When installing new construction windows do you rest them on the sill or do you shim them up 1/4 inch for an equil gap top and bottom? Do you nail every nailing hole? Do you sink the nails all the way tight against the tab or leave them slightly loose? Any tips would be great.
When in doubt, always follow manufacturers directions. I do it both ways, on the sill and spaced. If the sill plate is not level, you have no choice. But setting it up will keep it out of water should the window leak. And don't forget to install a sill shield for leak protection. Nail tightly, but not overly so. Caulk the nail fin, then install self stick flashing starting at the bottom, sides, top. Aluminum flashing on top up under house wrap, and down over the window.