Introduction to Alternative Anchoring Systems

All Steel Foundation-OTI with longitudinal bracing

Over the past few weeks we have been talking about conventional ground anchors as the tie down system for manufactured homes. But let’s look at some alternative anchoring systems that might be able to simplify the process for you.

As always, make sure that the manufacturer has approved whatever system you choose and that it is also approved by their Design Approval Primary Inspection Agency (DAPIA). If you are in a state that has oversight authority, make sure they approve it as well. To the best of my knowledge, the three systems that we are going to look at today are approved by most manufacturers. But, never take my word, you need to get copies of the approvals for your installation files. 

Xi2-Tie Down Engineering

 

Let’s take a quick look at the:

All Steel Foundation from Oliver Technologies Click Here for Oliver Technologies

L & L Bracing System (LLBS)  from Minute Man Click here for Minute Man

Xi2 from Tie Down Engineering Click Here for Tie Down Engineering

LLBS-Minute Man

I am a big fan of all three systems. They are much easier to install than conventional ground anchors, and they will save you significant time as they install quickly. While the systems are similar in many regards, they do have differences, so make sure you follow the instructions particular to the system you choose. We will limit this discussion to manufactured homes installed in Wind Zone 1.

Here are the some of the similarities of the three systems:

Only 2 devices (opposite corners of the home) are needed to anchor a typical 2 section manufactured home. 5/12 roof pitch and greater would require three or more systems.

For single section homes, typically you will need two devices and a ground anchor installed at each corner of the home.

The systems are limited to a home with a maximum pier height of 48”.

The systems can be bolted or “wet set” into frost protected concrete footings.

All Steel Foundation-OTI-replaces a pier and anchors end walls.

They are easily adapted to address longitudinal anchoring. 

 

Xi2-Minute Man- Beam Clamp

LLBS from Tie Down-Beam Clamp

When using these systems, it is important to make sure you don’t mix parts. If you are using the Xi2, don’t use parts from Minute Man or OTI, if installing the OTI, don’t use Tie Down or Minute Man parts. I also believe that for multi-section homes it is important that your fastening at the marriage line be consistent with the installation instructions for the home being installed. Watch for gaps between the sections that may impede the transfer of wind load across the marriage line (this is true of all manufactured home installations).

If you are not using these systems, I encourage you to reconsider. All three producers provide exceptional customer support. They have comprehensive information on their websites including videos, and are very helpful on the phone and in person! 

From my perspective, it is a rare occasion when a manufactured home installed using conventional ground anchors is anchored properly; site grading, rocky soils, underground utilities, and frost depths make conventional ground anchors a challenge for many installers. However, installers using these alternative systems have had great success with these products.

 

 

Advertisements

HUD/SEBA Manufactured Housing Installation Webinar

On Tuesday, July 25, 2017 HUD & their contractor, SEBA  will be holding a webinar where they will lay out the requirements for installers and retailers in the HUD administered manufactured housing installation states including Michigan.

You will be able to ask questions at the end of the presentations and it is important that you do. Pre-registration is required. See the announcement below.

On May 15, 2017, The Department of Housing and Urban Development (HUD) incorporated the State of Michigan into its HUD-Administered Manufactured Home Installation Program (Installation Program). The HUD-Installation Program, which oversees regulations set forth in 24 Code of Federal Regulations (CFR) § 3285 and 3286, has also been fully implemented in 13 other states that do not operate their own qualifying installation program.

Michigan installers and retailers will be part of the HUD-Administered program that ensures safe and quality installation of new manufactured homes. The program’s primary requirements are the supervision of the installation of all new manufactured homes by a HUD-Licensed Installer, and all new homes must be inspected by a qualified inspector. The HUD program also has standardized reporting requirements for all new home installations 

This webinar will be open to all, not just those in Michigan, who may feel in need of a refresher on program requirements or who are still learning about the program

In order to participate, you must register using the information below to receive the dial-in number and pass-code or webinar access. After registering, you will receive a confirmation email containing information about joining the webinar. After registering, attendees have the option to only dial into the call using the number you are sent. However, those who do so will be in listen-only mode. All participants are encouraged to use the webinar option (computer) to maximize your participation and be able to ask questions at the end of the presentation

Register

https://register.gotowebinar.com/register/4512819416180848643

Conventional Anchors- Part 2

Before we get too deep in the how many anchors are needed to properly tie-down (or stabilize) a manufactured home, let’s make sure we know where manufacturers require tie-down anchors. There’s not one simple answer, but be aware that you may need to provide anchors at the following locations:

End Walls (longitudinal anchors) – some manufacturers only require end wall anchors in Wind Zone 2 or 3, some require them in every wind zone, others only require them for short (less than 52’ or so) homes in wind zone 1.  It is critical that an installer know which manufacturers require end wall anchors. A few factories may weld a bracket to the chassis (frame) that might indicate you need longitudinal anchors, but that is hit or miss. The only way you will know for sure is to check the installation instructions.

One type of marriage wall straps, this one needs a pier and anchor.

Marriage Line anchors – again, this is manufacturer specific and there can be various types. In Wind Zone 1, only a few manufacturers require these. Generally, the manufacturer will install straps (sometimes called “G” straps) or brackets along the marriage line for you to attach to a ground anchor. Make certain you install the anchors directly below the bracket or strap before both home sections are set in place. 

 

Shear wall strap.

Shear Wall anchors – like the marriage line anchors above, these are rare in Wind Zone 1, but depending on the design of the home they could be required. Again, you should find brackets or straps. Shear wall anchors could be required on marriage walls or side walls. 

Porch Post anchors – again, these are primarily used in Wind Zone 2 and 3, but could be needed in Wind Zone 1. Watch for brackets or coiled up straps.

Typical Wind Zone 1 anchoring.

Side Wall anchors –  if you are using anchors and tie down straps to secure the home against a wind storm, every home requires anchors under the side wall, with diagonal straps to the frame for Wind Zone 1. Wind Zone 2 and 3 require both diagonal and vertical (to brackets along the side wall). 

To determine how to space the rest of the anchors needed, start digging through the maze of charts provided in the installation instructions. You may need to sort through as many as 21 different spacing charts in a single instruction manual! Make sure you pick the right one! Take a few extra seconds to read the title of the charts to be certain you have it right one!

So how do we determine pier spacing for the remaining tie downs needed to properly anchor the home? You can’t just install an anchor at every pier location. There are too many factors to consider. Let’s assume we are installing a typical two-section home (28′ wide) in Wind Zone 1. The home has 7’ side walls, a standard roof pitch (under 4/12), 99 ½” frame (distance between the I-beams) supported by 12” high piers  comprised of one 8” block, a 4” cap block, and a 12” I-beam (8 + 4+ 12=24”).

Looking at this chart, we need anchors spaced every 12’ (don’t forget, the first and last anchors should be within 2’ of the end of the home).

Angle gauge will tell you if you exceeded 60 degrees!

Did you notice the asterisk on the charts if your piers are higher than 25”? That means that the strap angle exceeded 60° and the strap must be attached to the far beam of the chassis. 

Confused yet???? I am!

If we add a 5/12 roof pitch, the spacing goes down to 10’4”. Taller piers, higher side wall and steeper roof pitch all impact anchor spacing! 

I checked another major manufacturers installation manual for comparison….that was a mistake!

They measure the pier height differently. Only to the top of the I beam, not the floor. PLUS…they require end wall frame anchors for every home they produce.

Maybe the take away here is to find a better solution to ground anchors, tie downs, strap angles and all of these confusing charts! So, let’s explore some of the alternative anchoring systems that are available. But that is a topic for our next post!

As always, check the installation instructions for the specific home you are installing and “Call Before you Dig” or “Drill” as the case may be!!

Anchoring-Part 1-Conventional Tie Downs

Ground anchors

The other day, a professional installer wrote to me about anchoring a manufactured home. He asked if he only needed a tie down anchor at each corner of the home or if he should install one at every pier. Since neither answer is completely wrong or completely right, I thought we should start talking about anchoring and try to shed some light on this critical issue. Over the next several weeks, we’ll talk about all the various anchoring systems.

Let’s start the discussion talking about conventional anchoring systems, you know, the ground anchors with steel straps to the frame.  How should they be installed to properly anchor or stabilize a manufactured home to protect from wind storms?

 I wish there were a simple answer. At this point, I would typically tell an installer to check the anchoring charts in the Manufacturers Installation Instructions (MII), but I believe that the instructions are extremely confusing and not easily understood or followed. But if we start thinking about the basic fundamentals of anchoring equipment, it can start making sense.

Even if you use one of the alternative anchoring systems (Xi2, Vector System, LLBS, or All Steel Foundation or some other system) they generally require conventional ground anchors and straps at each corner of single section homes. So, regardless of the anchor method you prefer, you must have a good understanding of how to properly install a conventional ground anchor and strap.  Here are the fundamentals all installers must know:

  • Ground anchors are designed to be installed in the ground. Not concrete!

    This is NOT proper anchoring!

  • Cross drive anchors are designed to be installed in solid rock. Not soil!
  • Ground anchors must be installed to their full depth, and extend below the maximum frost line.
  • Ground anchors should be placed roughly under the side wall of the home (sometimes call it the skirting line) at a slight back angle (10°).
  • If you are using conventional ground anchors and straps, the first anchor should be placed within 2’ of each end of the home. There is some variation depending on the manufacturer, so check the MII for each home.
  • The anchor must be suitable for the soil where the home is being installed. We will talk more about soil holding capacity and soil classification in another post.
  • Ground anchors must be at least 12” above the water table.
  • Unless the ground anchor and the strap are in-line, a stabilizing plate is needed to prevent the ground anchor from slicing through the ground when the load is applied.
  • Poor site grading can undermine a perfect anchoring job.

    Poor site grading led to loose strap

 

And we haven’t even mentioned the straps yet!

  • The tie down strap generally attaches to the top of the frame (or chassis) I-beam, wraps completely around the I-beam, and down to the anchor. As an alternative, you could use a positive connection swivel strap.
  • Where the tie down strap wraps around the I-beam, strap protection must be provided to prevent the strap from shearing off at the sharp edges of the beam.

    Strap protectors

    You can purchase them or make them out of strapping material.

  • Strapping material must be certified to ASTM D 3953-97, and have identifying markings every 5’.
  • The strap must wrap the anchor bolt 4 – 5 times.
  • The strap must resist corrosion and weather deterioration.
  • When installing the strap, you need to pre-tension the anchor, pulling it against the stabilizing plate.
  • The angle of the strap is the most critical consideration.

    Inexpensive angle gauge to show proper strap angle.

    Diagonal straps are required in Wind Zone 1. If the strap is greater than 60°, you have not protected the home from sliding off of the piers.

 

WOW! That is an awful lot of information, so let’s stop here for now. The most important thing that every professional installer must know is to make sure that the anchoring system you’re using is consistent with the manufacturer’s design.

Start thinking about your processes for installing tie downs. Make sure to cross check your work to the illustrations and details in the installation instructions for the homes you are installing.

Next week we will talk about how to figure out proper anchor locations and spacing.