Gravel pad foundation concerns

So I got myself into kind of a pickle.. I’m working on a gravel pad foundation, and my build is on a slope. I’m using 3/4 minus and compacting it every 4”. The footprint of the house is 12’x16’, and I had someone do some grading for me. The area that was “leveled” extends only 1’ beyond the house footprint on two sides.

When I started dumping gravel, in one corner I had to build it up 16” to get the site actually level, then 4” of gravel on top of that. Instead of building a retaining wall, i decided to level an area 1’ wider than the footprint on all sides, then slope the gravel in hopes of creating a hill that would retain the level zone. Outside of the area that I had leveled, especially in the low corner, the slope is comewhat significant. So now I’ve ended up with 15 yards of 3/4 minus.. It’s been built up so much at this point that I’m worried about erosion. If I continue to add gravel to make the slope less steep, will that save me? Am I overthinking this? Any input or suggestions appreciated.

The red line in the picture is where the level turns to slope.

Josh,

Why was the graded pad not level at least within 10cm (4") envelope? I do not think it's good that you had to add 16" in a spot.
When grading I would ONLY build on cut section and also leave at least 3 m (10') graded perimeter around the house, so you would have space for paving, protection from water (or adding some trenching).
How are you compacting it? Gravel does not really compact much, because it does not have finer fractions.
What structure do you want build?

I got the leveling done for free, the guy is 70, and he didn’t really want to work on it for too long. I guess I just took what I could get.

The area that the build will sit on (the level part of the pad) is the cut section , but the sloped gravel extends quite a ways beyond that.

I did make sure to leave 10’ between the two sides that were cut out of the slope. The other two sides are downhill.

I’m using 3/4 minus gravel, which is about half fines. It compacts exceptionally well. I’ve been using a plate compactor, and the end result almost looks like asphalt.

I’m building a stick frame tiny home out of salvaged materials.

Thanks for the response!

Cristobal Cristo wrote:Josh,

Why was the graded pad not level at least within 10cm (4") envelope? I do not think it's good that you had to add 16" in a spot.
When grading I would ONLY build on cut section and also leave at least 3 m (10') graded perimeter around the house, so you would have space for paving, protection from water (or adding some trenching).
How are you compacting it? Gravel does not really compact much, because it does not have finer fractions.
What structure do you want build?

josh ober wrote:The area that the build will sit on (the level part of the pad) is the cut section , but the sloped gravel extends quite a ways beyond that.

I did make sure to leave 10’ between the two sides that were cut out of the slope. The other two sides are downhill.

I’m using 3/4 minus gravel, which is about half fines. It compacts exceptionally well. I’ve been using a plate compactor, and the end result almost looks like asphalt.

This plus a light and flexible structure will be fine. Please remember to post some pictures of the construction process!

Josh, I just cannot understand what you are describing, any chance of a drawing?
How is the frame being supported, stumps?

"Stumps" is Australian for what we call posts in the U. S.

A gravel pad is not suited to point loads, but rather something like continuous sills.

Glenn, that is interesting fact.
We call timber poles that rise say, 6 feet or more posts and they are used on fences and 'pole ' houses when they are tall enough to hold roof truss assemblies.

Hi Josh,

Perhaps you could look at stabilizing the gravel with geocell tiles or grid?   This technique was developed by the US Army Corps of Engineers in the 1950s... and it did not get much traction for a few decades, but now is quite widely available. Geocell is good for soil / aggregate stabilization, used for foundation in agricultural buildings.
See more here if you are unfamiliar with these: https://www.backyardbases.com/farms/?srsltid=AfmBOorvToLHJjKJJfGYlnJrNLVpW6DiOzwwsyg6ZDQw5f1vOF6HTyoR
Scroll down to look at all the pics on that webpage.
There are lots of manufacturers, lots of slightly different products. All of the, help to lock the 3/4 minus aggregate into position for stable footing.

I used these grids for the access road onto the property and area around buildings: https://www.amazon.com/VIVOSUN-High-Density-Foldable-Installation-Driveways/dp/B0BZP1SXN3?th=1
I used these tiles for building footing for my greenhouse (work in progress): https://vodaland-usa.com/products/hexpave-grass-gravel-paving-system
See pics attached.

You would need to rework your gravel that you have so carefully perched  and compacted there, in order to implement the geocell, but it could offer you better stability within the challenges of your project. You could add a cinderblock / rebar / ground anchored short footer wall around that 16 inch build up area to give you a solid boundary.

Are you familiar with geocell grids?