Large shed base on sodden ground

[Ouch77]

I'm having second thoughts on a base for a new shed.

I'm planning on putting a large shed 3.5x8m (26x11.5ft in old money) at the top of my garden.
The ground is mostly quite flat, but I've recently had to remove/grind out a large tree stump that would have been in the way.

The ground in that area is a little moist, given recent weather, the undisturbed turf squelches a bit underfoot, and the area where the stump came out is quite spongy. There's a lot of clay in the subsoil I've discovered.

My original thought would be a standard shed-grade concrete slab, maybe with rebar given the size and potential for settlement, but I'm thinking now either it needs digging down a foot and putting type 1 in before the concrete, or something a bit more left field like concrete piers/piles and a suspended timber (or RSJ) frame.

What would others do in this situation?

 

[plastic_peanut]

Would ground screws be worth looking at? Plenty of informative websites and good for gardebuildings

 

[Ouch77]

Would ground screws be worth looking at? Plenty of informative websites and good for gardebuildings

Interesting, not aware of this technology, sounds good. The ground is pretty saturated at the moment, and given the size of the stump, some pretty long screws would probably be needed to get through the soup, but I like the idea of not chucking a tonne of concrete into the ground.

 

[Keithmac]

As plastic peanut says, ground screws with a good solid frame to put your shed on would be a good idea.

 

[Nanz]

As plastic peanut says, ground screws with a good solid frame to put your shed on would be a good idea.

View attachment 184605

Out of curiosity, which ground screws have you used here? Did you get them professionally installed or did you do this yourself?

 

[HERTS P&D]

Out of curiosity, which ground screws have you used here? Did you get them professionally installed or did you do this yourself?

Knowing Keith, he done it himself.

Andy

 

[Keithmac]

Sorry for the confusion, that was a picture I grabbed off the internet!.

I have a project planned at some point to use ground screws and I'll be doing them by hand.

 

[HERTS P&D]

See below:

Andy

 

[HERTS P&D]

Or these:

Andy

 

[Nanz]

Or these:

Andy

Thanks for those!

 

[HERTS P&D]

Watch this:

Andy

 

[Ouch77]

update,

Went with ground-screws in the end, there's a couple of companies that seem to offer an installation service (I was unsure I'd get them in straight), found a local-ish one who was willing to travel.

groundscrews

• Ouch77
• 18 Jun 2020

groundscrews

• Ouch77
• 18 Jun 2020

groundscrews

• Ouch77
• 18 Jun 2020

Things had dried out a bit by installation time, but hopefully it'll be just as stable when wet - 20 screws, each one being 4ft long. Reckon that'll do..

shed sub floor complete

• Ouch77
• 18 Jun 2020

more to follow in it's own thread at some point.

p.s. Very happy with the screws, top service by the fella that put them in, had it done in a morning, and each one was spot on location-wise. the neighbours and other trades have seen them and are impressed too.