Quick Answer
Lime plaster is a popular choice for finishing straw bale walls due to its breathability, durability, and aesthetic appeal. However, it requires regular maintenance to prevent efflorescence and cracking. Additionally, lime plaster can be more expensive than other finishing options.
Advantages of Lime Plaster for Straw Bale
Lime plaster offers several benefits when applied to straw bale walls. Its breathability allows for moisture transfer, reducing the risk of mold and mildew growth. A 1:1 ratio of hydrated lime to sand is a common mix for straw bale plaster, with an optional addition of 10% water. This mix provides a strong, yet flexible finish. A 1/4 inch (6 mm) layer of lime plaster can be applied in multiple coats, with a 24-hour drying time between applications.
Challenges and Considerations
One of the main challenges of using lime plaster on straw bale walls is its sensitivity to moisture. If the plaster is not fully dry, it can be prone to cracking and efflorescence. To minimize this risk, it’s essential to apply a thin layer of plaster and allow it to dry completely before adding additional coats. A 1:1:6 mix of hydrated lime, sand, and water can be used for a more water-resistant plaster. However, this mix may compromise the plaster’s breathability. Regular maintenance, including occasional repainting and reapplying a lime-based sealant, can help to extend the lifespan of the plaster.
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