I feel eaves are more to keep the drip line from rain from hitting the foundation than for any heat abatement. Typical spanish style roof will not have anything on the side that isn't sloping for example. Just sort of ends flush with the wall. Some don't have any eaves at all really.
Strange then then places with lots of rain and wind (Ireland, Netherlands come to mind) hate eaves. I guess it keeps builders in business.
Ironically when I had a 200 year old thatched cottage it had 'eaves' by virtue of the thatch extending almost a meter from the wall. It had built up slowly over centuries of rethatching.
My experience is mostly with Californian houses that definitely had eaves.
Just from some internet searching looks like in netherlands they use gutters extensively to move rain off the foundation. ireland too. the thatch houses it seems like they need to whitewash the masonry with limestone paint frequently that helps some.
Looks like the bottom row of masonry is actually failing here due to the rain damage and lack of upkeep on limestone paint. It will have to be repointed eventually.
Another thing with the califnornian spanish style home is the foundation is usually post and pier vs actual masonry exposed to a potential drip line. The one traditional californian design that tends to have eaves is the craftsman. I think it is a bit of an imported design from out east though, wasn't present in the mexican era. Some of these craftsman are on post and pier and don't really need them per say. But others actually have masonry foundations sometimes river rock foundations. I think there is also an aspect of venting the roof space through exposed rafter vents and you probably don't want water getting into unfinished wood.
When you look at even hotter climates, e.g. traditional adobe, no eaves there at all. Rafter beams just hanging out freely.
