Interior corners on the roof or house tend to cause problems, though. Debris builds up and ignites, and just impinges on the siding until you light something behind it.
You can also have firebrands entering through attic vents and bypassing the roof - there are vent types that are resistant to this, but tend to cost a good bit more.
Why we don't do this in urban wildland interfaces... no idea.
Check Class A roof tests. A lot of asphalt shingles, properly installed, actually are Class A fire rated - which is a 12x12 2kg grid.
https://www.builddirect.com/learning-center/building-materia...
Interior corners on the roof or house tend to cause problems, though. Debris builds up and ignites, and just impinges on the siding until you light something behind it.
You can also have firebrands entering through attic vents and bypassing the roof - there are vent types that are resistant to this, but tend to cost a good bit more.
Why we don't do this in urban wildland interfaces... no idea.