Hmmmm, you might try just buying Mathcad. I suspect that grade beams for homes aren't that difficult to by hand, you just want to computerize them. Mathcad allows you to type in the equations just as if you are doing them by hand. I do all of my simple calcs this way. I then save one as a template and re-use it as necessary. A long (i.e.,4-5 page) calculation might take you 2-3 hours to type, debug, format and extend. The debugging is easy, the formulas read normally. If you understand the equations you are working with then this will be no problem. The aspect of setting up the template that takes me the longest is the formatting (being a perfectionist I HAVE to get it JUST so) and the extensions. It's taken me a while to learn the self discipline not to cover all bases when I first write a sheet. Write the sheet to cover what you need now, then add on as new situations require.
