Building & Construction What is the 4 inch rule? February 6, 2026 by Myaya | Leave a Comment The 4-inch rule is a building code requirement that ensures safety by limiting the maximum size of openings in guardrails, balusters, and stair railings to prevent small children from slipping through or getting trapped. What is the 4-Inch Rule in Building Codes? The 4-inch rule is an essential safety standard in building codes designed to […] Read more ยป