Shed base

[Jupiter01]

Planning to build a shed, approximately 2.5mx2.5m. It will be timber construction with osb board and rubber roof.

I am comfortable with all aspects apart from the base and especially working with concrete. Do I need to create a concrete base for the whole area or can I have concrete pad foundations in each corner?

I’m undecided on the type of door I am going to have and how much weight this will introduce.

 

[Why Not Indeed]

For the amount of concrete you'll save, I can't believe it would make sense to not bother filling in "between" all the corners.

 

[Jupiter01]

The smaller pads would allow me to experiment with the amount of concrete and mixing required. I do t feel confident to estimate, mix and level a larger area, all in one go.

 

[Mike13]

Dependant on your soil there are alternatives. I put my log cabin on about 15 piers, using a hand auger to make 6" diameter holes to about a metre down. If I had used a raft it would have been 6 tonnes of concrete, but piers added to at about 1 tonne. I went a metre deep to get below the frost line to keep it stable. there has been no movement of the shed since it was done a few years ago. But I have quite a free draining sandy soil. If you have loads of clay to a significant depth then the raft has to be thick enough to hold together forever no matter what happens to the clay.

 

[Jupiter01]

Are there any structural weaknesses to my suggested approach of concrete bases in each of the 4 corners?

 

[Mike13]

Are there any structural weaknesses to my suggested approach of concrete bases in each of the 4 corners?

you need to have a stiff enough bearer beams in the base to support the whole length of the sides, extra piers reduce the strength required in the base. Also, I used composite beams as the lowest level so that the bearer beams get a frequent chance to dry out.

 

[Jupiter01]

you need to have a stiff enough bearer beams in the base to support the whole length of the sides, extra piers reduce the strength required in the base. Also, I used composite beams as the lowest level so that the bearer beams get a frequent chance to dry out.

Perhaps I can have an additional foundation midway, in each direction? I am just trining to get away from the daunting task of estimating and mixing the whole base in one go.