Load Bearing walls
Load bearing walls are for holding back large amounts of soil.
They almost always have a large reinforced concrete footing. The pressure over the years becomes tremendous, and we have all seen walls that lean the wrong way.
Even with proper drainage and proper footings, the earth always wins over time. These walls are not recommended for the average do-it-yourselfer, especially when failure could have an effect on buildings or property.
Walls up to five feet tall can be constructed with cut stone or split face concrete wall systems, but these walls have about a 25 year life expectancy, and then they start leaning and deteriorating. Walls that are within the ability of the average do-it-yourselfer though, are “terracing walls”.
Great DIY retaining wall projects
Nothing breaks up a flat yard or makes usable space on a sloped yard like short easy terracing walls. Short walls that are just 3 or 4 rocks tall are fairly easy to build, they don’t have to have any mortar, they will last 10 to 15 years, and then you can rebuild them usually by digging a small trench behind the wall, and coercing the rocks back into position. Good for another ten years.
Terracing walls don’t require a footing, but we recommend you bury the first layer in a few inches to prevent undermining and hide that bottom edge. Here are some examples of terracing walls in paradise. Many types of stones are suitable for these low walls. Natural stones, machine cut, and others. Choose a layered stone that’s flat on top and bottom. Once you get the bottom row leveled, the succeeding layers go quick.
Great do it yourself retaining wall projects
Machine cut, tumbled, strip rock, fieldstone, and others make for an attractive, easy to install and maintain edging. Usually only one or two stones tall, just to separate the bed from the turf. Its good to bury the first coarse in a couple of inches to lock it in and hide the bottom edge. Stone can be surprisingly cheap as an edging material. And nothing beats the look that natural stone edging gives the landscape.
Calculating stone for retaining walls by simply using this chart.
This largely depends on the height of the wall you intend to build. If the wall is to be only two or three rocks tall, then a six inch thick wall will do. If over three rocks high, then we recommend using a eight inch thick wall stone. Most machine cut stones are going to vary in length, so if you are building a straight wall, then mix all the different lengths together or leave some nice long ones for a more solid cap. If the wall has a bunch of tight curves, then shorter stones will yield a much smoother curve. The thickness of the stones is more a matter of personnel taste. Obviously thicker stones means less courses but are heavier than thinner stones. If you’re not used to lifting heavy rocks, then go with something in the 3 to 4 inch range.
How do they make this
Retaining wall stone and building stone are quarried several different ways. The lucky quarry has rocks that are layered with only a thin layer of shale or dirt between the layers. These stones need to be merely unearthed and processed. Other quarries have different methods of removing the stone from the ground, often using large saws to make grooves in the rock, then removing huge blocks which are then processed to more usable sizes. Some stones are blasted out of the ground, they can control the size of pieces that blasting creates with the amount of explosives used. Fire in the hole!
Some retaining and building stones are simply harvested off the surface. These are field stones and boulders and are usually not processed any further.
Once quarried, slabs and blocks are then moved to a cutting area where these big saws and choppers can snap and cut the stones into the desired sizes. This particular stone is generally quarried in large uniform thickness slabs. The slabs are then run through a guillotine chopper which can then cut them into any size strips. The force of these splitters is tremendous, they can snap stones up to 2 feet thick.. Just keep your fingers out of the way.
These big saws can cut through stone like butter. Sometimes huge blocks are sawn into thinner slabs which are then run through the chopper. Caps, stair treads, tiles, window sills and other stone products are sawn to exact dimensions using saws like these.
Tumbling stone takes the sharp edges off of the rocks and rounds the comers for a more cobble stone look. Tumbling takes some pretty serious equipment like this tumbler here. The stone will usually be cut into cubes or rectangles, then loaded into the tumbler, the stones are usually tumbled for 15 to 20 minutes, emptied and reloaded all day long. Lets get ready to tumble. Stones that are cut and tumbled
are always going to cost more because of the labor and machinery used to process these stones.
How to install
There are several different ways to build a retaining wall. A wet laid wall refers to the method of using mortar in the joints between the rocks. A wet laid wall will always require a substantial concrete footing. Because of the mortar that can be seen in the joints, these walls must be so sturdy that they can never move. The slightest movement will cause visible cracks that will have to be repaired, so these walls must be strong enough to withstand all that will be thrown at it. In addition to the massive footing, the wall itself should be thick enough to do the job. Usually a concrete wall that is veneered with stone, or a block wall is constructed first and then veneered with stone. The veneer should be mechanically fastened to the block or concrete wall and then all voids filled with concrete for a really solid structure. Sometimes drains will be installed to allow moisture to weep through. These walls a very costly to build because of all the materials and labor required, but will last a very long sime with no maintenance.
Dry laid walls use little or no mortar and are designed to flex and give with the earth’s movement without needing to be repaired. We know that when it rains a lot, the earth soaks up water and swells, when the earth dries out, it shrinks and cracks. These type walls can take the movement and not need to be repaired because there is no mortar joints to crack and need repair.
Dry laid retaining walls can be set on compacted, consolidated soil or bed of compacted screenings. We recommend the first course of stone be buried half way in to prevent undermining and to conceal the bottom edge. This helps lock it in as well.
It is often necessary to utilize a pretty hefty bed joint to aid in getting this bottom row level. Using a string or level as you go, the mortar bed gives you the ability to tap down the rocks to get them all level without having to trial and error each rock if you were simply putting them down on dirt.
One important tip to remember when building a retaining wall is to always make the wall perfectly level, starting at the lowest point, and stair stepping up as the grade dictates. When you are ready to top out or lay the final course, again stair step up or down as the yard dictates.
When you are ready for the second course, step it back one half to three quarters of an inch so the wall is leaning into the dirt it is retaining, this is called canter or batter.
Its common to use a little mortar between the courses for leveling and bonding, but leave the vertical joints open for drainage. If some of the mortar oozes out, you can scrap that off with a stick or screw driver or something.
You may want to fully mortar the top row to really lock them together. Clean any mortar off the stones same as you would with flagstone.
Its also important to put some weed fabric or landscape cloth behind the wall before backfilling to let the moisture out but keep the dirt from washing out.