DIY Retaining Wall Construction For Beginners
There are many variations in DIY retaining wall construction. The most common options are concrete blocks and natural stone. Each offers a different look. One is more uniform and formal. The other blends more with a natural setting. Regardless of which material is used, the area where the structure will be built requires some preparation.
Preparing the ground
The first step is preparing the footer or base. The ground should be leveled and tamped. Adding fine sand before placing the blocks or stone is optional. This is usually a thin layer of a couple inches. Planning for draining may also be a good idea at this point. The type of drainage system used will depend on the landscape of the area where the fence will go. Slotted draining tubing can run along or through the fence. Adding some gravel behind the wall, when it is complete, will also help with drainage and soil retention.
With stone, the ground does not need to be exactly level. Laying rocks of different thickness, to accommodate the changing slope of the ground, makes it easier. The ground should still be tamped, prior to placement of the first layer of rock.
For concrete blocks, an easy formula is to multiply the length of the structure by the height. Then divide by .75. The resulting number is the number of blocks needed. It is always best to add extra, in case of blocks are damaged when they need to be cut. Probably the only place they will be cut, is on the ends.
For natural stone retaining wall construction, base times height times width is calculated, then multiplied by 125 pounds per cubic foot. It is best to have concrete block or stone delivered, as it will likely take at least a ton for each, depending on the length and height of the wall.
Laying the stones or blocks
With concrete blocks, a staggered pattern is used. This makes the structure much stronger and looks professional. If the structure is four feet or lower, it can be gravity stacked. This means no adhesive or filler is used between layers or blocks. The concrete block version can have caps on the top layer, which are secured with concrete adhesive.
Stones are laid randomly, by placing pieces of varying thicknesses on each level. Include some very thick rocks randomly, to make the structure more sturdy. Try and save the flattest rocks for top caps. This looks good and keeps the fence stable. There is no additional draining needed for stone. There will be plenty of small gaps for water to flow through. However, a landscaping cloth can be added to the back side of both concrete and rock, to prevent staining from soil.