Equipment, Haddon, Rescue Company

Wood Cribbing and Shoring Lumber

Issue 8 and Volume 21.

By Carl J. Haddon

How many times in a week, a month, a year, or a career do our lives and the lives of those we serve rely on good cribbing, shoring, and stabilization materials and practices?

I’m an older dog, but I personally can answer that question with a single word: many. Regardless of whether you use wood cribbing or shoring lumber a lot or only occasionally, how much do you really know about the wood you bet your life, your crew’s lives, and your patient’s life on?

Allow me to offer a basic checklist of questions for you and your department to consider about the wood you choose or use for your cribbing and other stabilization needs:

  • What kind of wood is your cribbing made from?
  • What loads is your wood cribbing rated for?
  • How old is your cribbing?
  • How long have you had it in service?
  • When was the last time you inspected your cribbing or lumber, and what do you inspect for?

Fact: Most of us don’t have enough compartment space (on our apparatus) to carry all of the cribbing and lumber that we may require.

Fact: Many departments have implemented agreements with local lumber yards or home improvement stores to quickly provide them with emergency cribbing or shoring lumber day or night.

Fact: Wood cribbing placed under load force will make tell-tale noises before it catastrophically fails.

Let’s look at some of the checklist questions, and why I pose them.

What Kind of Wood?

Where in this country you work will often determine the type of wood that is available for your cribbing and shoring. In the East and Midwest, we find lots of cribbing made from oak. West of the Mississippi, I find lots of pine and fir being used, as oak typically is not available. Even though oak is a far denser wood than pine and fir, and most often thought of as a better wood for cribbing, Federal Emergency Management Agency (FEMA) engineers disagree because hardwoods like oak are denser, provide fewer warning signs, and catastrophically fail much faster than softwoods do.

1 What kind of wood is your cribbing made from? The region of the country in which you work will often determine the type of wood that is available for your cribbing and shoring. (Photos by author
1 What kind of wood is your cribbing made from? The region of the country in which you work will often determine the type of wood that is available for your cribbing and shoring. (Photos by author.)

What’s It Rated for?

Although I’ve never seen a load or pounds-per-square inch (psi) rating stamped into wood cribbing, I understand that a typical #1 Grade yellow pine or fir, 4 × 4, for example, is rated at roughly 6,000 psi for a single point of contact. Even if all pieces of wood cribbing had load rating stamps on them, so what? Let’s be real-when lives hang in the balance (especially our own), are we going to look at each and every piece of cribbing to make sure it is all the same type of wood and all the same age before we do the complex calculations to figure out if the type of stack that we build will hold the weight? I’ve seen and memorized the FEMA and Army Corps of Engineers charts on weight capacities for wood stack cribbing. I’ve also seen the results when crib stacks catastrophically fail in direct opposition to what those charts say.

How Old Is It?

When I ask the question about how old your cribbing is, I mean do you know how old the wood was when you got it and how old it is now? The “engineers” tell us that the wood cribbing and shoring lumber should not exceed 19 percent moisture content. Again, let’s be real. I can probably figure out the math (if no one is dying while I mutter through it) to come close to the load rating for a given crib stack. But, figuring moisture content? Really?

This brings me back to the “fact” that I stated above about departments having agreements with local lumber yards or home improvement stores for emergency cribbing and shoring lumber. If you’ve been to your local home improvement store or lumber yard lately and looked at the lumber available, you’ll be lucky to find straight, #1 Grade, kiln-dried anything. The vast majority of the wood available is very green, very wet, and not so straight. So, how do we know how old the wood we use is? Wood absorbs moisture. How do we know at any given time what the moisture content is?

2 What kind of loads has your cribbing or shoring been subjected to over the time that you’ve had it in service? Wood-all wood-has long fibers that constitute its makeup. We commonly refer to this as the “grain” of wood. An often overlooked fact is that as wood cribbing or shoring is subjected to forces of gravity or weight bearing, those fibers within the grain break down and weaken. Inspect your cribbing for cracks, splits, checks, warping, and contamination-just to name a few things.
2 What kind of loads has your cribbing or shoring been subjected to over the time that you’ve had it in service? Wood-all wood-has long fibers that constitute its makeup. We commonly refer to this as the “grain” of wood. An often overlooked fact is that as wood cribbing or shoring is subjected to forces of gravity or weight bearing, those fibers within the grain break down and weaken. Inspect your cribbing for cracks, splits, checks, warping, and contamination-just to name a few things.

How Long Have You Had It in Service?

A more important question is: What kind of loads has your cribbing or shoring been subjected to over the time that you’ve had it in service? Wood-all wood-has long fibers that constitute its makeup. We commonly refer to this as the “grain” of wood. An often overlooked fact is that as wood cribbing or shoring is subjected to forces of gravity or weight bearing, those fibers within the grain break down and weaken. That breakdown and weakening is compounded each time that piece of wood is subjected to weight and is further enhanced by the effects of weather, moisture, and chemical or fluid contamination.

So you see, the “engineers” charts are all well and good for pristine #1 Grade, kiln-dried, less than 19 percent moisture content, unused pieces of yellow pine cribbing. How many of those do you have on your truck? How many of those will you have after your next stabilization? Ultimately, how do you know how the weight rating of your cribbing and shoring lumber changes after you use it a couple of times? The fact of the matter is, you don’t know!

3 Although many consider oak better for cribbing, Federal Emergency Management Agency (FEMA) engineers disagree because hardwoods like oak are denser, provide fewer warning signs, and catastrophically fail much faster than softwoods do
3 Although many consider oak better for cribbing, Federal Emergency Management Agency (FEMA) engineers disagree because hardwoods like oak are denser, provide fewer warning signs, and catastrophically fail much faster than softwoods do.

How Often Do You Inspect Your Cribbing?

Have you ever inspected your cribbing? Many departments don’t because “it’s just cribbing.” Do you paint your wood cribbing for the sake of easy identification? If so, you might find that the paint makes inspection of your cribbing more difficult. Inspect your cribbing for cracks, splits, checks, warping, and contamination-just to name a few things. I would be remiss if I didn’t ask the question if anyone is old enough to remember why we did away with wood backboards many years ago? It was because of the biohazard contamination of the wood and that we couldn’t adequately decontaminate the wood of the spine boards. Makes sense, right? So, please tell me what the difference is between backboard wood that is contaminated by body fluid or other biohazard (that we can’t decontaminate) and all of that wooden cribbing we use in close proximity to the humans we are trying to disentangle at extrication scenes and their biohazards? Is a biohazard-body-fluid-contaminated splinter in your hand from a piece of wood cribbing or shoring any different from one gotten from a contaminated wooden backboard?

Perhaps it’s time to give a bit more attention to the (arguably) single most overlooked tool in your technical rescue toolbox-your lumber. Your life could depend on it in more ways than one.

CARL J. HADDON is a member of the Fire Apparatus & Emergency Equipment editorial advisory board and the director of Five Star Fire Training LLC, which is sponsored, in part, by Volvo North America. He served as assistant chief and fire commissioner for the North Fork (ID) Fire Department and is a career veteran of more than 25 years in the fire and EMS services in southern California. He is a certified Level 2 fire instructor and an ISFSI member and teaches Five Star Auto Extrication and NFPA 610 classes across the country.