Shed Base Drainage pipes, concrete, footings and foundations. Post your questions and find answers here

[RyanCP]

I've ordered a new 12x8 shed to arrive in a few days. The shed will sit in an area, which is currently grass and can get quite wet when it's rainy. I've weighed up the base options but still not sure of the best approach, but I don't think a poured concrete base is an option.
I have 6 spare concrete blocks (currently used as doorsteps; 36"x10"x6"), which I was thinking of laying in the corners and centres to support a timber frame for the base.
A few questions...
Should I dig down a few inches, so that the blocks are set into the ground (on compacted soil / pea gravel?) and so that the timber is virtually level with the surrounding ground?
Should I also lay a weed barrier and cover with pea shingle / gravel?
Should I anchor the frame to the blocks and if so, how?
Should I use 2x6 or 2x4 for the frame?
Any response is welcome, even if it's just general mockery if I'm way off track so far!!!
Many thanks.

[stoneyboy]

RyanCP,
"Should I dig down a few inches, so that the blocks are set into the ground (on compacted soil / pea gravel?) and so that the timber is virtually level with the surrounding ground?" Certainly compact under the blocks but leave them raised so air can circulate under the shed
Should I also lay a weed barrier and cover with pea shingle / gravel? No weeds won't grow under the shed but you may need to weed treat the perimeter
Should I anchor the frame to the blocks and if so, how? NO
Should I use 2x6 or 2x4 for the frame? Use 4x3 tanalised posts.
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[stokedan1]

if u dont put shed on a gud base it wont be long before it starts leaning over.

a gud option which isnt to costly is to dig off turf, put down some whackered type 1 MOT, and lay some flags on a sand cement bed. if your not any good at groundwork i suggest gettin someone do it for you.

when i do these bases i get hold of second hand 3x2 flags which 1 get for only £1.50 each you will need:-

16 flags £24 (if second hand) more if new
ton sharp sand - £35
3 bags cement - £12
3 ton mot - £50
labour - £40 -£50

[RyanCP]

Thank you for your replies. I'll have a go with the raised blocks and tanalised posts for the base frame. So far this morning, I'm struggling to find 12ft long 4x3 tanalised posts but I haven't looked very hard yet. The three local options have tanalised 3x3s and 4x4s up to 10ft long on their web site lists but I might need to go for a look as I'm sure they have more in stock than their web sites say.

Would I lay these posts on 16" centres? (i.e. 10x 8ft joists with 2x 12ft at either side?)

Perhaps I should start a new thread for this next question, but I'm 6'1" and the shed is 5'5" eaves to 7' apex, so I'm thinking of raising the internal height of the shed a few inches to save me some headache. When I've laid my base and set the shed floor onto it, can I use 3x3s around the edges and then secure the pre-fab walls to them? I'll probably need to find matching overlap cladding for the extra 3 inch and maybe another door, but I could use the extra headroom.
I can't help but think I'm missing something or compromising the shed stability if I lift the walls but not the floor.

[stoneyboy]

RyanCP,
"Would I lay these posts on 16" centres? (i.e. 10x 8ft joists with 2x 12ft at either side?)" depends which way the joists are run in the floor.
If the shed is one where the sides hang down over the floor then use 4x2 or taller if you want more headroom.
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[RyanCP]

Thanks again. The shed took longer to arrive than I expected so it only arrived on Monday, but not early enough for me to enjoy a bank holiday in the garden with it! I'm praying for good weather tomorrow (despite the forecast).

The best I could find was 3x3 tanalised. If I continue with the idea of resting the tanalised beams on the concrete blocks, what is the longest span recommended between blocks? I had envisioned using a total of 6 blocks, using 4 on the corners and 2 in the centres on the longest edges. Therefore, the longest span is about 1.4m. Is that okay?

[stoneyboy]

RyanCP,
If you haven't built the shed yet I'd suggest you use 4 blocks rather than 3 on the longest span.
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