Shed / Office roof install

[SALL2009]

This is a general question to get a better understanding behind the reasons of doing something a certain way.

I am researching building a office in the garden and have been reading up and looking at videos on the process.

In almost all cases, the base is built based on the required measurements and then placed in the desired location. Each wall is then built and then fixed in its desired location. But this is not the case when it comes to the roof. Each rafter is installed individually on the building, then the front and back plates are attached.

My question is why isn't the roof structure built as a unit based on the desired measurements and once fully ready, attached to the building?

 

[Notch7]

Generally the floor and roof are too big to build in one.

It's not too hard to assemble the wall framework laid flat then raised upright.

It's very hard to lift a whole roof up onto the walls ....only light sheds are done that way

 

[SALL2009]

Generally the floor and roof are too big to build in one.

It's not too hard to assemble the wall framework laid flat then raised upright.

It's very hard to lift a whole roof up onto the walls ....only light sheds are done that way

Thanks, that makes sense. The idea of building and then moving in place seems easier, but I bet it will be much heavier than I'm imagining in my head.