Cement and traditional buildings
So is cement really all that much of a problem in traditional buildings?
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Incompatibility with Historic Materials: Historic buildings are typically constructed with materials like lime mortar, which is softer and more flexible than cement. Cement is much harder and less porous, leading to incompatibility issues. When cement is used in a building originally constructed with lime mortar, it can cause damage to the historic masonry. The rigid nature of cement can lead to cracking in the softer, older bricks or stones, as they expand and contract at different rates due to temperature and humidity changes.
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Moisture Management Issues: Traditional building materials like lime mortar allow for the movement and evaporation of moisture. Whilst cement devoid of cracks can keep water out it will not keep out water vapour (read 'Interstitial Condensation'). Since cement is nowhere near as flexible as lime it will absolutely crack and allow rain driven water to enter. Cement's inability to allow water to move through it results in trapped moisture within the walls causing cold walls and condensation, decaying timbers sat within those walls, increased salt migration, frost damage and mould.
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Aesthetic Considerations: Cement mortars generally do not match the appearance of traditional materials used in historic buildings. The use of cement can alter the character and appearance of the building, affecting its aesthetic and historical integrity. Lime mortar, on the other hand, ages and weathers in a way that is often more harmonious with the original materials.
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Long-term Durability Concerns: While cement might initially seem more durable, its use in historic buildings can lead to long-term problems that compromise the building's integrity (as mentioned above). Cement will certainly fail more quickly than lime based materials as well.
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Historical Authenticity: The use of modern cement in the repair or restoration of historic buildings can detract from their historical authenticity. Preserving the original building techniques and materials is often a key aspect of historic conservation, and the use of cement can undermine these conservation efforts. Listed buildings are protected due to their particular construction method, age, character or cultural/ historical significance. The use of cement materials on these structures opens the door to legal issues.
