It's like when Americans say British people have fucked up teeth. I don't actually believe that, I just say it to make British people mad.

Mocking our construction is a European joke that they love because it makes Americans mad. Simple as

Ok, I'll walk you through it. I am OP btw

I believe the basic structure is called a "bait and switch", a fairly common writing trick

I asked a builder why this was, and he said that the lateral forces created by a slightly tilted window

This is the "bait" bit. It sounds like a real comment so far

has just enough force to rip the entire side of a house clean off

This is the part where, if you didn't have the reading comprehension of a six month old duck, you'd start to realise that, perhaps this wasn't a serious comment. There's no way a slightly tilted window is ripping the entire side of a house off, surely? That's the "switch"

due to houses having the structural integrity of wet newspaper,

This line is pretty much only there as a setup to the next line. Houses, I'm sorry to inform you, do not have the structural integrity of wet newspaper. That would be as dangerous as it is impractical

which is the preferred construction method in the States

This bit, unsurprisingly, isn't exactly true either

I hope, now that I've broken the comment into its constituant parts, that you're rolling on the floor, clutching your aching ribs and laughing tears of joy.

Explaining jokes always makes them far funnier