International Building Code regulations state that a deck railing must be at least 36 inches high if the deck is 30 inches or more higher than the adjoining ground. Some states and municipalities adopt variations of IBC regulations, and builders should always check local regulations for accurate guidelines.
There are no regulations governing the height of railings on decks closer than 30 inches to the ground, but guards must be strong enough to withstand people leaning against them. Guardrails should be able to withstand 500 pounds of pressure, and balusters must hold up to 125 pounds. Spacing rail posts no more than 6 feet apart typically provides adequate strength. Balusters,which are vertical rail components that stop people falling under the guardrails, should be spaced no more than 4 inches apart.