pine. To determine the strength of wood cribbing blocks, it is important to evaluate several factors, including the wood species, moisture content, length, and thickness. 

Plastic and steel may be used for cribbing due to the fact that they are sturdier and less susceptible to chemical corrosion than wood. But for most purposes, wood works well for cribbing.

Concrete is another sturdy, practical material for crib walls. It can hold a heavier load, which makes the crib walls more secure. However, there is less flexibility than with wood, which has more give with a heavy load. Concrete doesn’t rot or deteriorate, which makes it ideal for long-term projects. It won’t absorb water, which can be detrimental to a crib wall that must support heavy equipment.

Jobs in the Cribbing Construction Industry

People who do cribbing are known as cribbers. They work with wood and concrete to build crib walls as foundations for buildings and as a temporary construction structure.

Cribbing construction crews and other workers on job sites. They must stay up to date on the latest safety requirements and follow OSHA guidelines. They may begin their career as an apprentice under a journeyman until they have learned the trade at which point they become journeymen. 

According to OSHA, it’s up to employers to ensure workers have received the training they need to:

  • Operate the controls of an aerial lift
  • Inspect equipment
  • Assess a work environment
  • Perform cribbing and other tasks safely

Aerial lift certification training should teach workers involved with construction cribbing the safest ways to work with cribbing on an aerial lift or scissor lift. It should also teach these workers how to keep a structure sturdy and balanced and eliminate dangers.

Cribbing Construction Safety Risks

Stable, flexible woods should be used for cribbing. These woods can support heavy weights; plus, they are more prone than other woods to creak or make other noises if too much weight is present.

If cribbing makes noise, it should be replaced immediately. The longer the noise is present, the more likely it becomes that the cribbing is defective. If you do not address the issue, the cribbing could shatter, which could break your equipment or harm your workers. Brittle woods are susceptible to splitting or snapping under heavy weight. As such, these woods should always be avoided for cribbing.

For aerial lift operators, cribbing construction has to be undertaken with extra caution. Given the top-heavy loads and height of some aerial lifts, wood cribbing should only be done under professional, certified supervision. This includes cribbing with scissor lifts and common aerial work platforms.

Proper training is essential to ensure operators and workers involved with cribbing construction and aerial lifts are prepared to recognize and avoid hazards. Aerial lift training teaches operators how to safely perform tasks on and off cribbing.

Cribbing Construction Best Practices

There’s no denying the risks involved with wood cribbing. By understanding the potential for accidents, employees can guard against the very worst workplace hazards. Always be sure to consult your lift’s operation manual to see what it says about cribbing construction before beginning this kind of work. Select materials that are straight, solid, and free of obvious flaws. Design a cribbing stabilization plan and implement it with fidelity. Be sure to factor in the work surface below – unstable ground can impact the safety of your cribbing. Always wear the necessary PPE like glasses, a helmet, and a reflective vest, as well as a safety harness.

As you begin a cribbing construction project, be sure not to ignore the weather. Mud, rain, ice, and snow can impact your lift’s ability to maneuver. Don’t structure cribbing on surfaces that have been painted or finished. Never stack cribbing more than three times its width. It’s also a bad idea to pull all cribbing out from beneath a supported load at once. While there are risks involved with this kind of work, a little foresight can go a long way in preventing accidents.

Sign Up for Aerial Lift Certification Training with ALC

Proper cribbing construction falls right in line with proper aerial lift safety. For the best aerial work platform safety training, only one provider gives you OSHA-compliant instruction, flexible course scheduling, and affordable pricing — AerialLiftCertification.com. You can get workers certified with the Aerial Lift Operator Training Kit for $299, Train a Trainer course for $149, or the bundle at $399. Workers can learn through guided training, with self-paced learning, or through group training. To find out more about our aerial lift certification or to sign up for our training program, please contact us online or call us today at (888) 278-8896.

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