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02/02/2021

What Are Helical Tiebacks? (Definition, Components, & When to Use)

Let me take a wild stab in the dark at how you arrived at this article.

  1. You recently had a foundation inspection and your foundation inspector said that either your home will need helical tiebacks, or he was speaking in tongues.

  2. You received a set of repair plans for your home’s foundation and there, on the page, it calls for these thingamajigs called helical tiebacks – something that sounds like a mathematical torture device.

If you don’t fall under these two categories, then you must just really like reading my work and have an unquenchable thirst for the fascinating world of foundation repair and slope retention

Either way, let’s dive right in.     

Helical tiebacks are rods implemented to support, strengthen, anchor, and straighten retaining walls or bowed basements.

Helical tiebacks are the industry’s favorite solution to anchoring various structures from houses to retaining walls to art sculptures at the Coachella Music Festival. They are highly effective at providing additional lateral support for these structures.     

What components are involved in a Helical Tieback system?

Helical tiebacks are composed of three primary components:

  1. The lead/thread-bar
  2. A series of extensions
  3. An end cap/adapter

Lead Section

The lead is the driving force of the helical tieback system – it is a threaded metal bar comprised of various-sized helices that look like a massive screw.  

The helicals vary in size depending on the condition of the soil and what it will be required to anchor into. 

Weaker/less compacted soil requires larger flights. Conversely, denser/more compacted soils require smaller flights.

The reasoning behind the different sized flights is to ensure:

  1.   The helicals are able to produce the required capacities needed to retain whatever structure it is anchoring

  2. The helicals are able to achieve the required installation depth into strong native soils

Those items are the only reason for the varying sizes of the helical flights, or how large the screw-looking things are on the lead section.

Extensions

Extensions are the ugly stepsisters in Cinderella’s story – they aren’t glamorous and only serve to make the thread bar and adapter shine. 

This plain Jane component is made up of the same shaft as the lead section, but they do not have any fancy flights on them.

Extensions have a coupler at one end and a receiver at the other to fit together with another extension or lead or end adapter; however, you will have more extensions on your helical tieback system than the other 2 components (leads & adapters).

For example – you will only have 1 lead and 1 end adapter, but you could end up with 10 extensions or more depending on the required depth recommended.    

End Adapters

The end adapter is your transition piece from your helical tieback. They are threaded rods or large bolts that can be connected to a steel plate or whaler beam to restrain existing structures.  

For new construction applications, the end adapter would be a new construction cap.  This cap looks like a square plate and can vary in size. 

This cap is then surrounded by rebar within a wall unit and will eventually be encased in concrete and incorporated into the wall (like it was never there. Ooh, spooky).   

When should I use Helical Tiebacks?

There is a time for everything under the sun. And there is a right and a wrong time to use helical tiebacks. 

The last thing you want to do is try to install them and (a. either your contractor can’t install them or (b. they end up failing down the road.

Both are not great situations.   

Best Situation 

The optimal situation to implement helical tiebacks is when you know that the soils are going to be relatively soft and they don’t have large rocks or boulders mixed in. 

If there are, then you won’t get the results you are looking for (because you need to reach the correct depth).  

Clear access to the area when lateral anchoring is necessary is great. 

It is easy to install anchoring systems when there is a ton of room to mobilize large equipment, but typically with the residential homes around our area, we don't have that luxury.

Helical Tiebacks can be installed with minimal equipment needed. All you need is a drive head and a hydraulic power pack.  Both of which can be mobilized to a work area with little to no interference to your existing gates or landscaping.

Bad Situations

*Trigger Warning*

Now for the fun section… I am writing this because I have personally experienced these situations and have had the wonderful opportunity to have that pleasant conversation with a homeowner or engineer to let them know – sometimes it just won’t work.

It is very difficult to install helical tiebacks in dense soil or sand. The compacted material does not allow for the helical flight to penetrate deep enough to provide the anchor with an effective amount of loading.

If you ever had the pleasure of putting in fencing – think of the posts that you put in the ground. When you install a post at 6 inches it is relatively easy to pull out.

When you install the same post to 24 inches, then it’s very difficult to pull out (the opposite of King Arthur pulling Excalibur from the stone!)  

The deeper a helical tieback is installed, the more soil that would have to be moved for the tieback to pull out.

Rocky soils simply do not give us enough depth. In addition, rocky soils result in erratic installation readings for your contractor and the tieback may never end up achieving the loading that is required.

Helical tiebacks are notorious for getting a spike on loading pressure due to hitting or getting caught on a rock – this false reading could eventually lead to the tieback falling out in the future.    

Anchored

Now that you have quenched your endless thirst for knowledge about helical tiebacks (and reread the article at least three times), you can make an educated decision on whether they will be an effective repair recommendation for you and your home.

I would like to extend a personal invitation to my readership to reach out with any additional questions regarding helical tiebacks or ask for a FREE consultation inspection. 

We have found that these interactions provide fine scholars, such as yourself, a chance to get honest feedback on if helical tiebacks would be needed in your given situation. You might be interested in foundation repair cost or who are the best foundation repair specialists in Southern California. 

learn more about foundation repair cost

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