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NHBC Standards Update: Changes to Drip Detail Requirements for Rendered Walls
07 January 2025
The National House Building Council (NHBC) has introduced a minor but important change to its standards for 2025, specifically regarding cast stone detailing for copings, cappings and sills. This update is outlined in the NHBC Standard 2025 - Section 6.11.7.1 and aims to improve water management and protect rendered walls from damage.
What's the new requirement?
The updated NHBC guidance emphasises the protection of rendered walls by copings, cappings, and sills. Key points include:
- Efficient Drip Detail Placement: all copings, cappings and sills must include an efficient throat or drip detail that is positioned not less than 40mm away from the face of the rendered wall.
- Water Dispersion and Staining Prevention: extending sills or sub-sills beyond window reveals is now recommended to aid in water dispersion and reduce the risk of water staining on rendered surfaces.
What has changed?
The previous NHBC standard required a minimum 40mm projection with a throating or drip detail. The updated requirement refines this by specifying that the drip detail must be positioned at least 40mm away from the rendered wall's surface. This adjustment ensures water is directed further away from the wall, offering enhanced protection against water damage and staining.
When does this apply?
This new standard applies to NHBC - registered homes with foundations laid on or after January 1, 2025.
What does this mean for you?
To comply with this updated standard, we have designed a new sill detail that meets the revised requirements. These new designs are now available to order, and detailed drawings can be provided upon request.
Our team is here to help manage your current orders and transition to the updated standard.
Your Ibstock Account Manager will reach out soon to discuss your needs and assist with the management of existing orders and call-offs.
For further assistance or to request detailed drawings, don’t hesitate to contact us on 01909 775000.
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