Garage roof (calculate extra joists for storage floor)

[Cliveyp]

I’m looking to add some additional support to my new build garage roof trusses prior to boarding the space out and using it for some general storage. In typical ‘new build’ ways, the developer has said that the existing trusses are not suitable for supporting any more weight than the roof and snow load, and I’m tempted to agree.

Below is a quick photo of the lay of the land. Width of the garage is approx 3m, length approx 6m. I’m looking to run some joists across the width, potentially across between the block piers, and two extras in the gap between these. I don’t feel that the front and rear sections need the support due to the roof slope not really allowing much room for storing anything.

what size joists would be best for this? 150x50 adequate or should I be going bigger?

 

[jake7462]

Not entirely true - standard practise is for trusses to be designed for a storage load of 25kg/m2 over the bottom chord...

But yes 47 x 150 joists at say 400ctrs would be plenty - bolt a timber bearer to the wall and support the new joists on jiffy hangers.

 

[Cliveyp]

Not entirely true - standard practise is for trusses to be designed for a storage load of 25kg/m2 over the bottom chord...

But yes 47 x 150 joists at say 400ctrs would be plenty - bolt a timber bearer to the wall and support the new joists on jiffy hangers.

Thanks, I appreciate your input. The joists would be further than 400ctrs though - more like 970mm with the 4 spaced across the central ‘segment’. Am I much too far apart now?