Envelope and protection · Exterior Cladding
Timber Cladding (Weatherboarding)
Explains natural timber cladding as a living material: species and treatment choices, the way it moves and silvers, and how that differs from the manufactured wood-and-polymer boards it is often compared against.
Educational reference entry. Suitability depends on the complete assembly, substrate, exposure, installation method, manufacturer documentation, local requirements and qualified professional review.
Overview
What timber cladding is
Timber cladding is simply sawn or machined boards of natural wood, softwood or hardwood, fixed to the outside of a wall. Species differ enormously in their natural resistance to decay, in density, in how much resin or tannin they contain and in how they take a finish, so naming the species and its origin is the starting point of any serious conversation rather than a detail.
Boards are supplied in profiles that each imply a different fixing approach and a different elevation. Feather-edge and lap boards overlap and shed water down the face; tongue and groove and shiplap interlock; board-on-board and board-and-batten express vertical rhythm; open-jointed rainscreen boards leave deliberate gaps and rely entirely on the layers behind. Timber may also be preservative treated, thermally modified or surface charred, each of which changes how the board behaves and how it looks.
The defining characteristic is that natural timber is never still. It takes up and gives off moisture with the seasons, so it moves across the grain, and its exposed surface changes colour under sunlight and rain, typically weathering towards a silver-grey that arrives unevenly depending on shelter and orientation. This is the clearest line between timber and composite wood cladding: one is a natural material that continues to move and change, the other is a manufactured wood-and-polymer product with different movement behaviour and no capacity to be sanded back and refinished in the same way.
Terminology
Common names and aliases
These names describe the same thing. The library keeps one entry per material so that an acronym, a trade name or a regional spelling never becomes a second, thinner page.
- Wood siding (US)
- Weatherboarding
- Timber boarding
- Wood cladding
Applications
Common applications
Where this material is typically encountered. A typical application is not a statement that it suits your project.
- Whole elevations on houses, extensions and garden buildings where a natural material is wanted as the dominant surface.
- Upper floors or single elevations set above brick or render, used to lighten the mass of a building.
- Open-jointed rainscreen boarding on contemporary elevations, where the shadow gap itself is the architectural idea.
- Vertical board-and-batten treatments on gables, porches and outbuildings drawing on agricultural precedent.
- Screens, fins and slatted infill panels where the boards are ventilated on both faces rather than backing onto a wall.
- Repair and extension of existing weatherboarded buildings where matching the original profile is the objective.
Consideration
Where it is commonly considered
- Where a natural material that visibly ages is wanted, and the change from fresh timber to weathered grey is welcomed.
- On elevations with generous overhangs and sheltered aspects, which change how the timber weathers over time.
- Where the wall build-up allows battens, a ventilated cavity and free air movement behind and around each board.
- Where the owner accepts a recurring cycle of inspection and, for finished timber, recoating.
- In settings where local building character already includes boarded elevations and continuity is part of the intention.
Professional review
Where additional professional review is especially important
These are the situations where the answer depends on the specific building, and where a qualified professional should be involved before anything is decided.
- Where boards would sit close to ground level, paving or planting and stay damp with no drying air on the back face.
- Where an even, unchanging colour is expected, since differential weathering between elevations is inherent to the material.
- On buildings where local requirements for external wall construction have not been established by a qualified professional.
- Where the species and any treatment have not been confirmed, since natural durability varies widely between timbers.
- Where access for future inspection and recoating would be difficult or costly to arrange.
Properties
Key properties to discuss
Qualitative topics worth raising. Measured values, classes and grades come from the manufacturer's technical documentation for the specific product, not from a reference page.
- Moisture behaviour
- Timber exchanges moisture with the air around it and moves across the grain as it does, which is why boards need room to move, ventilation to both faces where possible, and fixings that do not lock them rigidly in place.
- Weathering and exposure
- Exposed timber greys under ultraviolet light and rain. Sheltered areas under eaves weather far more slowly than open faces, so an elevation often ends up with a gradient of colour rather than one uniform tone.
- Appearance
- Knots, grain, sapwood and colour variation are properties of a natural material, not defects, and boards from different parts of a batch will differ. Some species also bleed tannin or resin that can mark masonry below.
- Maintenance
- Left bare, timber is generally allowed to weather and is inspected rather than recoated. Where a stain, oil or paint is used, the recoating cycle becomes a continuing commitment that varies by product, exposure and orientation.
- Fire-related questions
- Fire is a whole-wall subject rather than a product-by-product one: what matters is the entire external wall build-up, and requirements differ by building type, height and location. Rules in this area have changed significantly in several countries and must be confirmed locally by a qualified professional.
- Repairability
- Individual boards can usually be replaced, which is a genuine advantage, but new timber inserted into a weathered elevation will stand out until it has caught up, and it may never match exactly.
- Installation dependency
- Fastener choice matters more than it does with most claddings, because some metals react with the acids in certain timbers and leave dark streaks running down the face from every fixing point.
Exposure
Exposure and environmental conditions
- How exposed each elevation is to sun and rain, since that governs the pace and evenness of weathering.
- Whether roof overhangs, canopies and reveals shelter parts of the face and leave others fully exposed.
- How close the lowest boards sit to paving, planting or a flat roof where splash and standing water occur.
- Whether the site is coastal, where salt spray and wind-driven grit act continuously on the surface.
- Whether dense vegetation or a shaded aspect keeps the face damp and encourages organic growth.
Assembly
Substrate and system dependencies
What this material sits on, is fixed to or depends on. This is usually where performance is won or lost.
- The batten and counter-batten arrangement, which creates the cavity and decides whether air can move behind the boards.
- The breather membrane behind the battens and how it is lapped, supported and finished at openings.
- Whether the background is masonry or a framed wall, which changes fixing method and the tolerance available.
- How the boards meet windows, doors, corners and the base of the wall, where most weathering problems begin.
- Whether open-jointed boarding is intended, in which case the layers behind become far more visible and far more important.
Appearance
Appearance and finish considerations
- Whether the timber is to be left to weather naturally or held at a colour with a coating, which is a long-term commitment.
- How much variation between boards is acceptable, since this can be reduced by selection but not eliminated.
- Whether boards run horizontally, vertically or diagonally, which changes both the look and the way water leaves the face.
- How the ends of boards are finished at corners and openings, because end grain is where weathering shows first.
- Whether tannin or resin from the chosen species could mark the masonry, paving or glazing beneath it.
Durability
Durability questions
Questions to raise rather than a service life to expect. No material has a universal lifespan — it depends on the assembly, the exposure and the upkeep.
- What the natural durability of the specific species is, and whether any preservative or modification process has been applied.
- How the detailing keeps water off end grain and out of horizontal surfaces where it can sit.
- Whether boards will dry out between wettings, which depends far more on ventilation than on the timber itself.
- How the fixings and any metal trims will behave in contact with that particular species over time.
- What happens at the most vulnerable positions: the base of the wall, external corners and the underside of cills.
Upkeep
Maintenance and repair considerations
- Whether the intention is a bare weathering elevation or a coated one, and who will carry out the recoating.
- How the higher parts of the elevation will be reached safely once scaffolding is gone.
- How individual damaged or decayed boards would be removed and replaced within a fixed run.
- Whether spare boards of the same species and profile are being kept for later repairs.
Installation
Installation dependencies
What the installation depends on — not how to do it. Method belongs to the manufacturer's instructions and the trades carrying out the work.
- Allowing the timber to acclimatise on site before fixing, since boards fixed at the wrong moisture content will move afterwards.
- Setting out board lines against openings so that courses meet heads and cills sensibly across the elevation.
- Choosing fasteners that suit the species, because the wrong metal will stain the face permanently.
- Sequencing with window installation so that flashings and trims are built in rather than retrofitted.
- Protecting stacked boards from rain and ground moisture during the period before they are fixed.
Documentation
Documentation to request
Ask for these in writing, for the specific product being proposed, and keep them with the project record.
- Confirmation of the species, grade description and origin of the boards actually being supplied.
- Details of any preservative treatment or modification process applied, and what the supplier says about it.
- The coating manufacturer's literature where a stain, oil or paint is being used, including recoating guidance.
- Drawn details showing how the boarding meets openings, corners, the roof edge and the base of the wall.
- Guidance from the supplier on handling, storage and acceptable moisture content at the time of fixing.
Conversations
Questions for qualified professionals
Bring these to the relevant qualified professional, manufacturer or authority. Requirements vary by project and location.
- What species is being supplied, and what does its natural durability mean for this particular exposure?
- Is the timber intended to weather naturally, or is a coating specified with a recoating cycle attached to it?
- How is air able to move behind and, where relevant, around each board once the elevation is complete?
- What fasteners are specified, and have they been chosen for compatibility with this species?
- How do the boards stop short of the ground, paving and any adjoining roof so that they can dry out?
- What are the current local requirements for external wall construction on this building, and who is confirming them?
- How will individual boards be replaced in future without dismantling large areas of the elevation?
- Could tannin or resin from this timber stain the surfaces below, and how is that being managed?
Blind spots
Commonly overlooked points
- Colour change is not a fault to be corrected but the normal behaviour of exposed timber, and it arrives unevenly.
- The back face of a board matters as much as the front, because timber that cannot dry from behind stays wet longer.
- End grain absorbs water far faster than the face, which is why corner and opening details do most of the work.
- A coating chosen at the start commits the owner to repeating that decision for as long as the cladding is there.
- Boards left in a wrapped pack on wet ground can be compromised before they ever reach the wall.
What this page does not do
- Nothing here assesses the durability or suitability of timber on any particular building; that requires a qualified professional who has seen the site.
- Requirements for external wall construction differ by location and building type and have changed over time, so current local requirements must be confirmed with the relevant authority.
- Treatment and modification processes vary between suppliers, and their claims belong to the supplier's own documentation rather than to this reference.
- This page describes general material behaviour and offers no installation method, no product recommendation and no endorsement.
Related entries
Related materials
Materials from the same family, an adjacent role in the assembly, or a shared application.
Inspiration
Related Ideas Library pages
Design directions where this material commonly appears.
Preparation
Related planning checklists
Owner-side preparation before the conversation where this material comes up.
Go deeper
Related Build Design Hub guides
Planning guidance and neutral comparisons behind the decisions on this page.
Exterior Cladding & Render
Reference entries for external wall finishes — fibre cement, timber and composite cladding, vinyl siding, metal and laminate panels, terracotta rainscreens and the render families.
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