Guide
On a rooftop or podium, weight isn't a detail — it's the brief. Get it right and the garden thrives within the structure's limits; get it wrong and you risk overload or remediation. Here's how we plan planter weight on elevated projects.
Every roof, podium and balcony has a designed load capacity set by the structural engineer. Planters, soil, water and plants all count toward it. The first step on any elevated project is to confirm the allowance (and where the stronger structure is) before sizing planters.
A planter's real load is its saturated weight: the planter, fully wet soil and mature plants after watering or rain. Always design to saturated weight, not the empty figure — it can be substantially higher.
The lighter the planter itself, the more of the load budget goes to soil and greenery. Aluminium is around a third the weight of steel, which is why we recommend it for most rooftop work. See benefits of aluminium and how we work on rooftop gardens.
Where needed, we position planters over beams or stronger zones, use feet to distribute point loads and protect the membrane, and configure soil volume to balance plant health against weight.
We provide unit and saturated weights and setout information so your engineer can confirm the design. Precise on-site measurement with the Leica ICS 50 means placement matches the plan exactly.