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Building components · Frame Members

Structural Bearing

Explains the bearing as an element in its own right, because it is where a very high proportion of structural problems actually occur.

Form:Connector or supportRoles:SupportStructure

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 bearing is

A bearing is where a member is supported: the length of joist sitting on a wall, the seating of a beam on a padstone, the point at which a truss meets a plate. All the load a member carries passes through it.

Treating it as an element rather than as a detail matters because a member can be entirely adequate and still fail at its bearing — through insufficient length, through crushing of what it bears on, or because the support was not where the design assumed.

Boundaries

How it differs from nearby elements

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

  • It is not the member, and it is not the support. It is the interface between them, and its adequacy depends on both.
  • It is not a connector. A connector is a manufactured piece; a bearing is the condition of support, which may or may not involve one.
  • It is not a wall plate, though a plate is commonly introduced precisely to improve a bearing.

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.

  • bearings
  • bearing point
  • seating

Dependencies

What it depends on

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

  • The length or area of contact, since load has to spread into the supporting element over enough of it.
  • What is beneath, and whether it can accept concentrated load without crushing.
  • Whether the member is restrained from moving off its bearing.
  • Any spreading element such as a padstone or plate introduced to distribute the load.

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

The whole of a member's load passes through its bearings, which makes them a concentration point rather than an incidental contact.

Tolerance & fit

Construction tolerances mean the actual bearing achieved on site frequently differs from the one drawn, and that difference matters.

Durability

Bearings are commonly at positions — wall heads, ground level — where moisture and exposure act on both the member and its support.

Movement

Where differential movement is expected between two elements, the bearing may need to allow it rather than resist it.

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 LibraryReinforced concrete →Padstones and spreader pieces at bearings are commonly precast or cast concrete.Materials LibraryEngineering brick →Dense masonry units are used to form a bearing where concentrated load arrives on a wall.Materials LibraryStructural steel →Steel plates and seatings form bearings for members of several materials.Materials LibraryStructural softwood →A timber plate spreads bearing where members land on masonry.

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 supportLoad-Bearing Masonry →The point at which spanning members deliver their load into the wall.Primary supportBeam and Block Floor →The seating of each beam on the supporting wall or foundation.Primary supportPrecast Plank Floor →Where each unit is seated, and where tolerance between units is resolved.Primary supportSteel Frame →Connections and seatings through which member loads pass into columns and foundations.

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.

  • Superstructure

Clarifications

Commonly misunderstood

  • That a member sitting on a wall is adequately supported. How much of it sits there, and what the wall does under that load, both matter.
  • That bearings are the same thing everywhere. A bearing designed to allow movement and one designed to restrain are opposite arrangements.

Conversations

Questions for qualified professionals

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

  • What bearing does this member actually have, and what does the design require?
  • Can what it bears on accept the concentrated load without a spreading element?
  • Is the member restrained against moving off its bearing?
  • Is differential movement expected here, and does the bearing accommodate or resist it?

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 bearing length, area, stress or padstone arrangement is stated here.
  • Bearing design is structural engineering work and is a common source of defects when improvised on site.

Structural Frame Members

The columns, beams, joists, rafters, plates and bracing that make up a load-carrying frame, identified by the position each occupies.

Browse all frame members entries →