Putting cinder blocks under leveling jacks?

[TxCowboy]

Strolling through the RV park and I'm seeing a lot of longtime park residence (include newly arrived Winter Texans) have cinder blocks under their landing gear.

Is this a good idea or is this just stupid and unsafe?

I can understand not wanting to expose the landing gear to the salt water corrosion so shortening the legs is good. (I spray the legs on the Landmark every week with a corrosion inhibitor). Shortening the leg extension by 8 or more inches sounds like a good idea.

On the other hand, that's a lot of weight to be sitting on top of six cinder blocks so that that make it unsafe? My brief readings on maximum compression on a cinder block is only about 2000 psi. Not sure how to convert that number to maximum weight though...

Back to the question -- safe or not?

Your thoughts?

 

[weekender01]

Strolling through the RV park and I'm seeing a lot of longtime park residence (include newly arrived Winter Texans) have cinder blocks under their landing gear.

Is this a good idea or is this just stupid and unsafe?

I can understand not wanting to expose the landing gear to the salt water corrosion so shortening the legs is good. (I spray the legs on the Landmark every week with a corrosion inhibitor). Shortening the leg extension by 8 or more inches sounds like a good idea.

On the other hand, that's a lot of weight to be sitting on top of six cinder blocks so that that make it unsafe? My brief readings on maximum compression on a cinder block is only about 2000 psi. Not sure how to convert that number to maximum weight though...

Your thoughts?

I agree that cinder blocks make a poor support of the RV. If you get enough weight over one of them it will break! It happened to a friend of mine when we all went to look at his 5th wheel. He had the front supported on cinder blocks and when we got to the front bedroom it broke. I would choose a different material.

 

[JohnD]

Cinder blocks are good for the short term camper . . .

But if you plan on staying for the winter . . . wood blocks would probably be a much better alternative!

 

[Dennyha]

Cinder blocks have plenty of compressive strength if the load is distributed across the whole block, AND the block is sitting with the hollow core in a vertical position. I shutter when I see someone with a load on a cinder block with the hollow core in a horizontal orientation (because that gives them a larger top surface to put their landing gear on. In this position, it is quite easy to crack a cinder block. They were not designed to take a load in this orientation. So, a cinder block can be a good choice if it is sitting on solid ground, in an upright position (hollow core is vertical), and a 2X8 is sitting on top of the cinder block to distribute the load to the whole block cross section.

I know, I know. Too Much Information.

 

[JanAndBill]

Short answer no. Go to the lumber yard get a pressure treated 6x6 and cut some blocks. Then cross stack them. If you have access to rough sawn oak even better.

 

[Piperflyer]

Cinder blocks have plenty of compressive strength if the load is distributed across the whole block, AND the block is sitting with the hollow core in a vertical position. I shutter when I see someone with a load on a cinder block with the hollow core in a horizontal orientation (because that gives them a larger top surface to put their landing gear on. In this position, it is quite easy to crack a cinder block. They were not designed to take a load in this orientation. So, a cinder block can be a good choice if it is sitting on solid ground, in an upright position (hollow core is vertical), and a 2X8 is sitting on top of the cinder block to distribute the load to the whole block cross section.

I know, I know. Too Much Information.

Good way of explaining it Dannyha, to many people put the cores horizontal and their is no strength in the block in that orientation. Used right, blocks are fine for support.

 

[TxCowboy]

Short answer no. Go to the lumber yard get a pressure treated 6x6 and cut some blocks. Then cross stack them. If you have access to rough sawn oak even better.

So, make a stack of wooden blocks 8 inches tall or higher and slightly wider than the size of the jack pad?

 

[jassson007]

What about mobile homes. Atleast down here they are all on cinder blocks. Now the spacing is about 60 inches or so between sets of blocks but these are 60-80 foot models too. Just not sure why couldn't use cinder blocks if used correctly


Sent from my iPhone using Tapatalk

 

[Bob&Patty]

If you do use wood...make sure you cross stack them. 2 one way and 2 the other way. Known as "cribbing".

 

[jayc]

I have some painted blocks that a friend gave me a few years ago but they have rotted out. They are cross stacked 2 X 4's and were obviously not pressure treated lumber. I had an idea to use the hard rubber pads that are designed to be used in horse stalls and available from Tractor Supply. I was going to cut them into 12"x12" pads and stack three or four of them and possibly fasten them together with wood screws or Gorilla Glue but after looking closely at them, I feel that they may be too soft and would likely crush under the weight. They would never rot and should last a long time but the pad costs $40 and that will buy a lot of lumber.

 

[jimtoo]

Those horse pads are about 3 times heavier than wood also and I would think you would get a little bounce if you stacked 3 or 4 together.

Jim M

 

[Lynn1130]

I guess my question would be, would you want to take the chance of several thousand pounds dropping 6-8 inches on the two landing gear? Several vehicle mods I have made to my truck have come with instructions NOT to use cinder blocks to block up the vehicle and I am pretty sure I know why. You can stack them anyway you wish but I would not be inclined to take the chance.

 

[jimtoo]

There has been many, many big tall buildings built with cinder (cement) blocks. They must be stacked upright to carry the load, not laying down and with a load spreading top. Like a flat cement piece or 2x8 or 10 cut to size.

Jim M

 

[Lynn1130]

You are correct Jim but IMHO I think we are apples and oranges here with buildings and one block under a couple of thousand pounds of 5th wheel. If it is verticle it is wobbly. If it is horizontal it is in danger of crushing.

 

[TxCowboy]

Cinder blocks have plenty of compressive strength if the load is distributed across the whole block, AND the block is sitting with the hollow core in a vertical position. I shutter when I see someone with a load on a cinder block with the hollow core in a horizontal orientation (because that gives them a larger top surface to put their landing gear on. In this position, it is quite easy to crack a cinder block. They were not designed to take a load in this orientation. So, a cinder block can be a good choice if it is sitting on solid ground, in an upright position (hollow core is vertical), and a 2X8 is sitting on top of the cinder block to distribute the load to the whole block cross section.

This is what I'm seeing most often (boldfaced above). In my case, I have the 6 point system so the weight is better distributed over the length of the RV.

 

[Bob&Patty]

Most of the time, cinder blocks in buildings are filled with cement and have rebar in them.

 

[HOGHAULER]

Boat yards have used cinder blocks for years. But yes follow the rules in Dennyha post.leave all jacks down but get weight onto blocks. That can be accomplished many diff ways.

 

[Dennyha]

The standard for compressive strength of a cinder block is 1900 psi minimum. That means for an 8" x 16" cinder block, which is about 50% solid, it can support a minimum compressive load of about 120,000 pounds, if it is supported evenly. I don't think anyone is going to crush it with their camper, unless it is used incorrectly.

 

[Bohemian]

There are cinder bl9cks and there are concrete blocks. Concrete blocks are heavier and stronger.

I would trust concrete blocks in he correct orientation, holes upright, topped with a matching size piece of pt wood.

 

[TxCowboy]

DELETED. Concrete blocks are stronger than cinder blocks.