Building a new home or structure near trees, hedgerows, and shrubs can be a challenging task, especially when dealing with shrinkable soils. Trees and plants can significantly affect soil stability, which in turn impacts the integrity of foundations. Understanding and following the NHBC Standards, particularly Chapter 4.2, is crucial to ensure that your construction project is both safe and durable.
Chapter 4.2 of the NHBC Guidelines provides comprehensive advice on how to approach building near trees. It starts by emphasising the importance of compliance with technical requirements to mitigate risks associated with root activity and soil desiccation. Accurate and detailed information in design plans is essential. This includes specifying the types, depths, and dimensions of foundations that might be influenced by nearby trees.
Trees can significantly impact shrinkable soils. They extract moisture from the soil, leading to volume changes that can cause the soil to shrink or swell. The guidelines helps you understand the water demand of various tree species and their potential mature heights. By recognising these factors, you can design foundations that accommodate these changes, ensuring the long-term stability of your structure.
Foundations must be designed to safely transmit loads to the ground without excessive movement. Whether you’re dealing with strip, trench fill, pier and beam, or raft foundations, it’s crucial to consider the specific conditions of shrinkable soils. Proper design and construction practices will help you manage potential ground movement due to soil desiccation and heave, ensuring your building remains secure.
Heave precautions are vital for protecting foundations from excessive ground movement. This includes using void formers or compressible materials to counteract heave forces. Additionally, new drainage systems should be designed to handle potential ground movement, ensuring that pipes and services remain functional and effective.
To help builders understand the practical application of these guidelines, Chapter 4.2 includes a worked example that demonstrates how to determine foundation depths based on soil conditions and tree characteristics. For those seeking deeper insights, the chapter also lists additional resources and references to authoritative texts on tree root damage and soil desiccation.
For a detailed understanding and to ensure your construction project adheres to all necessary standards, we highly recommend reading the full guidelines.
Click here to read the full NHBC Standards Chapter 4.2 on Building Near Trees