Building components · Wall Leaves & Backing
String Course
Explains the string course as a band within an elevation that frequently also sheds water, distinct from a coping at the top of a wall and a plinth at its base.
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 string course is
A string course is a horizontal band in a wall face. It may project from the wall, be set in a contrasting material, or simply be a course laid differently from those around it, and it commonly marks a floor level, a change in the wall above, or the division between parts of an elevation.
Where it projects, it does something functional as well: water running down the face is interrupted and, if the underside is formed to release it, thrown clear of the wall below. That makes a projecting string course a weathering feature as much as a visual one, and it also makes its upper surface a place where water and debris collect.
Boundaries
How it differs from nearby elements
The distinctions that keep this entry from being a restatement of its neighbours.
- It is not a coping. A coping is a published material laid on top of a wall to close and weather its exposed top; a string course runs across a wall face with masonry continuing above it, so it is never the termination of the wall.
- It is not a plinth. Both are horizontal bands, but a plinth is defined by being at the base of the wall where the exposure is ground-related; a string course sits within the elevation and commonly marks a floor line or a change of treatment.
- It is not a drip edge, although a projecting string course commonly incorporates one. The drip is the feature that makes water fall clear of the wall; the string course is the band, which may or may not be formed to shed water at all.
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.
- band course
- belt course
- banding
Dependencies
What it depends on
What has to be right elsewhere for this element to do its job.
- Whether it projects, since a flush band and a projecting band behave completely differently in relation to water.
- How its upper surface deals with water, because a projection with a flat top collects what runs down the wall above.
- The underside, since a projection that does not release water lets it run back against the wall beneath.
- Whether it interrupts anything running through the wall, such as a cavity, a barrier or a movement joint.
Considerations
Topics that genuinely apply here
Subjects worth discussing about this element. These are discussion topics, never measured values, ratings or performance claims.
A projection changes how water runs down an elevation, which is commonly visible as a difference in soiling and saturation above and below the band.
The junction between the band and the wall above it is where water can be directed into the wall rather than off it, particularly where the band is bedded into a cavity.
Where the band is a different material from the wall, the two move differently, and the horizontal joint between them is where that difference concentrates.
Projecting features take more weather than the wall face and are frequently the first part of an elevation to show decay.
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.
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.
Related elements
Neighbouring components
Typed relationships to other elements. There is deliberately no generic “related” category: an edge that cannot be classified does not exist.
Clarifications
Commonly misunderstood
- That a string course is purely decorative. Where it projects it changes how water moves down the elevation, whether or not that was the reason for it.
- That a band can be added to an elevation as a surface feature. A projecting band bedded into a wall interrupts what passes through that wall, including a cavity if there is one.
Conversations
Questions for qualified professionals
Questions worth asking someone with the project in front of them. This page cannot answer them.
- Does this band project, and if so how does its underside release water?
- What passes through the wall at this level, and does the band interrupt it?
- Is the band the same material as the wall, and how do the two behave relative to one another?
- Is staining or saturation below this band related to how it sheds water?
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 in an elevation. It states no projection, no unit size, no fall and no weathering performance, and none can be inferred from it.
- Whether a particular band is shedding water as intended, or is directing it into the wall, is a matter for inspection rather than 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 →