Thermal Bridging Visible Through Masonry Blockwork Wall
Thermal image revealing the masonry blockwork pattern beneath the wall finish due to differing thermal conductivities.
This thermal image displays a distinct grid pattern on an interior wall, indicating the underlying masonry blockwork and mortar joints. Foreground objects (balloons on ribbons) are visible at a differing temperature. The wall pattern emerges because the blocks and mortar conduct heat at different rates.
Technical insight
When a wall lacks adequate continuous insulation, the underlying structural materials can conduct heat at differing rates. Mortar joints and concrete blocks have distinct thermal properties; mortar often acts as a thermal bridge, conducting heat more readily than the surrounding blocks (or vice versa depending on the materials). This creates a geometric grid pattern visible to a thermal camera. If this occurs on a cold external wall during winter, these temperature differentials can lead to localised cold spots, increasing the risk of surface condensation and mould along the mortar lines. Upgrading with continuous internal or external wall insulation breaks this thermal bridge and normalises the surface temperature.
Likely cause
Likely: The wall lacks sufficient continuous insulation, allowing the differing thermal mass and conductivity of the concrete blocks and mortar joints to show through. Possible: Standard thermal bridging through the mortar joints of an uninsulated or poorly insulated wall.
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