What size brick jointer do I need?

Shop for Brick Jointers

Blade radius

Radius at either end The tool’s radius refers to the measurement of curvature at the end of the jointer. The radius should be clearly stamped on the midsection of the jointer.

The jointer pictured has a 1/2 inch (13mm) radius at one end and a 5/8 inch (16mm) at the other.

Consecutive radius sizes The majority of jointers are produced with a different radius at either end so the tool is more versatile.

Brickwork and mortar gap preference can vary considerably from project to project, so it’s useful to have a tool which can be used for more than one application. The radius at either end are usually consecutive sizes.

Jointer Sizes Jointer sizes commonly available are:

3/8 Inch (10mm)

1/2 Inch (13mm)

5/8 Inch (16mm),

3/4 Inch (19mm)

7/8 Inch (22mm)

Multiple radii

 Hubbard Barrel Jointer If you do require a tool with multiple radius attachments then the Hubbard barrel jointer may be the ideal choice. It comes with interchangeable barrels with radii measurements: 1/2 inch (13mm), 5/8 inch (16mm), 3/4 inch (19mm)  and 7/8 inch (22mm).

Choosing the correct radius for the mortar gap

Brick Jointer Radius Diagram The correct jointer radius should be the same size or a few millimetres larger than the mortar gap. This is so that the jointer is able to make contact with the brick above and below the joint. The tool is then able to provide the mortar with the correct amount of compression against the brickwork.
Sample brick size In the UK, when using standard building bricks, a gap of 10mm (3/8“) is left for a mortar joint before the next brick is placed. This is the standard gap between both bed (horizontal) and head (vertical) joints.

Checking the mortar gap between your brickwork

Tape Measure If you have built the wall yourself, you will be aware of the mortar gap width from the construction stage.

If not, be sure to measure the gap with a tape measure. Mortar gaps can range from 10 to 19mm, so it’s important to clarify the measurement before purchasing a brick jointer.

 Wonkee Donkee says: 'If you don’t know what the size of the mortar gap is between your bricks be sure to measure it. Then you can select the appropriate size jointing tool.'

Using a radius that’s too small

Tram Line Effect If the radius of your brick jointer is too small for the mortar gap it’s easy to apply too much pressure and leave a tramline effect in the mortar.

Using a radius that’s too large

 Brick Jointer that is too large If the radius of your brick jointer is too large you may not be able to fit the tool into the mortar gap or apply enough pressure for the mortar to compact correctly.