Shadow gap cladding uses a machined joint to create a deliberate recessed line between timber boards. The result can be fine and understated or strongly articulated, depending on board width, gap depth, orientation and finish. This guide explains the profile choices, suitable timber options, wall details, weathering expectations and quotation information to consider before selecting shadow gap cladding for a UK home, garden room or commercial façade.
What is shadow gap cladding?
A shadow gap profile is machined so adjacent boards form a defined recess when fitted together. The darker joint creates a repeated line across the elevation, adding depth without the pronounced overlap of feather edge or traditional weatherboarding. Profile geometry varies between suppliers, so the name describes a family of appearances rather than one universal board.
Some shadow gap products use a tongue-and-groove connection, while others form the line through a rebate or another interlocking detail. The visible face, installed cover, gap width, board thickness and fixing zone can all differ. Compare technical drawings and joined samples rather than treating boards with the same product name as interchangeable.
Shadow gap cladding can be installed horizontally or vertically when the exact product is designed for that direction. It remains the visible outer layer of a complete wall build-up. Boards, battens, cavity, membrane, fixings, openings and flashings need to work together to manage weather and natural timber movement.
- A machined profile with a deliberate recessed joint
- Available in horizontal and vertical arrangements
- Creates a precise repeated rhythm on residential and commercial façades
- Specified with the complete drained and ventilated wall build-up
External shadow gap cladding is not an internal detail
The phrase shadow gap is also used for interior panelling, skirting details and decorative wall systems. An external timber profile has different exposure, drainage, fixing and movement considerations. Confirm that the product is offered for exterior use and for the proposed board direction rather than selecting it from appearance alone.
Timber shadow gap cladding should also be distinguished from similarly named composite, fibre-cement or plastic products. These materials have different support requirements, joint behaviour and manufacturer instructions. Search results can mix them together, which makes the species, material and exact product description important in an enquiry.
A supplier profile drawing explains how the board fits and where it should be fixed. The appointed designer must still confirm how that product integrates with the building, including the cavity, membrane, insulation, openings and any project-specific fire, structure or planning requirements.
Why choose a shadow gap profile?
The recessed line gives an elevation a controlled rhythm. Narrow boards and fine gaps can create a detailed, almost joinery-like surface, while wider faces with deeper joints produce a bolder architectural pattern. The effect changes throughout the day as sunlight moves across the façade and strengthens or softens the shadow.
Horizontal shadow gap boards draw the eye across a building and can make a compact extension or garden room appear broader. Vertical boards emphasise height and can give entrances, gables or upper storeys a stronger presence. Either direction can work on domestic or commercial projects when the board and supporting arrangement are designed for it.
The profile also combines readily with render, masonry, metal and glazing. Setting out should respond to openings and material changes so the board module finishes deliberately. A visually precise profile makes narrow cut boards, misaligned courses and unplanned service penetrations more noticeable, which rewards early coordination.
Cedar, larch, Thermowood or another timber?
Canadian cedar is often considered for refined shadow gap elevations because it is relatively light and dimensionally stable, subject to the grade and product supplied. Its colour can range from pale honey to richer brown. UK cedar generally brings more knots and lively variation, offering a different character where British provenance is important.
Larch creates a stronger grain and a more robust visual expression. UK larch can suit garden rooms, barns, extensions and larger practical elevations where knots and natural variation are welcome. Imported larch products may offer different grades and machining characteristics, so origin and finished quality should be confirmed rather than assumed.
Thermowood provides a consistent toasted tone and improved dimensional stability compared with its unmodified source timber. Treated European redwood can suit opaque finishes, while Red Grandis may be considered for smooth factory-coated work. The right option depends on grade, exposure, finish, documentation, availability and budget—not a simple ranking of species.
Horizontal or vertical shadow gap cladding?
Horizontal boards are normally supported on vertical battens so drainage and ventilation can continue behind the cladding. The joint must be shaped to shed water in the intended direction. Rotating a profile designed only for vertical use can create ledges or expose parts of the joint incorrectly, even if the face looks similar from a distance.
Vertical cladding needs suitable fixing support while preserving a clear route for drainage and airflow. Depending on the wall and product, this may require a counter-batten arrangement. Batten sizes, spacing and build-up are project-specific decisions that should follow the selected product guidance and relevant design responsibility.
Some projects combine both orientations to distinguish volumes or entrances. The transition creates extra junctions, board-end details and setting-out decisions. Draw the change before materials are ordered and use samples in the intended direction, as light reveals horizontal and vertical joints differently.
Shadow gap and open rainscreen are different
A closed shadow gap profile creates the appearance of a dark recess while retaining an interlocking or overlapping joint behind the visible line. An open rainscreen deliberately leaves gaps between separate boards or battens, exposing the backing layer more directly. The two approaches can look related but require different wall strategies.
Open-jointed cladding places greater emphasis on the membrane, cavity, fixing layout and treatment of the visible backing. The designer must confirm that each component is suitable for the exposure and joint arrangement. A closed shadow gap profile should still be detailed as part of a drained and ventilated system rather than assumed to make the wall waterproof by itself.
Ask suppliers to identify whether the quotation is for a closed machined profile or separate open-jointed boards. Board dimensions, installed cover, linear quantity, fixings and accessory requirements can vary significantly, making the distinction important for both design and cost comparison.
Fixings, movement and junction details
Timber changes dimension as its moisture content changes. Species, grade, board width, profile and moisture condition influence that movement, so joint allowances and fixing positions should follow guidance for the actual product. Boards also need appropriate storage and handling before installation.
Fixings must be compatible with the timber, any treatment or coating, and the site exposure. Material, length, diameter, head style and edge distance affect appearance as well as performance. Some profiles may conceal fixings within the joint; that claim should be checked against the precise board, orientation and supplier instructions.
Corners, window heads, cills, reveals, parapets and the base of the façade should be resolved early. Trims may be timber or metal, or corners may use a more discreet project-specific detail. Whatever the appearance, junctions need to accommodate board depth and movement while directing water away and preserving required ventilation.
Weathering, coatings and maintenance
Uncoated exterior timber changes colour as sunlight and weather affect its surface. Fresh cream, gold, red and brown tones generally move towards grey, but the change rarely occurs evenly across every elevation. Eaves, neighbouring structures, trees and orientation can leave sheltered areas closer to their original colour for longer.
The recess of a shadow gap may weather differently from the board face, particularly during the transition period. This can strengthen the joint visually. If a more controlled colour is central to the design, a compatible pigmented, pre-weathered or opaque finish may be considered, with the actual system reviewed on a joined sample.
A coating creates inspection and maintenance requirements. Recoat timing depends on product, colour, preparation, exposure and application quality, so one universal interval would be misleading. Finished or unfinished façades should be observed for damage, failed junctions, blocked ventilation paths and places where debris or vegetation holds moisture.
Quantities and shadow gap cladding cost
The installed cover is essential for calculating quantity. A board’s nominal width can be greater than the face it covers once the tongue, groove, rebate or overlap is engaged. Compare quotations using the same finished dimensions and installed cover rather than relying only on a linear-metre or square-metre headline.
Elevation dimensions, board direction, available lengths, openings, corners and short returns affect the actual order. A sensible cutting and selection allowance depends on the design and length schedule. Dimensioned elevations let the supplier plan quantities more accurately than one total wall area.
Species, grade, machining, surface texture, treatment, coating and order volume influence the board price. The wider package may include battens, compatible fixings, membranes, insect mesh, trims and delivery. Installation and access should be shown separately unless clearly included, allowing complete scopes to be compared without inventing a generic national rate.
Planning a South West shadow gap project
A sheltered Bristol extension, an inland Wiltshire workplace and a coastal or elevated project in Devon, Dorset or Cornwall may face different combinations of driving rain, sunlight, salt-laden air and maintenance access. Share the delivery postcode and describe the building orientation and exposure when requesting advice.
For a home or garden room, photographs, sketches and approximate dimensions can support an early conversation. Larger housing, hospitality, education or commercial work may also require elevation drawings, profile data, finish samples, sourcing information and project documentation. An agreed benchmark panel can help establish board selection, joint consistency and fixing appearance.
The Cladding Centre can help compare cedar, larch, Thermowood and other shadow gap options for projects across the region. Send the actual dimensions, preferred orientation, finish expectations and delivery details through the quote page so the team can price the board quantity and supporting supply package around the real project.
- Share elevations, dimensions and delivery postcode
- Confirm horizontal or vertical orientation
- State the species, grade and finish preferences
- Request the profile drawing and installed cover
- Include corners, openings, trims and a sensible cutting allowance
- List battens, fixings, samples and project documentation required