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How to construct base for 'Build A Shed' garden shed?

Just Starting Out

How to construct base for 'Build A Shed' garden shed?

I am about to buy a garden shed from Bunnings (Build A Shed Skillion Series base dimensions 2.3 by 1.2m). I'm not concerned about assembling the shed but nowhere is there any guidance about constructing the base to which the shed will be attached, except, Bolt down kits & anchor bolts are included in the package.

Presumably a concrete base would be best. My questions are:

1. What thickness?

2. Should the base extend a certain amount from the base of the shed?

3. Would consider ordering a 'mini mix' concrete delivery but determining the amount could be tricky. If there is excess do they take it away? The site is behind a villa unit so no opportunity for disposal.

Any advice would be appreciated,

with thanks, John

Finding My Feet

Re: How to construct base for 'Build A Shed' garden shed

Hey John,


1. As a rule of thumb 100mm is a good thickness for a slab. In conjunction with reinforcing mesh this will give you a good base to attach your new shed to.


2. The slab should extend out around the shed at least 100mm to allow for the concrete anchors. If they're too close to the edge they can "blow-out" the side of the slab. This will also help with stopping water ingress assuming the slab is edged correctly to run away from the shed.


3. Generally speaking, concrete delivery services will not remove excess concrete as it is prone to "going off" inside the truck. Bunnings do offer Mixer Hire if over ordering is a concern.




Bunnings Team Member
Bunnings Team Member

Re: How to construct base for 'Build A Shed' garden shed

Hello @JohnRR 


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


It's fantastic that you've received excellent advice from @jzubrinich. Just to add to the suggestions made, I also recommend having a look at this discussion - How to pour a concrete slab by @tom_builds. In this discussion you'll see the basics of formwork and how to prepare the area before pouring concrete.


My best advice is to plan it out on paper first to make sure that you have all the steps mapped out. Having your building materials on hand, preparing the soil, building the formwork, putting in the steel mesh support and finally the pouring of the concrete.


Some concrete services also provide finishing work. This involves making sure that the slab cures slowly by keeping it damp. Accelerated curing can cause cracks and splits in the slab which is not desirable.


Please remember to wear personal protection such as gloves goggles and a mask when working on your project.


If you have any other questions we can help with, please let us know.          




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