Question
I live in Los Angeles; we are going to be using landscape ties to do some terracing in our back yard (approx. 6' drop over 24').  We are not thrilled with the idea of exposed landscape ties.  Can these be stucco'd over, or covered with a thin stone or brick surface or a nicer wood (like Ipe or similar outdoor decking material)?  Total surface area for each tie wall will be approx. 50' by 3' tall.

Thanks.


Answer
Hi David,

Boy! Do you have your work cut out for you!

The use of railroad ties is fairly common in landscapes for borders and in some cases, retention walls because of their weight and density. The only drawbacks to the use of railroad timbers is that of core rot, safety when it comes to humans being in close proximity to them where they can pick up splinters or rub against the toxic nature of the keocote that is typically the preservative being used. If these are antique ties then you will want to consider both of these issues.

As a precaution, may I suggest that if you choose to use a chainsaw to cut your timbers, have your workers wear long pants and long sleeved shirts, gloves and face protection. the preservative in the timbers is very toxic, will cause burns to skin, and if absorbed to any great extent into your skin, will make you sick (or at least give your liver a run for its money). Please do not attempt to do what I did as a teenager just starting out in landscaping before I had any sense at all. About ten days after my cutting up a significant amount of timbers for the first time with a chainsaw I made a few notes. [NOTE TO SELF: Never wear bathing suit or shorts and no shirt or face and eye protection and never only wear flip flops when cutting up railroad ties on a 90 degree day in June]

Now about the use of timbers for such a dramatic elevation in your terrace, especially in SoCal. I would recommend that you attach stainless steel cables to several of your timbers (one anchor cable for every four timbers) that are anchored into the soil at least 10 feet behind the retaining wall drop off using a series of cork screw anchors of not less than 24 inches and set at a depth of at least 18 inches below the finished grade. If the cork screw anchors are not available, you can use a post hole digger or motorized augur to make an anchor piling to attach your stabilization cables to. This stabilization feature will prevent rain or run-off erosion and help in the event of seismic activities associate with the region. You can also use a full length tie (if you are planning to set the ties vertically) as an anchor piling by setting it the full length into the ground by way of the use of a mechanical auger or in some cases something as simple as a post hole digger. If you choose this method, pour three to four bags of RediMix concrete around the Piling halfway up from the bottom and then wash in with water. Most lumber supply or fencing supply houses carry post cement designed specifically for this type of application.

Next, using the anchored timbers as your foundation to your wall, see that you interlock all other timbers to these anchoring timbers. You can do this by placing a few timbers running perpendicular to the main retaining wall and drilling holes through the support timber into the retaining wall timbers then adding lag bold with large locking washers. Remember that the wall is only as permanent (and sturdy enough for a fascia) as its weakest connection.

As for a fascia for your timbers. You can attach anything you would like to the timbers in the way of woods, and if properly executed, even a stucco or brick finish. Some precautions and general instructions though:

1) It most likely goes without saying that you cannot attach the word directly to the timbers and that if you do, that the timbers must be very secure otherwise you will experience a distortion and/or breakage of your finished surface, whatever you choose to do.

2) I do not recommend that you attach the finished fascia directly to the surface of the timbers, but rather that you build a framework over the timbers. As an example, if you chose to put a vertical redwood finish over the wall, you would run horizontal furring strips every 12 to 16 inches from top to bottom and then attach your wood planking directly to the furring strips. The main idea here is to build the framework for your finish just as if it were a exterior wall for a house. My company has added finishes over retaining walls that utilize railroad timbers with redwood, cypress, and pressure treated pine that is then sealed and stained to client's taste.

3) I do not recommend stucco since in a landscape environment, insects (wasps, termites, ants, etc) enjoy making their home behind stucco (even on building structures).

Without seeing a photo of the site, and having taken soil samples to determine the density and characteristics of the soil and surrounding earth, I cannot give you specific instruction or specifications for securing the retaining wall according to industry standards, but the two possible solutions I have offered may be ample anchoring systems for your particular situation.

Please let me know if I can be of any further help or encouragement in the making of your landscape hopes a reality.

Warm regards,

David
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