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

 

Welcome to the forums! You are from New Zealand, so our information may or may not be the best, since we are primarily a North American forum.

If your timber framing provides a ceiling, albeit larger beams, you can do as you suggest and install 2x8 lumber utilizing joist hangers across the span every 16" or 24" on center to provide a nailing surface for your sheetrock (we don't use the term plasterboard), and it will likewise give you a surface to lay in your insulation from above. Don't forget to provide for ingress and egress from the attic space via stairs or at least a scuttle hole.

 

Thanks for that. The existing beams (excuse me if I have the wrong terminology) are 2x6 so I will run 2x6 joists perpendicular to these beams at 16" intervals. I plan on using joist hangers - can I install these first and have the hanger flush with the existing beam to get a flat surface to hang the sheetrock or will the new joist have to be flush with the existing beam meaning the joist hanger will protrude just a little below the timber?

 

Have you considered a drop ceiling (AKA suspended ceiling) if insulation is your main concern. Running the grid for the panels might be easier then adding ceiling joists and laying the panels in would be a lot easier than hanging and floating (finishing) Sheetrock (plasterboard). They make 2'x4' insulation bats you just put on top of the panels as you drop them in. It also makes it easy to run any future electric needs.