Building components · Terminations
Weep Opening
Explains the weep as the exit of a drainage path, which is useless without the tray that collects water to it.
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 weep is
A weep opening is a gap deliberately left in the outer leaf of a wall so that water collected behind it can get out. They are placed above every point where water is being gathered — at the base of a cavity, above a tray, over an opening head.
They only work as the exit of a path. Water has to be collected onto something that directs it toward the opening, which is why weeps and trays are always designed together.
Boundaries
How it differs from nearby elements
The distinctions that keep this entry from being a restatement of its neighbours.
- It is not a ventilation opening, although the same opening sometimes serves both purposes. Weeping and ventilating are different requirements met at different positions.
- It is not a cavity tray. The tray collects and directs water; the weep is where it leaves.
- It is not a defect in the mortar. A weep is deliberate, positioned and commonly formed with a purpose-made component.
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.
- weep holes
- weeps
- drainage openings in masonry
Dependencies
What it depends on
What has to be right elsewhere for this element to do its job.
- The tray or surface beneath it that collects water and directs it to the opening.
- Being kept clear of mortar and debris, since a blocked weep drains nothing.
- Its position relative to the level water reaches, since a weep above that level is never used.
- Being present wherever a tray or interruption collects water, not only at the base of the wall.
Considerations
Topics that genuinely apply here
Subjects worth discussing about this element. These are discussion topics, never measured values, ratings or performance claims.
A cavity that collects water and cannot discharge it holds that water against the construction, which is the condition weeps exist to prevent.
Weeps are blocked by mortar during construction more often than by anything afterwards, and it is not visible once the wall is complete.
Whether weeps are clear can be checked from outside, which makes them one of the few cavity features that is inspectable.
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.
Junctions
Interfaces this element takes part in
Junctions where the condition between this element and another governs how the construction behaves. These name the junction and the subjects it raises; they are not details, arrangements or approved ways of building.
Cavity Tray to Weep Discharge
Where water collected within a wall must actually leave it, and where a collection with no exit becomes a reservoir.
Raises: Moisture · Drainage · Buildability · Weathering
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.
- External Wall
Clarifications
Commonly misunderstood
- That weeps let water in. They are the exit of water that is already inside, and blocking them keeps it there.
- That weeps are only needed at the base of a wall. They are needed above every tray and every interruption that collects water.
Conversations
Questions for qualified professionals
Questions worth asking someone with the project in front of them. This page cannot answer them.
- Where does the design require weeps in this wall, and are they all present?
- What collects water and directs it to each weep?
- Have the weeps been kept clear of mortar during construction?
- Are weeps provided above openings and at every cavity interruption, not only at the base?
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 spacing, size, position or component type is stated here.
- Weep and tray arrangements are specified as part of the wall design.
Terminations & Weathering
The elements where a plane stops, turns up, sheds water or is deliberately interrupted — parapets, upstands, flashings, drips, weeps and movement joints.
Browse all terminations entries →