Block and beam flooring: Damp protection for the concrete beam ends
23.04.2019
With the continued increase in block and beam ground floor construction it's essential that damp protection for the porous beam ends and exposed rebars (reinforcing bars) is not overlooked.
Where the concrete beams are installed below the main building DPM (damp proof membrane), over time the ends of the beams and the exposed rebars are subject to any moisture occurring in the sub floor void. This can lead to rusting of the rebars and ultimately compromise the integrity of the building.
Paragraph 4.16 of Approved Document C in England and Paragraph 4.17 of Approved Document C in Wales state that the reinforcement (rebars) should be protected against moisture
"Any suspended floor of in situ or precast concrete including beam and block floors, next to the ground will meet the requirement if it will adequately prevent the passage of moisture to the upper surface and if the reinforcement is protected against moisture."
Traditionally, protection has been provided by painting with a bitumen compound or 'wrapping' with DPM material and gaffer tape. Painting can be messy (particularly if working in inclement conditions) and not 100% consistent. 'Wrapping' can be even less effective and comes with a manual handling risk, as the beams must be lifted to facilitate the process.
Other methods of providing damp protection to the ends of concrete beams are available, but, either the appointed Principal Designer or Principal Contractor will need to specify the method to be used and ensure that it is suitable, and meets the requirements of the Building Regulations.
Disclaimer:
Every care has been taken to ensure that the above content is correct at the time of publication. Any reliance on the content should be verified by the dutyholder(s) and their professional advisers. It is the responsibility of the dutyholder(s) and/or person carrying out the work to ensure compliance with the relevant building regulations and associated legislation.
This content is given in good faith by LABC. It is not definitive, and compliance will be a matter for the relevant building control authority to decide as the enforcing body for the building regulations, and ultimately for the appropriate tribunal or court to determine.
