How do I make sure it stays where it is supposed to?

Pointers on anchoring, what kind of things will impact holding power of anchors,
anchoring after moving a structure

A phrase Norm has used thousands of times in his career is, “There is no such thing as too many anchors.” We consider it important to help customers understand the aerodynamics involved with a greenhouse shape.

The relatively small cost of the anchors is a short-lived savings after a building has blown away or shifted. By understanding and implementing what is required you can ensure a long term usage of your structure.

The job of your anchoring system is to counter the three aerodynamic forces working on your building.

  • Down force is usually seen as snow load
  • Up lift and lateral shift are forces typically associated with wind load
  • Wind going over a structure creates lift similar to wind going over an airplane wing

The first thing you will need to assess is what you are actually working with. If you have bedrock close to the surface, you have large rocks, or you have straight sand, it will impact your options for anchoring.

The actual holding power of your soil is an important consideration. Soil that has been recently excavated has considerably less holding power than soil that has not been moved in a long time.

The total surface area of an anchor post in contact with the soil is an important consideration. Large and short may have more contact area than long and slender.

When anchors can be used in alternating directions, it will multiply their individual holding power.

Wet soil usually does not have the same holding capacity as well drained soil. An important consideration here is rainwater which is shed by the building. As an example, with a 16’ wide structure, 8’ of rainwater goes each way. This means that the narrow area next to your building get 8 times the rain that the rest of the property gets. If you have poorly draining soil, this could be a potential problem.

If you are planning to use the movable structure option, proper anchoring has some additional challenges. Since your building is vulnerable to sudden increases in wind during this process, your anchoring protocol needs to be done quickly. Always do a test in the new area to confirm what you will be working with. With the quickness that is required, there is also a reminder that taking shortcuts will come back to haunt you.

We would like to reiterate, “If you are not 110% sure, please ask” There is no situation out there that is so unusual that we have not already been through it.

Your long term success is very important to us!

Video: Installing Anchors into a Base Beam

The main function of anchors is to prevent uplift. Do not forget about the “foundation function” as well which is meant to prevent settling or lateral shifting.

Improperly anchoring a building from up lift, down force and lateral movement will all, equally, cause problems and expense.

There are many different ways of anchoring a building because there are so many circumstances which people are dealing with.

When anchors can be installed at opposing angles, they work against each other and therefore will multiply their  holding power.

  • Care must be taken to stay away from anchors that will bend (i.e. re-bar).
  • When the anchors are going straight into the ground, care must be taken to ensure proper holding power. This is most often done with plugs of concrete.
  • When anchors have been extended out of the ground, care must be exercised to eliminate the possibility of outward lean.
  • It is important to consider the total amount of square inches of contact area between anchors and soil. Many time fewer big anchors is less holding power.

One thing which simply can not be stressed enough is that there simply is no such thing as too many anchors. Anchors are generally very inexpensive, especially when you are looking with hind site at some damage.

For more details and to watch an illustration, please see our YouTube Video below