This is a follow up for this question where I was asking for help on cutting in half and relocating a shed. The job is done and the result looks like this enter image description here
I have take the shed out of there in order to build a proper base for it. (due to weather conditions I had to cut short my work last year). Now I would like to build a base using concrete slabs. As you can see in the picture my neighbor already has his shed in the same position. Below is a schematic representation of the result with some relevant dimensions included

enter image description here

Question: what is the correct way to manage the rain water between these two sheds in such a way that nobody gets hurt. I have a gutter attached to the long side of my shed but my neighbor does not have one. I am plannig to ask him to attach one to his shed

The other issue here is this: I already dug a 5" base for my shed and I am going to add there gravel, slabs and a bed for slabs. Do I need to slope the subgrade (the soil) in order to make sure that the water moves away from the wall of my house?

Edit: I am contemplating a solution like this:

enter image description here

I will use concrete edging (long blocks 1.75"x2X35").The concrete edging will go below the subgrade level. The subgrade will be level. I need to focus on preventing lateral water infiltration. Above is the shed and I have a gutter so no need to worry about what comes from above. I need to worry above what comes for my neighbor if he refuses to add a gutter to his shed. Below the bottom of my 6" deep cement blocks everything is a fair game, the water can go equally toward my house or his house. I was afraid that by digging the base for my shed I am going to create an area where the water would collect if in excess because it will be gravel and sand.

  • A deep/strong perimeter footing will support the structure even if there is water intrusion. 1 3/4" x 2" blocks buried below subgrade is insufficient. Use a course of concrete filled cinder block, coat the outside with bitumen. May 3, 2015 at 21:13
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    I was overthinking the whole thinkg. The base of my neighbor is one pice of concrete slab (i.e not precast) So if the water gets between the two sheds it will have to choose between his excavation initially created to create a base for his shed one one side and my excavation on the other side. I ended up sloping my side a little bit and that was all
    – MiniMe
    May 4, 2015 at 1:12

3 Answers 3


Sloping the soil would never be a bad idea, but more important is supporting the perimeter with a proper foundation. Why do you need a slab at all? Assuming you have a reason for using a slab I would normally recommend a "floating slab" setup, but that is probably not feasible because you are placing a pre-built structure there. A floating slab would require the perimeter foundation to extend above grade in order for your floor to be level with grade. Not possible because your walls and floor are already built. An alternative would be one like shown below (dimensions shown could be reduced appropriate to your structure size). It is critical that the soil and gravel below be compacted.

enter image description here

  • this is too complicated see my edit
    – MiniMe
    May 3, 2015 at 18:51

Before putting your blocks down dig a trench put some perf pipe in it and fill with gravel run the trench to a lower location away from the home, if legal take it to the road or a ditch so it can flow with the rest of the run off. One of the town's I lived in did not allow the run off to be trenched to the road so everyone stopped at the sidewalks or curb with a small area of gravel the water bubbled up and into the street , it never made sense to me but this was legal where a pipe opening to the road was not.this would take any water away and if gravel filled to grade no grass will grow with only rock.


I ended up adding no slope and counting on the fact that I will at most get half the water off my neighbor's shed, which will disperse under my shed. Two years and a half after the project was done I am not seeing any problems. No french drain, no other things required

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