Tanking
Contents |
[edit] Introduction
Tanking is a term used for creating a tank-like seal to protect walls against water penetration. The Building Regulations stipulate that tanking must be applied to all new build structures below ground, but tanking can also be applied to existing buildings, to prevent water penetration into basements and cellars, as well as helping to tackle rising damp.
The two main methods of tanking are by using a membrane or a coating. The type of damp and the precise requirements of the building will determine the most appropriate method to use, and sometimes a combination is required to ensure walls remain dry.
[edit] Tanking membranes
Tanking membranes (or cavity drain membranes) consist of a studded or dimpled plastic sheet which is fixed onto the internal face of masonry, block or rendered walls and sealed with tape.
The studs create an air gap cavity between the wall and membrane. Where there is no visible water in the cavity, ventilation may be adequate to prevent the accumulation of moisture. Where water is present, drainage or a or sump and pump may be necessary.
Tanking membranes can have a plain surface which allows battening and insulation boards to be attached to them, or a mesh surface for direct plastering.
[edit] Coating
Tanking coatings include; bitumen, asphalt, resin/tar and tanking slurry.
Liquid bitumen is painted onto cleaned masonry or render but is best for smaller jobs or for coating externally below the damp-proof course. It can prove difficult to apply to masonry in older buildings as it can separate from the wall if applied incorrectly.
Resin/tar coatings are typically epoxy or polyurethane resins extended with tar or bitumen. They are generally able to withstand higher pressures than bitumen coatings.
Asphalt is typically applied in a thick coat with a further wall constructed to prevent it from delaminating under water pressure.
Cement based tanking slurry is typically used for larger areas. It can be applied with a brush, and once dry, overcoated with a breathable render and finished with plasterboard or plaster.
Both floors and walls may require tanking to prevent water ingress.
[edit] Related articles on Designing Buildings Wiki
Featured articles and news
Not buildings. Happy holiday from DB.
Future Homes Standard: Industry calls for more ambition
As the Government FHS consultation finally closes.
Improving government projects with data and AI
Enabling better outcomes, efficient modern delivery and influential leadership on government projects.
BSRIA Living Laboratory Innovation Challenge
Final days for submission, closing March 29.
Windows, their frames, forms, factors and functions.
The hidden subtleties of U-Value calculations
Different contexts and what to include as variables.
A brief run down with related articles.
Electrical sector calls for safer public EV charge points
Serious concerns about electrical safety in the public domain.
Building Blocks manifesto presented to parliament
Architects Declare call in for support of five critical policies.
The four elements of project management with APM
Analysis, expectations, collaborative communication and partnerships.
City of London launches Heritage Building Retrofit Toolkit
Empowering owners to initiate necessary adaptations.
Guidance on RAAC in listed buildings
Published by Purcell, endorsed by IHBC, SPAB and C20.
Learning from the past.
Reluctance to hire people with criminal convictions revealed
Employing People with Criminal Convictions Report.
Tackling unconscious bias; Women's History Month
Personal reflections, as the last week of March approaches.
Comments
It is clearly stated in British Standard 8102 for below ground structures, that Cavity Drain Membranes ARE NOT tanking. they are good repair products but must not be the primary water proofing system in a new build they can make a Type A or B water proofing systems can create a tanked area.
Regards
Nigel