Expansion joints in brickwork and blockwork - what you need to know

What is an expansion joint in brickwork and blockwork?

An expansion joint in brickwork and blockwork is a means of solving potential problems caused by movement. This movement could be a result of thermal expansion, moisture movement, creep and structural loading or the effect of chemical changes. Mostly the builder needs to work with the potential consequence of water and heat that will create internal stresses, which could lead to costly repair.

In brickwork and blockwork you should use foam expansion joint fillers. This is a flexible and lightweight joint filler made from a closed cell foam. It provides resistance to mechanical, thermal and chemical factors in a build. It is supplied in strips and is positioned at different points in the structure to take some of the tension that runs through a building.

How to place an expansion joint

In terms of vertical movement, the south, south west and south east facing elevations will be likely to experience most movement. However, all brickwork should be supported with foam expansion joints.

The general thinking in the construction sector is that your expansion joint will be spaced at approximately 10 – 12 metres. This joint will be continuous for the full height of the brickwork or blockwork, from floor to roof of a house, for instance. The first of these should be placed no more than 6 metres from a corner. This is because the spacing should be continuous around the corner.

The amount of filler placed can be calculated as follows: 30% more than your distance between joints but measured in millimetres not metres. So, if you have 12 metres between joints then the joint should be 16mm (12m + 4(30%) = 16mm).

Joint positions will also be impacted by the type of brick, the change in height of external materials, the placement of windows and door openings, the location of wall ties, and the bed joint reinforcement.

Evidence from research suggests that the vertical movement in a build is the same as that of horizontal movement. This means you should also consider placing horizontal joints in buildings over 4 storeys. If the building is less than 12m then the brickwork could be laid uninterrupted for the full height.

The SITEWORX foam expansion joint filler

Our Siteworx foam expansion joint filler Is made from polyethylene foam, which comes with low moisture properties. This is the perfect filling for expansion joints in brickwork and blockwork, as it expands and contracts with the movement through a building. To help match mortar, the foam comes in white or cream. This foam also comes in a variety of sizes and properties, which allows you to decide on your priorities. Are you looking for economy or are you looking for the best expansion and contraction properties?

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