Buttering a brick is the process of applying mortar to the end (and sometimes the face) of a brick before placing it in the wall. Done correctly, it creates a full, strong bond that keeps your brickwork structurally sound and weathertight — a must in New Zealand's varied climate, from the wet West Coast to the wind-driven rain of Wellington.
What Does "Buttering" Actually Mean?
In bricklaying, buttering refers to spreading mortar onto the header face (the short end) of a brick so that when it is pushed up against the previous brick, the vertical joint — called the perpend — is fully filled. Some situations also require buttering the bed face (the flat underside), though in most standard laying the bed mortar is spread on the course below rather than on the brick itself.
Getting Your Mortar Mix Right First
Before you butter anything, your mortar needs to be the right consistency. A standard mix for general brickwork is 1 part cement : 1 part lime : 6 parts sand (by volume), though this can vary depending on exposure and brick type. The mortar should:
- Hold its shape when squeezed — not slump or crumble
- Slide cleanly off the trowel without sticking excessively
- Have a smooth, plastic feel — often described as "peanut butter" consistency
If you are unsure about the correct mix for your specific project or local conditions, check with your supplier at Bunnings, Mitre 10, or PlaceMakers, or consult a licensed bricklayer.
Step-by-Step: How to Butter a Brick
1. Load Your Trowel
Scoop a generous amount of mortar onto your brick trowel — enough to cover the header face of the brick with roughly 10–15 mm of mortar. Experienced bricklayers do this in one smooth scoop.
2. Hold the Brick Firmly
Hold the brick in your non-dominant hand with the header face pointing upward or toward you. Keep a firm grip — you'll be applying pressure with the trowel.
3. Apply the Mortar
Using the flat of the trowel, press and spread the mortar firmly onto the header face of the brick. The key word here is press — you want the mortar to adhere to the brick surface, not just sit on top of it. Spread it to cover the full face, leaving a slight mound or ridge in the centre (this helps it squeeze out evenly when the brick is pushed into place).
4. Trim the Edges
With a quick flick of the trowel edge, trim any mortar that overhangs the sides of the brick. This keeps your perpend joints neat and prevents excess mortar from smearing the brick face.
5. Lay the Brick
Place the buttered brick down onto the mortar bed and push it firmly toward the previously laid brick. Apply even downward and horizontal pressure so the mortar squeezes out slightly on all sides — this confirms you have a full joint. Tap gently with the trowel handle to level if needed.
6. Check and Clean Up
Use a spirit level frequently to keep courses level and plumb. Scrape off any mortar squeeze-out with your trowel before it sets. Joints should be finished (tooled or raked) while the mortar is still "green" — firm but not hard.
Common Buttering Mistakes to Avoid
| Mistake | Why It's a Problem |
|---|---|
| Too little mortar on the header | Creates voids in the perpend — allows water ingress |
| Mortar too wet or too dry | Poor adhesion, weak joint, or crumbling |
| Not pressing mortar into the brick | Mortar falls off before the brick is placed |
| Skipping the butter entirely | Open perpends — a common cause of leaks in NZ |
| Letting mortar skin over before laying | Bond is severely weakened |
Why Full Perpend Joints Matter in NZ
New Zealand's NZ Building Code — particularly Clause E2 (External Moisture) — requires that external walls resist the penetration of water. Open or poorly filled perpend joints are a leading cause of moisture issues in brick veneer and solid brick construction. BRANZ research consistently highlights correct mortar jointing as critical to weathertight performance. Always aim for full, solid joints.
For brick veneer construction specifically, the work must also comply with NZS 3604 (Timber-framed buildings) where applicable, and your local council may require a building consent depending on the scope of work. Always check with your local council before starting any structural or external brickwork — Schedule 1 exemptions are limited and vary by project.
Tips for Consistent Results
- Keep mortar fresh — discard any mortar that has been sitting for more than about 90 minutes or has started to stiffen
- Dampen dry bricks lightly in hot or windy weather to prevent them drawing moisture out of the mortar too quickly
- Work in the shade where possible on hot NZ summer days to extend your working time
- Practice the motion — buttering smoothly and quickly comes with repetition
When to Call a Professional
If you are tackling anything beyond a small garden wall or minor repair, it is strongly worth engaging a qualified bricklayer. Structural brickwork, retaining walls over 1.5 m, and all external weathertight walls on a home are areas where poor technique can have serious and costly consequences. A licensed bricklayer will also know whether your project requires a building consent — always confirm this with your local council or visit MBIE Building Performance for guidance. You can find experienced, local bricklayers on tradedirectory.co.nz.
Licensed Building Practitioner (LBP)
