How to Build a Brick Arch Step by Step

The arch is one of the most beautiful and load-bearing solutions in building: it works in compression and can support heavy loads. Building an arch correctly takes a little skill — here we explain, step by step, how to construct a brick arch.

The key element: the centring

The arch is built over a centring: a timber former in the exact shape of the arch, which supports it until the mortar has cured. Without a good centring there is no good arch — so this is where the greatest care is needed.

Materials and tools

Materials:

• Bricks, ideally solid bricks or perforated bricks
• Cement and sand mortar, 1:3
• Board and battens to make the centring
• Props or supports for shoring

Tools:

• Saw or jigsaw (for the centring)
• Trowel and float
• Spirit level, plumb line, tape measure and pencil
• Rubber mallet

How to build the arch step by step

1. Build the centring

   Draw the arch curve (semicircular, segmental, etc.) onto a board and cut it out. Strengthen it with battens: this is the former on which the bricks will rest.

2. Set the centring to the right height

   Shore it up with props at springing level — perfectly level and centred within the opening. Make sure it can carry the weight.

3. Set out the voussoirs

   Lay the bricks (the voussoirs) out 'dry' on the centring so they sit symmetrically about the keystone, the central piece. The joints open slightly towards the outside, in a wedge shape.

4. Prepare the mortar

   Mix a 1:3 mortar following our guide on how to mix mortar.

5. Build up from the springers towards the keystone

   Set the bricks on both sides at the same time and work up symmetrically. The joints must always point towards the centre of the arch.

6. Finish with the keystone

   The last piece, at the top in the middle, is the keystone: set it firmly wedged in place. It 'locks' the whole arch together and gives it strength.

7. Let it cure before striking the centre

   Wait until the mortar has cured — at least 24 to 48 hours, depending on conditions. Take your time over this step.

8. Remove the centring (striking the centre)

   Ease off the props gradually and remove the former. The arch now supports itself entirely in compression.

Tips from the professional

• Always work symmetrically: both sides at the same time, building up evenly.
• Keep the joints wedge-shaped — thinner at the intrados (the inner face) and a little more open towards the outside.
• Don't strike the centre too soon: this is the most common mistake and it ruins the arch.
• For large or load-bearing arches, a structural calculation and skilled hands are recommended.

A well-built arch lasts forever. If you would like one in your home or as part of your renovation — decorative or load-bearing — we will build it for you in Calpe and the Marina Alta: wall building and construction work · request a quote.