Although modern renovation plasters are a superb alternative to tradional types; don’t overlook the possibilities impervious coverings – along with hybrid and insulated plasterboards. So says Hudson Lambert, director of Safeguard Europe.

Impervious coverings come in a few varieties, yet easily the most popular are meshed cavity drainage membranes. These are attached to walls using special fixing plugs, and then can be plastered over using traditional gypsum, lime or other plasters. Effective as they are, it should be remembered that despite a notional air gap behind the membrane, these systems are not breathable and will drive rising damp further up the wall unless controlled at source using a high specification remedial damp-proofing cream or rod.

More recently, fleeced DPMs are a natural development from meshed cavity drainage membranes. First, a flexible waterproof adhesive is applied to wall, then the fleeced DPM applied over adhesive and, finally, traditional plasters can be applied on top.

These have the same disadvantages as meshed cavity drainage membranes; yet are faster to apply and their lower profile makes it easier to blend them in with existing plaster finishes.

Beyond these two types of membrane are new systems based around ‘hybrid’ plasterboard. The design intention of these is to utilise the convenience of plasterboard, yet enhance it to reliably allow its on walls susceptible to damp. This is especially useful in situations where speed is important (e.g. tenanted properties where decanting may be inconvenient) and decoration can take place as soon as the system is installed (when using dry joints rather than a plaster skim).

Although they are not suitable where wall surfaces are particularly uneven, they are Breathable (except where foil-backed or insulated plasterboard is used) and BBA approved types are available – which acts as reassurance to clients such as local authorities.

Installation is relatively straightforward: water-repellent/salt-disrupting silane cream is applied to wall and plasterboard applied in the traditional way (although water/salt resistant MS-polymer adhesive is used instead of traditional gypsum-based plasterboard adhesive). ‘Synergistic’ chemistry ensures a high strength chemical bond between the silane cream and the MS-polymer adhesive (due to covalent bonding between the silane components of both materials).

While a plaster skim is usually applied over the plasterboard, using a ‘dry jointing’ method allows the fastest results – and means walls can be re-plastered and re-decorated in less than 24 hours.

If required, the system can be used in conjunction with insulated plasterboard. However, as is always the case when using internal wall insulation, certain precautions are required to minimise condensation risk and it will hinder drying out of the wall compared with when standard (porous) plasterboard is used.

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