How to install and waterproofing a new shed?

BronFern

Hi everyone- first poster here. I have some questions about installing and hopefully making waterproof a new shed. 
I had an older shed installed on a concrete slab. The slab is a bit uneven in places and I had issues with water (not sure exactly where- felt like everywhere). 
I have now removed the old shed and bought a new one but want to avoid the mistakes of the past. A picture of the slab is hopefully below. 
Would I be best to re-level the slab using a levelling compound (or similar) or try building in a floor- like I have sees others do in here? Or both? 
Thanks

 Red box is around the puddle of water. 

 Example of current state of the edges.

EricL

Hello @BronFern 

Welcome to the Bunnings Workshop community. It's sensational to have you join us and thanks for sharing your question about your shed base.

I believe that this is the perfect opportunity to level your concrete shed base with self-levelling compound. This will in essence prevent water from freely flowing into your shed base and creating a humid environment inside your shed. Another option is to create a concrete base on top of your existing base. One of the most easily missed steps when building a shed base is the inclusion of a rebate. I've placed an image below to give you an idea of what I'm referring to.

When a shed base is built, they often place a visual reminder to create a rebate in the base. This in essence provides a higher flooring area inside the shed and prevents water from flowing in and you end up with a very dry floor. Should you wish to go in this direction, just keep in mind that you should have the exact measurement of the interior floor area of the shed that you've purchased.

Here are some handy step-by-step guides:  

• How to waterproof a shed floor
   
• How to pour a concrete slab 
   
• How to level a concrete floor? by @DxMxGxD 
   

If you need further assistance, please let us know

Eric