Which type of retaining wall is the easiest and cheapest to build
Most homeowners build fieldstone or timber walls because they are the most popular materials in my area, but modular block and poured concrete or concrete block walls also are excellent options. Each type of wall requires a different set of tools and building skills. Railway or wood landscape ties are a good, inexpensive material for someone comfortable building with wood. A poured-concrete wall is likely the strongest choice, but the installation is probably best left to professionals.
Choosing the most appropriate material is the first decision you need to make when starting a retaining-wall project. Before you begin building a wall, you also need to consider the elevations of the new finished grades, the appropriate base and how to backfill properly. Building two or more small walls also may be easier on your back because you don’t have to lift the stone, block, or timbers too high, or set up staging. If you decide to build a terraced retaining wall, start with the lowest wall: You’ll create flat areas to stand on while working on the upper walls, and you can incorporate steps, which have to be built from the bottom up.
Even the most attractive retaining wall can lose its charm if the wall is too massive for its surroundings. If there is enough area to divide the change in grade into multiple stepped walls, a series of small walls might be more visually appealing. Terraced walls also may avoid the need for permits, engineers, and complicated construction details. The area between terraced retaining walls does not have to be level and can be used for lawn or gardens.
About base and backfilling:
One truth about all retaining walls is that they are only as good as the base they are built on. The right depth and type of base depends on the material and the landscape.
Dry-laid stone usually are backfilled with large stones, and the voids are filled with rubble. If the wall is separated from the earth with filter fabric, drainage behind the wall often is unnecessary. Block walls should be backfilled with gravel and a perforated drainpipe and separated from the earth with filter fabric. This method also can be used for a timber wall in a wet area, a wet-stacked stonewall, or a poured-concrete wall. Weep holes are another option for poured-concrete walls and wet stonewalls.
For some projects, excavating for the base and backfill is the most laborious part of the job. If this is the case, it might be worthwhile to hire an excavator or to rent a backhoe for a day.
Using railway ties or timbers to build a retaining wall
Using wood to build a retaining wall means it won’t last as long as blocks or concrete but it is much easier, and in most cases the least expensive option. If you are comfortable with basic carpentry, you shouldn’t have problem building a wood or landscape tie retaining wall. In dry area, a wood wall can be built without base or tricky backfill. Steps can be made by joining two 6×6 timbers and are incorporated easily into these walls. It is simple to make 90° and 45° corners, curves are a little more tricky.
Timbers range from used railroad ties to manufactured landscape ties. If you can find them, used railroad ties are fairly inexpensive, but they are often treated with creosote. They also are normally inconsistent in dimension and often not very straight. This combination can make for tricky building. The most commonly used material is pressure treated 6×6 landscape timbers. You use a rough-sawn, dimensional 6×6 for a rustic look, or a planned 6×6 (actually 51/2 in.) for a more-finished look. Far shorter walls a 4×6 timber also can be used. The length of the ties also varies a 12 ft. or 16-ft beam can cover a lot ground but is difficult to handle as is quite heavy. An 8-ft. tie is more manage-
for one person.
The obvious drawback to using wood is that they eventually rot. Pressure treated timbers will last longer than untreated by years, but be aware that the manufacture warranty on new pressure treated board may not be honored if the tie is cut. This is because you open up the grain on the end so that water can get in. Just remember to use a sealer on the ends when you do make a cut.