Anchoring Landscape Timbers
Using landscape timbers for building retaining walls or raised bed gardens is an economical method of soil retention. Perhaps the most difficult portion of the job is to dig out the ground for the first layer of timbers. In some areas of the country this may also entail digging a trench deep enough in order to lay down a gravel base for water drainage. Once the first course is in the ground, anchoring the timbers so they will not move can be nothing more than repetition once you have the proper tools.
Material List:
Shovel
Gravel (optional)
Landscape timbers (8 foot long)
Large drill
½ inch by 8-inch long diameter drill bit
5/8-inch diameter rebar 12 inches long (3 per 8 foot timber)
3-pound hammer
Dig out the ground with the shovel for the first course of the landscape timbers. Retain the soil to back fill in around the lower timbers once in place. If the location is a wet area, you may want to lay in some gravel to accelerate drainage water away from the bottom of the first course. Typically the bottom gravel bed maybe from 6 inches to 10 inches deep depending on the water problem. The deeper the gravel bed, the more water can drain away from the timbers.
Lay the first landscape timber across two others in a perpendicular fashion. This will elevate the timber so you can drill out the holes without the drill bit entering the dirt. This can dull the end of the drill bit.
Fasten the ½ inch diameter by 8-inch long drill bit into the large drill. Drill out three holes along the length of the landscape timber. Two holes should be located approximately 8 inches from either end of the 8-foot long timber. Locate the third hole near the middle.
Set the timber in the trench. Slide the three rebar pieces, one each, into the holes. Drive the rebar through the timber and into the soil with the 3-pound hammer.
Continue with this process until the bottom course of timbers is set down.
Stagger the next course of the timbers on top of the bottom course by half the length. In other words, start the second course where the end of that timber lays in the middle of the bottom one. This length of stagger will hold the timbers together once the holes are drilled and the rebar is pounded into place.
Drill out the second course of timbers while it is laying on top of the bottom course. Align the sides and then position the drill approximately in the same location. Two holes at both ends and one hole in the middle. Observe caution so you do not hit the lower rebars with the drill bit.
Drive the rebar into the bottom course with the 3-pound hammer through the second course. Continue on with the landscape timbers until you have reached your desired height.
Words to the Wise
Consult local building regulations as some areas may require special permits for the construction of wooden structures in your yard.
Read and observe all timber preservative warnings. Some chemicals applied to the landscape timbers may not be suitable to some plants and animals.
