Skip to main content
HELPERG Ecosystem
Build Design HubBuild Design Hub

Building components · Wall Leaves & Backing

Masonry Infill Panel

Explains infill masonry as a panel bounded by frame members on every side, distinct from a continuous leaf and from the opaque panel of a glazed facade.

Form:Unit or moduleRoles:SeparationWeather controlProtectionFinish

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 infill panel is

An infill panel is masonry built into the space between the members of a structural frame. The frame carries the building; the panel encloses it, resists wind on its own face, and delivers that wind load back into the members around it. Unlike a leaf that runs continuously past the structure behind it, an infill panel has a junction with a frame member on every side.

Those junctions are what make infill a distinct position rather than simply a piece of wall. The frame moves — it deflects under load, and it shortens, expands or creeps depending on what it is made of — while the masonry has its own movement behaviour. If the panel is built tight to the frame it can be loaded by movement it was never intended to carry, so the arrangement at the head and the sides of the panel is central to how it behaves.

Boundaries

How it differs from nearby elements

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

  • It is not a spandrel panel. A spandrel is the opaque panel within a glazed facade that conceals the floor zone behind a curtain walling grid; an infill panel is masonry built into the openings of a structural frame and belongs to no glazing system.
  • It is not an outer leaf. An outer leaf is a continuous skin running past the structure behind it, supported at its base and restrained back; an infill panel stops at a frame member on every side and has a junction with each of them.
  • It is not part of the frame's structure, although it is commonly stiff enough to attract load it was never intended to carry — which is why the gap and the restraint at the head of a panel matter more than they appear to.

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.

  • frame infill
  • infill masonry
  • blockwork infill

Dependencies

What it depends on

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

  • The arrangement at the head of the panel, which is what allows the frame above to move without bearing on the masonry.
  • How the panel is restrained at its sides, since wind on its face has to reach the frame members either side of it.
  • The relative movement between the frame material and the masonry, which differs according to what the frame is made of.
  • The continuity of the control layers past every junction with the frame, since the perimeter of the panel is where they are most easily interrupted.

Considerations

Topics that genuinely apply here

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

Movement

Frame and masonry move differently and independently, and a panel built tight into a frame can be loaded by that difference rather than by anything applied to it.

Structural transfer

The panel is intended to carry wind on its own face into the frame around it, not to carry the frame — and the distinction shows up at the head of the panel.

Fire

The junction between the panel and the frame is a line through the enclosure, and how it is closed is a separate question from how the panel itself performs.

Tolerance & fit

The panel has to fit an opening formed by another trade, so the tolerances of the frame and of the masonry meet at its perimeter.

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 LibraryConcrete block →Blockwork is among the most commonly encountered infill materials within framed construction.Materials LibraryAerated concrete block →Met where a lighter unit with different thermal behaviour fills the same position.Materials LibraryClay blocks →Encountered where clay units are used as the infill masonry within a frame.Materials LibraryClay facing brick →Where the infill is also the visible face, brick is commonly met on the outer side of the panel.

Materials

Commonly incorporates

Materials this element commonly contains as a distinct constituent part, rather than being made of.

Materials LibraryMasonry mortar →The bedding and jointing between units, whose behaviour relative to them affects how the panel accommodates movement.

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.

ProtectionFinish surfaceConcrete Frame →Fills between columns and slab edges, where the frame's own long-term movement has to be accommodated at the panel perimeter.ProtectionFinish surfaceSteel Frame →Built between steel members, where deflection of the member above the panel is the governing consideration at its head.ProtectionFinish surfacePortal Frame →Masonry panels within a portal frame enclose the lower part of the wall while the frame carries the building.ProtectionTwin-Leaf Cavity Wall →An infill panel may itself be built as a cavity wall between frame members, in which case both leaves stop at the frame.SubstrateDirect Render →Where a render is applied over infill masonry, the junctions with the frame are where the render has to accommodate movement it cannot resist.

Clarifications

Commonly misunderstood

  • That infill masonry is structural because it looks like a wall. It encloses and resists wind on its own face; the frame around it is what carries the building.
  • That a tightly built panel is a better panel. Where the frame is expected to move, masonry packed hard against it can be loaded by that movement, and cracking at the perimeter commonly follows.

Conversations

Questions for qualified professionals

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

  • What is the arrangement at the head of this panel, and does it allow the frame above to move independently?
  • How is the panel restrained back to the frame at its sides?
  • What is the frame made of, and how does its movement behaviour compare with the masonry's?
  • How do the air, water and fire separation lines run past the perimeter of the panel?

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

  • This entry describes a position within a frame. It states no panel size, no gap, no restraint spacing, no fire rating and no load capacity, and none can be inferred from it.
  • Whether a particular panel is restrained and detailed as its design assumed is a matter for structural and fire assessment on site rather than for a reference entry.

Wall Leaves & Backing

The distinct vertical layers that make up a wall — outer and inner leaves, the cavity between them, and the backing that supports what is fixed to the face.

Browse all wall leaves & backing entries →