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Whilst the winter of 2016/17 saw most homes escape any serious flood events, for some the arrival of storms such as Doris and Ewan has acted as a firm reminder of the very real threat posed by the seemingly increasingly disruptive UK weather. For some still the events of December 2015 are also a recent, and painful memory, as a result of the havoc that storms Desmond, Eva and Frank wreaked on over 16,000 residential homes in England.
With flooding set to remain a very real threat to many UK homeowners for the foreseeable future, Toby Champion, Commercial Director at Newton Waterproofing Systems, examines how waterproofing measures can assist those who are recovering from or facing the threat of future flood events.
It is when the waters recede that flood victims are left with the greatest challenge – how to make flood-damaged properties fit for reoccupation quickly, and how to protect our homes from a repeat of such catastrophes in future?
Frequently, the post-flood cleanup can be as frustrating and torturous as the flooding itself, and making affected properties habitable again can take a lot longer than expected. From health and safety assessments, flood damage assessments, flood characteristic investigations and future flood risk assessments, to the stripping out of irreparable fixtures and fittings, a whole host of factors can prevent occupiers from returning to their homes.
However, one of the most onerous delays to the reinstatement and reoccupation of flood-affected properties is the unavoidable requirement to allow saturated structural walls to dry out, which can be as painfully slow as one month per inch of wall thickness. Furthermore, the process cannot begin in earnest until all contaminated finishes and organic materials have been removed and a ‘Decontaminate Building and Sanitation Certificate’ has been issued.
Either expediting or circumventing this part of the flood recovery process is therefore a crucial element in ensuring swift reoccupation of a property.
This 3D cross-section demonstrates a typical and full Newton System 500 cavity drain waterproofing installation.
Over 3,000 square feet of Newton’s cavity drain system was installed to prevent water ingress in the Grade II listed Pickenham Hall, Norfolk.
Designing an effective and achievable flood management strategy is vital to being able speed up reoccupation, and cavity drainage systems, comprising of membranes, drainage and pumps, can be a key contributor to success.
The High Density Polyethylene (HDPE) membranes employed as part of such a system are designed with a cuspated profile, creating an air gap between the membrane and the surfaces to which it is applied. Once installed with specially sealed fixings as part of a comprehensive cavity drainage system, the membranes have two major benefits for flood-affected properties:
By providing a barrier that is completely impermeable to water, the membranes separate the damp structure from the internal environment, allowing new internal surfaces and finishes to be installed immediately. They are also permanently effective against damp, salts, staining, and moulds, just a few of the potential side effects of the drying process that can impact internal environments.
Secondly they use positive vapour pressure to ‘move’ dampness out of the property. Internal vapour pressure in the air gap created by the cuspated profile of the membrane is greater than external vapour pressure outside. The result is a vapour pressure equalisation process, occurring where internal pressure moves out to the lower pressure externally. In doing so, dampness in the external walls is moved outwards of the property.
By maintaining the status quo of the structure whilst simultaneously protecting internal environments, an effective cavity membrane system allows finishes to be applied with the peace of mind that the membrane will prolong their longevity and allow the walls to dry naturally behind. Most important of all though, is that in most cases the property can be reoccupied significantly earlier than if the walls were required to dry naturally to a point where new finishes could be applied directly.
Furthermore, when installed as part of a comprehensive Cavity Drain System that also employs suitable drainage, the system will have additional benefits beyond just providing a solution for post-flood damp proofing. Once installed, the system will assist in future-proofing the property against further flooding, forming an integral part of an overall designed flood remediation solution. By depressurising water as it enters the structure, the system is able to manage and drain it to a sump, before safely pumping it out and away from the structure, protecting both the occupants, and their possessions, inside.
Our staff are able to provide guidance for projects of all sizes, whether you require some general advice about damp or waterproofing, or support with technical drawings and specifications.