http://ecode360.com/index/NE1082/W see window grills. Newburgh abides by NYS codes or the stricter of the two…http://www.cityofnewburgh-ny.gov/buildingcode-enforcement
Head’s up, it’s best to get verification rather than self interpret. Fwiw, the general rule requires x amount of accessible egress per x amount of living space. I’ve actually had to rework new windows to gain an additional sq.’ as larger units didn’t work into the aesthetics. That said, look up at Newburgh’s mid-rise rentals and count how many have safety grills you see. Doesn’t make sense.
Btw, if it comes down to it, have a local tile/marble supplier cut your mantel pieces according to size. Hone them yourself with 3,4,600 grit wet/dry sandpaper (lots of water) to take down the shine and present that vintage look. I did my bath floor as such and it looks great.