Structural and base materials · Masonry & Blocks
Masonry Lintels over Openings
Sets out what a lintel does above a door or window, how the common types differ from each other, and why bearing, support and sizing are matters for a qualified professional.
Educational reference entry. Suitability depends on the complete assembly, substrate, exposure, installation method, manufacturer documentation, local requirements and qualified professional review.
Overview
What masonry lintels is
A lintel is the component that carries the wall, and often the floor or roof above it, across the top of an opening. Without one, the masonry over a door or window has nothing to sit on. In housing and smaller buildings the usual forms are pressed or galvanised steel sections, precast concrete units and prestressed concrete units.
The types are not interchangeable. A steel cavity lintel is shaped to sit in both leaves of a cavity wall at once and is profiled so that water reaching the cavity is directed back out through weep openings above the head of the opening. A precast or prestressed concrete lintel is a single element bearing at each end, usually used within one leaf or in solid walls, and prestressed units in particular are made to work in one orientation only.
Everything that matters about a lintel is an engineering decision: what it carries, how far it reaches across the opening, how much bearing it needs at each end, what supports that bearing, and how the wall is propped while the work is done. None of that can be read off a page, and altering an opening in an existing building brings the same questions in a harder form, because the loads above are already there.
Terminology
Common names and aliases
These names describe the same thing. The library keeps one entry per material so that an acronym, a trade name or a regional spelling never becomes a second, thinner page.
- Prestressed lintels
- Precast lintels
- Steel cavity lintels
Applications
Common applications
Where this material is typically encountered. A typical application is not a statement that it suits your project.
- Over window and door openings in external cavity walls, carrying both leaves across the head.
- Over openings in internal masonry walls, including openings formed during alterations.
- In garage openings and other wide spans, where the load coming from above is substantial.
- Over openings in solid masonry walls, where a single element carries the full thickness.
- As part of forming a new opening in an existing wall during a renovation project.
Consideration
Where it is commonly considered
- Wherever an opening is formed in a masonry wall and the masonry above needs supporting.
- Where an existing opening is being widened, or a new one created in an existing wall.
- Where the wall above an opening also carries floor or roof loads down into it.
- Where a cavity wall needs an element working in both of its leaves at once.
- Where an existing lintel is showing signs of distress and its replacement is being considered.
Professional review
Where additional professional review is especially important
These are the situations where the answer depends on the specific building, and where a qualified professional should be involved before anything is decided.
- Choosing a lintel by matching whatever is already in the wall, without anyone assessing the loads.
- Using a prestressed unit the wrong way up, or cutting it to length, which changes how it works.
- Building on a lintel before its supports and bearings have been properly formed.
- Any alteration that changes what a lintel carries, including new loads added above it later.
- Positions where corrosion, fire or thermal considerations apply, all of which need professional assessment.
Properties
Key properties to discuss
Qualitative topics worth raising. Measured values, classes and grades come from the manufacturer's technical documentation for the specific product, not from a reference page.
- Installation dependency
- Lintels are set on prepared bearings at each end and the masonry is built up over them in a controlled way. Temporary support of the wall while that work is done is a designed operation in its own right.
- Moisture behaviour
- Over a cavity opening, the lintel and the cavity tray arrangement direct water that reaches the cavity back out through weep openings. Whether that works depends on the detailing rather than on the lintel alone.
- Substrate dependency
- The lintel is only as good as what its ends bear onto. The bearing surfaces, the masonry beneath them and any padstone arrangement are all part of the structural design.
- Thermal behaviour
- A lintel crossing a cavity is a place where heat can move more readily through the wall, which is why thermally broken and insulated types exist; any figures belong to the specific product's documentation.
- Weathering and exposure
- Steel lintels in older buildings can corrode where water has been reaching them, and the expanding metal lifts the masonry above, showing as cracking at the head of an opening.
- Documentation
- Every lintel comes with manufacturer's information about what it is intended to carry, and keeping a record of what was installed where makes future alterations far simpler.
- Maintenance
- Lintels are built in and are not maintained directly. What can be maintained is the detailing above and around them, so that water is not being delivered to a concealed steel component.
Exposure
Exposure and environmental conditions
- Is water reaching the lintel through the cavity, and does the detailing direct it back out again?
- Is this a coastal or aggressive environment where the corrosion protection of a steel lintel matters more?
- Are the weep openings above the opening clear and doing what they were put there to do?
- Has there been any history of damp appearing at the head of this opening?
- Is the opening in a wall that takes driving rain on the building's most exposed elevation?
Assembly
Substrate and system dependencies
What this material sits on, is fixed to or depends on. This is usually where performance is won or lost.
- Bearings at each end sit on masonry that has to be able to take the load, which is part of the structural design.
- Cavity trays, damp-proof courses and weep openings around the head of an opening are separate elements working with the lintel.
- The window or door frame below is fixed to the structure and should not be carrying the wall above it.
- Where the wall above carries floors or roof, the load path continues down through the bearings into the structure below.
- Temporary support during installation is designed for the specific situation and is not a standard arrangement.
Appearance
Appearance and finish considerations
- Most lintels are concealed by the masonry and the finishes, so appearance is rarely the deciding factor.
- Exposed steel lintel edges above openings can be visible as a line and are sometimes finished to suit the elevation.
- Where a lintel is expressed deliberately, as with a stone or concrete head, it becomes part of the composition.
- Cracking at the corners of openings is often the first visible sign that something at the head is not right.
Durability
Durability questions
Questions to raise rather than a service life to expect. No material has a universal lifespan — it depends on the assembly, the exposure and the upkeep.
- What protects a concealed steel lintel from water that reaches the cavity?
- Has any existing lintel been inspected, particularly in an older building with a history of damp?
- Is there cracking above an opening that might indicate movement or corrosion below the surface?
- Are the bearings intact, or has anything been cut away beneath them during past work?
- Has any later work added load above an opening that was not designed to carry it?
Upkeep
Maintenance and repair considerations
- How would a concealed lintel be inspected if there were reason to be concerned about it?
- What would replacing a failed lintel involve, and how would the wall be supported meanwhile?
- Are weep openings above windows and doors being kept clear rather than sealed up during decorating?
- Is there a record of what lintels were installed and where they are in the building?
Installation
Installation dependencies
What the installation depends on — not how to do it. Method belongs to the manufacturer's instructions and the trades carrying out the work.
- The wall above has to be supported while an opening is formed or a lintel replaced, and that support is designed.
- Bearings are prepared before the lintel goes in, and the masonry beneath them has to be sound.
- Prestressed units have a defined orientation and must not be cut, notched or drilled on site.
- Masonry is built up over a lintel in a controlled sequence so that it is not overloaded while the mortar is green.
- The cavity tray and weep arrangement is installed as the work proceeds, since it cannot be added afterwards.
Documentation
Documentation to request
Ask for these in writing, for the specific product being proposed, and keep them with the project record.
- The manufacturer's information for the exact lintel supplied, including what it is intended to carry.
- The structural engineer's calculations or notes covering the openings, kept with the project record.
- A drawing or schedule showing which lintel went where in the building.
- The temporary works arrangement agreed for forming or altering openings.
Conversations
Questions for qualified professionals
Bring these to the relevant qualified professional, manufacturer or authority. Requirements vary by project and location.
- Who has sized the lintels for these openings, and on what basis?
- What is carried above this opening, and does that include floor or roof load?
- How will the wall be supported while this opening is formed?
- What bearing arrangement is provided at each end, and what sits underneath it?
- How does water reaching the cavity get out again above this opening?
- In this existing building, is there any record of the lintel that is already there?
- Is there any sign of corrosion or movement at the head of these openings?
- Does the lintel need to be thermally broken here, and who decides that?
Blind spots
Commonly overlooked points
- Widening an existing opening changes what the lintel carries and is not a like-for-like exercise.
- Weep openings above windows are often sealed during later decorating or repointing, blocking the route water is meant to take.
- Prestressed concrete units behave differently from ordinary precast and cannot be cut or reversed.
- The bearing at each end matters as much as the lintel itself, and it is easy to compromise during other work.
- A lintel installed years ago may have been sized for loads that later alterations have since changed.
What this page does not do
- Lintel type, size, bearing and support are engineering decisions for a qualified professional and cannot be determined from a reference page.
- Nothing here confirms that any existing lintel is adequate; that requires inspection and assessment by someone qualified to do it.
- Forming or altering an opening in an existing building is subject to local requirements that must be confirmed before work begins.
- Water management above an opening depends on the whole detail working together, not on the lintel alone.
Related entries
Related materials
Materials from the same family, an adjacent role in the assembly, or a shared application.
Inspiration
Related Ideas Library pages
Design directions where this material commonly appears.
Preparation
Related planning checklists
Owner-side preparation before the conversation where this material comes up.
Go deeper
Related Build Design Hub guides
Planning guidance and neutral comparisons behind the decisions on this page.
Masonry & Block Materials
Reference entries for unit masonry — clay and concrete bricks, blockwork, mortars, and the ties, lintels and accessories that hold masonry construction together.
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