Two questions come up more than any others: how tall does my railing have to be? and what is the 4-inch rule? Here is the plain-English version.
The short answer
Under the residential code you need a guard anywhere the drop is more than 30 inches, and that guard has to be at least 36 inches tall. Plenty of situations call for 42 inches instead — most commercial work, many multi-family buildings, and some states as a matter of course.
Every Barzel railing is built in both heights. Tap 36" or 42" on the product page and the drawing and the price move with it.
Which one do you pick?
- A house deck, porch or interior loft — 36" normally passes. If you are not sure, 42" always does.
- A rental, mixed-use or commercial space — go 42".
- A high deck, a rooftop, or anywhere kids play — a lot of people choose 42" even where 36" would pass.
Codes do vary by town, and your building department has the final word — a two-minute call settles it. Send us your project and we will tell you what we usually see in your situation.
The 4-inch rule
Height gets the attention, but an inspector checks the gaps just as closely. The rule is simple: a 4-inch sphere must not pass through any opening in the railing. It is a child-safety standard.
This is where a lot of railings fail. The bar spacing works at one length, then the design gets stretched to cover a wider opening and the gaps open past 4 inches.
Ours does that math on its own. Whether your panel is 3 ft 2 in or 9 ft 11 in, the spacing on every Barzel design stays inside the rule at every length. Slide to your measurement and the drawing on screen is the layout we weld.
Stairs follow a different rule
A stair handrail is measured from the nosing line, not the floor, and it sits between 34 and 38 inches. There are separate rules about the shape, so your hand can close right around it — our handrails are built to meet them. If the stair itself also needs a guard, send us the rough numbers.
Ready to size yours? Pick a design, tap your height, and slide to your length. Free shipping in the continental US, welded in our New Jersey shop.