Building envelope · Facades & Cladding
Ventilated Rainscreen Facade System
This entry sets out how duty is divided in a rainscreen facade - which layer screens, which drains, which controls water and air - so a reader can see why an open joint is deliberate and where the assembly depends entirely on the wall behind it.
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 rainscreen facade is
A rainscreen facade splits work that a solid wall does in a single plane across several separate ones. The visible skin intercepts wind-driven rain and most of the wind pressure, but nobody expects it to exclude water altogether. Behind it a cavity is held open so that anything crossing the skin runs down a defined face and leaves at a defined point, and so that air can move through the space and carry away moisture that would otherwise sit against the construction.
The nearest sibling is the brick slip cladding system, and the boundary is visible from the pavement. A rainscreen tolerates open joints because the drained cavity behind it is doing the work; a brick slip facade presents a continuously jointed face whose pointing is expected to keep most water out. Where shadow shows through the gaps between panels, the facade has already told a passer-by which of the two it is.
Behind the cavity, the backing wall holds what actually matters: the sheet or applied coating that governs water and air, and the insulation sitting outboard of the structure. The subframe carrying the cladding has to cross both of those layers, which is why the fixing arrangement is at once a structural question, a thermal question and a penetration question rather than an ironmongery choice made late.
Pressure equalisation is often described as the mode in which such a facade works: the cavity is compartmented so that pressure within it can rise towards pressure outside, easing the force that pushes water inward through joints. Whether a particular facade behaves that way depends on compartmentation, joint geometry and exposure, and is assessed by the facade designer rather than assumed from the presence of a gap. It is not the materials-library entry cladding-support-systems, which is the bracket and rail product rather than the drained and ventilated arrangement it is used within.
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.
- rainscreen cladding system
- drained and back-ventilated facade
- ventilated facade
- back-ventilated cladding
- open-jointed cladding
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.
- Intercept the bulk of wind-driven rain at an outer surface that is never asked to be free of joints.
- Give water that passes the screen a defined face to run down and a defined place to leave from.
- Keep air moving behind the cladding so the backing construction can dry outwards instead of staying damp.
- Locate the water and air control layers on the backing wall, where they stay continuous and independent of the visible finish.
- Carry cladding self-weight and wind load back to the structure through a subframe that also absorbs building and cladding movement.
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 meaningful in this system. The roles below sit in sequence, and moving one relative to another changes what the assembly does. The sequence is conceptual only: it states no thickness, no dimension, no fixing and no order of work on site.
- Layer 1 of 8. Order is meaningful.Finish surfaceOuter cladding screen
The visible panels, boards or planks. They take wind pressure and most of the driving rain, shade the construction behind them and set the appearance, but they are not relied on to exclude water at their joints, and those joints may be open by design.
- Layer 2 of 8. Order is meaningful.Cavity or voidBack-ventilated cavity
The continuous space between cladding and backing wall. It is open to outside air near the base and the head so that air can move through it, and it is intended to stay unobstructed so that water running down the back of the cladding is not carried across to the wall. Whether a particular cavity does that is settled by the facade design and by what is actually built.
- Layer 3 of 8. Order is meaningful.Drainage planeDrainage face and cavity outlets
The face at the back of the cavity that water is intended to run down, together with the trays and openings that let it out again. Wherever a bracket, a floor edge or an opening head interrupts that face, water needs somewhere to go before it is trapped.
- Layer 4 of 8. Order is meaningful.AttachmentBrackets, rails and cladding fixings
The subframe carrying cladding self-weight and wind load back to the structure. It is the only element crossing every layer, so it decides where load transfer, movement, thermal continuity and penetration of the control layer are all resolved together.
- Layer 5 of 8. Order is meaningful.Thermal layerOutboard insulation
Insulation held against the backing wall within the cavity, outside the structure. Sitting on the cold side, it stays exposed to cavity air and to any water crossing the cladding, and it is compressed or interrupted wherever a bracket passes through.
- Layer 6 of 8. Order is meaningful.Control layerWater and air control layer on the backing wall
The sheet or applied coating behind the insulation that actually governs how much water and air reach the interior. Because it is completed early and covered by everything else, its laps and terminations become unreachable once cladding work starts.
- Layer 7 of 8. Order is meaningful.Primary supportBacking wall or supporting frame
The masonry, framed wall or floor edge that receives the brackets. What it is built of governs how a fixing can be made into it, and how accurately it was built governs how much adjustment the subframe has to absorb before cladding lines can be held true.
- Layer 8 of 8. Order is meaningful.Edge and terminationClosures, trays and perimeter details
Base, head, reveal and floor-edge components that close the cavity where it must stop and drain it where water would otherwise stand. They also keep the cavity from becoming a route for pests. Fire-related provisions within a cavity are determined separately by qualified professionals.
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.
The concept holds only while each layer accepts a smaller job than it appears capable of. The cladding is allowed to leak, which is what makes an open joint acceptable; the cavity accepts that leakage, which is what makes drainage compulsory; the control layer on the backing wall accepts whatever reaches it, which is what makes its continuity more consequential than the fixing of any single panel. Shift responsibility one layer outward and the logic collapses.
A cavity that is not continuous stops working where it is blocked. Insulation bulging outward, dropped mortar, a squashed closure or a horizontal member with no path around it turns the drained face above into a shelf, and water that had a route down now has somewhere to stand. The same interruption halts air movement, so the wall above the blockage loses its drainage and its drying at the same moment, in the same place.
Every bracket passes through the insulation and usually through the control layer as well, so three things happen at one point: load is transferred, a path is created around the insulation, and the sheet is perforated. Whether the penetration is sealed, whether an isolating pad separates bracket from wall, and how closely brackets are grouped are decided together, because easing one of those consequences generally worsens another.
Each layer is covered permanently by the one outboard of it, so nothing inboard remains reachable. A lap or a penetration left open at the control layer cannot be got at again once cladding work is under way, and no later trade is in a position to correct it. That is why this facade tends to fail as a small number of concealed defects rather than as visible decay, and why its meaningful inspection points sit early in the programme.
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.
Finish surface
Board, panel and plank families of these kinds are commonly encountered as the outer screen. What a given product can span between rails, how it is fixed and how its joints behave are set by the manufacturer's documentation and by the facade designer.
Attachment
Bracket and rail components of these families are commonly encountered carrying cladding back to the structure. Which arrangement a particular wall can accept depends on the backing construction and on structural design that this entry does not attempt.
Thermal layer
Insulation of these kinds is commonly encountered against the backing wall within the cavity. Whether a board can accept exposure to cavity air and to weather before the cladding is complete is a question for its documentation and for the designer.
Control layer
Sheet and tape families of this sort are commonly encountered forming the water and air control plane behind the insulation. Compatibility between a membrane, its tapes and the surface beneath is established from the documentation for both, not from the role.
Substrate
Backing constructions of these kinds are commonly encountered receiving the subframe. What a fixing can achieve in a given background, and how much deviation the subframe must absorb, are matters for the structural and facade designers rather than for a catalogue.
Edge and termination
Tray, flashing and closure components of these families are commonly encountered where the cavity has to stop or drain. Their geometry follows exposure and the surrounding detail rather than the material name, and belongs with the designer.
Components
Building components that fill these roles
The discrete elements commonly occupying each role in this assembly. This is a different statement from the material families above: those name what a role is commonly made of, these name the positioned elements that occupy it. Commonly encountered, never recommended.
Attachment
Cavity or void
Control layer
Drainage plane
Edge and termination
Finish surface
Jointing and sealing
Primary support
- Backing Wall →Supports the rainscreen and carries the weather and air control layers behind it.
- Subframe →The assembled support carrying the cladding and setting out its plane.
- Bracket →Carries the rail system off the backing wall and across the insulation.
- Rail →Carries the panels and distributes their loads to the brackets.
Protection
- Cavity Barrier →Subdivides the ventilated cavity so it is not continuous across the facade.
- Joint Baffle →The element within each open panel joint, working alongside the ventilated cavity and the water control layer rather than in place of them.
- Rainscreen Panel →The visible outer skin shedding most water while the cavity and backing manage the rest.
- Spandrel →Opaque zones within a facade have equivalent requirements where the wall passes a floor.
Substrate
Boundary
Where this system ends and meets another
The edge of this system. Everything above is inside it; each junction below is a condition at its boundary, where an adjacent system or an adjacent building condition takes over. Junctions are where most assemblies actually fail, so they are set out explicitly rather than left inside the prose. What resolves one is a detail designed for the specific building — not a rule of thumb.
Openings punched through the screen
An opening interrupts the cladding, the cavity, the insulation and the control layer at once, and the frame arrives long after the control layer was completed. Whether water reaching the cavity above the opening can pass around it decides whether the head becomes a collecting point.
Read about Window Opening Interface →Interruptions in the drained face
Wherever the cavity is stopped by a floor edge, a plinth or a closure, water arriving from above needs a tray and an outlet at that level. A stop without an outlet is the most common way a drained facade quietly becomes an undrained one.
Read about Cavity Trays →The plane the cladding is not
The visible skin is not the water control plane, and confusing the two is the error this facade is most prone to. The control layer system owns how that plane is nominated and lapped; this entry owns the requirement that it exists independently behind the cavity.
Read about Water Control Layer →Brackets crossing the insulation line
Support brackets pass through the insulation by design, so the insulation line is repeatedly interrupted at points chosen for structural reasons. How that is treated, whether by isolating components or by bracket arrangement, is settled by the thermal and facade designers together.
Read about Thermal Bridging Control →Head of the cavity at the roof
At the top the cavity must be ventilated, closed against pests and weathered, and the roof edge is usually built by a different trade at a different time. Which element covers the head of the cavity, and whether it obstructs air movement, is decided in the detail.
Read about Eaves System →Elements hung off the facade
Fins, canopies and brackets fixed after the cladding is complete are new penetrations through a finished screen. Whether they reach a backing element chosen to receive them, or simply land on cladding designed only to carry itself, is a question that has to be asked before installation.
Read about External Shading →Mass Timber Structure
Brackets and rails fix directly into the structural plate, so every fixing is a penetration of a load-carrying element and of whatever controls water behind the cladding. The fixing pattern is settled with the panel design rather than after it.
Read about Mass Timber Structure →Cold-Formed Steel Frame
Brackets fix into thin sections rather than solid material, so the fixing positions follow the frame and were fixed at fabrication. A facade setting-out that ignores that pattern either misses the studs or requires the frame to be reworked.
Read about Cold-Formed Steel Frame →Insulating Formwork Structure
A drained and back-ventilated cladding hung off this wall has to reach a fixing that is genuinely held. Support rails taken through the insulating face to the ties or the core turn a facade decision into a structural one, and the pair are settled together.
Read about Insulating Formwork Structure →Structural Insulated Panels
The panel is not the weathering surface. A drained outer layer stands off the panel plane and its rails are fixed back to the facings, so the fixing pattern and the panel layout have to be reconciled before either one is set.
Read about Structural Insulated Panels →Volumetric Modular
An outer layer applied on site runs across every joint and has to accommodate the variation those joints absorb. Where its supports are fixed back to individual units, relative movement between units becomes a facade question rather than a structural one alone.
Read about Volumetric Modular →Vapour Control System
A ventilated cavity outboard of the sheathing gives a wall a route to dry outward that a closed outer skin does not. Whether that route is being relied on changes what resistance is acceptable in the layers behind it.
Read about Vapour Control System →Penetration Sealing
A drained and back-ventilated facade expects water behind the cladding, so a service crossing it has to be sealed at the control layer rather than at the visible outer skin. Sealing only the outer panel makes the detail look finished while the plane behind it stays open.
Read about Penetration Sealing →Timber Frame Wall
The cladding is a separate system whose fixings, support spacing and wind loading all land back on the studs. Changing the cladding therefore changes the number of penetrations through the membrane and the depth of the void the wall has to accommodate.
Read about Timber Frame Wall →Light Steel Frame Wall
The rainscreen's brackets land on the studs through the outboard insulation, so the facade's weight, its fixing pattern and its wind loading are all transmitted through the wall. The two systems have to be designed together rather than in sequence.
Read about Light Steel Frame Wall →Vegetated Facade
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 Vegetated Facade →Bracket Supported Balcony
Where the wall is a ventilated rainscreen, the bracket has to reach past the cladding and the cavity to structure behind, and the cladding has to be closed around it without stopping the cavity working. Support and facade are set out together or not at all.
Read about Bracket Supported Balcony →Mass Timber Wall Build-Up
The outer screen and its supporting brackets sit beyond the insulation and are fixed back into the panel, so the facade's fixing pattern is a pattern of penetrations through a continuous thermal layer into a structural air barrier. The two systems share the cavity, and which of them owns the weather-resistive layer has to be settled explicitly.
Read about Mass Timber Wall Build-Up →
Internal junctions
Junction conditions inside this system
Junctions between the components within this assembly, rather than at its boundary. An entry exists only where the condition between two elements governs how the assembly behaves — two parts touching is not on its own a junction worth naming.
Cavity Barrier Across a Cavity
Where a barrier interrupts a concealed cavity, and where two requirements of that cavity are in direct tension.
Cavity Barrier →Drained Cavity →
Fire continuity · Moisture · Drainage · Buildability
Cavity Barrier to Service Penetration
Where a service crosses the one element installed specifically to stop a concealed cavity running continuously.
Fire continuity · Air leakage · Drainage · Buildability
Cavity Tray to Weep Discharge
Where water collected within a wall must actually leave it, and where a collection with no exit becomes a reservoir.
Moisture · Drainage · Buildability · Weathering
Facade Bracket Through Insulation
Where a facade support crosses the insulation to reach the backing wall, forming both the load path and the main thermal bridge.
Thermal continuity · Structural transfer · Moisture · Buildability
Rainscreen Panel to Support Rail
Where a cladding panel is hung from the member carrying it, and where wind acting on the visible face leaves the facade.
Structural transfer · Movement · Drainage · Buildability
Sill to Frame
Where a frame meets the sill, at the point a window's whole collected water arrives.
Moisture · Weathering · Movement · Buildability
Support Bracket to Support Rail
Where the rail carrying the cladding meets the bracket carrying the rail, and where the facade's setting-out is recovered.
Structural transfer · Movement · Moisture · Buildability
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 cavity is expected to be wet at times, which is normal rather than a defect. What matters is whether every part of it drains and dries, because a length of cavity that cannot do either sits against insulation and against the control layer indefinitely.
- Thermal
- Continuity of the insulation is interrupted at every bracket, and moving air within the cavity means the insulation face is not a still boundary. Both effects belong in an assessment carried out by a qualified professional rather than inferred from the layers alone.
- Fire
- A continuous ventilated cavity running behind cladding raises questions about barriers within that cavity, about the materials chosen and about the building's height and use. Those are determinations for the relevant authority and for qualified professionals, and this entry states none.
- Movement
- Cladding panels, the subframe and the structure behind all move differently with temperature and load. Fixings that grip a panel rigidly at more than one point convert that difference into stress at the fixing rather than allowing it to be taken up in the joint.
- Buildability
- Several trades work in sequence over the same square metre of wall, each covering the last. Where a package boundary falls between the control layer and the subframe, responsibility for the sealed penetration around every bracket needs an owner before work starts.
- Maintenance and access
- Panels are usually demountable, which is one of the reasons this facade is chosen, but only if fixings remain reachable and replacement panels can still be matched. Access equipment for a facade is planned around the building, not around the cladding.
- Documentation
- The control layer, the trays and the bracket penetrations are photographed or they are unrecorded, because cladding covers them permanently. A later leak investigated without that record turns into an exploratory strip of finished facade.
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.
- Which surface is nominated as the water and air control plane, and whether it is continuous behind every bracket and tray, belongs on the drawings.
- Where the cavity is compartmented, and what that does to drainage as well as to pressure behaviour, is worth resolving before panel setting out is fixed.
- How water arriving at each floor edge, plinth and opening head leaves the cavity determines whether the drained face is genuinely drained.
- What the brackets are fixed back to, and whether that background was built to the accuracy the subframe assumes, changes the adjustment the system needs.
- Whether cladding joints are open, lapped or closed changes how much water the cavity is expected to handle rather than whether it handles any.
- How a damaged panel would be removed and replaced much later, and whether a matching panel would still exist, is a design decision made now.
- Which package owns the sealing of each bracket penetration through the control layer should be settled before either trade is appointed.
- Whether the facade will be inspected and recorded before the cladding covers it is a programme decision with consequences for the building's whole life.
Boundaries
Commonly misunderstood points
Distinctions that are easy to blur, and the places where a familiar term means something narrower than it sounds.
- The cladding is read as the layer that keeps water out, when the assembly is designed on the assumption that water gets past it.
- An open joint is taken for a defect or an omission, when it is a deliberate consequence of putting the control layer elsewhere.
- The cavity is treated as empty space, when its continuity, its outlets and its air paths are the working parts of the facade.
- Ventilation and drainage are assumed to be the same provision, when a cavity can be open to air at the head and still have nowhere for water to leave at the base.
- Brackets are seen as fixings rather than as layer crossings, when each one is simultaneously a load path, a thermal interruption and a hole in the control layer.
Conversations
Questions for qualified professionals
Bring these to the relevant qualified professional, manufacturer or authority. Requirements vary by project and location.
- Which layer in this facade is relied on to control water, and where exactly is it in the section?
- How is the cavity drained at each floor edge, opening head and change of cladding, and where does that water discharge?
- What is the subframe fixed back to, and has the accuracy of that background been checked against what the system assumes?
- How is the insulation held in place and protected between the time it is fixed and the time the cladding covers it?
- What provisions within the cavity have been determined by the fire strategy, and who is responsible for them on this project?
- How would a leak be traced and repaired once the facade is complete, and how much cladding would have to come off?
- What access arrangement is assumed for future inspection, cleaning and panel replacement on this elevation?
What this page does not do
- No layer in this assembly is watertight on its own; resistance to water belongs to the completed and correctly detailed facade as a whole.
- Cavity barrier provision, cladding materials and their behaviour in fire are determined by qualified professionals and by the relevant authority, not by this reference.
- Fixing anything back to cladding panels rather than to a nominated backing element loads a component that was designed only to carry itself.
- Retrofitting this facade to an existing wall changes how that wall dries, and whether the wall can accept the change is assessed by a professional who has examined it.
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.
Applications
Building contexts this system is used in
The functional parts of a building this assembly is commonly met in. This is membership, not a ranking and not a recommendation: several systems answer any one context, and which of them suits a project is a design decision. A context appearing here does not mean the system is suitable, permitted or adequate for it.
- Facade · Envelope
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.
Browse all facades & cladding entries →