Shed project - foundations

[Tim Watts]

Hi,

Have touched on this before... But some new thoughts.

Will be hand building a shed - approx 3x2-2.5m (garden tools, DIY materials, random) - and it will go quite near a shared sewer line (about 1m away).

I am less bothered about the sewer collapsing as I am about my shed falling over if/when Southern Water want to come and dig a bloody big trench down my garden to fix their sewer.

Shed will be supported on 4 corner pads with wooden bearers.

I was thinking to make the pads as concrete piles, dug as narrow as possible with a post hole digger and a little deeper than the sewer line (without measuring it's about 2.5 feet). The other side away from the sewer can be more modest.

That way there should be no risk if someone starts trenching right up close.

But I did wonder if anyone made very lightweight versions of these screw piles:

pile-70049-1598655.jpg

I'd be looking for about 1.2m long, single screw blade, fairly light that could be drilled in by hand with a bar.

There are lightweight ones for decking and fencing - but they tend to not be very long and depth is what matters here. Loading will be tiny - few kN max load per pile.

I suspect not - but in case my googling failed... And it would easier than mixing all that concrete :)

Nearest I found was:

Possibly long enough - wrong head, though might be possible to adapt.

[Dave Liquorice]

How big is this sewer? 5", 12", walk down it without stooping?

Assuming a 5 or even 12" pipe I think you are worrying to much. The sides of a trench don't give way with the weight of a digger digging it less than a metre away each side...

I'd be more worried about the digger clouting the shed than it collasping into the trench.

Has this sewer been a problem in the past with blockges or roots? What is the realistic likely hood of SW wanting to dig it up?

[Tim Watts]

On Wednesday 21 August 2013 00:38 Dave Liquorice wrote in uk.d-i-y:

6" salt glazed. Supports 3 other houses at that point - not mine, I tee in further down the garden.

I'll plead the 4th on that.

Quite high, if I phone in a blockage, which I reckon could happen in the next few years.

[Alan Braggins]

You think digging it up would be "unreasonable searches and seizures" and should require a warrant issued upon probable cause? :-)

[Tim Watts]

On Wednesday 21 August 2013 13:07 Alan Braggins wrote in uk.d-i-y:

OK - 5th...

Just because I got a "U" at history O-Level...

[Peter Johnson]

If your shed did collapse because of Southern Water's activities then surely it would be up to SW to fix the damage.

[Tim Watts]

On Wednesday 21 August 2013 14:32 Peter Johnson wrote in uk.d-i-y:

Maybe - but prevention is bette rthan cure.

And if I delve too deeply there are probably 6 million rules about foundations (of any sort) near a sewer (as opposed to a drain).

I was wondering if a post auger (hand turned or small petrol one on hire) might make light work of it.

A 150mm dia hole 1.2m deep would need 21 litres of concrete to fill which would be probably 40kg. Which is bugger all in concrete terms. Times 4 per shed. In fact less, as the rear piles would not need to be 1.2m long - 0.6 would be more than enough.

Not a great deal to remove either if the sheds ever go - better than the 6-8 m3 I have now under one shed, an old greenhouse base and a long run of path.

[Jim K]

snip

yup wish I'd read that before working it out!! It is f*ck all concrete.

Post hole borers - mmm what's ground like? I once hired a petrol one-man version to dig holes for posts. Kept hitting bricks and fecked my elbow up bad (tennis elbow) I had to have physio for ~8 weeks to be able to sleep through the night... moral/top tip:- get a 2 manner unless you know the ground is "easy"...

Cheers Jim K

[Tim Watts]

On Thursday 22 August 2013 10:07 Jim K wrote in uk.d-i-y:

Clay. With some rocks up top.

Good tip.

I'll either use a manual one or make sure it has a leg torque bar and safety brake.

On a relate note, this bloke's a nutter (but he did suceed):

Using a manual post hole digger to dig a well bore hole. 15 feet or something!