Green Wall Glossary David Hurtado Oct 12, 2026 Table of Contents When a general contractor’s submittal log comes back with three different line items — “living wall,” “vertical garden,” and “preserved moss panel” — all referring to what the architect drew as a single wall elevation, the first casualty is the schedule. Someone has to stop and work out whether the subcontractor priced irrigation and lighting, or just a panel that gets screwed to a backer and never touched again. We see this gap most often between the design intent documents and the trade pricing that follows them. A design team may call out a preserved moss wall in the finish schedule, while the mechanical set shows a dedicated water line and drain for what the irrigation subcontractor assumes is a living system. Knowing the difference between living and artificial green walls up front changes which drawings, which trade, and which maintenance clause actually apply, and it is usually the first thing we clarify on a call before pricing starts. The terms below are the ones that come up most often in specification sections, submittal reviews, and facilities walkthroughs for vertical greenery of any kind: living, preserved, or replica. We have organized them by where they tend to surface: system type, structure and mounting, growing medium and water management, and material or maintenance performance. A quick-reference table follows the definitions for anyone who just needs the short version. Core System Types You Will See Called Out in a Spec Before the individual terms, it helps to picture how often a single project ends up drawing from the full range of green wall systems — live, preserved, and replica — sometimes across different floors of the same building, each chosen for a different light condition or maintenance budget. Green Wall Green wall is the umbrella term for any vertical surface finished with vegetation, real or replicated, rather than paint, tile, or panel material. It covers living systems, preserved moss, and replica foliage alike, which is exactly why the term alone is not specific enough to price or install from. Every other term on this list exists to narrow it down. Living Wall A living wall is a system of actual, living plants rooted in a growing medium that is itself mounted to or built into the wall, as opposed to plants rooted in the ground and climbing up it. Because the roots and the water supply both live on the vertical surface, a living wall always carries irrigation, drainage, lighting, and ongoing horticultural maintenance requirements that the other systems on this list do not. Green Façade A green façade uses climbing or trailing plants that are rooted at grade or in a planter and trained up a trellis, cable, or mesh attached to the building face. The wall surface itself provides structural support only. The plant draws its water and nutrients from the ground, not from anything mounted on the wall, which is the main thing that separates a green façade from a living wall in a specification. Preserved Moss Wall A preserved moss wall starts as harvested moss that goes through a glycerin-based preservation process, which keeps it soft and color-stable indefinitely without soil, water, sunlight, or trimming. Preserved moss wall systems get specified instead of a living wall whenever a space has no natural light, no plumbing access, or a maintenance budget that cannot support a standing horticultural service contract. Replica Green Wall A replica green wall is built from manufactured foliage engineered to match the color variation, leaf shape, and depth of real plant material, with no live component at all. Replica green wall systems are the most forgiving option for exterior applications, low-light interiors, or anywhere a facilities team wants a fixed, unchanging appearance year over year. Vertical Garden Vertical garden is a marketing term, not a technical one, and that is exactly the problem with it. We have seen it used in bid documents to mean a living wall, a green façade, and occasionally a replica panel, all within the same proposal package. When the term shows up in a specification without a system type attached, it is worth asking the design team which of the terms above they actually mean before pricing anything. Structural and Mounting Terms Modular Panel System A modular panel system builds the wall out of individual, pre-planted or pre-finished units, typically one to four square feet each, that lock into a shared frame and can be pulled and replaced one at a time. The distinction between modular and non-modular green wall systems matters most when something fails: a modular system lets a facilities team swap a single damaged cell, while a continuous system usually requires working on a larger section at once. Continuous Mat System A continuous mat system plants or finishes the wall as one unbroken surface rather than discrete panels, most often using a layered felt or fabric substrate stretched across the full elevation. It tends to read as a more seamless surface with fewer visible seams than a modular layout, but repairing or replacing a damaged section usually means working across a wider area than a single module. Backer Panel The backer panel is the structural layer between the wall substrate and the planting or foliage layer, and it is what actually carries the installed weight, not the moss, foliage, or growing medium sitting on top of it. Specifications that call out backer panels and attachment methods as their own line item are doing so deliberately, since the backer material, whether plywood, felt, or a mesh composite, determines how heavy a system can get and whether it can be serviced from the front. Mounting Frame (Standoff Mounting) A mounting frame is the substructure, usually aluminum or steel, that attaches to the building wall and holds the backer panel off the surface rather than directly against it. Standoff mounting, the most common version, leaves an air gap behind the finished wall that helps with drainage, ventilation, and running irrigation or electrical lines out of sight. Z-Clip Attachment A Z-clip attachment is a two-piece interlocking bracket, shaped like the letter Z in profile, with one half fixed to the wall and the other to the back of the panel. It lets a heavy panel hang securely while still being removable from the front for service, which is why it shows up so often in mounting hardware schedules for both living and replica systems. Freestanding Green Wall A freestanding green wall is self-supporting, built into its own structural frame rather than attached to a building wall at all, which makes it a room divider or a feature element as much as a wall finish. It carries its own footing, weight, and often its own irrigation or lighting supply, independent of whatever the adjacent walls are doing. Growing Medium and Water Management Terms These next terms apply specifically to living systems. A preserved or replica wall has no growing medium and no water system to define. Anyone who has read through a full installation process and technical considerations submittal for a living wall knows that irrigation, drainage, and structural review get reviewed as separate line items, each with its own inspection point before planting ever begins. Growing Medium (Substrate) The growing medium, also called the substrate, is the material plant roots actually grow into, commonly a mineral wool, coconut coir, or engineered soil blend rather than native soil, since native soil is too heavy and holds water unevenly on a vertical surface. The substrate choice drives root volume, water retention, and how long the system can go between irrigation cycles. Vegetation Mat A vegetation mat is a thin, fibrous felt layer that holds the growing medium and root structure in place against gravity, usually stitched or layered in pockets that individual plants are inserted into. It is the component most directly responsible for how quickly roots establish and how securely plants stay seated during the first several months after installation. Hydroponic System A hydroponic system grows plants with a nutrient solution delivered directly to the roots instead of through a soil-based substrate, usually through a recirculating reservoir and pump. It is lighter per square foot than a soil-based living wall and easier to automate, but it also depends more heavily on consistent power, pump maintenance, and water chemistry monitoring. Drip Irrigation Drip irrigation delivers water to each planting pocket or row through a network of small-diameter tubing and emitters, rather than overhead spray, which keeps water off the foliage and off the surrounding floor or finishes. It is the standard water delivery method for interior living walls specifically because it can be dialed down to the exact volume a given plant density needs. Drainage Layer The drainage layer sits behind or beneath the growing medium and channels excess irrigation water down to a collection point instead of letting it pool against the backer panel or the building wall. A drainage layer that is undersized or missing is the single most common cause of water damage complaints on living wall installations, which is why it gets its own line in most structural reviews. Root Zone The root zone is the depth and volume of growing medium available to plant roots, and it limits plant selection more than light or irrigation does on its own. A shallow root zone narrows the plant list to species with compact root structures, while a deeper system opens up a wider range of plant sizes and growth habits. Material, Performance, and Maintenance Terms Fire-Retardant Treatment Fire-retardant treatment refers to a chemical process applied to preserved moss or replica foliage so the finished material meets flame-spread requirements for interior finish materials in commercial buildings. It is typically documented with a test report from an independent lab, and a specifier should expect that report referenced by name in the submittal, not just a general claim of compliance. Acoustic Rating (NRC) NRC, or noise reduction coefficient, is a single number between zero and one that describes how much sound a material absorbs rather than reflects, and some preserved and replica green wall products carry a tested NRC rating because of the texture and depth of the foliage layer. A living wall is rarely tested or rated this way, since the acoustic performance of a planted surface depends on more variables than a lab panel test can capture. Preserved Moss Varieties Preserved moss comes in a handful of distinct forms that behave differently once installed: sheet moss, which grows flat and is used for large, even coverage areas; reindeer moss, technically a lichen rather than a true moss, which has a clumped, textured form and a wider color range after preservation; and bun moss, which keeps a rounded, three-dimensional shape and reads as more sculptural up close. Specifying by variety, not just “preserved moss,” avoids a mismatch between the sample board and what arrives on site. Maintenance Access Panel A maintenance access panel is a section of the mounting system built to be removed without disturbing the surrounding finish, usually positioned near irrigation valves, electrical connections, or structural anchors that need periodic inspection. Living systems need these far more often than preserved or replica walls, but even a replica installation benefits from at least one access point if lighting or power runs behind it. None of these categories are arbitrary. They mirror how Green Roofs for Healthy Cities classifies vegetated wall systems across the industry, and the same terms show up consistently from one manufacturer’s specification to the next as a result. Quick-Reference Glossary Table The table below condenses every term above into a one-line definition for anyone scanning a submittal or a specification section under time pressure. TermShort Definition Green WallUmbrella term for any vegetated vertical surface, living, preserved, or replica. Living WallActual plants rooted in a substrate mounted to or built into the wall. Green FaçadeClimbing plants rooted at grade, trained up a trellis or mesh on the wall face. Preserved Moss WallChemically preserved moss panels requiring no soil, water, or light. Replica Green WallManufactured foliage with no live plant component. Vertical GardenInformal, non-technical term used loosely for any of the above. Modular Panel SystemWall built from individual, replaceable planting or finish units. Continuous Mat SystemUnbroken, non-modular planting or finish surface. Backer PanelStructural layer carrying the installed weight of the finish system. Mounting Frame / Standoff MountingSubstructure holding the backer panel off the wall surface. Z-Clip AttachmentInterlocking bracket hardware for hanging and servicing panels. Freestanding Green WallSelf-supporting system not attached to a building wall. Growing Medium / SubstrateMaterial that plant roots grow into on a living wall. Vegetation MatFelt layer holding growing medium and roots in place. Hydroponic SystemNutrient-solution delivery to roots without a soil-based substrate. Drip IrrigationLow-volume, targeted water delivery through tubing and emitters. Drainage LayerLayer that channels excess irrigation water to a collection point. Root ZoneDepth and volume of growing medium available to plant roots. Fire-Retardant TreatmentChemical process meeting flame-spread requirements for interior finishes. Acoustic Rating (NRC)Noise reduction coefficient describing sound absorption performance. Preserved Moss VarietiesSheet, reindeer, and bun moss, each with a different installed look. Maintenance Access PanelRemovable section providing service access to hardware behind the finish. Conclusion A shared vocabulary does not replace a well-drawn detail or a complete specification section, but it does prevent the kind of mismatch that surfaces late: after bids are in, after a submittal gets rejected over a mislabeled system type, or after a facilities team inherits a wall nobody explained to them. Most of the confusion we run into traces back to one of two things: a term being used as a style descriptor rather than a system type, or a structural and mounting term being skipped over because it sounded like installer-only detail. Both are avoidable once everyone on a project, from the design team to the trade contractor to the facilities manager, is reading from the same list of terms. FAQ Is a vertical garden the same thing as a living wall? Not necessarily. Vertical garden is used loosely across the industry to describe a living wall, a green façade, or even a replica panel, so the term by itself does not tell you which system, or which irrigation and maintenance requirements, actually apply. Always confirm the underlying system type before pricing or installing from a document that only says “vertical garden.” Do preserved moss walls need any water or light? No. A preserved moss wall goes through a preservation process that keeps the moss pliable and color-stable on its own, with no soil, irrigation, or light requirement of any kind. That is the main reason it gets specified in interior corridors, below-grade spaces, and other areas where a living system could not survive. What is the real difference between a modular and a continuous mat system? A modular system is built from discrete, individually replaceable units, while a continuous mat system is one unbroken surface. The practical difference shows up at repair time: a modular system lets a facilities team swap a single damaged section, while a continuous system typically requires working across a wider area to fix the same kind of damage. Why do some specifications separate the backer panel from the planting or foliage system? Because the backer panel, not the moss or foliage layer, carries the installed weight of the whole system and determines the mounting hardware and wall load calculations. Treating it as its own line item keeps the structural review separate from the finish selection, which is how most reviewing engineers prefer to see it submitted. Can a replica green wall carry a tested acoustic rating? Yes, some replica systems carry a tested noise reduction coefficient because of how the foliage layer’s depth and texture interacts with sound, while a living wall is rarely tested this way at all. If acoustic performance is a project requirement, ask for the specific NRC test report rather than assuming any vegetated finish performs the same.