Can someone explain OSB as joists/flooring and exterior layer in houses in the USA?

[bygges]

I have noticed that OSB in house construction in the USA seems to be part of almost every aspect of a house. Can someone with knowledge explain to a curious person how their joists with OSB work? Compared to 220 x 45, it must be immensely weaker, right? Is the OSB board glued to the top and bottom to, well, is it 28 x 70 furring strips?

And why do they use OSB on the outside of houses, is it instead of our exterior gypsum board or does it have a load-bearing function, i.e., to tie together standing studs?

 

[Daniel 109]

I have noted that OSB in house construction in the USA almost seems to be part of every stage in a house. Can someone with knowledge explain to a curious person how their floor joists with OSB work? Compared to 220 x 45, it must be much more slender? Is the OSB glued on the top and bottom to, well, is it 28 x 70 glespanel?

And why do they use OSB on the outside of houses, is it instead of our exterior gypsum board, or does it have a load-bearing function, i.e., to bind together the vertical studs?

It is a type of lightweight beam. The OSB is glued to the studs above and below.
The boards contribute to making it a rigid construction.

 

[Tjrex]

Google lättbalk and you'll find a lot of info.

 

[Peter787]

I've noted that OSB in house construction in the USA seems to be part of almost every phase of a house. Can someone with knowledge explain to a curious person how their floor joists with OSB work? Compared to 220 x 45, it must be incredibly much weaker? Is the OSB board glued on the top and bottom to, well, is it a 28 x 70 open panel?

And why do they use OSB on the outside of houses, is it instead of our exterior gypsum or does it have a load-bearing function, i.e., to tie together the upright studs?

Regarding the floor joists, compare it with what is called "Lättbalk" in Sweden, where the middle part 'the web' of the beam is made of masonite.
For a static load and correctly calculated, they hold as well as a glulam beam.
The downside is fire resistance and dynamic loads, primarily in the lateral direction.
Everyone has probably seen American suburban areas on TV after a hurricane...

 

[bygges]

Thanks for the info about lightweight beams!

What's the deal with OSB as a surface layer before the paneling?