Which mortar joint profile should I use?

The profile you tool into a joint is doing two jobs at once. It decides how the wall looks, which is why people choose it, and it decides what rainwater does when it hits the joint, which is why it matters. The joints are where the great majority of driving rain gets into a solid wall, so the shape of them is not a cosmetic decision on an exposed elevation. The cross-sections show what a raindrop does at each profile.

Step by step

1. Look at what the wall already has.On any repair or repointing job this decides it. A patch in a different profile is more obvious from the street than a patch in a slightly different colour, because it catches the light differently along the whole area.
2. Weigh exposure before appearance on a new wall.A sheltered garden wall can take a recessed joint. A gable facing the prevailing wind, a parapet, a chimney or a coastal elevation cannot. Bucket handle or weatherstruck on anything that takes real weather.
3. Match the profile to the brick.Crisp modern wirecut brick suits a tooled bucket handle. Irregular handmade or reclaimed brick usually looks wrong with a machine-precise joint and better with a flush or lightly struck one.
4. Wait for the right moment to tool.The mortar must be thumbprint firm — it takes a print and holds it. Too soon and the tool drags the mortar out of the joint; too late and it will not compress and the surface stays open and porous.
5. Tool the perpends first, then the beds.Doing the short vertical joints first means the long horizontal lines run through unbroken when you do them, which is what makes brickwork look properly finished.
6. Compress rather than smooth.The point of tooling is to press the surface of the mortar back into the joint, which densifies it and closes the pores. Lightly stroking the surface achieves nothing. Firm pressure and one pass.
7. Brush off afterwards, at the right time.Once the joints have firmed further, a soft brush over the face removes the crumbs the jointing tool left. Brushing too early smears mortar into the brick face and stains it.
8. Keep the recess shallow on a raked joint.If you must have a recessed joint, keep the rake shallow, use a hard frost-resistant brick, and accept that it will need attention sooner than a tooled joint would.

Tips

• A short length of garden hose or copper pipe makes a perfectly good bucket handle jointer, and many bricklayers prefer one to a bought tool.
• Weatherstruck joints are cut with a small pointing trowel and a straight edge. Getting the slope consistent across a wall takes practice — do a hidden panel first.
• On an old lime-pointed wall the original joint is usually flush or very slightly recessed and often quite wide. Copy it, including the width.

Alternatives

• Bucket handle (concave, rounded): Pressed back into a smooth curve with a rounded jointer or a length of hose. Tooling compresses the mortar surface, which makes it dense and weather resistant, and the curve sheds water. The best general choice and the modern standard on new brickwork.
• Weatherstruck: Cut back at the top of the joint and left proud at the bottom, forming a sloped ledge that throws water outwards. The traditional choice for exposed elevations and parapets. It must slope the right way — struck the wrong way it collects water.
• Flush: Cut off level with the brick face. Simple, forgiving, and the right answer where the bricks are irregular, handmade or reclaimed and a tooled joint would emphasise every variation. Common on lime-pointed historic work.
• Recessed / raked: Raked back a few millimetres behind the face, giving a strong shadow line and emphasising the bricks. Looks excellent and weathers worst — it creates a ledge that holds water, and the joint has less cover. Sheltered elevations and hard frost-resistant brick only.
• Overband / ribbon: Not a profile. Mortar smeared over the brick faces above and below the joint, usually because nothing was raked out. It traps water in the wall, hides the true state of the joints and accelerates decay of the brick face. Where you find it, it should come off.

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