Installing a lintel above a brick garden wall opening is a satisfying DIY project if you plan carefully and use the right materials. Done correctly, the lintel carries the weight of the brickwork above the gap and prevents cracking or collapse over time. Read on for a practical, step-by-step guide tailored to New Zealand conditions.
What Is a Lintel and Why Does It Matter?
A lintel is a horizontal structural member — typically steel or concrete — that spans an opening in a wall and transfers the load of the masonry above it to the piers or wall sections on either side. Without a properly sized and seated lintel, the brickwork above a gate or decorative opening will crack, sag, or eventually fall. Even in a non-structural garden wall, a lintel is essential for any opening wider than a single brick course.
Planning and Materials
Choosing the Right Lintel
For most NZ garden wall openings, a galvanised steel angle lintel (also called an angle iron or steel angle) is the most common and practical choice. It sits neatly under the first course of bricks above the opening and is available from Mitre 10, Bunnings, and PlaceMakers.
Key sizing considerations:
- Lintel length = opening width + minimum 150 mm bearing on each side (many bricklayers recommend 200 mm for added safety).
- Steel angle size — for a standard single-skin garden wall (110 mm brick), a 75 × 75 × 6 mm or 100 × 75 × 8 mm galvanised steel angle is commonly used. For wider or taller openings, seek advice from a qualified bricklayer.
- Galvanising is important in NZ's coastal and high-humidity environments to prevent rust staining and corrosion.
Pre-cast concrete lintels are another option and are available from some masonry suppliers, though steel angles are generally easier to handle for DIY garden wall work.
Tools and Supplies You'll Need
- Galvanised steel angle lintel (correct length)
- Bricklayer's trowel and jointing tool
- Spirit level and tape measure
- Angle grinder (if cutting bricks to fit)
- Mortar mix — use a 1:1:6 cement:lime:sand mix or a pre-mixed bricklaying mortar suitable for exposed garden walls
- Temporary timber props or acrow props (if working on an existing wall)
- Safety glasses, gloves, and dust mask
Step-by-Step Installation
1. Mark Out the Opening
Measure and mark the opening width clearly on the wall. Double-check that the piers or wall sections on each side are wide enough to provide at least 150 mm of bearing for the lintel.
2. Prepare the Bearing Surfaces
The top of the last brick course on each side of the opening must be level and clean. Rake out any loose mortar and brush the surface. If you are building a new wall, lay the brickwork up to the intended lintel height on both sides before placing the lintel.
3. Set a Mortar Bed
Apply a 10–12 mm mortar bed on top of the bearing surfaces on each side. Keep the mortar consistent in thickness so the lintel sits level.
4. Place and Level the Lintel
Lift the lintel into position with the vertical leg of the angle facing upward and toward the front face of the wall — this creates a shelf for the bricks to sit on. Check it is perfectly level with your spirit level in both directions. Adjust the mortar bed as needed. A lintel that is even slightly out of level will cause uneven brick courses above.
5. Allow the Mortar to Set
Leave the lintel undisturbed for at least 24 hours (longer in cold or wet weather) before laying bricks on top. Do not load the lintel with brickwork until the mortar has achieved adequate strength.
6. Continue Bricklaying Above the Lintel
Lay the first course of bricks directly onto the lintel, maintaining your normal 10 mm mortar joints. Stagger the brick joints (running bond) as usual. The lintel will carry the load of these courses across the opening.
7. Finish Joints and Clean Up
Point and finish all mortar joints around the lintel and the new courses above it. Remove any mortar smears from the brick faces promptly with a damp sponge.
NZ Building Code and Consent Considerations
A freestanding garden wall is generally exempt from building consent under Schedule 1 of the Building Act 2004, provided it meets certain height and construction criteria. However, rules vary — always confirm with your local council before starting work. If the wall is attached to a building, or if the opening is in a retaining wall or boundary fence, different rules may apply.
For guidance on masonry construction standards, BRANZ publishes useful technical resources for NZ conditions. The MBIE Building Performance website is the authoritative source for Building Code requirements.
Safety Notes
- Wear safety glasses and gloves when cutting or handling steel and bricks.
- Use a dust mask rated for silica dust when cutting or grinding masonry — silica dust is a serious health hazard. See WorkSafe NZ for guidance.
- Steel lintels can be heavy — get a second person to help lift and position them.
- If working on an existing wall, prop the brickwork above with temporary supports before removing any bricks to create the opening.
When to Call a Professional
While a simple garden wall lintel is within reach of a capable DIYer, there are situations where you should engage a qualified bricklayer:
- The opening is wider than about 1.2 m, or the wall is unusually tall or heavily loaded.
- You are unsure about lintel sizing or the structural adequacy of the piers.
- The wall is attached to or supports a building structure.
- You need a building consent and producer statement from a licensed tradesperson.
- The existing brickwork is in poor condition or you are working near a boundary.
A skilled bricklayer will ensure the lintel is correctly specified and installed to last. You can find qualified local bricklayers on tradedirectory.co.nz.
Sources & Further Reading
- BRANZ – Masonry and bricklaying technical resources
- MBIE Building Performance – Building consent and Schedule 1 exemptions
- WorkSafe NZ – Silica dust and construction safety
- Mitre 10 – Bricklaying and masonry supplies
- Bunnings – Steel angle and lintel products
- PlaceMakers – Masonry and building materials
Licensed Building Practitioner (LBP)
