Transforming a wrought iron balcony into an urban garden is an exciting project, but its success hinges on one critical question: how much weight can it safely hold? There is no single "typical" weight limit, as capacity depends entirely on the balcony's original design, construction quality, installation method, and current condition. A well-built, professionally installed wrought iron balcony might safely hold several hundred pounds, but this must include the weight of the planters, soil, plants, water (which is surprisingly heavy), and people.
Before adding several planter boxes, you must consider key factors. First, assess the balcony's attachment to the building; is it bolted securely or simply bracketed? Examine for rust, corrosion, or weld cracks, which significantly weaken the structure. Understand that weight is not just added; it's leveraged. A planter at the balcony's edge exerts more force than one placed against the wall. For estimation, a large wooden planter box (e.g., 4 feet long) filled with damp soil can easily weigh over 200 pounds (90 kg).
For your safety, always consult a qualified structural engineer or contractor. They can inspect the specific connections, metal gauge, and design to provide a professional load assessment. Do not rely on guesswork. Distribute weight evenly, use lighter soil mixes, and consider smaller, multiple planters instead of a few massive ones. Prioritizing this assessment ensures your green oasis remains a secure and joyful retreat, not a structural hazard.