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Building components · Paving & Decks

Deck Bearer

Explains the bearer as the deck's primary structure, whose connections are where deck failures concentrate.

Form:Linear memberRoles:StructureSupport

Educational reference entry. What this element has to do, and whether any particular arrangement of it is adequate, depends on the whole assembly, the loading, the exposure, local requirements, the manufacturer's instructions and qualified professional design.

Overview

What a bearer is

A bearer runs beneath and across the deck joists, collecting their loads and carrying them to posts, walls or the ground. It is the deck's primary structure, and the joists are secondary to it.

Its connections matter more than its size. Where a deck is attached to a building, the member fixed to the building carries a substantial share of the whole deck, and how that connection is made — and how it passes through the building's cladding and control layers — is where elevated deck failures concentrate.

Boundaries

How it differs from nearby elements

The distinctions that keep this entry from being a restatement of its neighbours.

  • It is not a deck joist. Joists carry the boards; bearers carry the joists.
  • It is not a beam in a building frame. The exposure and the connection into an existing building are different problems.
  • It is not a sole plate. A plate spreads a wall's load; a bearer collects and spans.

Terminology

Common names and aliases

These names describe the same element. The library keeps one entry per component so that a trade term or a regional name never becomes a second, thinner page.

  • bearers
  • deck beams
  • ledger and bearers

Dependencies

What it depends on

What has to be right elsewhere for this element to do its job.

  • Its connections, particularly where it is fixed to an existing building.
  • The posts or supports beneath it and what those bear on.
  • Its exposure, since it is in the same wet environment as the joists and is commonly less ventilated.
  • Whether the fixing into a building passes through cladding and control layers without creating a water path.

Considerations

Topics that genuinely apply here

Subjects worth discussing about this element. These are discussion topics, never measured values, ratings or performance claims.

Structural transfer

Where a deck is attached to a building, the connection carries a large share of the deck's load and its failure mode is sudden rather than gradual.

Moisture

A bearer fixed against a wall traps water between the two unless the connection is designed to keep them separated and drained.

Durability

Corrosion of fixings and decay at a wall connection are both concealed conditions in the position most critical to the deck.

Buildability

Fixing through cladding into a structure means penetrating the building's water and air control layers at multiple points.

Materials

Commonly formed from

Material families this element is commonly realised in. This states common practice only — it is not a statement that any of these materials suits this component in a particular building, which depends on the whole assembly and on qualified review.

Materials LibraryPreservative-treated timber →Treated softwood is the usual form, with treatment appropriate to the exposure.Materials LibraryGlued-laminated timber →Engineered timber is used where spans between supports are longer.Materials LibraryGalvanised steel →Steel bearers are met in elevated and larger deck structures.Materials LibraryHardwood timber →Durable hardwood is used where longevity in exposure governs.

Assemblies

Building systems this element is met in

The role this component fills inside each assembly. A role describes what the element does there — it is not a statement that this component suits that system in any particular building.

Primary supportTimber Deck Framing →The primary members carrying the joists to posts or to the building.Primary supportBracket Supported Balcony →Where the deck is carried on brackets, the bearer transfers load into them.Primary supportPedestal Terrace Paving →Bearers spread pedestal support where a framed deck sits above a waterproofed surface.

Where it is met

Application contexts

Building contexts where this element is commonly encountered. Association is not recommendation: appearing here does not mean the component suits every instance of that context, or any particular one.

  • Deck & Terrace
  • External Works

Clarifications

Commonly misunderstood

  • That fixing a deck to a house is a simple attachment. It is a structural connection through the building envelope.
  • That the visible boards indicate a deck's condition. The bearer and its connections are where the structural risk sits and they are the least visible parts.

Conversations

Questions for qualified professionals

Questions worth asking someone with the project in front of them. This page cannot answer them.

  • How is the bearer connected where the deck attaches to the building?
  • What does the connection pass through, and how are the control layers made good?
  • Is there separation and drainage between the bearer and the wall?
  • What supports the bearer away from the building, and what do those supports bear on?

Go deeper

Related Build Design Hub guides

Planning guidance behind the decisions this element involves.

Preparation

Related planning checklists

Owner-side preparation before the conversation where this element comes up.

What this entry does not do

  • No span, section, fixing, spacing or capacity is stated here.
  • Attaching a deck to a building is a structural connection through the envelope and requires qualified design.

External Works & Paving Elements

The laying course, wearing course, edge restraint, deck framing and guarding posts that make up trafficked surfaces outside the building.

Browse all paving & decks entries →