Building envelope · Facades & Cladding
Vegetated (Living Wall) Facade System
This entry sets out what a living wall asks of the building it is fixed to: containment working against gravity, an irrigation and drainage loop, a separation keeping a permanently damp system off the wall, and access without which the planting cannot continue.
Educational reference entry. How this system behaves depends on climate, jurisdiction, loading, substrate, the adjacent systems it meets, how the building is used, the manufacturer's instructions and qualified professional design.
Overview
What vegetated facade is
Plants are grown on a vertical face, either rooted at the base and trained across a support grid, or held in modules and containers carrying their own growing medium up the elevation. Both arrangements share the same underlying construction problem: a facade that is alive needs water, drainage and containment, and the wall behind it needs to stay out of contact with all three.
The nearest sibling is the ventilated rainscreen facade system: both stand a frame off a wall on brackets over a void that is deliberately kept open, so the test is what the void is doing. Behind a rainscreen it drains and ventilates a backing wall that is wet only when it rains. Behind a planted assembly it separates the wall from something irrigated and damp by design, and carries a supply and a drainage route as well as air. On a building the difference reads as pipework, outlets and access provision rather than as a change of cladding.
A living wall also differs from every other facade in this category by depending on something that grows, dies and is replaced. Its condition over time is a function of water reaching the right places, of maintenance actually happening, and of whether anyone can physically get to the plants. A living wall that cannot be reached is already failing, regardless of what it is built from. Irrigation design, water demand and structural capacity are determinations for qualified professionals.
Terminology
Common names and aliases
These names describe the same assembly. The encyclopedia keeps one entry per system so that a trade term or a regional name never becomes a second, thinner page.
- living wall
- green wall system
- vertical greening system
- planted facade system
- green facade
Purpose
What this system is intended to do
The job the assembly exists to perform, conceptually. An intention is not a guarantee that any particular build achieves it.
- Establish and keep a planted surface on a vertical face where plants would not otherwise root or hold.
- Contain growing medium against gravity so that it stays where it was placed rather than migrating downwards.
- Deliver water to a face that receives far less rainfall than a horizontal surface of the same area.
- Collect and remove what the planting does not absorb, and keep both the water and the medium off the construction behind.
- Keep the building fabric separated from a permanently damp system that sits directly in front of it.
Composition
The roles this system is made of
What each part does in the assembly and what it depends on — never a product, a thickness, a fixing or a determination that anything is adequate for the role.
Order is not meaningful in this system. These roles interact as parts of one whole rather than stacking up in a sequence, so the list below is not a build-up and nothing should be read into the order it appears in.
- Primary supportSupport frame back to the wall or ground
The framework carrying the planted assembly, its growing medium and the water held within it. Because a saturated planted system weighs considerably more than a dry one, what the frame is fixed back to is a structural question resolved before anything is planted.
- Cavity or voidSeparation void between planting and wall
The space held open between the planted assembly and the construction behind. It keeps the wall out of contact with wet medium, gives water somewhere to run, and lets air move behind a face that is otherwise damp for most of its life.
- ProtectionProtective sheet over the construction behind
A sheet or coating shielding the wall from moisture, from roots and from the irrigation supply in front of it. It works with the void rather than instead of it, since a sheet alone leaves a wetted surface pressed against the building.
- SubstrateGrowing medium and its containment
The medium the plants root into, and the trays, panels, pockets or bags holding it against gravity. Containment here is structural rather than incidental: if it fails, the plants lose their root zone, and the medium arrives on the pavement below.
- Finish surfacePlant layer
The living face, chosen for the orientation, exposure and light that this particular elevation receives. It is the only component in this category that changes by itself, and its condition is the most visible measure of whether everything behind it is working.
- Service zoneIrrigation supply and control
Pipework, emitters and the control that decides when water is delivered and how much. On a vertical face water arrives unevenly, so the distribution is designed rather than assumed, and any failure appears first as dieback in a band across the wall.
- Drainage planeCollection, drainage and overflow
The route by which water not held in the medium leaves the assembly, together with somewhere for it to go. Whatever is applied has to be collected, or it appears at the base of the wall, on the pavement, or against the construction behind.
Interaction
How the parts work together
The reason this is a system rather than a list of parts: what depends on what, and what stops working when one part is changed.
Turning the assembly vertical changes the role of every part. Growing medium that would simply lie on a roof now has to be held, so the containment becomes a structural component whose failure removes the root zone rather than merely spilling material. Water that would arrive as rainfall now has to be delivered, so irrigation moves from an aid to a dependency. And the assembly's weight changes with how wet it is, so the frame is designed around a saturated condition rather than the condition it is planted in.
Irrigation and drainage are one loop, not two provisions. What is applied at the top has to be intercepted and removed at the bottom, and the plants take only a share of it. A blocked outlet does not stop the supply; it turns a controlled wetting into a continuously wetted face, and the water finds the lowest route available, which is often the junction between the assembly and the wall. Overflow needs a destination that is neither the building nor the footway.
The separation is what keeps a damp system from becoming a damp building. The planted assembly is wet for most of its life by design, and the construction behind it needs to be able to dry. A void that is bridged by a bracket, a pipe run, an accumulation of medium or a root finding a joint puts the two in contact, and the consequence appears inside the building long before it appears on the plants.
Finally, the living component makes maintenance structural rather than optional. Plants die back, get replaced, outgrow their containment and shade one another; emitters block and controls drift. Whether any of that can be attended to depends on access designed alongside the facade. A living wall usually fails as a maintenance and access problem that first shows itself as a horticultural one.
Materials
Material families commonly met in each role
Commonly encountered, not recommended. Whether a material suits a given project depends on the whole assembly, the exposure, the manufacturer's documentation and qualified professional review.
Attachment
Frame, bracket and mesh components of these families are commonly encountered supporting planted assemblies and climbing plants. Because a saturated system is heavy and permanently damp, the arrangement and the metal are matters for the design team.
Protection
Sheet families of these kinds are commonly encountered protecting the construction behind a planted face. Whether any of them can be exposed to constant damp, to roots or to an irrigation supply is a question for the manufacturer's documentation.
Jointing and sealing
Sealing components of these kinds are commonly encountered where brackets and irrigation lines cross the construction behind. Each crossing sits in a permanently damp zone, which is a condition the designer confirms against the product documentation.
Junctions
Where this system meets others
Interfaces are where most assemblies actually fail, so they are set out explicitly rather than left inside the prose. What resolves a junction is a detail designed for the specific building — not a rule of thumb.
The wall behind a permanently damp face
The construction behind is asked to sit in front of a wet assembly for its whole life. Which plane controls water on that wall, and whether it can still dry, becomes a more demanding question than it would be on an exposed elevation.
Read about Water Control Layer →Brackets and irrigation lines crossing the wall
Every frame fixing and every water line that reaches the building is a penetration made in a damp location and then covered by planting. The seal has to tolerate that environment, and it will not be inspectable once the assembly is established.
Read about Penetration Sealing →Planting stood off a clad wall
Where the wall behind is itself a screen over a cavity, the planted frame is fixed through cladding that was designed to carry only itself. What the brackets actually reach, and whether the cavity behind stays drained, has to be established before fixing.
Read about Rainscreen Facade →Where collected water goes
Run-off and overflow arriving at the base need a destination that is designed rather than incidental. Discharging onto paving produces staining, slipperiness and freezing, and discharging against the wall reverses the point of the separation.
Read about Surface Water Collection →Where irrigation water comes from
Supply may come from the mains or from collected rainwater, and the two impose different requirements on storage, filtration and control. The choice affects what happens to the planting during a dry spell as much as it affects the demand placed on the mains supply.
Read about Rainwater Harvesting →
Considerations
Topics worth discussing
Which topics genuinely apply to this system and what to raise about them. Measured values, classes and ratings come from a qualified professional's design for the specific building, not from a reference page.
- Moisture
- The assembly is designed to be wet, so the question is never whether moisture is present but whether it is separated from the construction behind and able to leave. A wetted band on an internal wall usually traces back to a bridged void or a blocked outlet.
- Durability
- Fixings, containment and pipework live permanently in a damp, sometimes fertilised environment, which is a harsher setting than the same components would see on an open facade. That environment, rather than exposure to weather, sets how they age.
- Maintenance and access
- Planting, irrigation and drainage all need attention that cannot be deferred without visible loss. Whether the whole face can be reached safely, and how, decides more about the facade's future than the choice of planting does.
- Interfaces
- This facade brings water supply, drainage, structure, planting and the building envelope into one assembly, each usually designed by a different party. The junctions between those responsibilities are where the provisions tend to go unowned.
- Fire
- Vegetation, growing medium and the void behind them raise questions about a facade that this entry does not answer. They are determinations for the relevant authority and for qualified professionals, considered for the specific building and its use.
- Documentation
- The irrigation layout, the fixing positions and the drainage route become invisible as soon as the planting establishes. Recording them is what makes a later fault traceable rather than a matter of stripping back a living facade to look.
Design
Questions the design has to answer
The decisions this assembly turns on. They are questions rather than answers, because the answer depends on the building.
- What holds the assembly when it is fully saturated, and whether the wall or structure behind can accept that, is a structural question asked first.
- How water is delivered across the whole face, and what happens to the planting when the supply is interrupted, needs answering before planting is chosen.
- Where collected water and overflow discharge, and whether that destination stays clear in winter, is part of the drainage design rather than an afterthought.
- What keeps the assembly separated from the construction behind, and whether anything bridges that separation, decides how the building fabric ages.
- How every part of the face will be reached for replanting, pruning and irrigation checks is a design decision, not an operational one.
- Which orientation and exposure this elevation actually has determines what can grow there, and it cannot be changed by the system chosen.
- Who is responsible for the planting after handover, and with what information, decides whether the facade survives its first dry season.
Boundaries
Commonly misunderstood points
Distinctions that are easy to blur, and the places where a familiar term means something narrower than it sounds.
- A living wall is treated as a planted version of a green roof, when gravity reverses the role of containment and of water supply.
- The planting is seen as the system, when the working parts are containment, irrigation, drainage and the separation behind them.
- Irrigation is regarded as an optional refinement, when a vertical face receives little of the rainfall a horizontal one collects.
- Dieback is read as a plant selection problem, when it more often marks where water stopped arriving or where drainage stopped working.
Conversations
Questions for qualified professionals
Bring these to the relevant qualified professional, manufacturer or authority. Requirements vary by project and location.
- What does this assembly weigh when fully saturated, and what has been confirmed about the structure carrying it?
- How is water delivered across the whole face, and what happens to the planting if the supply or the control fails?
- Where does collected water and overflow discharge, and how is that route kept clear and free of freezing?
- What separates the planted assembly from the construction behind, and how is that separation kept unbridged?
- How will every part of the facade be reached for pruning, replanting and irrigation maintenance?
- What has the fire strategy determined about vegetation, growing medium and the void behind this facade?
- What information will be handed over about the irrigation layout, the fixings and the drainage route?
What this page does not do
- Nothing in this assembly keeps the building dry on its own; that depends on the separation, the drainage and the protection behind acting together.
- A living wall imposes an ongoing maintenance and water commitment, and withdrawing either produces a dead facade rather than a dormant one.
- Fixing a planted assembly to cladding rather than to a nominated structural element loads a component designed only to carry itself.
- Irrigation demand, structural capacity and any water supply arrangements are determinations for qualified professionals for the specific building.
- Vegetation, medium and the void behind them are considered by fire design carried out separately, and this entry makes no determination about them.
Related systems
How this system relates to others
Every link states what the relationship actually is, rather than leaving a bare list of related pages to be read as a suggestion.
Alternatives
Different systems answering the same need. Listing them together is not a comparison and does not suggest one is better — which, if either, suits a project is a design decision.
Meets these systems
Systems this one physically meets. The junction is usually where the design problem lives, so these are worth reading together.
Commonly built alongside
Systems routinely present in the same building without necessarily touching this one.
Go deeper
Related Build Design Hub guides
Planning guidance behind the decisions this assembly involves.
Preparation
Related planning checklists
Owner-side preparation before the conversation where this system comes up.
Inspiration
Related Ideas Library pages
Design directions where this system commonly appears.
Facade and Cladding Systems
Outer skins carried on a wall that is already complete behind them, where the support, the joint and the cavity carry the durable knowledge rather than the finish.
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