We are expert in railing and fittings of stainless steel glass railings, stainless steel hand railings, stainless steel spider fittings, stainless steel clamps, modular stainless steel work, stone cladding clamps, stainless steel clamps, handle. Under the Ontario building code, horizontal railings that are used as deck, ramp, or stair guards are illegal. All guards must be vertical, unless, of course, the raised building platform is less than 36 inches above grade. ... That bottom railing should not be more than 4 inches from the floor.

The IRC requires that the space between your balusters or boards must be less than 4″. To be on the safe side, I recommend using 3.5″ for your spacing. The last thing you want is to build your railing, and have an inspector not pass it because he's able to fit a 4″ object through your railing.