System Platon

	INGRESSING WATER (top)


	Platon cavity membranes are capable of dealing with (quite) large volumes of water, so ingressing water will not usually require remedial action. But if the flow rate is such that it will be able to carry silts/dissolved lime with it, then this inflow should be stemmed/controlled prior to fitting the membrane. This can be achieved as follows.

-	If ingressing water is localised then the application of PAM Quick Set plugging compound (TQS) will often be sufficient. (See TQS data sheet).
-	If ingressing water is more general and cannot be dealt with by localised plugging, consideration should be given to applying a general coat of 3:1 render incorporating an accelerator in the mix.

	When water is flowing through concrete or mortar (particularly when it is new) there is a tendency for dissolved lime to be brought into the cavity. This lime can then come out of solution and block up cavities and drains. If this is a risk, then the source of water ingress needs to be treated in the same way as silt bearing water, as described above.

	NB. Regardless of conditions at the time of inspection, BS 8102 says it must be assumed hydrostatic pressure is going to occur at some time during the lifetime of the basement. This means that some form of water removal system must always be fitted with the Platon cavity membrane in below ground structures.

	DRAINAGE TYPES (top)


	There are two principle forms of drainage, these are Natural (gravity) and Mechanical (Sump & Pump) and can be used in conjunction with falls or drainage channels. However, when assessing the type of drainage facility to be used and because the drainage is the key to the success of the cavity membrane system, it is important to take into consideration the following points:

-	Natural- (combined foul chambers & integral gullies) where drainage with gravity is feasible within the bounds of the property or at a point of exit from the property, it is most important to establish that the 'internal drainage' is in good working order and to question as to whether the local drains are connected to public drains or a soakaway. Drains can and do block up or back up causing flooding, including escape of foul waste and pungent smells. Soakaways can also fill up during periods of heavy rain, which would lead to flooding and failure of the cavity membrane system. In situations where the Platon membrane installer finds that the only possibility of draining the cavity membrane is into a foul/soakaway system or his client so instructs, liability for the waterproofing system should therefore be excluded in the event of blockage of the foul pipes or the soakaways filling up. Isola Platon and PAM Chemicals advice is to always recommend the inclusion of sump & pumps.

-	Mechanical- (sump & pump) PAM Ties Ltd produces an off-the-shelf sump & pump drainage system, ‘The Aqua Pump’ which has been specifically designed for the purpose of controlling ground water ingress. The simple to fit sump pump kit comprises of a polyethylene pre-formed sump chamber with a structural lid. The submersible Aqua pump is controlled by an automatic integral float switch and comes with a non-return valve and a high level water alarm that warns of mechanical or power failure. However, it would be prudent to install a double pump system ‘The Aqua Pump plus Kit’ which consists of two pumps in the sump chamber. This secondary pump would provide a back up pump in case of mechanical failure of the principal pump. Consideration should also be given to installing a battery back-up pump in case of a power failure and is also available from PAM. (See technical data sheet attached).

-	Drainage Channel- (PAM Pre-formed peripheral Conduit) PAM Ties Ltd also produces a drainage channel ‘The PAM Aqua Channel’ which is a P.V.C drainage conduit specifically designed for the control of water ingress in below ground situations. It is fitted around the perimeter of the floor at the vulnerable wall/floor junction and can be used in most waterproofing situations, and is particularly suited for use in conjunction with Isola Platon Cavity Drain Membrane systems. Water entering the building through the walls is controlled behind the Platon Membrane and diverted to the Aqua channel at the base of the wall. The water enters the Aqua channel through pre-drilled drainage holes and must then be diverted to a suitable drainage point, either natural or a sump and mechanical pump. Jetting eyes (cleaning ports) can also be incorporated into the Aqua channel.

-	Falls- (Floors) it is essential that there are no undulating surfaces or depressions in the floor. In new build or whenever floors are being replaced, the floor slabs can be designed and constructed to falls 2ºor 3º towards the water collection facility i.e. sump chamber. Where an existing solid floor is to be retained a sand/cement screed can be laid over the entire floor gently sloping towards the sump. In all cases the floor should always be tested by spraying with a hose, to ensure that all water finds its way to the water collection point before laying the cavity membrane. NB wherever possible (head height permitting) we recommend that Platon P20 be used on floors. This is because the P20 membrane has a far greater drainage capacity and significantly reduces the risk of hydrostatic pressure building up within the cavity.

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	MEMBRANE SUITABILITY (top)


	Platon cavity membrane can be applied to almost all sound building structures below ground, which are affected by dampness or water ingress. However, they are not recommended for installation in the following situations.

-	Where the cavity membrane system cannot be drained, otherwise the system will fail. (See drainage facilities and guidance notes)
-	Fixed onto internal flat soffits unless the soffit has an existing fall or a fall can be formed at the design stage (in the case of new build construction) or created using sand & cement renders, otherwise water would pond behind the membrane and build up like a balloon. The weight of water would inevitably burst the membrane seals, which are not designed to hold water under pressure. (See sketch Illustration)
-	Under or on top of concrete/stone staircase treads & risers, because of the many convoluting junctions and angle details. In such circumstances, we recommend they be treated independently using an epoxy vapour barrier.