Question 1

What is an expansion joint?

Accepted Answer

An expansion joint is a deliberate gap in brickwork or concrete that allows for movement caused by temperature changes, moisture variation, or minor structural shifts. It prevents cracking by relieving internal stress. In UK construction, expansion joints are essential for long walls, slabs, and masonry panels.

Question 2

Where should expansion joints be placed?

Accepted Answer

Expansion joints should be placed at calculated intervals based on the material and building layout. They’re commonly positioned every few metres in brickwork or slabs. They’re also needed where walls change direction, height, or connect to other structures. Common spacings for expansion joints are:

Clay brickwork: typically every 6–12 m, with closer spacing for darker or highly exposed bricks.
Blockwork: usually every 6–9 m, depending on block type and moisture movement.
Concrete slabs: commonly every 4–6 m or roughly 30–40 times the slab thickness.

Question 3

What UK standards apply to expansion joints?

Accepted Answer

Different British Standards apply for expansion joints depending on whether they’re being used for concrete or bricks and blocks

For brickwork and blockwork: see BS 5628 (Masonry Code of Practice) & PD 6697 / Eurocode 6
For concrete structures: BS 8500 and Eurocode 2 cover expansion and control joint design.

If you’re using sealants and fillers, BS 6093 and ISO 11600 specify performance and installation standards.

Question 4

Do concrete driveways need expansion joints?

Accepted Answer

Yes. Concrete driveways need expansion joints to allow for seasonal temperature changes and drying shrinkage. Without them, uncontrolled cracking will occur.

Question 5

Do expansion joints need to be filled?

Accepted Answer

Yes. Expansion joints are normally filled with compressible filler boards or flexible sealant. This prevents debris and water from entering the gap while allowing ongoing movement. In external areas, expansion joint filler also reduces frost damage risks, which are common in the UK climate.

Question 6

What’s the difference between a concrete expansion joint and a control joint?

Accepted Answer

A concrete expansion joint allows slabs to expand and contract freely without causing stress cracks. A control joint, also called a contraction joint, manages shrinkage cracking by creating a weak plane for cracks to follow. Expansion joints handle movement; control joints guide shrinkage.

Question 7

What happens if you don't use movement joints in brickwork?

Accepted Answer

With the UK's varied climate, brickwork without expansion joints can develop serious structural issues. Brickwork expansion joints allow space for the natural expansion and contraction of bricks and mortar caused by temperature and moisture changes. These movements can cause visible cracking in the brickwork – typically vertical or stepped cracks following mortar joints. Cracks not only looks bad but also compromise the integrity of the brickwork, allowing water to get in.

Brick and concrete expansion joints

Fillcrete Brickfill Expansion Joint Roll 10mm X 100mm X 10m

175mm Speed Pro EML Brick Reinforcement Coil Galvanised 20m

63mm Speed Pro EML Brick Reinforcement Coil Galvanised 20m

35/40/50mm Concrete Spacer (single)

Fillcrete Fillaboard Expansion Joint Strip 2.4m x 150 x 12mm

Fillcrete Fillaboard Expansion Joint Strip 2.4m x 100 x 12mm