Ground screw advice needed please

[Joe1975]

Considering using ground screws for an upcoming workshop build. I have to be careful with my back and am trying to build without dealing with too many heavy products. Also need a quick build - just built a 5m x 3m studio which took over a year! The workshop will be fairly high spec though with insulation, cladding and double glazing, EPDM roof etc.

The workshop will be 8’ x 16’. So was going to stick to the 4’ recommended spacing. This amounts to 15 screws.

I have approximately 500-600mm of topsoil over solid chalk. I was going to use 800mm screws, assuming that as long as I get down to the chalk they should be pretty solid. I will leave 50-100mm above ground. The next size up is 1000mm which I think would get pretty difficult to drive (potentially 400mm) into chalk. Would you agree?

Does anyone have any experience with ground screws, and could possibly advise on the above (or any other aspects of using them) please.

They’re quite expensive aren’t they! (Cost about £400)



My other idea is to just use five 2.4m oak sleepers resting on a bit of hardcore. These are heavy, so will obviously get some help. Should last for 30 years plus?

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But it might be quite difficult to get them all settled and perfectly level. Also worried about ventilation underneath. I would use strips of damp proof membrane between sleepers and joists. (Cost about £200)

What method would you use?

 

[BucksDad]

Paging @Molynoox who used ground screws for his build and probably uses them for the ones he builds now

 

[Molynoox]

Paging @Molynoox who used ground screws for his build and probably uses them for the ones he builds now

Yes I'm quite a fan of groundscrews - fast to install, same price or cheaper than concrete, less mess, gives a ventilation gap underneath, good with tree roots.
Its not all gold but out of the options it's the one I feel is the best compromise

for a 5x3 it would be about £1100 fully installed using 1250mm length screws
get yourself a few quotes. It will take them 2-3 hours to install and then you can start building on it straight away

you can install some yourself using a T-bar but you are restricted to the 800mm ones - I would just pay for the pro install and get the longer screws. They can also give you a force test for £350 which will tell you exactly how strong the ground is and what screws you need, if concerned.

all prices ex VAT

Martin

 

[Ollie78]

I built a shed on things a bit like ground screws bit not quite, more like ground nails with a giant washer on them.
Found it they are called quickjack QuickJack for Soft Surfaces - Adjustable Height Base | Shed Base Kits

They were quite easy to install, you get then near where you want install the joists then final level using a sledge hammer and then the spinny plate bit.
You need quite a few of them though.

Ollie

 

[Jameshow]

I built a shed on things a bit like ground screws bit not quite, more like ground nails with a giant washer on them.
Found it they are called quickjack QuickJack for Soft Surfaces - Adjustable Height Base | Shed Base Kits

They were quite easy to install, you get then near where you want install the joists then final level using a sledge hammer and then the spinny plate bit.
You need quite a few of them though.

Ollie

Good for lighter sheds?

Depends on the loads you intend in putting in the workshop? Heavy cast iron I'd want ground screws or concrete.

Our holiday lodge is on concrete blocks every 5ft.

 

[John Brown]

I used Quickjacks. They'd be fine if the bl00dy moles hadn't tunnelled underneath and reduced the already borderline clearance on one side. As it is I'm probably going to have to do some excavating, which is hard because I laid weed control fabric with a bit of MOT type 1 on top. The mole workings have pushed up the fabric and the type 1. Probably allowed the Quickjacks to sink a bit too. I hate moles.

 

[Inspector]

I used Screw Piles/Helical Piles to hold up my deck that I built. They go down 10 feet to get below the frost line and I have 4 that support the 10' x 12' off the house dropping down to the lower deck that is 14' x 16'. So two hold up the small deck (joist hangers attach the deck to the house side) above the lower deck which they also support and the second pair hold up the other end of the larger lower deck. With your shed size you could get away with 4 in the corners or 6 if you wanted to make shorter beams. My beams are built up from 2 x 12s glued and screwed together. Joists are all hung between with metal joist hangers. Contact one of the companies below or ones you search out for a quote. They drive in fast until the meet the proper resistance and are cut off at above the ground and a saddle placed on top (bolted or welded). Might just be competitive in price and definitely faster to install. They will be done in a couple hours and as soon as they are done you can go ahead and start building.

https://www.alternativepilingsoluti...MIoqOIxNOd_gIVUhxlCh3FvgZYEAAYAyAAEgKXFfD_BwE
https://www.ukhelix.com/screw-pile-supplies/
https://groundsun.co.uk/screw-pile-foundations/
https://www.screwpilesltd.co.uk/screw-piles-design-installation.html
Pete