I was told by my building inspector that our area has a ground snow load of 45, how do I use this value to calculate the rafter live loads?

I thought I read somewhere that the snow load could be reduced by having a roof with an angle of 20* or more, is this correct, if so what is the reduction calculation?

You don't have to do a conversion, because there are span charts in the building Code, and you read the rafter size directly from the charts using the ground snow load.

So the ground snow load would be used as the live load. But what about ways to reduce the snow load? Is there a certain degree roof say 20* that lets you reduce the GSL? On charts that I have seen there was no 45 live load so would you have to use the 50 live load? Thanks for taking the time to look at these questions.

Why cut corners? What is the cost difference between 2x8 rafters and 2x10 rafters? The labor is the same. So it's only the cost of materials that is in question...and if the charts are close to maximum for the load and span, you'll want to go up to the next sixe lumber anyway!

r6,
Richard is correct, you have to read the chart that exceeds the minimum requirements which would be the 50psf on the appropriate chart for cieling attached or not. As for the 20 degrees, any roof less than 3/12 pitch (or 25 degrees) sturctural members that support rafters and ceiling joist, such as ridge beams, hips and valleys, shall be designed as beams. So, being over 25 degrees allows for less design criteria but it does not change the snow load requirements listed in the charts. It may have been that note that you were thinking. Good luck and ideally your building inspector (assuming your speaking of your county code inspector not your real estate inspector) should be able to help you calculate the spans.