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Do I need a retaining wall outside shed?

830 Views 6 Replies 4 Participants Last post by  Beginner2
Hello great forum people,

I'm continuing with my pizza oven project. Th oven is nearly done as the picture shows.

Now I need to make a roof structure to protect the oven from the weather. I intend to do a simple shed style roof sloping front to back, but I want to add a section to it so I can have a cooking table and also a shed connected under the same roof to store some tools, have a small work bench etc. This is all DIY and I am by no means very experienced but I like such kind of projects like most others do to get a break from family and keyboard activities. I've begun digging out a bit and it currently looks like this:

As the image shows, I'm building all this on a slope, so need to dig out a lot of soil to level. Planning to dig deeper post holes and pour 6" concrete post stands to anchor wooden 4by4s for the corners of the roof structure.

We get the occasional strong rain and I know this is going to require some drainage. Also due to the slope situation. So I am thinking whether I need to also make a 3' retaining wall (CMU with cores grouted, rebar etc.) to keep the pressure of the slope away from the oven stand (could have done that before the oven, but didn't...) and away from the shed that I'm planning to build next to the pizza oven stand itself. I've drawn a simple diagram outlining my idea. But since I've never done anything like this before, I wanted to share it for comments and caution or things I need to keep in mind before going ahead with the excavating and digging.

The much easier way out for the shed and roof structure would be just to dig to level of the oven stand foundation and then connect CMUs with the oven stand, and throw a drainage pipe behind the wall and call it a day, i.e. without retaining wall itself. But I am afraid then that the pressure of the sloping soil which already sits right up against the oven stand would push the oven stand and shed over time due to erosion and water flow. Is that a warranted concern, and how would you go about doing this?
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Hello Marksr,

The wall will be max 3 feet - or if I dig to level of the pizza oven foundation I would have dug 3 feet down into the slope. So depending on where I put the dirt it could be 3 feet or more/less depending on whether I put dirt behind the wall. So not at all high.

I am thinking to pour some kind of footer but want to make it as simple as possible. I've seen (on youtube, yeah), people say you can dig a bit deeper (4-5" and put a couple inches of gravel, and then a dry mix of sand and cement and then dry stack on top of that. That would be the simplest, but I am in dense clay soil, so maybe that won't be enough to withstand the weight. A bit more elaborate would be to dig 4-5" deeper and then have the first cmu be half covered in concrete to level and then 2-3 courses on top of that. Probably dry stacked but grouted to allow water to permeate, or... water proof mortared and with a separate french drain behind the wall and out. So these are all options that are more elaborate or more simple. I've started digging away the dirt but just not sure yet how elaborate a wall I need to construct for just 3' of retaining wall.

Heck the laziest option would even be to not have make a separate retaining wall, but just make a 3' wall as outer wall of the shed. Not sure if that would be a good idea though.

Any inputs much appreciated!
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Huesmann yes some kind of earth barrier to lead water around the space is a good idea, which I will try to form from the excavated dirt later on.

Nealtw - Space is not so much a constraint but the slope itself is. We have kind of a patio connected to the house itself but in mosquito season it's not really enjoyable to be there. This planned space which I have sketched in this post isn't going to be very big (maybe 6-7m2) so it could be mainly a prep area for pizzas with a small table and a few chairs for audience and a hidden rack for tools in the far right edge. The thing is that I have a growing collection of tools etc which do not have a proper (dry) storage space yet but crowd our laundry room with cables and dust etc, so that also needs a solution. Ahh...and my wife is pregnant with our second, so yes there are several areas that need more space and attention...:smile:
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