Edit: I gave spec's on local condition that were incorrect
for the Houston area, after doing a search I found these spec's for the conditions of the Houston area.
>>As far as roof and ceiling framing is concerned, I tend toward a "standard" 24 inch spacing for the rafters and joists, use No. 3 SYP is possible and choose depths accordingly. Contrary to what some here have opined regarding "wind uplift," when you are doing a home in the Houston metro area, a rural location here gives you AT LEAST 110 MPH (3-second gust) and Exposure "C", which can really kick the h*ll out of a rafter with a long span, so the depth becomes an issue. I tend to like 8' nominal myself.
Anyway, just had an architect send back my plans, with the comment that "you've got 24 inch spacing, we always use >>>16 inch<<<" and "why are you using 8 inch deep rafters? 6 inch should always be 'good enough.'" That was the essence of his complaints<<