Suggestions for small shed foundation?

[mikebarker]

Hello all! I am planning to build a small wooden storage shed as a project to gain some carpentry skills. It will be approx 3.5m wide x 2.5m long (Staying under the limits of permit requirements where I am in Victoria). I am on a sloping block and have had a small area cut into the slope, and one side built up to level it by an excavator (See attached images).

Essentially, the built-up side is quite soft so I don't think I should use the concrete foundation blocks that are often recommended.

I've been looking into multiple options, I was initially sold on a gravel pad (This article was very persuasive and helpful and this video too) but I'm now also exploring options for some footing, similar to what you would use for a deck but there are so many options I'd love the community to offer some ideas based on the area I have.

I was planning to dig some holes and use those cardboard footing tubes and pour concrete in and then use some kind of bracket to attach some lengths of 90x90 treated pine as the basis on which to build the shed floor joists.

I am open to pouring a concrete pad but I'm not a huge fan of the permanence of it (or the cost!) but I'm not against it if it's the best solution.

I also think I should retain the left side where it has been cut into. It's not very high approx 300mm, a single sleeper would probably do it. Suggestions on a simple approach to this would be welcomed. I expect if I go the gravel pad route then this would just be one of the sides of the container for the gravel.

So, to summarise:

1. Which solution would be favourable for this size, area and ground, factoring in cost/simplicity? Gravel pad, footings (and what kind) or a concrete pad?

2. What approach should I use to retain the side that has been cut into?

Thank you all so much!

Front view, area to be potentially retained on the left

Side view

[mikebarker]

Update: I finished the retaining wall and it's ready for gravel! It took a lot longer than I thought, I was really nervous about concreting for some reason (I used this quick set). I think the permanence of it bothers me but the wall has ended up really sturdy, level and square. I ended up increasing the footprint slightly to 3.1m deep and 3.7m wide as I am hoping to do a 3m wide and 2.4m deep shed (an 8x10 foot basically and any links to solid plans would be welcomed) and I realised I wouldn't have had space at the front and back to screw the joists to the back/front plate. I still think I'm going to struggle putting the roof on as I don't have much room for a ladder but that's a problem for another day 😆

You'll notice I opted to create wedges at the front to accommodate the level difference. I think this should work well. I still need to backfill it once I add an agi drain along the back but then it's done. I'll update you with a final image once the gravel is in.

Right side - lowest pointFrontLeft side - highest point

[MitchellMc]

That looks terrific, @mikebarker. You've done a sensational job, and I'm sure you'll now have a suitably stable base to build your new shed on.

While searching for suitable plans, check out our range of prefabricated sheds, as you might find something that suits your needs. I love the range of Stilla Cedar sheds.

I look forward to those final pics.

Mitchell

[mikebarker]

Thanks! Oh I forgot to ask, should I be putting a weed barrier down under the gravel?

Also, thanks for the links, those sheds look lovely, but the whole point of this project is for me to learn how to build one from scratch 🙂 

[MitchellMc]

Adding weed matting certainly wouldn't hurt @mikebarker!

Mitchell

[Dave-1]

Good Morning @mikebarker 

Love it! Thats a decent amount of work and shifting soil!

My first thought was "Why is there a kink in the sides?" lol But when I looked closer I really liked your solution! I also have that dread etermnal feeling about concrete but sometimes we just have to use it. The base looks solid and cant wait for the gravel and the next stage  

BTW the roof will be easy as you will be able to stand inside your shed as you put it up (On a ladder of course lol)  When I was building my deck I was thinking the same until I realised as I built the base then I would have something to stand on to do the walls and the roof. 

Nice long weekend work!

Dave

[mikebarker]

Thanks @Dave-1 🙂 good to know that you have some roofing experience of this kind. I'll likely fire up a second post re: the shed build and get various tips on that side of things there.

@MitchellMc It was recommended that I put in a small ag drain, what are your thoughts on that? Could you recommend what size and where I should place it? I assume it'll be behind the wall at the top of the slop (Left of the shed) and curved around the front down the slope, or does it need to be inside the trench under the main gravel load?

[Dave-1]

Morning @mikebarker 

Once I get around to posting the deck I built showing the "roofing" and how high it ended up being but was managable it will seem a lot easier.

With regards to your question to @MitchellMc and an ag pipe/drain. I always think more drainage installed while you are building something the less headaches you will heave down the track. Are you worried about surface water running down the hill into the back of your shed? or subsurface water pooling behind the shed?

Id suggest a dish drain for the surface water and then feed the water to somewhere were you can use it (garden bed, low point for fruit trees)

Ag pipe for subsurface water works as well, Id just make sure it is socked to stop fines getting in and cover it with gravel. 

And definently fire up a second post (I have "stages" of projects that I post) I figure if it helps one person then its not wasted and even with the amount of photos I take I still miss important shots sometimes lol.

Dave

[mikebarker]

@Dave-1 Ah I was wondering if I needed a socked pipe! I've just had a meter and a quarter of gravel delivered for the base so plenty of gravel for the pipes 😄

I think the concern was water buildup from the slope, behind the wall but I'm not totally sure. My concreter just suggested I put some pipe in. It'll never touch the shed. It's going to be on 100mm of gravel and then on plastic footings.

[Dave-1]

Morning @mikebarker

It sounds like it will drain nicely whichever way. I try and plan for the "rare" occasions where there is an inunadation of rain. Id still go for some form of dishdrain, trench to chanel the surface water away. The concreter has probarly been doing the job for years and knows better then you and I for sure.

Fixing water ingress issues in garage is the project where I used the ag socked pipe. (step 5 I think it shows up) I was amazed at how it worked with the gravel to keep the area dry. It really let the water drain so well aftere we were hammered with rain there was not even a hint of a puddle and the pavers had already started drying.

Dave

[MitchellMc]

Hi @mikebarker,

I think the concern here would be the water travelling on the surface and subsurface that will run under the retaining wall and potentially fill up the retained area. Since you haven't put the gravel in yet, I'd take this opportunity to run a socked agline around the internal perimeter. Just do one big loop, keeping as close to the walls as possible. I'd put the start and finish at the back side, connect a T-section to the two ends and then another short piece of pipe that goes down and under the retaining wall and out the back side to remove water from beneath your shed.

Mitchell