Shed Foundations (moved from Projects)

[Mark-UK]

I'm building a 22' x 16' wooden shed but not sure which base to go for.

I'm seriously considering an all concrete base but it's expensive, so, I'm also considering using breeze blocks instead.

Would breeze blocks be a solid enough foundation?

Any advice would be appreciated

Thank you

 

[theprinceofdarkness]

Breeze blocks are made from cement and ash, I do not think they are available any more. Do you mean concrete blocks, they are available in at least four grades, dense, medium, low and aereated (for insulation Celcon etc.). Either the medium or dense would do, the less dense ones do not like wet then freeze cycles.
Your shed floor sits on joists, so if the joists are supported, then all is well. In a proper building the joists would be supported every four foot, with the joists being 4" X 2". So if you joists are thinner/narrower, they will need supporting more often. It is a good time to install under floor insulation if you intend to use the shed as a man cave in the winter.
Frank

 

[Mark-UK]

Thanks for the advice Frank - much appreciated

 

[Mark-UK]

I'm probably going to use concrete slabs laid on pits of gravel. How many slabs will I need for a shed's 20'x16' foundation?

 

[theprinceofdarkness]

So how many joists or bearers have you got? 16' width then you need about 5 per joist (across the width).
Frank

 

[Mark-UK]

To be honest, I am not really sure. This is the first time I've done anything like this. About all I know, is that the gaps between floor joists shouldn't be more than around 16" apart. Even then I'm not too sure about that.

 

[Mark-UK]

I was thinking of going with the following set up:

So a 4 ft gap between the slabs and a total of 30 slabs used.

Is the 4 ft gap too wide, should I go with a 2 ft gap?

 

[theprinceofdarkness]

If your joists are 4" X 2"* then 4' should do, its the domestic floor support (also depends on what you want to put in it). If the joist are smaller then you should decrease the gap between the blocks.
* 4" = vertical height
Frank

 

[Mark-UK]

The joists are 4"x2" but was considering 4"x4" for added rigidity

The shed is for woodworking and sometime in the future I hope to have a lathe in there. Not sure if OSB on those joists will support the weight though.

 

[theprinceofdarkness]

Wood lathes only weigh a few hundred weight, metal lathes as much as you like but typically a ton for a 6" Harrison or Colchester, Myfords on the other hand go at 1 1/2 hundred weight. I have a one ton mill (30" square base) sitting on a 4mm spreader plate , on OSB, on wooden joists, but they are resting directly on a concrete base.
If you are going for the full ton, then an arrangement of blocks every 4', will lead to a structure that settles and vibrates. Because of the quantum leap required in the loading, from a few garden rakes to a one ton lathe, I feel that proper foundations should be built. If you build the walls off the floor joists with the flooring inside the walls and studs, then a floor panel or two can be taken out and proper foundation dug in at the correct place when you get your seriously heavy machine.
Frank

 

[Mark-UK]

Thanks for the advice Frank