i agree with Nigel in various ways, I actually bought 8inch techs to tap into the frame. “the cladding had a cavity”
however, the wood techs do not need it. they hold very strong on there own. ide go with these any day over the likes of rivets, (sorry peter) but techs are much faster and are better on the whole.see a link, this sign was heavy, each section I mean. the whole thing ways god knows what… only wood techs holding it up. see cladding, we could only catch the high parts at about 2inch wide max.
screw through the box frame/straps into the cladding.