DAMP-PROOF MEMBRANES | SPONSOR
SIGNED, SEALED AND DELIVERED | TREMCO ILLBRUCK
Tremco Illbruck, leading providers to a range of market sectors including waterproofing and flooring systems, looks at how developments in damp-proof membranes (DPMs) can allow screeds with high relative humidity (RH) readings and containing underfloor heating (UFH) to be covered early.
Even in the midst of a recession, few developers will wish to extend the build phase or fit out to their projects, so the flooring contractor continues to be faced with the demand to complete the installation of finishes in less than ideal conditions, either physical or logistical.
In response to this, the leading manufacturers of flooring products have developed solutions to guarantee success in almost any situation. There are, though, a number of key aspects to achieving the desired outcome that both contractor and consultant have to consider, and that must be incorporated into the contract arrangements.
Concrete or sand/cement screeds still predominate in the industry and overlaying them with an epoxy DPM may be an effective way of dealing with residual damp. However,
only a limited number of reputable manufacturers have developed and tested epoxy systems able to deal with RH readings up to 97%, and written specifications should always be obtained to ensure adherence to manufacturers’ guidelines.
With calcium sulfate screeds, there is no option but to wait for them to dry out to a point where testing indicates an RH of 75%, although some manufacturers now permit application of a surface applied DPM at 87% RH or below. Force drying can shorten this process, but is fraught with practical and programme difficulties and calcium sulfate screeds containing UFH systems must be allowed to dry out naturally in all cases.
Meanwhile, the popularity of UFH systems – preferred for their compatibility with modern high performance
condensing boilers and all types of heat pumps – has created a number of issues for the flooring contractor, both in terms of sequencing and long term performance. While in refurbishment situations, UFH loops or electrical heating cables are often incorporated into shallow screeds or dry panel overlay systems, in new-build work the pipework is normally laid within a deep section screed. This ensures efficient heat transfer, and the warmth can help a concrete/ screed subfloor to dry out far more quickly than it would naturally. The critical consideration for the flooring contractor, however, is the RH at the time the floorcovering is laid – and the material’s vapour permeability.
Vinyl floor coverings exhibit very low porosity and act as a cap to evaporating moisture. This can then lead to the contractor being called back due to the occurrence of blistering or other failure mode. The recourse chosen by a large proportion of specialist flooring contractors is to utilise a specially formulated, DPM. Tremco ES100 presents a DPM system that has been developed to enable it to be applied over concrete and sand cement
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substrates containing UFH systems, with RH of up to 97% and which cures overnight to facilitate the early installation of compatible smoothing underlayments and primers.
It is essential for any installation contract to be based on an agreed specification. The writing of this, along with the identification of suitable sub- contractors for the tender stage, is something with which any reputable manufacturer will be able to assist. This type of design service should also be backed up by the availability of well-trained technical representatives able to offer site guidance and supervision.
Possibly the most important point to consider for the specifier, conscious of claims for professional liability as well as the end user, is that the cost of rectifying any failure – both in direct cost and interruption to the use of the building – normally far outweighs any percentage difference in the initial pricing of competing systems.
www.tremco-illbruck.co.uk
www.tomorrowsflooring.com
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