Window and Door Reveal Design: Depth, Shadow Lines, Flashing and Interior Finish

A window or door is usually described by the things that are easy to see: the frame profile, the glass, the handle, the colour. Yet the detail that most often decides whether an opening performs well over twenty years is the one that is almost invisible once the building is finished. That detail is the reveal. It is the returned surface between the outer face of a wall and the outer face of a frame, and it sits at the meeting point of architecture, weatherproofing, structure and interior finish. When it is designed deliberately, a reveal gives an opening depth, produces a clean shadow line, and allows water, air and vapour to be managed in a predictable way. When it is left to be resolved on site, the same junction becomes the source of leaks, draughts, cracked plasterboard and callbacks.

This article sets out a design approach for reveals around aluminium windows and doors, written for architects, builders, façade consultants and informed owners working in Australia and New Zealand. It deals with the geometry of the reveal, the difference between interior and exterior conditions, shadow lines, frame position within the wall, sill and flashing logic, drainage, the separation of air, vapour and water control layers, thermal and acoustic continuity, lining and plasterboard interfaces, the contrast between new build and renovation, long-term maintenance, and the standards framework that governs the work. It deliberately avoids prescribing dimensions, costs or performance figures, because those values belong to a specific project, a specific wall build-up and a specific tested system, not to a general article.

What Is a Window and Door Reveal?

A reveal is the short return surface that lines the perimeter of an opening between the wall structure and the window or door frame. In its simplest form it has three parts: the reveal face, which is the surface you see when you stand at an angle to the opening; the reveal return or set, which is the depth of that surface measured from the wall face to the frame; and the junction, which is where the reveal meets the frame, the wall lining, the sill or the head. The depth of the reveal is not a stylistic choice made in isolation. It is the product of the wall build-up, the position of the frame relative to the structure, and the thickness of the finishes on both sides.

Reveal design is therefore the discipline of deciding, before anything is ordered or built, how deep the opening will appear, where the frame will sit inside it, how the edges will be finished, and how each control layer will cross from the wall into the frame without being interrupted. It is a coordination task as much as a detailing task. A reveal that looks effortless in a photograph is usually the result of a set-out drawing that fixed the frame position, the lining thickness, the flashing upstand and the sill profile before the first lintel was poured.

The reveal is a system, not a surface

It helps to think of the reveal as a small system with four obligations. First, it must shed water outward and never trap it. Second, it must allow the wall’s air and vapour control layers to connect to the frame in a continuous, buildable way. Third, it must accommodate movement between the frame and the structure without transferring that movement into brittle finishes. Fourth, it must present a consistent visual line, because the reveal is one of the few places where a millimetre of variation is read as a defect. A detail that satisfies only the first and fourth obligations will look correct on the day of handover and fail in the first driving rain. A detail that satisfies only the second and third will perform but look unresolved.

Why the definition matters early

Reveals are frequently confused with architraves, trims and window surrounds. An architrave is a separate moulding applied to cover the junction between the lining and the frame. A reveal is the surface the architrave might cover, or, in a trimless detail, the surface that replaces the architrave entirely. Confusing the two leads to late decisions. If the design intent is a trimless reveal, the plasterboard set-out, the frame fixing position and the stopping sequence all change, and those changes are inexpensive at documentation stage and expensive after lining has begun. Defining the reveal early is not pedantry. It is the cheapest risk control available on a project.

Interior and Exterior Reveals: Two Different Jobs

The inside and outside faces of the same opening are asked to do different work, and treating them as mirror images is a common source of failure. The exterior reveal is primarily a weather detail. The interior reveal is primarily a finish and services detail that also has a role in thermal and acoustic comfort. They share a frame, but they do not share a logic.

Exterior reveals

On the outside, the reveal is exposed to wind-driven rain, ultraviolet light, pollution and, in coastal areas, airborne salt. Its geometry determines how much water reaches the frame and how quickly that water can leave. A reveal that is too shallow, or that slopes back toward the frame, will deliver water directly onto the most vulnerable joint in the assembly. A reveal that is deep enough to shelter the frame but drained at the base will keep the weather seal under far less pressure. The external reveal also carries the visual expression of thickness: a deep reveal reads as a solid wall, while a shallow one reads as a thin panel. This is why the same window system can look elegant in one wall and mean in another.

Materials matter here. Rendered and painted reveals need a stable substrate and a defined edge; fibre cement and compressed sheet reveals need careful jointing and sealing; precast and masonry reveals rely on the accuracy of the structural opening. Whatever the material, the exterior reveal should be detailed so that water reaching it is directed away from the frame and never behind the cladding. That usually means a slope, a drip, and a flashing that turns up behind the cladding and down over the frame.

Interior reveals

Inside, the reveal is where the wall lining turns through the opening. It governs how the window sits in the room, how curtains and blinds will operate, how much daylight reaches the adjacent surfaces, and how the junction with the floor or sill is finished. A deep internal reveal gives a window a seat, a sense of thickness and a place to put a curtain track. A shallow internal reveal keeps the wall plane quiet and makes the opening feel larger, but leaves little room for a lining return and demands greater accuracy from the frame installation.

Interior reveals also carry services and tolerances. Power outlets, blind pockets, curtain recesses and heating elements are often pushed into the reveal zone, and each of them affects the lining build-up. The reveal is the place where the builder’s tolerance meets the plasterer’s tolerance, and where a small error in the structural opening becomes a visible taper. The earlier the interior reveal is drawn at full scale, the fewer of these conflicts survive to site.

Splayed, square and angled reveals

A splayed reveal widens toward the room and increases the amount of light entering the space. A square reveal keeps the opening reading as a precise rectangle. An angled reveal can follow a raking ceiling or a non-orthogonal plan. Each has consequences beyond appearance: a splay changes the width of the lining return, the position of the frame relative to the wall face, and the way a blind or curtain will sit. Splayed reveals also complicate the junction at the sill if the sill is to remain level. None of these options is inherently better. What matters is that the choice is made once, documented, and carried consistently through the set-out, the frame order and the lining.

Shadow Lines and the Architecture of Depth

A shadow line is the dark band created where two surfaces meet at an angle and light cannot reach fully into the corner. Around windows and doors, shadow lines do real work: they separate the frame from the wall, hide small variations in the junction, and give the opening a crisp edge. They are also the most fragile part of a minimal detail, because a shadow line depends on consistency. If the gap varies along the head, the eye reads it immediately, even if the variation is small.

How a shadow line is formed at a reveal

There are three common ways to create one. The first is a physical setback, where the frame sits behind the wall face and the reveal itself produces the shadow. The second is a recessed bead or stop, where a small set-down at the frame-to-lining junction creates a continuous groove. The third is a flush detail with a deliberate joint, where a narrow gap or a dark gasket provides the line. Each depends on a straight, continuous substrate. A shadow line cannot correct a wavy wall; it exposes it.

The depth and width of the shadow are governed by the geometry of the corner and the direction of the light, not by a fixed drawing convention. A deeper setback produces a broader, softer shadow, while a shallow setback with a sharp arris produces a thin, hard line. Because the sun angle changes through the day and the year, a detail that reads well at midday may lose its line in the early morning. Physical mock-ups are far more reliable than renderings for this reason.

Trimless and flush-finish details

Trimless reveals remove the architrave and bring the lining close to the frame, often with a narrow shadow gap. They suit contemporary interiors and reduce visual clutter, but they concentrate risk. The plasterboard edge must be cut accurately, the frame must be set out to suit the lining rather than the structure, and the joint must be reinforced against movement. Where a trimless detail meets a raking or curved wall, the difficulty multiplies. A trimless reveal should be treated as a high-skill detail and specified with the same rigour as a façade junction.

Where shadow lines fail

The typical failures are predictable. Cracking appears along the joint because the frame and the wall move differently. The gap varies because the frame was packed and fixed before the lining set-out was confirmed. Paint bridges the gap and destroys the shadow. Sealant is applied too generously and creates a rounded fillet where a sharp line was intended. Each of these is a sequencing and specification problem, not a design impossibility. A movement joint, a controlled setback and a clear instruction about which trade finishes which surface will prevent most of them.

Frame Position: Setback, Flush and Centre

The position of the frame within the wall thickness is the single most consequential decision in reveal design. It determines the depth of the external reveal, the depth of the internal reveal, the thermal path through the junction, and the amount of water the frame is asked to resist. There are three broad options, and most projects use a combination of them depending on orientation and wall type.

Setback frames

A setback frame sits toward the interior, leaving a deep external reveal and a shallow internal one. This is the traditional approach in cavity brick and rendered masonry construction, and it has clear advantages: the wall shades the frame from direct rain, the external reveal can be detailed with a proper sill and drip, and the building reads as having substantial walls. The cost is a reduced internal reveal, which limits curtain detailing, and a longer thermal path that must be insulated or otherwise addressed. A setback frame also places the frame closer to the inner leaf, which affects fixing and the position of the damp-proof course.

Flush frames

A flush frame aligns with the outer wall face, producing a nearly flat façade and a deep internal reveal. It is common in curtain wall and some residential systems where a continuous external plane is wanted. The advantage is architectural: the glazing reads as part of the wall rather than as a hole in it. The disadvantage is exposure. A flush frame takes the full force of wind-driven rain at its perimeter seals, so the reliance on flashing, drainage and sealant quality increases sharply. Flush frames demand a well-designed drained and ventilated cavity behind the cladding, and they demand that the external seal be treated as a secondary defence rather than the primary one.

Centre and intermediate positions

Placing the frame near the middle of the wall balances the internal and external reveals. It can be a good compromise where both faces are visible and neither a deep sill nor a deep internal ledge is required. In insulated framed walls, the frame position also interacts with the insulation line: a frame set toward the cold side will sit outside the main insulation layer unless the reveal is insulated, which changes the condensation risk at the frame. Intermediate positions are legitimate, but they must be chosen with the wall build-up drawn, not assumed from a nominal wall thickness.

Frame position and load path

Frame position is not only a weathering decision. It affects how the window is fixed, how wind load is transferred to the structure, and how the frame responds to deflection of the lintel or slab. A frame fixed near the inner face of a flexible wall may experience different movement from one fixed near the outer face. The fixing detail, the packer arrangement and the allowance for structural movement should be resolved together with the frame position, and the installation should follow the system supplier’s tested method rather than a generic site convention.

Sill Details: Slope, Drip and the Internal Upstand

The sill is where gravity brings every drop of water that lands on the opening. It is also where the internal floor level, the wall lining and the frame meet, which makes it the most congested junction in the whole assembly. A well-designed sill has a clear job: collect water, move it outward, and discharge it clear of the wall below without allowing it back into the construction.

External sill geometry

An external sill needs a fall away from the frame, a projection beyond the wall face, and a drip or throating on its underside so that water leaves the sill rather than tracking back along the soffit. The junction between the sill and the frame should be protected by a sealant or gasket that is compatible with both materials, and the sill should be supported continuously so that it does not deflect and hold water. Where a sill is tiled or paved, the fall must be built into the substrate, not created by the tile adhesive, because adhesive-bed falls are unreliable and often reverse.

Material selection follows the same logic. Aluminium sills with a powder-coated finish are common and can be formed with integral drips and end caps. Stone and concrete sills need a machined drip and a verified fixing method. Timber sills need a durable species, a finish on all faces, and a separation from the frame to prevent staining. In every case, the sill should be detailed as a water-shedding element, not as a decorative cover over an unresolved joint.

Internal sills and floor junctions

Inside, the sill may be a flush floor junction at a door, a raised ledge at a window, or a deep seat in a thick wall. Each has a different set of requirements. At a door, the critical issue is continuity: the internal floor finish, the waterproofing (where present), the frame threshold and the external paving must be sequenced so that water cannot migrate inward under the frame. At a window, the internal sill should be level and flat, with a clean junction to the lining and enough clearance for the window to operate and be cleaned.

Where a window sits above a wet area, the internal sill junction should be treated as part of the waterproofing system, not as a separate finish trade. The waterproofing membrane should turn up to the frame and be sealed to it in a way that the membrane manufacturer and the frame supplier both accept. This is one of the most commonly missed interfaces on residential projects, and it is almost always cheaper to detail at documentation stage than to rectify after tiling.

Flashing, Damp-Proofing and Drainage Paths

Water management around an opening relies on the principle of shingling: each layer laps over the layer below so that water always has a path downward and outward. The reveal sits within that sequence, and its flashing must connect the wall’s weather-resistive barrier to the frame without creating a pocket where water can sit.

Head and jamb flashings

At the head, a flashing should be installed behind the cladding and above the frame, with an upstand at the back and a fall to the front, terminating in a drip clear of the frame face. The ends of a head flashing need to be closed or turned, because an open end is a direct path for water into the wall. At the jambs, flashings should lap over the sill flashing and behind the cladding, and the sequence must be built in the correct order. A jamb flashing installed after the cladding is not a flashing; it is a patch.

Sill flashing and the shingle sequence

The sill flashing is the most important piece in the set. It should extend behind the frame, turn up at the back, slope to the front, and discharge over the wall cladding below with a drip. Its ends should turn up and be sealed to the jamb flashings so that the whole perimeter forms a continuous tray. Where the frame has a drained cavity, the sill flashing should be detailed so that water leaving the frame’s weep paths lands on the flashing and not behind it. The correct sequence is: structure, weather barrier, flashing, frame, cladding, sealant. Any departure from that order should be a deliberate, documented decision.

Weep paths and drained cavities

Many aluminium window and door systems are designed to collect water that passes the external seal and drain it back to the outside through weepholes or a drained cavity. Those paths only work if they are kept clear. Sealant applied across a weep path during installation will dam the system and force water to find another route. Equally, a reveal that is packed solid with mortar or foam at the sill will block the discharge path. The installation method should identify which openings must remain clear, and the site inspection should check them before the cladding closes the detail.

Drainage also depends on the relationship between the frame and the reveal. A frame recessed behind a deep reveal is partly protected, but the cavity behind it must still drain. A frame set flush with the cladding has less shelter and needs a more robust secondary defence. In both cases, the design intent should be that the primary weather seal is the flashing and drainage path, while the sealant is a secondary measure that can be renewed.

Vapour, Air and Water Boundaries Are Project-Specific

One of the most persistent misconceptions in opening detailing is that there is a single correct way to terminate the air barrier, the vapour control layer and the waterproofing at a frame. There is not. The correct detail depends on the wall type, the climate, the internal environment, the frame system and the sequence of construction. What is universal is the requirement that each layer be continuous, or that its termination be deliberate and understood.

Three control layers, three different questions

The water control layer answers the question: where does liquid water go? It should be continuous, shingled and drained. The air control layer answers the question: where does air leak? It should be continuous around the opening, sealed to the frame, and supported so that it is not damaged during installation. The vapour control layer answers the question: how much moisture diffuses through the assembly, and in which direction? Its position depends on the climate and the wall build-up, and in some assemblies the same membrane performs more than one function.

At the reveal, these layers converge within a narrow zone. The frame manufacturer’s installation instructions will define how the frame is to be sealed and what substrates are acceptable. The wall system designer will define how the wall’s own layers terminate. The two sets of requirements must be reconciled in a single detail, because the person on site will otherwise choose the simpler of the two and leave the other discontinuous.

Who owns the interface

Responsibility is the hidden issue. The window supplier is responsible for the frame and its tested performance as a system. The builder is responsible for the opening and the wall. The waterproofer, plasterer and renderer each own a surface that meets the frame. If no one owns the interface, the sealant bead becomes the default solution for every discontinuity, which is precisely the outcome that good detailing is meant to avoid. A project-specific interface drawing, signed off by the parties who will build it, is worth more than any generic specification clause.

Thermal and Acoustic Boundaries at the Reveal

The reveal is a narrow band, but it can dominate the thermal and acoustic performance of an opening because it is where the wall’s continuous layers are interrupted. Insulation, membranes and linings all stop at the frame, and the frame itself is usually a better conductor than the wall. The result is a localised weak point that is easy to overlook on a whole-wall calculation.

Thermal continuity

In a thermally broken aluminium system, the frame is designed so that the inner and outer sections are separated by an insulating element. The reveal detail should preserve that logic. If the frame is set toward the cold side of the wall, the inner face of the frame may sit close to the dew point, and the risk of surface condensation increases. Insulating the reveal, keeping the frame within the insulated envelope where possible, and avoiding direct contact between the frame and uninsulated structure are the main levers. The exact configuration must be assessed for the specific wall and climate; generic rules of thumb are unreliable.

Thermal bridging at fixings is part of the same question. Packers, brackets and continuous fixing angles can create a conductive path across the insulation. Where a project relies on the frame’s thermal break for comfort, the fixing strategy should be reviewed alongside the reveal detail rather than after the frame is installed.

Acoustic weak points

Sound behaves similarly. An acoustic window is only as good as its perimeter. Gaps at the reveal, a backer rod that is too small, a sealant that has debonded, or a lining that is rigidly connected to the frame can each reduce performance. Acoustic sealing relies on mass and continuity: the seal should be continuous, compressed correctly and compatible with both surfaces. Where a reveal contains a service penetration or a blind box, that interruption should be sealed as carefully as the frame perimeter itself. Acoustic performance claims should always be read as system performance, tested as an assembly, not as a property of the glass alone.

Lining, Plasterboard and the Reveal Interface

The lining is where the reveal becomes visible, and it is where most of the perceived quality of the opening is decided. A perfectly installed frame will look ordinary if the lining is out of square, and a modest frame will look precise if the lining is true.

Set-out and tolerances

The lining set-out should be derived from the frame position, not from the structural opening. This means the frame must be installed to a known line, and the lining must be packed to meet it consistently. A common approach is to establish a datum on the wall, set the frame to that datum, and then line to the frame with a consistent reveal width. Where the structural opening is out of square, the lining should absorb the variation rather than the frame, because a frame cannot be adjusted after glazing without affecting operation.

Fixing, movement and cracking

Plasterboard should not be fixed rigidly to both the frame and the wall in a way that prevents movement. A controlled joint, a suitable bead and a flexible sealant at the frame interface will accommodate the small movements that occur as the building settles and as the frame expands and contracts. Where a trimless shadow gap is used, the edge should be cut cleanly, supported behind, and finished with a bead that protects the arris. Corners are the highest-risk location, and they should be inspected before stopping rather than after painting.

Wet areas and fire-rated elements

In bathrooms, laundries and other wet areas, the lining at the reveal should be part of the waterproofing system, with the membrane carried to the frame and sealed. In fire-rated walls, the reveal must not compromise the fire-resisting construction: penetrations, sealants and linings should be specified as part of the tested system, and any substitution should be assessed rather than assumed. These are project-specific matters, and they should be resolved by the relevant consultant rather than by the window installer alone.

Renovation Versus New Build

The design logic of a reveal is the same in new build and renovation, but the freedom to execute it is not. In new construction, the opening can be set out to suit the frame, the flashing can be installed in the correct sequence, and the lining can be planned before the frame is ordered. In renovation, the existing structure, finishes and weathertightness constrain almost every choice.

New build

New build allows the reveal to be designed as part of the wall system. The structural opening can include the correct tolerances, the flashing can be continuous, and the insulation and air barrier can be detailed before the frame arrives. The main risk is coordination rather than physical constraint: frame position, lining thickness, floor level and cladding depth must be agreed before the slab or frame is set out. Mock-ups of a typical opening, including the sill and one jamb, are the most effective way to test the detail while it can still be changed cheaply.

Renovation

Renovation usually means working with an opening that was built for a different window, in a wall whose layers may be unknown. The existing frame may be embedded in the wall, the damp-proof course may be discontinuous, and the internal lining may not be removable without damaging adjacent finishes. In these conditions, the reveal design should start with an investigation: what is the wall build-up, where is the weather barrier, is there a sill tray, and how is the opening supported? Replacement frames can often be detailed to fit within the existing reveal, but only if the new frame’s installation requirements are compatible with the existing drainage and flashing arrangement.

Partial renovation carries its own risks. Replacing a window without renewing the flashing may leave the new unit dependent on a detail that has already reached the end of its life. Conversely, opening the wall to install new flashing may require temporary weather protection and additional making good. Both options are legitimate, but the decision should be explicit, and the owner should understand what is being renewed and what is being retained.

Maintenance and Inspection Over the Life of the Building

A reveal is not a maintenance-free detail. It is a detail that fails slowly if it is inspected, and quickly if it is not. The most useful maintenance regime is a simple, repeatable inspection that focuses on the places where water and movement concentrate.

At least annually, and after any severe storm, the following should be checked: sealant joints at the frame perimeter for cracking, shrinkage or debonding; weep holes and drained openings for blockage by paint, sealant or debris; sill falls for ponding or reversal; flashings for lifting, corrosion or separation from the wall; and internal linings for staining, swelling or paint blistering that might indicate water behind the finish. In coastal environments, salt deposits and corrosion at fixings deserve particular attention, and the frequency of inspection should reflect the exposure.

Maintenance should also include the moving parts that the reveal serves. Window and door hardware, seals and drainage channels need cleaning so that the system can perform as designed. A reveal that is visually perfect but whose drainage path is blocked will still admit water. Recording inspections, with photographs of each elevation, turns maintenance from a reactive exercise into a predictable one and provides evidence if a defect is later disputed.

Standards and Compliance: NCC, ABCB and the AS/NZS Framework

In Australia, window and door work sits within the National Construction Code (NCC), which is maintained by the Australian Building Codes Board (ABCB). The NCC sets the performance requirements for weatherproofing, structural safety, energy efficiency, fire safety and health, and it is given legal effect through state and territory legislation. The NCC does not usually prescribe a reveal detail. It states the outcome that must be achieved, and the designer selects a detail and a tested system that can achieve it. Compliance is therefore demonstrated through a combination of design documentation, product certification, installation conformity and inspection.

Australian standards relevant to the opening

Several Australian Standards support that process. AS 2047 is the key product standard for windows and doors in buildings, and it is the reference against which window systems are typically tested and certified for their intended application. AS 4284 is the performance test standard cited for window and door systems, and it is the basis on which water penetration performance is demonstrated. AS 1288 covers glass in buildings, including the selection of glass types and thicknesses for the application, and AS 2208 covers safety glazing, including the identification and use of safety glass where required. AS 4666 is the installation standard cited for window and door installation, and it addresses how a tested product is translated into a compliant installed assembly.

These standards do different jobs and none of them can substitute for another. A certified window is not automatically a compliant installation, and a careful installation cannot compensate for a product that was never tested for the exposure. The reveal sits precisely at that boundary: it is where the product meets the building, and where the performance claimed for the product must be preserved by the surrounding construction.

New Zealand

In New Zealand, compliance is achieved through the Building Code and the consent process, with verification methods and acceptable solutions providing routes to demonstrate performance. SNZ TS 4211:2022 is the technical specification referenced for window and door systems, and SNZ 4223 is the standard referenced for the installation of windows and doors. Together they set out how products are tested and how they are to be installed so that the tested performance is retained. As in Australia, the reveal detail must be consistent with the installation standard and with the specific system’s instructions, and it must be documented well enough for inspection.

What certification does and does not prove

A certificate is evidence about a tested configuration. It does not prove that the frame on a particular site was installed at the tested position, sealed in the tested manner, or surrounded by the tested wall build-up. That is why installation standards and inspection matter as much as product certification. It is also why a change of reveal depth or frame position should prompt a review of the installation method, because the performance that was tested may depend on the geometry that the certificate describes.

Meichen’s Verified Capability

Meichen International Windows and Doors, trading as MC Windows, is a manufacturer of aluminium window and door systems with a focus on the Australian and New Zealand markets. The company reports 18 to 19 years of industry experience and has dedicated itself to the ANZ market since 2017, operating from a 20,000 square metre manufacturing facility in Zhaoqing, Guangdong, with local partnerships in Sydney.

Its certification record covers 43 product series in Australia and 13 product lines in New Zealand. The Australian standards referenced in its documentation are AS 2047 for windows and doors, AS 4284 for window performance, AS 1288 for glass in buildings, AS 4666 for installation and AS 2208 for safety glazing. In New Zealand, the relevant references are SNZ TS 4211:2022 and SNZ 4223. The company states water tightness of up to 960 Pa under AS 4284 for its systems, and describes its product range as including ultra-slim frame systems, thermal break systems, non-thermal break systems, curtain walls, louvres, balustrades and shower enclosures. It is actively pursuing CodeMark certification, and its supply chain includes aluminium from AAG, glass from CSG and hardware developed for ANZ requirements.

These are verified company facts, not project-specific performance claims. Any project application still depends on the selected system, the actual wall build-up, the exposure category and the installation method, all of which should be confirmed with the supplier and documented for the specific job.

Specifying a Reveal: A Practical Checklist

A disciplined sequence reduces most of the risk described in this article. The following checklist can be used at design review, at tender clarification and at site inspection.

Confirm the wall build-up, including cladding, cavity, insulation, structure and internal lining, and draw the reveal at full scale at a jamb, head and sill.
Fix the frame position within the wall and record it on the drawings, together with the resulting internal and external reveal depths.
Decide whether the reveal is square, splayed or angled, and confirm that the decision is carried into the frame order and the lining set-out.
Define the shadow line strategy, including the bead, gap or setback, and state which trade finishes the junction.
Detail the sill with a fall, a projection, a drip and a continuous support, and coordinate it with the internal floor level.
Draw the flashing sequence in the order it will be built, including head, jambs and sill, and confirm that laps are correct.
Identify the water, air and vapour control layers, show how each terminates at the frame, and name the party responsible for each junction.
Review thermal continuity and fixing penetrations, and confirm that the installation method matches the tested system.
Specify the lining, bead, sealant and movement joint, and confirm the fixing pattern around the opening.
Plan inspection hold points before cladding, before lining and before painting, and record them with photographs.
Agree the maintenance regime with the owner, including the inspection frequency and the items to be checked.

Frequently Asked Questions

What is the difference between a reveal and an architrave?

A reveal is the returned surface between the wall face and the frame, forming the depth of the opening. An architrave is a separate trim that covers the joint between the lining and the frame. A reveal can exist with or without an architrave, and a trimless detail removes the architrave while keeping the reveal.

How deep should a window reveal be?

There is no universal depth. The reveal depth is the result of the wall thickness, the frame position and the thickness of the internal and external finishes. It should be derived from a full-scale section of the specific wall build-up, not selected from a table. The design question is whether the resulting depth satisfies weather protection, thermal continuity, lining set-out and the intended appearance.

Does a deeper reveal improve weather performance?

A deeper external reveal shelters the frame from direct rain, which reduces the demand on the perimeter seals. That benefit is real but conditional: the sill must still drain, the flashing must still be continuous, and the frame’s own drainage paths must remain clear. A deep reveal with a blocked sill will perform worse than a shallow one with a correct fall and drip.

Should the window frame be flush with the outside face?

It can be, and many contemporary façades use a flush frame to achieve a continuous external plane. A flush frame is more exposed, so it relies more heavily on a drained and ventilated cavity, correct flashing and a robust secondary seal. The choice should follow from the wall system and the exposure, not from appearance alone.

Can a shadow line be created without a physical gap?

Yes. A shadow line can be formed by a setback, a recessed bead, a dark gasket or a deliberate joint. What it cannot be formed by is sealant smeared across a junction, because a rounded fillet reflects light and removes the line. The detail needs a defined edge and a consistent depth to read as intended.

Why do cracks appear along window reveals?

Most cracks at reveals come from differential movement between the frame and the wall, combined with a rigid finish and a joint that has no capacity to accommodate movement. Accurate set-out, appropriate packers, a controlled joint and a flexible sealant at the frame interface reduce the risk. Cracking can also indicate water intrusion or inadequate fixing, so it should be investigated rather than simply patched.

Is a building approval enough to confirm the reveal is correct?

No. An approval confirms that the documentation addresses the applicable requirements. It does not confirm that the frame was installed at the documented position, that the flashing sequence was followed, or that the drainage paths are clear. Those outcomes depend on inspection during construction and on the installation standard being applied on site.

How often should window and door reveals be inspected?

A practical approach is at least annually and after severe weather, with more frequent checks in exposed coastal locations. The inspection should cover sealant condition, drainage openings, sill falls, flashing condition and signs of moisture at internal linings. Recording the results makes it easier to detect gradual deterioration.

Conclusion

Reveal design is quiet work. It rarely appears in a marketing image, and it is usually hidden behind a lining or a bead by the time a project is complete. Yet the reveal is where the promises made by a window system are either kept or lost. It controls how water leaves the opening, how air and vapour cross the wall-to-frame junction, how much shelter the frame receives, how the interior reads, and how easily the detail can be maintained. A project that defines the reveal early, draws it at full scale, sequences the flashing correctly and inspects the result will avoid most of the failures that are otherwise attributed, unfairly, to the window.

The technical principles are stable: shed water outward, keep control layers continuous, allow for movement, preserve thermal and acoustic continuity, and finish the junction with a clear line. The variables are local: wall type, climate, exposure, frame system, lining and the standards that apply. Resolving those variables is the designer’s task, and it is best done before the frame is ordered. A reveal that has been thought through is not just a better detail. It is a longer-lived building.