How to build a concrete slab at back gate?

[bodega]

I’m wanting to cement this area and have a concrete slab here for us to walk on. It is in the back corner of our garden which leads to a back gate that goes out to a laneway shared by the street. 

The area is roughly 1650 x 900 and will only have foot traffic on it, so from my research the slab needs to be ~100mm thick (Please correct me if wrong). I plan to potentially attempt doing some sort of crazy paving on the top of the slab.

The area rarely gets sun and the soil shown here is constantly damp and mostly bad quality soil or clay from previous rebuilds. The amount of bricks and old cement blocks I’ve dug up here is insane.

Questions:

What I’m most concerned about is what should be underneath the slab, should I place sand or crushed rock? 

How much fall do I need to have on the slab?

How close to the laneway do I need to concrete up to? Do I leave a gap between gate and laneway?

Do I concrete up next to the wooden retaining walls I've built or have a small gap between?

What would be best practice for the questions above?

Any ideas/suggestions would be appreciated!

[EricL]

Hello @bodega 

I suggest looking at this guide - How to pour a concrete slab by @tom_builds. Before you begin, I suggest checking the rules and regulations of your local council in regards to how far you can concrete your walkway. Just to be on the safe side I would probably just stop at the fence post so that it is technically still within your property line. For a 1.6 metre long concrete walkway, the standard recommended fall for drainage is 1:100, which means 1 centimetre of fall for every 1 metre of length. This ensures water runs off the surface and doesn’t pool. But please always check your council rules and regulations just to confirm.

Yes, it’s strongly recommended to lay a base layer of compacted material like crusher dust or road base gravel under your concrete walkway before pouring. This base gives the concrete a solid, stable foundation and helps prevent it from cracking or shifting over time, especially if the soil underneath is clay, sandy, or uneven. I recommend concreting up next to the wooden retaining walls you've built.

If you need further information, please let us know.

Eric

[bodega]

Thanks @EricL , appreciate the reply.

For the base layer of compacted material like crusher dust or road base gravel, can I use a tamper to compress it? 

[JacobZ]

Hi @bodega,

Yes, a tamper would be perfect for compacting your base material for this project.

As it is a relatively small area, it would not be an excessive amount of work and it will produce a great result.

Let me know if you have any further questions.

Jacob