Welcome to the forum. Although you can post in any forum, the USA forum is here in case of local regs or laws
Ok. Im surprised. Ill take ur word for it. Only thing is that removal of grate, if required becomes difficult.Perfectly correct should be through the grate.
Reply to the thread, titled "External drain pipe" which is posted in DIY Plumbing Advice on Plumbers Forums.
We recommend City Plumbing Supplies, BES, and Plumbing Superstore for all plumbing supplies.