Replacing garage roof with Coroline

[John Davison]

Hi,
I’m planning to replace my double garage roof with a coroline roofing sheet. The current roof is concrete sheets which while intact are leaking at the joints and are very old. The roof is in need of replacing and I’d like to tackle it in the summer.
The garage is 6.2m front to back and 7.35m wide, stone built. The roof has a 10 degree slope running from the front to the back. The roof currently has a central steel beam running downhill with the slope front to back, with timber joists spanning between the steel and the side walls, perpendicular to the slope. There are only 5 joists, 8” by 2” over the entire length with the roofing sheets screwed into them.
I’m keen the use the coroline as an easy replacement but it needs purlins at 600mm centres so I have two problems:
1. The current joists run the wrong way to use to attach battens.
2. The current centres are too wide to use directly.

Any thoughts on options?

Am I best using hoist hangers to add in some more joists, closing the centres and just attaching the new roofing sheets directly on? I am thinking I could get away with a smaller beam size given the lightweight roof? Alternatively I could put battens in both directions to create a grid?

 

[catlad]

Hi John
counter batoning is one option if you can cope with the extra height! adding extra joists is the other option 4x2" between the ones you have would be ok if you put a noggin/brace at the central point between your 8x2" if that makes sense.
the other option is buy some anti condensation box profile steel sheets cut to size then you don't need to bother with the extra joists.

 

[Mw Roofline]

We’ve got about 200 new coroline sheets in the lock up that we might sell off cheap due to a cancelled job. Don’t spose you anywhere near Brum?

 

[Mw Roofline]

Thanks Catlad, thanks MW Roofline. No problem John, here to help.