Structural and base materials

Timber & Wood-Based Materials

Wood is not one material. Solid timber, engineered products such as glulam and CLT, and wood-based panels such as plywood, OSB, MDF and chipboard behave very differently, and the differences between them matter far more than the fact that all of them started as trees.

The recurring themes across these entries are moisture, movement and grade. Wood responds to the humidity around it, it is anisotropic, and how a given piece performs depends on species, grade, treatment and how it is detailed. Structural sizing, grading decisions and treatment specification belong with qualified professionals.

20 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.

Solid softwood and hardwood used structurally and for joinery
Engineered timber products and wood-based panel products
Treatments and modifications that change how timber behaves
Not covered: structural sizing, grade selection, span tables or treatment specification

Start here

Frequently referenced entries

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

Plywood →Panel built from thin wood veneers bonded with the grain of each layer running across the last, which is where its stability and striped edge come from.Cross-laminated timber →A large panel made from layers of solid timber boards bonded together with each layer running perpendicular to the last, so it works as a structural plate.Oriented strand board →Panel pressed from large wood flakes laid down in deliberately oriented layers, giving a mottled face, a coarse edge and moisture behaviour unlike veneer or particle boards.

All entries

Every timber & wood entry

The complete set for this category, in reference order.

Entry describes

Role in an assembly

Part of a building

Structural softwood →Sawn coniferous timber sorted for strength and used for framing, joists and roof members, where moisture movement and correct sizing govern how it behaves.

Hardwood timber →Sawn timber from broadleaf trees, used for joinery, flooring and trim; the hardwood label is botanical, and density and movement vary widely between species.

Plywood →Panel built from thin wood veneers bonded with the grain of each layer running across the last, which is where its stability and striped edge come from.

Oriented strand board →Panel pressed from large wood flakes laid down in deliberately oriented layers, giving a mottled face, a coarse edge and moisture behaviour unlike veneer or particle boards.

Medium density fibreboard →Panel pressed from wood broken down to individual fibres, so it has no grain at all, machines to a crisp edge and takes paint well, but drinks finish at cut edges.

Chipboard →Panel pressed from small wood particles scattered without direction, giving a crumbly edge, particular fixing behaviour and a well recognised vulnerability to water.

Hardboard →Thin, dense fibre sheet used for facings, backs and underlays, sharing its fibre origin with thicker fibre board but pressed harder and supplied as sheet rather than board stock.

Wood veneer →A thin slice of real timber bonded to a panel, where the veneer decides how the surface looks and the substrate beneath decides how the panel actually behaves.

Cross-laminated timber →A large panel made from layers of solid timber boards bonded together with each layer running perpendicular to the last, so it works as a structural plate.

Glued-laminated timber →An engineered member built from graded timber laminations bonded face to face all running the same way, used for beams, columns and curved structural elements.

Laminated veneer lumber →A structural product made by bonding thin peeled veneers into a billet and cutting it into sections, giving unusually consistent and straight concealed members.

Timber I-joists →Engineered floor and roof joists with an I-shaped section, formed from timber flanges bonded to a thin web board and supplied as part of a designed layout.

Prefabricated roof trusses →Factory-assembled triangulated roof frames of graded timber joined by pressed metal connector plates, designed and supplied as a complete braced roof system.

Thermally modified timber →Timber altered by controlled heating with oxygen largely excluded, which changes how the wood takes up moisture and typically leaves it more brittle than before.

Preservative-treated timber →Timber into which preservatives have been introduced, commonly under vacuum and pressure, to reduce the risk of decay and insect attack in the situation it is going into.

Engineered bamboo →Boards and panels made by breaking bamboo culms down into strips or strands and bonding them back together, a grass-derived material that does not behave like hardwood.

Chemically modified timber →Timber whose cell-wall chemistry has been altered by reaction or impregnation and cure, changing the wood substance itself rather than adding a preservative to it.

Film-faced plywood →Plywood faced with a bonded resin film and sealed at the edges, made to be struck and reused, and to leave its own face as the surface of the concrete cast against it.

Flame-retardant treated timber →Timber and wood-based panels put through a treatment concerned with fire, introduced either by impregnation into the wood or applied as a coating on the surface.

Timber connectors →Manufactured metal connectors joining timber to timber or timber to structure — hangers, straps, anchors, hold-downs and pressed plates, each designed around its own fastener.

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.

Structure

Materials that carry load or form the primary frame.

Substrate and base

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

External surface

The visible outer face of a wall or roof.

Internal surface

The visible inner face people see, touch and walk on.

Jointing and fixing

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

Timber connectors →

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.

Foundations and groundworks · 1
Structural frame · 13
External walls · 4
Roofs · 10
Internal walls and ceilings · 11
Floors · 14
External works and landscape · 4

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.

Materials planning guides →Planning and comparison guidance for material choices.Construction guides →How structural and carpentry stages are planned.Structural discussion preparation →Questions to prepare before a structural conversation.

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.

Structure and supportPrimary Structural Frames and Load-Bearing Wall Systems →Complete primary load paths from roof to foundation in masonry, timber, steel and concrete, together with the stability system without which none of them stands up.Structure and supportFloor Structure and Build-Up Systems →Horizontal decks read together with the stack placed on them, told apart by what spans, what is infill and what is only a topping over both.

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 →

HELPERG Ecosystem

Web products

Mobile apps