Concrete base for garden office on a sloping garden

[roccles]

I am looking into building a garden office/log cabin (4m x 4m) at the back of my garden and have started considering the foundations for this build but am concerned about the the slope at the back of my garden as it is pretty steep.

To have a level concrete base the back wall of the base to be about half a metre higher than than the front. Would this be ok or is there a chance that the back wall will break and collapse over time?



Maybe there is another solution I should be looking at. Any help would be greatly appreciated.

Cheers

 

[roccles]

@Orionaut @BigBoy Thank you. I have come across a product called foundation screws at (https://www.ukhelix.com/product/eco-diy-manual-install-screw-piles/) which look promising. There are about £40 quid each so would be cheaper than pouring a concrete base. Has anyone come across these before?

 

[roccles]

Thanks for the link, it looks like they got a company into do them which I have also looked into - https://stop-digging.co.uk/ online calculator gives an estimate of £1152 including installation. The ones in the OP would be DIY but about half the price but require a lot more work my end making sure everything is dead level and striaght.

 

[roccles]

Also need some hefty kit to install them which you won't have and it's probably going to be a bugger getting them all level!

The level is obviously my main concern and am wondering if I might as well just pay the extra to make sure that it all done correctly as the whole build is reliant on these

 

[roccles]

How "log cabin" are we talking? Are you on about buying one of those office sheds, in which case excavate out the top part of the slope, and use a post auger to put some solid posts down to clay or hardbed depending on what you have and then concrete them in, more than enough strength for a glorified shed.

It will be a 4m x 4m timber frame building insulated floor, walls and roof, clad with OSB, breathable membrane, and then a cladding. So not massive.

I am considering digging down now as it will also allow be to increase the roof height which will be handy.

 

[roccles]

I'd love to use screw piles to support a workshop / deck in our garden because I'm sick of concrete being used too much.

Just not quite sure how expensive it would be to do an area about 4m x 7m

For my 4m x 4m building I have been quoted 900 quid which would be 9 screws (3 x 1m screws at the highest level, 3 x 1.5m screws in the middle and 3 x 2m screws at the back)

 

[roccles]

I knocked the shed down last night so I can get a better feel for the plot. I would be looking to get the back of the new garden office close to the back fence which annoyingly is where the steepest drop is.

 

[roccles]

given the drop and the fact you cannot see it I would be putting a retaining wall in, you can get it as close to the fence as possible then and back fill with whatever rubish you more around to put the base down.

I think this might be the best way to proceed. I need to get down there and give it a good clean.

If I was looking to this myself do you think sleepers would be the easiest to work with? Vertical or Horizontal?

 

[roccles]

All depends on how permanent it needs to be, no need for the base to be concrete in fact it would be better for the base of the building to be ballast and piers to allow for water to drain. A block and mortar retaining U on the sloped end will be far stronger than sleepers and would not give if the land were to slip.

Sleepers are great for retaining planted beds or grass edges but for buildings of any weight I would always use a block wall.

Is a block and mortar wall something I could so myself? I can dig, measure and follow instructions but have no experience this area of DIY, would I need to worry about drainage etc?