The first time I mixed mortar I did what most people do: tipped a bag of sand, added some cement, poured in water and mixed. The result was a lumpy, inconsistent mix where half the cement had clumped with water before being distributed through the sand. The bricks laid in it were fine, but the mix was wasteful and harder to work with than it needed to be.
Mortar mixing has a sequence. Do the dry mix first, every time.
What you need
- Sharp sand (coarse, gritty texture - not soft or building sand for structural work)
- Portland cement
- Clean water
- Measuring tools (shovel, bucket) for consistent ratios
- Spot board, barrow or mixing trough
- Mixing shovel (or cement mixer for larger quantities)
- Optional: plasticiser additive (1 capful per 25kg bag equivalent)
Mix ratios quick reference
| Application | Mix ratio (cement:sand) |
|---|---|
| Engineering brickwork, copings, exposed work | 1:3 |
| Standard bricklaying (hard brick) | 1:4 |
| Standard bricklaying (general) | 1:4 to 1:5 |
| Soft brick, internal work | 1:5 to 1:6 |
| Pointing over existing work | Match original - typically 1:4 |
| Blockwork | 1:5 to 1:6 |
A full mix ratio guide is in Mortar Mix Ratios Explained.
How to mix mortar by hand: the steps
Step 1: Measure out the dry materials
Measure your sand and cement by volume using the same shovel or bucket throughout. If you are making a 1:4 mix and using a bucket as your measure, that is 1 bucket of cement to 4 buckets of sand.
Tip the sand onto your spot board first, then add the cement on top.
Step 2: Dry mix thoroughly
This is the step most people skip. Mix the dry sand and cement together before adding any water. Turn the mix over repeatedly until the colour is consistent - no grey cement streaks, no areas of pure sand. This typically takes 2-3 minutes of active mixing.
Why this matters: If you add water to unmixed dry materials, the cement wets and clumps before being evenly distributed. You end up with strong cement-rich pockets and weak sand-rich areas. Dry mixing first prevents this.
Step 3: Make a crater and add water gradually
Push the dry mix into a mound and make a crater in the centre. Add a small amount of water into the crater - start with roughly half the water you think you will need.
Work from the edges of the crater inward, gradually pulling dry mix into the water. Keep adding small amounts of water as needed.
Never pour in too much water at once. An over-wet mix is weak and hard to work with, and there is no way to recover it except adding more dry material (which means re-mixing from scratch to get a consistent result).
Step 4: Mix thoroughly, checking consistency
Continue mixing and turning the mortar, checking consistency as you go. The mix is ready when:
- All dry powder has been incorporated (no dry grey patches)
- The mortar holds its shape when pressed into a ball
- It sits cleanly on a trowel without slumping off
- Running a trowel through it leaves clean edges (the "slump test")
- It feels buttery and workable, not stiff or crumbly
Step 5: Add plasticiser if using
If you are using a liquid plasticiser (such as Febmix), add it to the water before mixing rather than to the already-mixed mortar. One capful per 25kg bag equivalent is typical, but follow the product label. Plasticiser improves workability and reduces the water needed.
Do not use washing-up liquid as a plasticiser. It was once common practice but it is not recommended. It introduces air voids and may affect long-term durability.
Batch size and working time
Only mix what you can use within 30-45 minutes. In summer and warm conditions this window is shorter; in cold weather it is longer.
If mortar starts to stiffen before you have used it, do not add water to re-slacken it. Reworked mortar with added water has reduced strength. Discard and mix fresh.
As a guide:
- A 25kg bag of pre-mixed mortar or loose materials yields approximately 0.012-0.015 m3 of mortar
- This lays approximately 25-30 standard bricks
For larger jobs, a cement mixer is faster and more consistent. A 140-litre mixer can handle the equivalent of 2-3 bags per batch comfortably.
My tips on mixing mortar
Keep your water clean. Dirty water with silts or organic matter can affect set time and strength. Use tap water or clean collected water.
Work in the shade. Mixing and laying in direct sunlight dries the mortar too fast in summer. If you cannot avoid it, mix smaller batches and work faster.
Measure consistently. The most common reason for inconsistent mortar is inconsistent measuring. Use the same shovel throughout a job, not a mix of a shovel here and a bucket there.
Cold weather caution. Below 5°C, do not lay mortar. Below 2°C, do not mix it. The water in the mix can freeze before it sets, permanently weakening the joint.
Use the Mortar Calculator to work out how many bags of sand and cement you need before you start mixing.