garage slab engineering

I was told by various people here in Victoria, that if I built my standard colourbond steel shed on a slab, the slab would need to be designed by an engineer. The site is ordinary, flat, clayey soil, nothing unusual. I presume the engineer would just pull out the standard design he's used a thousand times (you know the one), adjust it for my dimensions (7x12m), print out the design, and send me the bill. No engineering calculations involved at all, just a few minutes on the computer. Am I right, and roughly how much does an engineer charge for this basic service? By the way, I decided to build the shed on concrete piers, and pour the slab later. That way the slab is not structural (its just paving really), so no rubber stamp is needed.

Spose it depends on what your local council requires. When I built my shed (9m x 6m) in 1998 my plans didn't have any engineer's approval on them. It passed through my council with no hasstles.

The concrete slab is 100mm thick with F62 mesh. I poured the pier footings and slab monolithly.

I would be checking the requirements of your local council, most shed plans come with the specs for the slab on them and this are usually sufficent for approval.

We just got our shed plans approved by council and they (the plans from the shed people) already had slab specs on them. If I remember correctly the plans had both pad and slab type footings specified (you choose which to use).

Hopefully our slab will be down today - can't wait for my 7.5 x 12 shed to be done.

As far as I know the slab must be designed for the building to go on it. In general in the industry the shed plans include the slab and this will be easiest way to go. If not take the building plans along to a local engineer and he can do a one off.

You will find that most colorbond shed mobs will supply you with engineer's plans for both the shed and slab. It was for mine.

You are right about the slab design. Very basic.

The slab does not have to engineered in this case, but the piers do have to be done to code as they carry the shed.

I built a 7x13 on top of a slab. I didn't have to specifically get an engineer to do the plans. I drew them, but did the specifications as required for building standards. The beams had to be 300mm wide, minimum 400mm deep, and down further to clay if required. The trench mesh had to be 200mm wide, cant remember the spec, and 50mm off the bottom on hats, the slab had to be 100mm thick with 72 mesh (7mm with 200mm squares), again on hats. The slab had to also be on top of 100mm of washed sand, not the trenches.

Council approved drawings
Council inspected trenches
Council inspected steelwork

The guy pumping the concrete, and my brother-in-law who screeded the slab all agreed it was all correct, and exactly how they would do it. Everone was happy, with no engineer.

Council then inspected frame. Had to modify a small thing that took an hour, then re-inspected
Council did final inspection and passed.

Thanks for your replies and all the info everyone. The shed came standard with specs for piers but not for the slab. I suppose they could have supplied slab specs no problem, just cost maybe $500 more. I ended up getting the kit quite a bit cheaper than other places, and all components are good quality (according to my shed builder friend who helped put up the frame).