Envelope and protection

Exterior Cladding & Render

External cladding is the layer people see, but it is rarely the layer that keeps water out on its own. Most modern cladding is designed to work with what sits behind it: a drainage cavity, a breather membrane, support rails and carefully detailed junctions around openings and at the base of the wall.

These entries describe cladding and render materials and the dependencies that follow them. Fixing design, wind loading, cavity and fire-related detailing, and anything to do with what may be permitted on a given building are matters for qualified professionals and the relevant authority.

15 reference entries · educational materials reference · suitability always depends on the complete assembly and qualified professional review

Scope

What this category covers

Where the boundary of this part of the library sits, including what it deliberately leaves to qualified professionals.

Board, panel, plank and rainscreen cladding materials
Applied render systems used as external wall finishes
The support and cavity components cladding depends on
Not covered: fixing or support design, wind loading, fire-related detailing or approval questions

Start here

Frequently referenced entries

A starting point, not a ranking — these are simply the entries most people arrive looking for.

Fibre cement cladding →A cement, mineral filler and fibre board supplied as planks or flat sheets, normally hung on battens or rails over a ventilated cavity rather than fixed flat to the wall.Timber cladding →Sawn or machined boards of natural timber fixed over battens to face an external wall, a material that moves with moisture and changes colour throughout its exposed life.Cement render →A site-mixed or bagged sand-and-cement coating applied in successive coats onto masonry or lath, comparatively hard and dense, and normally finished with a paint or decorative topcoat.

All entries

Every exterior cladding entry

The complete set for this category, in reference order.

Entry describes

Role in an assembly

Part of a building

Fibre cement cladding →A cement, mineral filler and fibre board supplied as planks or flat sheets, normally hung on battens or rails over a ventilated cavity rather than fixed flat to the wall.

Timber cladding →Sawn or machined boards of natural timber fixed over battens to face an external wall, a material that moves with moisture and changes colour throughout its exposed life.

Stone cladding →Thin natural or cast stone facings carried on fixings or a backing wall, giving the appearance of stonework without any of the load-carrying role of solid stone construction.

Vinyl siding →Extruded plastic profiles that interlock and hang loosely from nailed flanges, designed to expand and contract freely, which is exactly why fixing them tightly causes problems.

Metal composite panels →Flat sheets of two thin metal skins bonded to a core, routed and folded into cassettes in a workshop and hung on a subframe, usually with open joints and a drained cavity behind.

HPL cladding →Rigid panels made from layers of resin-impregnated paper pressed under heat and pressure, hung on a subframe with fixings that must let each panel expand and contract.

Terracotta rainscreen →Extruded and kiln-fired clay elements clipped to horizontal rails with open joints, a system in which the drained cavity behind is not an add-on but part of the basic idea.

Composite wood cladding →Extruded boards of wood flour bound in a polymer matrix, often with a co-extruded outer shell, behaving quite unlike the natural timber whose appearance they are made to suggest.

Cement render →A site-mixed or bagged sand-and-cement coating applied in successive coats onto masonry or lath, comparatively hard and dense, and normally finished with a paint or decorative topcoat.

Monocouche render →A factory-blended dry render mixed with water on site and applied as a single through-coloured layer, then scraped back to expose its aggregate, needing no paint to reach its finished appearance.

Lime render →A lime and sand coating applied in thin coats to older solid walls, softer and more vapour-open than cement systems, where compatibility with the background is the whole subject.

Cladding support systems →The brackets, rails, battens and fixings that carry cladding back to the structure and create the cavity behind it, the layer that decides how the visible finish actually performs.

Cellular PVC trim board →An externally graded foamed PVC board, normally capped with a bonded weathering skin and supplied in pre-formed sections, fixed so that a long board can move along its length.

Dry dash and roughcast →Thrown external render finishes: in dry dash, aggregate is cast onto a wet receiving coat and left proud; in roughcast, the aggregate is in the mix and the whole wet mix is thrown.

Thin-coat render →A two-part external render: an adhesive base coat with glass-fibre mesh embedded in it, then a ready-mixed acrylic, silicone or silicate topcoat textured by the float.

Browse by role

By the role the material plays

The same entries, clustered by what they typically do in an assembly. A material can appear in more than one cluster because it genuinely plays more than one role.

Substrate and base

Backgrounds and bases that other materials are fixed or applied to.

Cladding support systems →

Weather barrier

Layers that shed or resist rain, wind and weather.

Moisture and air control

Thin layers that control where moisture and air are allowed to move.

Lime render →

External surface

The visible outer face of a wall or roof.

Jointing and fixing

Materials that bond, seal, support or connect other materials.

Cladding support systems →

Where they appear

Parts of a building this category touches

An orientation aid only — it does not imply that any entry is suitable for that part of a particular building.

External walls · 15
Roofs · 1
External works and landscape · 3

Elsewhere on Build Design Hub

Planning guidance for this subject

This library explains what materials are. These sections help with choosing between them and preparing for the conversation.

Exterior materials guides →Planning guidance for facades and external walls.Facade ideas →Design directions for facades and external character.Building envelope checklists →Preparation before envelope conversations.

Building Systems Encyclopedia

The assemblies these materials sit in

A material page explains what a substance is. These pages explain how the assembly around it is organised, what roles its components perform and which interfaces matter.

Building envelopeFacade and Cladding Systems →Outer skins carried on a wall that is already complete behind them, where the support, the joint and the cavity carry the durable knowledge rather than the finish.Building envelopeExternal Wall Build-Up Systems →Complete external walls read as a layer order: where in the thickness of the wall water is stopped, and in which direction the wall is allowed to dry afterwards.

Materials & Systems Encyclopedia

Reference entries for building materials, product formats and system components — what they are, what their behaviour depends on and what to ask about them.

Browse the full Materials Library →

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