Ceiling for flimsy garage

[Crisp]

I have a large garage - about 700 square feet/65sqm. It has a concrete floor, timber frame and metal siding and roof.
I'd like to add a plasterboard ceiling (and walls eventually) so that I can insulate and regulate the extreme temperatures inside.

I'm a novice when it comes to DIY at this scale...

The roof is a series of 6 trusses, each around 1.8 metres (6ft) apart!

So, i need something to hang the ceiling from.
I'm thinking of installing some 2x4s in between each joist to bridge the 1.8m gap. Either at 1.2m spacing or 600mm (24").
Would I also need to run battens perpendicular to the 2x4s?
I've added an image to help explain.

I just want the cheapest and easiest solution so that I can attach plasterboard and pop some insulation on top. I realise this is going to be a big job but I'd like to keep it as simple as possible.

Any advice would be greatly appreciated.

 

[Barry123]

Drywall is generally installed on supports 18" on center for walls and 24" on center for ceilings. My main concern for your situation would be moisture buildup, as regular drywall will fall apart in moist environments. That is the reason to use moisture resistant backer board around showers and tubs.

Another option would be to install suspended ceiling tiles. Here are step-by-step instructions for that: http://www.popularmechanics.com/home/interior-projects/how-to/a168/suspended-ceiling-tiles-install/