Can concrete facing bricks be used below the damp proof course (DPC)?

Concrete facing bricks can be used both below and above the damp proof course (DPC), although they cannot be used as the damp proof course itself. 

The DPC has the key function of preventing the damaging effects of rising damp to a property that is caused by ground moisture moving upwards through the exterior wall. Whilst the low water absorption levels of concrete facing bricks of around 6 to 8% are not low enough to form a damp proof course in their own right, they do help to minimise the DPC’s exposure to groundwater.  

What are the benefits of using concrete facing bricks above and below the DPC? 

Concrete facing bricks are an attractive alternative to clay bricks for use as the exterior walls of buildings both above and below the DPC and have many benefits when compared to other choices. 

• Low water absorption properties 

Concrete facing bricks have typically low water absorption levels of 6 to 8%, making them suitable for use in areas likely to be exposed to ground water such as beneath the DPC. 

• High compressive strength 

Concrete facing bricks meet the compressive strength requirements of 22N/mm2 and continue to gain strength as they age. 

• Fine dimensional tolerances  

The composition of facing bricks and precise manufacturing methods mean they can be produced to fine and more accurate tolerances than clay alternatives. 

• ​​​Reduced possibility of efflorescence 

The concrete facing brick curing process can help reduce instances of efflorescence that can cause unsightly white stains on the surfaces of external walls. During the manufacturing process, Tobermore concrete facing bricks are vapour cured for a minimum of 12 hours. This can significantly reduce the possibility of efflorescence, but it is worth noting that getting rid of efflorescence altogether for either type of bricks discussed here is not possible. 

• Excellent colour retention 

Concrete facing bricks have vibrant colours with excellent colour retention. Like clay bricks they are through coloured, so that chips or damage to the bricks are not easily noticeable, nor do they detract from their visual appearance. 

• High frost resistance 

High frost resistance properties (F2) of facing bricks make them suitable for use where they will be exposed to water and helps provide house builders with a highly durable solution for external walls. 

Craig McBride, Tobermore’s Technical and Product Training Manager, comments:

“Concrete facing bricks should be manufactured to meet the requirements of BS EN 771-3:2011+A1: 2015 ‘Specification for masonry units – Aggregate concrete masonry units (Dense and lightweight aggregates)’. As well as their low water absorption properties, concrete facing bricks can have compressive strengths in excess of 22N/mm2 and continue to gain strength as they age. The manufacturing method and composition of facing bricks means that they can be produced to fine and more accurate tolerances than the clay alternatives and can be processed to significantly reduce instances of efflorescence. These benefits illustrate why concrete facing bricks can provide housebuilders and architects with a highly durable and functional solution for external walls.” 

Building Regulations and use of concrete facing bricks below DPC  

As with all construction materials, it is important to follow the relevant standards and best practice guidance when specifying a damp proof course above concrete facing bricks. From a standards perspective, the most relevant document1 is PD 6697: 2019 – ‘Recommendations for the design of masonry structures to BS EN 1996-1 and BS EN 1996-2’. Those standards set out codes of practice for the use of reinforced and unreinforced masonry. PD 6687:2019 sets out the key information relevant to the UK market and recommends concrete facing blocks have a minimum compressive strength of 22.5N/mm2 for most situations. 

Best practice on installation can be found in the National House Building Council (NHBC) technical guidelines. This guidance states that the DPC should be positioned at least 150mm above the external finished ground or paving level and be of the correct width and fully bedded and either welded or lapped by a 100mm minimum.  

The foundation below the DPC should be properly compacted and prepared to provide a level stable base upon which the concrete facing bricks are laid. Installation instructions from the concrete facing brick manufacturer should always be followed. This will help to ensure that the correct mortar mix is used and that the bricks are installed and bedded in correctly to provide robust layers beneath the DPC with no gaps that could provide a route for water to enter the structure.  

Where can I get more information on the use and benefits of concrete facing bricks?

Craig comments on the product offering at Tobermore: “We have an extensive range of facing bricks such as our Kingston smooth facing brick and our Lansdowne rustic effect facing brick. They are manufactured to strict quality standards and have Environmental Product Declarations (EPDs) to verify their environmental performance. Our concrete facing bricks are in-stock and ready for delivery with over 98% of deliveries to Great Britain arriving on the day of request”. 

For more information, please contact our sales team who will be happy to go through the choices available to you when specifying concrete facing bricks both above and below the damp proof course.