In the field of property care and preservation, below-ground waterproofing is a crucial element in ensuring the longevity and structural integrity of buildings. With advancements in technology, materials, and construction practises, it is imperative that industry standards are updated to keep up. Similarly, it is incumbent on property preservation specialists, construction engineers, and surveyors, to stay abreast of the latest updates in order to ensure best practise. 

A recent and significant update in British Standards is the BS8102:2022, which sets the guidelines for protection against water ingress in below-ground structures. In this blog post, we take a look at the intricacies of below-ground waterproofing, exploring its significance, challenges, and the most significant updates incorporated into the BS8102:2022.

Why is below-ground waterproofing important?
Below-ground waterproofing is a fundamental aspect of construction, primarily focused on safeguarding structures against the ingress of water. This is particularly vital for below-ground structures such as basements, tunnels, and foundations, where the pressure from surrounding soil and water tables can exert significant stress. Properties built into hillsides will also require significant below-ground waterproofing. 

Much the same as in above ground structures, water ingress can lead to a myriad of issues, from the growth of mould and deterioration of decorative fixtures, to serious structural damage. This can eventually impact the overall functionality of the property, rendering it unsuitable for habitation or commercial use.

Challenges in below-ground waterproofing
Achieving effective below-ground waterproofing poses particular challenges. Unlike above ground structures, below-ground elements are constantly in contact with moisture-laden soil and are susceptible to hydrostatic pressure. Additionally, the presence of joints, penetrations, and the dynamic nature of soil conditions can further complicate the waterproofing process.

Traditionally, materials like bituminous coatings, cementitious renders, and external membranes have been employed for below-ground waterproofing. These can each carry their own set of risks in terms of susceptibility to ingress and difficulties in maintenance, as well as in installation. However, developments in both materials and practises have inspired innovative solutions that not only provide robust waterproofing but also consider environmental impact and sustainability.

What is the purview of BS8102:2022?
As with all British Standards for construction and property services, BS8102 has undergone several updates over the years. The latest iteration, BS8102:2022, represents a comprehensive revision aimed at addressing contemporary challenges and incorporating advancements in technology and construction practices.

BS8102:2022 maintains its focus on defining the roles and responsibilities of all stakeholders involved in below-ground waterproofing, and is designed to demonstrate a systematic method for assessing and managing the risks associated with water ingress in below-ground structures.

The key elements of BS8102:2022 include:

• Risk assessment and management: The standard emphasises the importance of conducting a thorough risk assessment, considering factors such as groundwater levels, soil types, and the proposed use of the below-ground space. This approach ensures that waterproofing solutions are tailored to the specific needs and challenges of each project.
  
• Types of waterproofing: The previous, 2009 version of BS8102 categorised waterproofing systems into three types – Type A, Type B, and Type C. The updated version has now subdivided the types into two new categories, Grade 1A and 1B.
  
• Professional competence: The standard outlines the qualifications and competencies required for professionals engaged in the design, installation, and maintenance of below-ground waterproofing systems, such as our CSRT and CSSW accredited surveyor, Nic.
  
• Integration of sustainable practices: Recognising the growing importance of sustainability in construction, BS8102:2022 encourages the use of environmentally friendly materials and practices in below-ground waterproofing. This aligns with the industry’s broader push towards greener and more sustainable construction methodologies.
  

What are the notable updates to BS8102:2022?
The changes to the scope of BS8102:2022 are perhaps the most notable, these meaning that the overall design of a structure should now include not only the below-ground waterproofing but also the wider conditions. The scope of the previous version extended only to the protection of below-ground structures against water from the ground, while the updated version now considers the risk of moisture and water entering the structure through doors, light wells and air bricks.The updated standard also now includes buried roofs and podium decks.

Another notable change is in the inclusion of better coverage for below ground structures such as tunnels, something we’ve had recent experience of during our work at the Greenholme Mills development. Additionally, the standard includes a new section on the importance of dealing with buried decks below ground level, and how these differ from roofs above ground level. There is also an emphasis on ensuring waterproofing designs are continuous with the damp proof course level, or 150mm above the external ground level.

Below-ground waterproofing is a critical component of property maintenance and construction, ensuring the longevity and resilience of structures against water ingress. The updates to BS8102:2022 mark a significant step forward in addressing the challenges posed by below-ground waterproofing, providing a comprehensive framework that considers risk management, collaboration, professional competence, and sustainability.

As the industry continues to evolve, adherence to updated standards like BS8102:2022 is paramount for achieving durable and sustainable below-ground structures. By staying informed and implementing the best practises outlined in the standard, professionals such as our own highly qualified surveyors can contribute to the creation of resilient buildings that stand the test of time, even in the face of challenging below-ground conditions. Our team uses these best practises and the outline that standards such as BS8102:2022 provides to utilise below-ground waterproofing in basement conversions, property extensions, the development of historical buildings, and in highly specialised commercial projects.