Spacers to top of page

I would like to create a wider space above the top system of a page--not by adjusting the top margins, which would affect all pages, but only on specific pages. I have tried to achieve this using a Staff Space Up, which sometimes pushes the system away from the margin, and sometimes just seems to trail off beyond the edge of page. I can't figure out why this happens only on certain pages.

I suppose I could also achieve this by creating a horizontal frame above the top system.