Timber rainscreen cladding creates a distinctive outer skin while allowing drainage and ventilation behind the boards. The term covers several different appearances, from closed machined profiles to open-jointed battens, and those differences affect the backing layer, fixings, quantities and junction details. This guide explains the decisions to resolve before selecting timber, approving samples or requesting a quotation for a UK residential or commercial project.
What is timber rainscreen cladding?
A rainscreen is an outer cladding layer separated from the wall behind by a cavity. The visible boards reduce the amount of direct weather reaching the backing layers, while the cavity provides a route for drainage and ventilation. The timber is therefore one component of a complete wall design rather than a waterproof barrier by itself.
Timber rainscreens can use horizontal, vertical or diagonal boards, although each arrangement needs suitable support and junction details. The design may present a relatively continuous face or intentionally leave open gaps between boards. Board width, depth, spacing and surface finish determine the rhythm and shadow of the finished elevation.
The term is used on homes, extensions, garden rooms, schools, hospitality buildings, offices and other commercial façades. Scale changes the coordination and documentation required, but the basic questions remain: what is the intended appearance, what lies behind the boards, how will water drain, and how will the system be inspected and maintained?
- An outer timber layer separated from the wall by a cavity
- Designed with drainage, ventilation and backing layers
- Available in closed-profile and open-jointed appearances
- Used on residential, community and commercial façades
Open-jointed and closed rainscreens
An open-jointed timber rainscreen uses separate boards or battens with visible gaps between them. Those gaps expose the backing layer more directly to ultraviolet light and wind-driven rain. The membrane, support system and cavity arrangement must be selected and detailed for that condition rather than borrowed from a closed cladding detail.
A closed machined profile uses an overlap, tongue, groove or rebate to create a more continuous outer face. Shadow-gap boards can produce the appearance of a dark recess while retaining a joint behind the visible line. Even a closed profile remains part of a drained and ventilated build-up; it should not be described as making the external wall waterproof on its own.
These approaches can look similar in photographs, especially when dark backing is visible behind narrow open joints. Ask suppliers to identify the precise board section, installed cover and intended joint arrangement. This prevents an open batten system from being priced or detailed as if it were a closed interlocking product.
Choosing timber for a rainscreen
Canadian cedar is often selected for refined rainscreens because it is relatively light and dimensionally stable, subject to the grade and product supplied. Its natural colour range can run from pale honey to deeper brown. UK cedar generally has more knots and lively variation, offering a different character where British-grown provenance forms part of the brief.
Larch creates a stronger grain and more robust appearance. UK larch can suit housing, rural buildings, workshops and larger practical elevations where natural knots and variation are welcome. Imported larch products may differ in origin, grading and machining, so the precise offer should be reviewed rather than assuming every product sold as larch is equivalent.
Thermowood provides a consistent toasted tone and improved dimensional stability compared with its unmodified source timber. Treated European redwood can suit painted or value-led systems, while Red Grandis may be considered for smooth factory-coated work. Species, grade, dimensions, finish, exposure and available documentation should be compared together.
Board shape, spacing and orientation
Rectangular battens create a simple slatted face, while bevelled or shaped boards can alter the apparent gap and help the designer control views towards the backing layer. Board depth influences shadow, and the ratio between face width and joint width determines whether the elevation reads as timber-dominant or strongly striped.
Vertical boards emphasise height and can suit entrances, gables and substantial façades. Horizontal boards draw the eye across the building and may reinforce a long, low form. The support arrangement changes with orientation: it needs to provide appropriate fixing positions while maintaining the intended drainage and ventilation route.
Spacing should be set from the actual product dimensions and movement guidance, not from an idealised image. A full-size sample panel can establish board selection, joint consistency, backing colour and fixing appearance. On larger projects, it also creates a shared benchmark for the client, designer, contractor and installer before full installation.
The membrane, cavity and battens
The layers behind an open-jointed rainscreen have a greater visual and environmental role than those behind many closed profiles. Any exposed membrane or backing board must be suitable for the proposed joint width, orientation and site exposure. Its colour can also affect the finished appearance, as pale or reflective material may remain visible between boards.
The cavity provides a route for water to drain and for air to move behind the cladding. Batten depth, spacing and any counter-batten requirement depend on the substrate, board direction, fixing design and complete external wall specification. Ventilation openings and insect protection should be coordinated without obstructing drainage.
Insulation, sheathing, membranes, cavity barriers and support components have to work together. Product data can inform the design, but the appointed professionals must confirm the build-up for the specific building, including fire, structure, moisture, energy and regulatory requirements. A timber supply quotation is not a substitute for that coordination.
Fixings and natural timber movement
Timber changes dimension as its moisture content changes. Species, grade, board size, grain and moisture condition influence that movement, so joint spacing and fixing positions should follow guidance for the actual product. Wider or deeper boards may behave differently from narrow battens even when machined from the same species.
Fixings need to be compatible with the timber, any preservative treatment or coating, and the site exposure. Material, length, diameter, head style and distance from board edges affect both appearance and performance. In an open system, fixings are often visible and their alignment becomes part of the architectural finish.
Boards should be stored and handled in line with supplier instructions before installation. Setting out datum lines and trialling the fixing pattern on a sample area helps avoid wandering joints or inconsistent heads across long elevations. Damaged or unsuitable pieces can then be identified before they reach a prominent position.
Corners, openings and cavity interfaces
Corners can use expressed metal or timber trims, paired boards, mitred details or other project-specific solutions. The chosen approach must accommodate board depth, fixing zones and movement while keeping the intended joint rhythm. Open joints make the treatment of board ends and the backing layer particularly visible.
Window and door heads, cills and reveals need to direct water clear of the wall and preserve the designed cavity. Board modules should be coordinated with openings so narrow strips and awkward final gaps are avoided. Flashings may remain visible between boards, making their colour and alignment part of the design decision.
At parapets, roof abutments and the base of the façade, the rainscreen meets other weathering elements and changes in ventilation. Services such as lights, signs, vents and pipes also need independent support or suitable penetrations. Resolving these interfaces on drawings improves both appearance and material accuracy.
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 boards do not all change at the same rate. Orientation, neighbouring buildings, trees, roof overhangs and joint depth can create a varied transition across the elevation.
An open rainscreen exposes board edges and parts of the back or support zone more visibly than many closed profiles. If a coating is selected, the specification should define which faces and cut ends are treated, how site cuts are handled and what maintenance guidance applies. A joined or multi-board sample is more informative than one coated face.
Recoat timing depends on the particular product, colour, preparation, exposure and application quality, so a universal interval would be misleading. Finished or unfinished rainscreens should be inspected for damaged boards, failed junctions, blocked cavity openings, loose fixings and places where vegetation or debris retains moisture.
Quantities and timber rainscreen cost
Open-jointed rainscreens are often calculated from board width, joint width and linear length rather than treating every square metre as solid timber. A change in spacing can alter both the visual timber coverage and the quantity required. Closed profiles use their installed cover, which is usually smaller than the nominal board width once the joint is engaged.
Elevation dimensions, openings, corners, board direction, available lengths and cutting allowance determine the actual order. Long vertical boards may reduce end joints but affect transport, storage and access. A project-specific length schedule can be more useful than one total area, particularly on large commercial elevations.
Species, grade, finished dimensions, machining, texture, treatment and coating all influence the board price. The wider supply package may include battens, fixings, membranes, insect mesh, trims, samples, documentation and delivery. Compare complete scopes rather than a board-only rate with a quotation covering the wider system.
Planning a South West rainscreen project
A sheltered Bristol development, an inland Somerset school and a coastal building in Devon or Cornwall can face different combinations of wind-driven rain, salt-laden air, sunlight and maintenance access. Building height, elevation orientation and surrounding exposure should be shared when requesting products and quotations.
Residential enquiries can begin with drawings, photographs and approximate dimensions, while larger housing, education, hospitality or commercial schemes may need profile drawings, finish samples, sourcing information and project documentation. Identify the design team’s requirements early so proposed products can be compared on more than appearance and price.
The Cladding Centre can help compare cedar, larch, Thermowood and other rainscreen options for projects across the South West. Send the elevations, preferred board arrangement, joint width, finish and delivery details through the quote page so quantities and supporting components can be considered around the actual specification.
- Share elevations, dimensions, orientation and delivery postcode
- Confirm whether joints are open or closed
- State the species, grade, board dimensions and finish
- Identify the proposed joint width and visible backing colour
- Include corners, openings, trims and length requirements
- List samples, fixings, battens and project documentation required