Fence post spikes for shed base

bekind_always

Hi, I have an uneven garden and want to build a 13'x11' metal shed on it. I could spend time levelling it off, putting a concrete base down and off I go, but it's a lot of work. Would metal fence post spikes, hammered into the ground, suffice? I would need plenty of them, but I was thinking that I could put around 9" of 4x4 fence post in the lowest part of the ground, to make up the slope of the garden, and smaller posts around the rest, maybe just a couple of inches at the highest part of the garden. I could then build my timber base on that. Will it work?

CliveOfIndia

bekind_always said:

Will it work?

No

bekind_always said:

it's a lot of work. Would metal fence post spikes, hammered into the ground, suffice? I would need plenty of them, but I was thinking that I could put around 9" of 4x4 fence post in the lowest part of the ground, to make up the slope of the garden, 

That's gonna be a lot more work than levelling off the ground to near-as-dammit, sticking in some shuttering and ordering a bulk delivery of concrete to be poured in.

bekind_always said:

want to build a 13'x11' metal shed on it.

That's a big old shed.  Presumably not cheap.  Don't ruin it by sticking it on a Heath-Robinson base.  Get yourself some shuttering in place, get a load of concrete ordered, then stick it on that.  If the base ain't perfectly level, you can then adjust it with some half-decent timbers to rest the shed on (though ideally you'd take the time to get it spot on).  I really can't see fence-spikes being up to the job.

WIAWSNB

I'd agree about the metal post spikes, as these are designed to sink into the ground! 

However, there are screw-in 'piles' designed for just this job, and I have to say I find them appealing. 

I hate the idea of a concrete slab, as - once laid - they remain a pita in perp. The poor sod who needs to remove your carp shed will then be faced with this ugly concrete mass

So, I'd certainly investigate these screws and see if they are up to the task.

A lot will come down to the underframe of your proposed shed - will it have significant beams to support the shed, or will it need propping up every couple of feet?

I've long decided that when I build my next shed/summer house/garden room - if ever - I'll dig a series of small-size foundation holes, such as to suit 2' slabs - and drop the aforementioned slabs in there on a wee bed of concrete. From there, either non-rotting posts (composite?) or else simple brick pillars come up to above ground level. Lay the main beams across these, and fire away.

Concrete slab ma botty. 

Martin_the_Unjust

https://www.easyscrewfoundations.com/

WIAWSNB

Martin_the_Unjust said:

https://www.easyscrewfoundations.com/

Pffft - an 8' beam and a couple of donkeys will screw that in. 

Eldi_Dos

@ bekind-always

If you do go down the route of using metal fence spikes or ground anchors you really have to be sure no services are in that area.Usually entails some pilot holes to check position and depths.

bekind_always

I like the look of the easy screw foundation kit. I'm not keen on a concrete slab, just because it's so permanent, although many people will say that's the whole point of it! I feel that fence post spikes or easy screw foundations should do the job. Has anyone else used fence post spikes and not have their shed sink!

Eldi_Dos

If you are wanting to ensure no movement on fence post spikes, mark out your positions and excavate around 300 to 400 mm depth. Instal your spikes then shovel some concrete around them, leaving enough space that you can backfill with soil to ground level. Make sure concrete is well set before anyone touches them again.

Section62

bekind_always said:

I like the look of the easy screw foundation kit. I'm not keen on a concrete slab, just because it's so permanent, although many people will say that's the whole point of it! I feel that fence post spikes or easy screw foundations should do the job. Has anyone else used fence post spikes and not have their shed sink!

What are you planning on keeping in the shed, and how often will you go in it?

If you are absolutely sure you don't want a slab then the next best would be strip foundations with dwarf walls built on them.  This would be similar to what

WIAWSNB had in mind - but without the need for 2' slabs.

The thing you want to avoid is differential movement - which is easy with a nice thick concrete slab, but harder the more individual foundations you have.  Strip foundations could be built with the top surface below ground level so if you want to get rid of the shed and go back to lawn, all you need to do is demolish the dwarf walls and then soil and seed the strips.

Fence post spikes really aren't suitable, and the screw foundation approach is good for temporary buildings, but I'd say is likely to be more expensive and harder to DIY than traditional methods.

The key thing though is how much load your shed will impose on whatever foundation you have, and how 'dynamic' that load is - hence my initial question.  If you'll have a lot of stuff in the shed, and you'll be in and out of it regularly, then the foundations need to be better.  Fence post spikes are designed to be driven (hammered) into the ground - if you load the shed up and move around in it a lot then the effect will be exactly the same as hammering, and no matter how carefully you originally levelled everything, sooner or later you'll have an uneven and poorly supported floor.  Likewise, spike/screw methods aren't always suitable if the ground is variable - if you have any soft or disturbed areas the loadbearing capacity will be less, leading to the risk of differential movement.

bekind_always

My brain is telling me to put in the hard work and build a concrete base. My back is telling me to find an easier solution. There will be a lot of weight in the shed as I want to use it for woodworking (heavy machinery, benches, in and out a lot). Thank you for everyone's input. I'll keep a look out for anymore replies, but i think I'll have to start digging the garden up and make some shuttering.

Section62

bekind_always said:

My brain is telling me to put in the hard work and build a concrete base. My back is telling me to find an easier solution. There will be a lot of weight in the shed as I want to use it for woodworking (heavy machinery, benches, in and out a lot). Thank you for everyone's input. I'll keep a look out for anymore replies, but i think I'll have to start digging the garden up and make some shuttering.

Definitely a solid concrete floor then.  Vibration from the machinery would be an added problem, and without solid support the machines can vibrate excessively.  If you have a lathe for woodturning this really does need a solid base if you turn large items.

That said, if you do cabinet making there is a lot to be said for having a wooden floor - among other things, it can reduce the amount of damage if you drop any of your edge tools.  The ideal is having an area of wooden flooring inset into a concrete floor - the concrete for the building and power tools, the wood area for cabinet making.

The other thing to be aware of with metal sheds is the risk of condensation on the ceiling - which can drip off onto anything below.  You really don't want condensation drips on the tables/beds of machinery as it quickly mucks them up.  If you've not thought about this yet then I'd suggest you ask the shed manufacturer if they can do insulated sheets, or anti-condensation coating (fabric).