What Is A Shed 'Base Plate'?

Question

I've assembled a 8x12 shed kit in my backyard. I'm now preparing for the final inspection of the lengthy (and costly) permit process. I've been informed that I also need to:

Install two 30-40 inch shed anchors and attach to the shed's base plate on opposite corners.

Unfortunately, I have no idea what a base plate is. My attempts at searching online shows pictures of things that look like this:

Or

The problem is, I don't have anything that resembles either of those. The 'base' of my shed looked like this.

Because I've finished assembling the shed, I no longer have access to the larger 4x4s.

Given that I've finished the shed and I don't want to rip it apart, it seems reasonable that the 'base plate' would just be the exposed piece of wood at the bottom of the shed, but I'm concerned that this is wishful thinking and that it would make more sense to anchor the larger 4x4s which are no longer accessible.

Answer 1

To answer the question, the base plate is the typically the first piece that goes on the ground that everything else is attached to. I say typically, but you have 2 beams that take that place. If it was a metal shed, that would be a different story.

In your case, the base plate is the bottom plate that sets on the floor of the shed, it is continuous on all sides except where the door is. Usually the tie downs are connected to this before the siding goes on. The corner posts are also a strong point of attachment too.

Many jurisdictions in the US do not require a permit for a small shed as yours. If the permit is needed for a homeowners association, the requirements are such that the only concerns are how it looks.

If that is not the case, and anchors are truly required, the anchors you need are pretty much a deformed steel rod, 30-40" long driven into the ground, and made so it can be attached to the outside corners of your shed by screws or lag bolts. Perhaps even a cable or two.

If this is an option, because of aesthetics, a hole can be drilled into the floor of your shed in the corner and the rod driven through the hole and screwed into the corner post.

This is a sample of anchor they will be referring to. This type can be twisted into the ground on the 2 outside corners you need, there will be 2 extra... Get the eyelet close to the ground, tie the supplied cable to the shed at the floor framing and twist the rod into a little farther to tighten it a little more. It could still be done from the inside, it would take a 3" hole to go through and tied to the corner post from the inside.

Answer 2

My experience with a few sheds and the additional research performed today indicate that the base plate in the example provided is the structure in the first picture.

Requiring or recommending that anchors be secured to opposite diagonal corners would lead me to believe that the forces of nature applied to the base plate would be transferred through the 2x lumber framing, then to the 4x members and then to the anchors.

This requires that the attachments between the 2x lumber and 4x lumber be secure enough to handle those natural forces.

Without access to the 4x locations, as noted in the post, one would use opposite diagonal corners or perhaps all four, but provide for as much distribution of force as possible from the 2x lumber to the anchors.

If the inner portions of the frame are accessible, doubling up by adding another set of 2x lumber to be anchored would improve/increase the distribution of natural forces applied to the shed. This same logic applies to the four-corner option, rather than limiting yourself to two.

If one is particularly concerned about the forces of nature being applied to the shed, there appears to be sufficient room to add one each additional anchor and doubler to the longer sides.

Our professionally installed sheds secure the ground anchors at each end and each corner, 48" deep at the exposed 6x lumber, but strangely enough, into end grain, which I would not consider to be particularly strong (but it meets engineering design and local code!)