Board on board cladding creates a deeply shadowed timber elevation by layering cover boards over the gaps between a first row of boards. It can feel agricultural and familiar on a barn, crisp and contemporary on a home, or suitably robust across a substantial commercial building. The apparent simplicity hides several important choices: board rhythm, overlap, species, cavity design, weathering and the quantity calculation behind a reliable quote.
What is board on board cladding?
A board on board system normally begins with a row of vertical underboards fixed with deliberate gaps between them. A second row of cover boards sits over those gaps, creating an overlapping two-layer arrangement. The cover boards form strong vertical shadow lines while helping to protect the joints behind them from direct weather exposure.
Unlike a machined tongue-and-groove profile, the visual joint is created by the relationship between separate rectangular boards. Changing board widths, spacing and overlap can make the façade feel fine and ordered or broad and rustic. Because both layers contribute to the appearance and material requirement, nominal wall area alone does not tell you how much timber will be needed.
Board on board is commonly associated with vertical timber cladding, but the exact product, support arrangement and orientation must be confirmed for the project. It remains part of a designed rainscreen or external wall build-up rather than a waterproof wall by itself.
- Two layers of boards create depth and strong shadow lines
- Often installed vertically on homes, barns and commercial buildings
- Board widths and overlaps can be adjusted to suit the visual brief
- Requires a drained, ventilated and correctly detailed wall build-up
Board on board or board and batten?
The terms board on board and board and batten are sometimes used interchangeably, but suppliers and designers may mean different arrangements. In a board on board system, the front and rear pieces may be similar boards. Board and batten cladding often describes wider backing boards with noticeably narrower battens covering their joints.
Both approaches produce a layered vertical elevation, yet their rhythm can be quite different. Equal-width boards create repeated peaks and recesses, while narrow cover battens place more emphasis on the broader board face behind. Some proprietary products reproduce the look within a machined profile rather than using two independent layers.
Do not rely on the name alone when comparing quotations. Ask for a profile drawing or sample panel showing finished dimensions, the width of each component, intended overlap, installed cover and fixing zones. This makes it much easier to compare material quantities and confirm that every supplier is pricing the same visual result.
Which timber species suit the profile?
Larch board on board cladding is popular because its pronounced grain and knots complement the depth of the profile. UK larch can bring a robust, characterful appearance to barns, workshops, garden rooms and larger value-conscious schemes. Imported larch products may have different grading, dimensions and machining characteristics, so origin and exact specification should be confirmed.
Cedar can produce a lighter, more refined elevation. Canadian cedar is often considered where stability, low weight and a controlled architectural face are important, subject to the grade selected. UK cedar tends to be more knotty and varied, which can work well where local provenance and natural character matter more than close visual uniformity.
Thermowood, treated European redwood and other suitable products may also be offered in board on board arrangements. The best choice depends on appearance, exposure, maintenance expectations, project documentation, availability and budget. Always review samples representing the actual species, grade and finish rather than approving a generic photograph.
Designing the board rhythm and shadow lines
The balance between underboard, cover board, gap and overlap defines the elevation. Narrow repeated modules can feel precise and contemporary, while wider boards create a bolder agricultural character. A mixture of widths may add a more irregular rhythm, but it needs careful setting out to avoid awkward sequences around corners and openings.
Shadow depth changes with the thickness of the two layers and the direction of light. A south- or west-facing wall can show stronger contrast during the day than a consistently shaded elevation. Dark finishes make recesses feel deeper, while pale untreated timber initially produces a softer pattern before natural weathering alters the colour.
A full-size sample area is valuable for important façades. It allows the client and design team to assess normal timber variation, joint proportions, fixings and finishing in realistic light. On a larger project, the agreed sample can also establish a benchmark for setting out and workmanship before the main installation begins.
Cavity, battens and junction details
Board on board cladding should be supported over a wall build-up designed to drain and ventilate. The batten arrangement must provide appropriate fixing positions for both layers while maintaining the intended cavity. Batten dimensions, spacing, membranes, insect mesh and cavity barriers depend on the selected product and building design rather than one universal detail.
The base of the cladding, roof edges, corners, parapets and changes of material should be resolved before boards are ordered. Window and door heads need to direct water out, cills need to throw it clear and reveals must integrate with the wider weathering strategy. The extra depth of a layered profile affects trim dimensions and how neatly it meets frames and adjoining finishes.
Vertical boards also place end grain at horizontal junctions. Clearances, flashings, end treatments and factory-finish requirements should follow supplier guidance and the project specification. Drawings should show how ventilation remains continuous and how any required fire-safety measures are incorporated within the complete façade design.
Fixings, movement and installation planning
Both rows of boards must be secured in accordance with the chosen product’s guidance. Fixing material, length, head style and position need to suit the timber, treatment, coating and exposure. The arrangement should allow expected timber movement without assuming that the cover board permanently restrains the boards behind it.
Natural timber responds to changing moisture conditions. Board width, species, grade and moisture condition influence movement, so storage and handling are part of achieving a consistent elevation. Boards should be protected appropriately before installation, with damaged, twisted or unsuitable pieces identified before they become part of the finished façade.
Setting out should begin from agreed datums and take account of corners, openings and the end of each elevation. Small changes to the module can become obvious over a wide wall. On commercial projects, coordination with windows, signage, lights, ventilation grilles and other penetrations helps avoid improvised cuts that interrupt the intended rhythm.
Weathering, coatings and maintenance
Uncoated timber changes colour outdoors as ultraviolet light and weather affect its surface. Fresh gold, cream, red and brown tones generally move towards grey, but the overlapping profile can weather at different rates. Recessed areas receive less direct sunlight and rain than exposed faces, so tonal contrast may remain visible during the transition.
A compatible coating can influence colour and moisture uptake, but it creates inspection and maintenance requirements. Factory application may provide more controlled coverage, particularly where the overlap makes some faces difficult to reach after assembly. Confirm whether every exposed face, cut end and concealed area requires treatment within the selected system.
Local exposure matters. A sheltered building in Bristol, Bath or inland Wiltshire will not necessarily weather like a coastal or elevated site in Dorset, Devon or Cornwall. Discuss prevailing weather, orientation, nearby vegetation and access for future care before deciding between natural silvering, a translucent finish, an opaque colour or a pre-weathered appearance.
What affects board on board cladding cost?
Board on board cladding uses two layers, so its material requirement cannot be estimated from the net wall area alone. The widths of underboards and cover boards, gaps, overlaps and rejected or cut pieces all affect the total linear metres. A quotation should be based on the agreed arrangement and installed cover rather than a single headline square-metre figure.
Species, grade, finished dimensions, length mix, surface texture, coating, treatment, order quantity and documentation also influence cost. Corners, reveals, flashings, trims, fixings, membranes and delivery form part of the wider supply requirement. Complex elevations with many openings can need more material and coordination than a simple wall of the same net area.
For an initial quote, share the postcode, approximate dimensions or elevations, intended board arrangement, species and finish preference, programme and any known technical requirements. A sketch and photographs may be enough for a shed or garden studio; drawings and schedules make comparisons clearer for homes, housing schemes and commercial façades.
- Confirm the widths of both board layers and intended overlap
- Compare quantities using installed cover, not nominal width
- Include corners, openings, trims, fixings and reasonable wastage
- Identify coating, sourcing and documentation requirements early
- Approve representative samples before placing the full order
- Request pricing against the actual project location and programme