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Cribbing: Soft, Hard, or Plastic?

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  • Cribbing: Soft, Hard, or Plastic?

    A Posting from Forum Moderator Ron Moore

    When asked about my thoughts on vehicle rescue cribbing, I see two ways of approaching the subject. Soft or hard wood?. Plastic is completely out of the question in my opinion for any type of individual pieces of cribbing other than the pre-formed plastic stepchocks. In my opinion, individual pieces of plastic cribbing should be illegal for fire departments to use at a crash scene! They should be banned from existence.

    FEMA recommends that crews doing structural shoring use soft wood, construction-grade lumber for their building collapse rescue. Soft wood allows the heavy loads of a crushed building to sink in as it compresses. You'll hear the creaking and cracking as the wood takes on the load. Soft wood is cheap so if the wood cracks or get contaminated at a scene, you just throw it away.

    A box crib of 4x4 dimensional pine lumber, either regular pine or pressure-treated, can support a <br />load of 24,000lbs if constructed properly. Put three pieces parallel on each layer and it will support more than double that.

    The smallest building collapse cribbing is generally 24 inches in length and is sized as 2x4, 4x4, 6x6 and even larger.

    For extrication, the recommendation I make is hard wood. This is the strongest material under all <br />situations. Plano Fire Rescue bought "cribbing paks" from Frank Maltese, of the Branch <br />Corporation <[email protected]>. His wood is true dimension hard wood maple. 1x4, 2x4, 4x4 and <br />wedges with rope handles. These are very durable and are well liked by our crews. Kind of a once <br />in a lifetime investment because the wood holds up so well.

    I believe that vehicle rescue cribbing should be a maximum of 18 inches in length. We tried 24 inch stuff but it is too long for most car crash operations.

    For a department just starting out, wondering what cribbing they should invest in, I'd try this. If you can get hard wood fine. Go with it. If not, purchase regular construction-grade wood at a Home Depot-type place and cut it into 18" lengths. Secure strap handles (such as pieces of old seatbelts) onto the ends and bundle it into a carry bag. See how the guys like it. If it holds up OK, you're a hero. If the wood continues to crack or fail, or is to soft for your use, transition over to hard wood.

    A note on building wedges. If you want to build a wedge, start with a 4x4 block that is 22 inches long. Measure 4 inches in from each end and mark it. Cut on a diagonal between the 4 inch marks at each end. Leaving 4 inches solid at the thick end of a wedge makes a very strong wedge with a good <br />angle. You can do the same to create a 2x4 wedge.

    Two pair of stepchocks will also be very valuable. These can be the plastic manufactured material or you can build them yourself out of wood.

    Quantities of cribbing and how many of each size you carry is your decision. Consider space on your response vehicles, your most common crash scenario, and the types of vehicles that you generally encounter. At least have enough on-hand to get you through your bread and butter rescue calls.

    Any other suggestions, comments, things you're doing to make your own cribbing, lessons learned, training tips, or hidden secrets you want to share????
    Ron Moore, Forum Moderator

  • #2
    Ron, I have never had the luxury to have used plastic cribbing, but fromwhat people have told me they seem tohave liked it for vehicle extrication.

    What are the downfalls to plastic cribbing as compared to hard wood cribbing?

    The other question was that I see you mentioned a company that has pre-packed rescue cribbing with various sizes,but there was no mention of 6x6's. is that something that is not used any longer for extrication at all? <img src="confused.gif" border="0">


    • #3
      The only reasonably good application for plastic cribbing at crash scenes is as pre-formed stepchocks.

      The material that makes up the individual pieces of plastic cribbing is so hard and so dense, that it remains slippery under all conditions. The plastic wedges, which are 4x4s cut on the diagonal, are especially prone to releasing themselves from their position at a crash scene.

      To address this inherent risk, plastic cribbing manufacturers have introduced the revolutionary concept of "Lincoln Logs" for rescue personnel. Now with notches near each end, the plastic blocks lock together. What they fail to tell you is that in order to lock the notches together, you have to always build the cribbing in the exact shape of a box crib every time, at every incident. That's not realistic.

      The other short-lived solution of slippery plastic cribbing was to apply a sand-based paint to the working surface of the cribbing. Not only does it cost $164 a gallon and only covers two sides of ten blocks, it peels right off as soon as you put it into a cribbing application.

      In my opinion, you're always safer, more efficient and have better long-term vehicle stabilization with wood cribbing compared to plastic cribbing.

      6x6 cribbing is not practical for vehicle rescues with cars, our bread-and-butter crash. There is no guarantee that you even have six inches of clearance under a car to begin with. Where 6x6 wood comes into play is for big rig stabilization applications: bus, truck, machinery, etc. In this case, 6"x6"x24" and 6x wedges are a good thing.

      Ron Moore<br />Forum Moderator
      Ron Moore, Forum Moderator


      • #4
        We're currently using F7 grade oregon for cribbing and the plastic holmatro blocks, chocks, wedges, etc.

        We can't fault the Holmatro stuff- love it!

        We're not getting any slippage, etc and find it very diverse to use....


        • #5
          While I am also not a big fan of plastic except for the stepchocks, I must say Turtle Plastics has recently made a significant improvement in their product.

          All of the new cribbing will be available with a diamond grid surface for the interlocking feature. The surface is similar to that found on the bases of the Hurst rams and diamond tips. It is not painted on, it is formed into the material.

          I agree with Ron about the "lincoln log" version of cribbing. Unless used on it's side, each piece needs to be 90deg to the next... not always possible or feasible. You also need more cribbing to overcome the ground out areas that reduce the height of each piece.

          We are a delaer for the plastic products and sell a lot of step chocks and not a lot of cribbing.


          • #6
            Personally,I prefer using the good soft wood for cribbing. As in structural collapse, the pine will compress into the others to form a good locking base. As far as the plastic cribbing goes, the step chocks are pretty good to work with, but can be slick if any moisture or oils get on them.

            I actually had a 12" square plate 1" thick fly loose on a training exercise and hit me in the chest from 6 feet away. We were using the plates to increase the surface area for a roof raise on a school bus extrication when the top plate slipped and flew about 6 feet through the air and hit me in the chest. Luckily the plate had turned and the flat, larger area hit me. Otherwise, it would have resulted in a serious injury. I proceeded to ask if we had any wood cribbing on the truck and told him what he could do with his plastic cribbing.

            Use what works best for your department. If the plastic cribbing with the grip surface works, then use it. The most important thing to remember is to train with what you have and learn the best way to use it.
            Tell me, I will forget. Show me, I will remember. Involve me, I will understand.


            • #7
              I have not been actively involved in vehicle rescue lately as to understanding the best way to build/construct stepchocks. I have seen them of hardwood, 2"x6" wood, some almost 3' long and about 18" tall. I think most were nailed together. Can you recommend the best/optimum dimensions for stepchocks? Also can you recommend the best way to construct stepchocks from wood?

              I doubt there is any money available in the budget for purchasing stepchocks from a vendor(hey we just purchased a simple hydraulic tool), but if we could purchase them....can you note a website link here on the bulletin board of vendors? I had not heard of plastic stepchocks.

              Any help would be appreciated here in Alabama. Thanks


              • #8
                The topic of cribbng always brings up the question, which is better and how much of it should be carried on a rescur truck. My answer to that question is what ever it takes. Most serious stablization situations take lots of cribbing and can be difficult to preplan for.

                I have just posted a new page on my website <www.cribpac.com/lift> that explains a lot. I call it "know your load". Like a good foundation of a house, Cribbing can be the foundation of a rescue situation. The cribbing may be called on to do more then you had planed for. In situations like that you don't want to be second guessing about what kind of cribbing you should have used. I use rough cut hardwood so when I incounter a heaver and unstable load I know what to expect.

                I have had a piece of cribbing come out from under a set of hydraulic spreaders like a RPG. So I sure agree with you about plastic in an unstable situation. I have also seen softwood start cracking and not stop. When hardwood starts to talk I stop and think. I'll stick with hardwood.

                Frank Maltese <a href="http://www.cribpac.com/lift.html" target="_blank">know your load</a>

                [ 01-25-2002: Message edited by: CribPac ]</p>


                • #9
                  <a href="http://www.cribpac.com" target="_blank">HEAVY LIFTING, KNOW YOUR LOAD</a>

                  [ 01-25-2002: Message edited by: CribPac ]</p>


                  • #10
                    I like to use rough sawn oak or hickory. It is very strong and not slick. When it gets contaminated with fluids we throw it away. We have a lot of sawmills in our area and can get all we want for nothing. Sizes 2"x4", 2"x6", 4"x4", 6"x6" and for big loads 7"x9" railroad cross tie pieces from the mill, before being creosoted. The rectangular tie piece is good when one side of a stack has to be a couple of inches higher than the other side. Turning the top tie the tall way makes up for another 2" piece. The only drawback is the weight, but then what lightweight, common material is strong.


                    [ 01-25-2002: Message edited by: DD ]</p>


                    • #11
                      I have been using cribbing for 30 years. We have soft and hard woods,and recently bought a complete set of plastic pieces. We carry over 100 pieces of cribbing between the 2 rescue trucks.

                      Plastic cribbing was a huge waste of money. Any attempts to use it "off center" or on any sort of an angle or slope results in slipping. We have the "new stuff" with the little squares molded into it. It is like using Legos - it only fits at certain angles. Don't waste your money or risk your operation on this stuff.

                      We use a combination of hard and soft wood. hard wood, rough cut, is the preferred material. The rough cut gives the surface enough texture to grip each other, even in the snow and rain. We use soft wood as top pieces or wedges when you need to drive a piece in to finish your crib. The soft wood has a finished surface, to make it easier to drive in.

                      Using wood cribbing allows you the walk away and leave it there if you have to, without straining your budget. It also allows you to stockpile it at the station or on reserve or last due apparatus with little or no impact on your budget.
                      Dan Martelle


                      • #12
                        In reference to cribbing, do you use treated or untreated wood? We have to make our own cribbing due to financial restraints. This has been the topic of discussion at our house.

                        The cribbing we presently have is treated, but I don't see where it makes a differece. If the cribbing becomes contaminated, you should trash it anyway. What are your thoughts?
                        Begin with the end in mind.

                        Be safe out there!!


                        • #13
                          We use both hard and soft woods, all rough sawn, we painted all pieces ourselves, we added sand to the paint to help prevent slippage, it has worked very well, the paint makes it easy to clean the cribbing, we carry 6x6, 4x4, 4x6, 3x4, 2x4, 1x6, wedges made from 3x4s, and several pieces of 3/4 in. plywood cut 24 in. by 24 in., we also carry several pieces of microlams in different lengths, the plywood and micro's make good bases for lift bags as well as cribbing.


                          • #14
                            We use both hard and soft woods, all rough sawn, we painted all pieces ourselves, we added sand to the paint to help prevent slippage, it has worked very well, the paint makes it easy to clean the cribbing, we carry 6x6, 4x4, 4x6, 3x4, 2x4, 1x6, wedges made from 3x4s, and several pieces of 3/4 in. plywood cut 24 in. by 24 in., we also carry several pieces of microlams in different lengths, the plywood and micro's make good bases for lift bags as well as cribbing.

                            As far as the question about pressure treated lumber, it isn't any stronger than non treated lumber, plus some pieces weigh a heck of a lot more than non treated lumber, plus the cost is higher, for these reasons we stopped using pressure treated lumber long ago.


                            • #15
                              Unpainted hard wood is the best way to go. Painted wood can slip, plastic can slip. Soft wood can crush or shift with deformation etc. We attach straps to the end of the cribbing so it easy to carry and remove. We also have used plastic milk crates to carry and organise cribbing. We have also painted ends of wood (not where cribbing surfaces are utilised) to identify wedges blocks quickly etc.
                              Some days yer the fire hydrant and some days yer the dog.


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