Here is an interesting article from the book called “Better Home and Gardens HandyMan’s Book” by Compliments of “Citizens Savings”. This article helps homeowners in Retaining walls of Wood project.
These retaining walls are all built of wood. They are durable, too. Their useful life is at least 25 years, even in warm climates. On a square-foot basis, they cost about a third less than a stone wall laid up without mortar joints. Those are the strong points.
Here is the limitation:
These walls are not suitable for retaining banks higher than 3 feet. If higher walls are required, consult a landscape architect or nursery contractor for advice on additional bracing procedures and drainage. Use retaining walls like these to create level terraces out of gentle slopes.
The type of wall you build will depend on the height needed and on the materials available. Before starting on the wall, determine its location. The location of a retaining wall depends on both your landscaping plan and on the slopes, you’re trying to tame.
Construction of the simplest retaining walls means some soil will have to be moved, for the wall footing and for leveling of the terrain. Leveling requires either digging out in front of the wall(cutting) or building up soil behind the wall(filling). Locate walls for minimum earth moving.
This wall illustrates two important construction details: how to incorporate a flight of steps in a retaining wall, and how to utilize hidden posts for support. When posts are placed in front of a wall, the soil forces the wall tightly against the posts. But, when the posts are behind the wall, the joints must carry the full pressure of the soil behind the wall. To carry this weight, fasten the face boards with 6-inch carriage bolts. Hidden posts are not advised for walls higher than 30 inches.
Here’s a simple method of combining a planter with a seat wall. The planter can be removed at any time; it gives you an opportunity to introduce more color to your landscaping theme. The gravel at the base of the wall promotes drainage, eliminates a trimming problem. The gravel would also be desirable if grass were used instead of paving. Notice that the paving units coincide with intervals between posts.
This wall is 36 inches high. To give it enough the strength to resist extra pressure of the soil, posts are sloped backward and set in concrete. Slanting of posts is especially recommended where winters are severe. The bench detail shows a practical and quick way of attaching a seat to
exposed posts. The seat should be about 16 inches above the ground. With the exception of the bench itself, unfinished, rough-sawn lumber is satisfactory.
A low retaining wall
A low retaining wall, in this design, is made more interesting and useful by extending posts to support a trellis fence. The seat posts are set in concrete; others are set in soil. Notice that the wall extends above grade to protect the bench from any run-off water from slope above. The strip immediately behind the wall should be painted to ground cover or grass to prevent unnecessary erosion.
The mechanics of holding up a bank with Wood are relatively simple. But design skill is required at the ends of a retaining wall. One good method is shown here. The wall is extended beyond the slope and converted into a fence, which terminates in a corner and lamp post. Alternate posts, inside outside for looks.
Wood retainers can also be used to construct tree “wells”. The purpose of the well isn’t to keep soil away from the trunk, but to let air down to the roots. The well serves as a vent. Unless the
vent leads to a porous fill over the original grade, it doesn’t help much. But air can circulate through a layer of coarse rock with little difficulty, thus preventing suffocation of the tree roots.
How to cut materials costs
if you set posts accurately, you will be able to use most wood just as it comes from the yard. You won’t need to cut it because it will already fit.
Only one precaution is necessary. The interval by ends and corner posts should be reduced by half the post width. If this isn’t done, the standard dimension lumber will cover only half the end post.
Ask for lumber treated commercially
with preservatives. They add to wood costs, but pay for themselves by doubling
or tripling its useful life. Heart grade redwood is suitable where shipping
costs aren’t prohibitive.
Estimate costs by multiplying height
of the wall by its length, in feet, to get square feet of wall. Double this to
get approximate number of board feet. Multiply by cost of lumber per board
foot. Add 10 per cent for posts, scrap and nails to get approximate cost.