Retaining walls are a classic part of landscaping because of the geography of certain areas and their inherent benefits. From maximizing space, to flood control, soil erosion control, and good old aesthetics, retaining walls offer many perks. Landscapers and contractors will also use them to make bays for mulch, gravel, and soil.
Mafia block or bunker block large retaining walls are used by landscaping, construction, and supply yard crews. They are specifically designed to be larger and fit together in order to accomplish bigger jobs. The use of cranes and other large equipment is necessary due to their much higher weight.
In today’s article, we take a look at the various materials you can use to build your own retaining wall with these blocks or smaller ones if they are ‘overkill’ for your project. For most people, the cost is often the determining factor when choosing what materials to use. As a result, we will take a look at the costs of mafia and bunker blocks and compare them with those of some of the alternatives.
What Is Used To Build A Large Retaining Wall?
So, you’ve decided to put up a retaining wall on your property, or you need a material bin on your land. And you’ve heard about how useful mafia blocks or bunker blocks can be. But, how practical is it to decide to use them?
However, while you do know that retaining walls look nice or are at least practical, you might not be well-versed in what goes into building a larger one…and the associated costs of doing so.
We’ll kick off by discussing the slight differences in mafia, bunker, and bin blocks. These are the large concrete blocks used to construct sometimes massive retaining walls.
Mafia And Bunker Concrete Blocks
As you have probably seen, concrete is one of the most popular choices for retaining walls. Yet, what you may not have seen is the wide variety of blocks that it can come in. For landscapers, lumber yards, contractors, and supply stores, Mafia Blocks or Bunker Blocks have many uses for separating materials.
It should be noted here that all three for the following block types are only separated by slight differences. In general practice, these names become interchangeable and are usually chosen out of habit rather than distinction in the blocks themselves. That being said, there are some slight differences in their construction or aesthetics on closer look.
“Mafia blocks”, in particular, are concrete blocks that are usually formed from concrete washout (the remnants from a concrete mixer). Mafia block masons usually source the washout from major concrete manufacturers and get to work molding blocks with a wide range of applications.
Historically, New York City was a major hub for concrete suppliers, many of whom had Italian heritage…hence “mafia”.
Mafia blocks are usually used as dead weight support for infrastructures such as highways and bridges. Somewhere along the line, though, it has been discovered that mafia blocks are sometimes well suited to life as landscaping retaining walls.
Bunker blocks (or large concrete masonry blocks) are constructed out of standard concrete blocks material. They are made from high-grade concrete and are often molded into consistent shapes. They have a wide range of uses in industry, construction, and landscaping.
The benefits of using concrete for a retaining wall mainly revolve around the sheer strength of the material. Downhill soil erosion will pretty much be a thing of the past if your retaining wall is erected properly. This required engineering in walls over 4′ in height and adequate below grade foundations to avoid water erosion and structural compromise.
These are blocks specifically designed to be used not as retaining walls, but as building and landscaping material dividers in supply yards. They are formed into three sided bays with 6′ to 8′ tall walls meant to keep one type of soil, gravel etc. from mixing with another.
Since these blocks are not engineered specifically to hold the load of soil, water, and rock like some others, they sometimes are not rated as load bearing. This makes them cheaper to make and cheaper to buy due to less aggregate and more air in the mix.
What Size Are Mafia And Bunker Blocks?
For these larger concrete blocks, the size and weight can become very unwieldy. They are not small for a reason and are meant for larger jobs. What are the normal sizes of mafia and bunker blocks?
The typical stock sizes of mafia and bunker blocks are 2′ high by 2′ wide by 6′ in length. The demensions are further enhanced by interlocking designs that allow for mortarless assembly. Their ‘tabs’ and lifting handles are roughly 6 – 8″ in height and create easier and sturdier construction.
That being said, for jobs that are specifically engineered to larger forces and loads, these blocks can take custom sizes, weights, and shapes. Sometimes this will be for aesthetic purposes as well as load bearing requirements.
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How Much Do Mafia Or Bunker Blocks Weigh?
With concrete blocks this large, there must be a lot of weight associated. What do the average mafia or bunker blocks weigh?
The weight of each block is substantial. A mafia or bunker block weights normally in excess of 3600 lbs or over 1.8 tons. To lift and safely maneuver these, an 8 ton rated machine is recommended. The normal design of each unit incorporates interlocking ‘tabs’ and lifting handles.
That type of weight is not in the normal arena of most home or land owners. Those that are comfortable operating larger machinery can attempt it, but for safety purposes a very important rule must be followed.
Important: For all retaining walls (which in some areas includes material bins) over 4′ in height, engineers must be employed to ensure proper loads are accounted for and safety is maintained.
How Much Do Mafia And Bunker Blocks Cost?
With the sheer size of these, it is important not only to know what they cost, but what the cost of delivery could be. With that in mind, what is the average cost per block and per job?
Mafia and bunker blocks cost anywhere from $25 per block to $50 per block. Delivery costs are included many times for higher priced blocks, but can range from $10 to $30 per block. If the supplier is not willing to place them for you, you may also have to rent other equipment.
Some delivery services will place the blocks in accessible locations on your property and could save you time and money. This alleviates the need to rent large equipment to move them into place.
For a typical material bay, 36 – 40 blocks will be used to form the three sides. This averages out to around $1200 for the blocks themselves. Then you will need a concrete pad laid at around 6-8′ thick.
The average cost to have a concrete base poured for a material bay is $6 per square foot. With the average size of a material bay being 30’x30′ or 900 square feet, the cost you can expect for this base would be $5400.
Retaining walls holding back earth is a completely different animal. If the job is big enough that bunker or mafia blocks are required, structural engineers will need to be involved and the many local and state codes will have to be followed. This makes each job unique and the costs can become rather high.
Are Bunker Or Mafia Blocks Too Big For Your Job?
Now comes the question that faces many homeowners. Are these just too big for your job, or are they the right fit?
When building a retaining wall for most situations, mafia or bunker blocks may be overkill. They are designed for large jobs with large sizes and weights to go with them.
If you are trying to tackle a 4′ high wall or below on your property, it is likely that you will not need the hassle of dealing with these larger options. Smaller cinderblocks and similar materials could do the trick.
How To Build A Smaller Retaining Wall
But just how is a retaining wall erected? Let’s take smaller blocks as our material of choice here since in most cases the larger bunker or mafia blocks will not be needed. Cinderblocks are normally what most will use when constructing a masonry retaining wall.
For starters, you must take a look at your local building codes and regulations to determine if the retaining wall you have in mind is permitted. You’ll also need to consult your local utility providers so you are aware of any wires or pipes near the worksite.
Next, you’ll need a few tools and materials, including:
- Flat-bottom shovel
- Landscape fabric
- Gravel and sand
- Concrete adhesive
- Concrete blocks (2x1x1 feet)
- Spirit level (24-inch preferably)
- Hand tamper
Concrete blocks can be sourced from a wide range of sources at variable costs. You can even source them for free if you’re lucky (or connected) enough.
- The first step of actual construction is the creation of the base which will support the entire structure. The base also sets the tone for the rest of the wall’s shape and balance.
- To construct the base, you must dig a trench along the length of the proposed retaining wall. The trench must be a little wider than the blocks you will use (1 foot, in this case) and about 5-6 inches deep. Use the shovel to dig the trench in a flat manner, while using the flat bottom and the hand tamper to keep things level.
- Next, the trench must be lined with landscaping fabric (in a U-pattern that goes up the sides of the trench), which will protect the bottom of the base from excessive moisture build-up. Once the fabric is in place, you can use the shovel to add a layer of gravel and sand to fill up the trench. Use the hand tamper and spirit level to ensure everything is flat before you start laying blocks.
- Next, install your row of cinderblocks to fill up the trench. Ideally, the cinderblocks should sit flush with the surrounding ground surface. Use the hammer to force the cinderblocks in position at the bottom of the trench. Once the cinderblocks are lined up, use a spirit level to ensure they are even. Don’t hesitate to add more sand and gravel underneath the cinderblocks.
- At this point, you can start applying your concrete adhesive on top of the cinderblocks and placing the first layer of concrete blocks. Repeat the process of applying adhesive and blocks until the wall is high enough for your needs. If your retaining wall is to be built near a property boundary or fence, its height must be equal to its distance from said boundary.
Small Job Retaining Wall Costs
On the cost side of things, setting up a concrete retaining wall could cost you anywhere between a few hundred dollars (or less) and several thousand dollars. Some professional jobs can even exceed US$10,000 depending on concrete quality, labor, location, and machinery used.
The height, width, and length of the wall are also major factors behind pricing, as are any decorative touches and difficult job site obstacles.
Generally, concrete blocks cost from $10 per square face foot to over $100 per square safe foot from major concrete suppliers. The cost may be steep in some cases, but the fact that a concrete wall can last for more than a century makes it worth it.
Stone retaining walls are also a popular choice due to their strength and longevity. A stone wall can last for over a hundred years if built properly.
Stone veneer can cost $10-$15 per square foot, while boulder rock can be in the $8-$12 range. Gabion rock, which is growing in popularity, can be significantly pricier and can reach up to $40 per square face foot.
Bricks offer the durability and longevity of concrete and rocks, while also being easier to handle and align neatly. Some bricks tend to absorb moisture though, which can result in a compromised wall. However, you can still expect more than 50 good years from a brick retaining wall.
Brick prices are highly variable, and bulk orders typically come with discounts. That said, you can expect to pay $14-$15 per square face foot.
Environmentally conscious homeowners have also begun turning to rammed earth as a green alternative to concrete and brick.
It also doesn’t hurt that rammed earth blocks (made of compressed earth and bound with cement) are much more affordable than poured concrete blocks.
These blocks typically range between $5-$10 per square foot face.
Wood is one of the traditional retaining wall materials, with many 20th century properties sporting one. If you want your wall to have a more “natural” look to, wood might be the best choice.
Unfortunately, wood eventually rots and weakens, which gives you about 30 years of retaining before it starts sagging badly.
The price of timber varies but the average range is about $15-$30 per square foot.
The Final Touches On Mafia And Bunker Blocks…
There you have it. Big and small retaining walls using large or small blocks are not as simple as stacking heavy things on top of each other. They are large investments, and if not done correctly, a good way to loose much of that money.
Choosing to use large masonry blocks like mafia or bunker blocks should only be done if the specific job calls for it. They are not something to be handled by novices due to their size, weight, and overall cost.
If you are the average home or land owner, cinderblocks are going to be in your wheelhouse. If you know that mafia blocks or bunker blocks are what you will need, I hope to have given you some helpful information for your retaining wall or material bin plans.
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