Can you elaborate on "weight loads on ceilings" ?
This post has kind of inspired me to follow up on my plan to make a storage area in the roof cavity over my garage.
Do you mean non-trafficable ceilings? My house is designed with timber ceiling joists around 450mm apart suspended from the A-frame roof.
I asked about it on some DIY sub a while back and the consensus was that it's fine for some boxes of junk.
Obviously I share your and OPs concerns about overhead loads. I'm trying to figure out how comfortable I am with this.



