Polythene And Polyethylene Sheet

Polythene And Polyethylene Sheet

Polythene or polyethylene sheet is often used as a damp-proof membrane with oversite concrete for all but severe circumstances of dampness. It's endorsed that the sheet needs to be not less than 0.25 mm thick (1200 gauge). The sheet is provided in rolls four m huge by 25 m long. When used beneath concrete oversite the sheet must be laid on a blinding layer of sand or compacted fuel ash spread over the hardcore.

The sheets are spread over the blinding and lapped a hundred and fifty mm at joints and continued across surrounding walls, underneath the dpc for the thickness of the wall.

The place site situations are reasonably dry and clean, the overlap joints between the sheets are sealed with mastic or mastic tape between the overlapping sheets and visqueen roll the joint accomplished with a
polythene jointing tape as illustrated in Fig. 29.

For this lapped joint to be successful the sheets should be dry and clear else the jointing tape won't adhere to the surface of the sheets and the joint will rely upon the weight of the concrete or screed urgent the joint sufficiently closely to make a watertight joint. As clean and dry situations on a building site are rare, this type of joint ought to be only used the place there is unlikely to be heavy absorption of ground moisture.
Where site circumstances are too moist to make use of mastic and tape, the joint is made by welting the overlapping sheets with a double welted fold as illustrated in Fig. 30, and this fold is kept in place by weighing it down with bricks or securing it with tape until the screed or concrete has been placed. The double welt is formed by folding the edges of sheets collectively after which making a welt which is flattened.

The plastic sheet is successfully unattainable to fold and so stiff and elastic that it's going to at all times are inclined to unfold in order that it requires a deal of endurance to fold, hold in place after which contrive to fold alongside the joint. By utilizing the maximum measurement of sheet available it's doable to minimise the number of joints.

The sheet must be used in order that there are only joints a technique as it's impractical to kind a welt at junctions of joints.

The place the extent of the damp-proof membrane is below that of the dpc in partitions it is vital to turn it up in opposition to walls in order that it may well overlap the dpc or be. turned over as dpc as illustrated in Fig. 31. To keep the sheet in place as an upstand to walls it is essential to preserve it in place with bricks or blocks laid on the sheet towards partitions till the concrete has been positioned and the bricks or blocks removed as the concrete is run up the wall.

At the inside angle of partitions a reduce is made in the upstand sheet to facilitate making an overlap of sheet at corners. These sheets which are generally used as a damp-proof membrane will function an effective barrier to rising damp, offering they aren't punctured or displaced throughout subsequent building operations.

Il Comitato Processione Venerdì Santo

ringrazia la famiglia Aviani e la famiglia Centoscudi, per la disponibilità dei terreni senza i quali la Sacra Rappresentazione non sarebbe così suggestiva.
Un ringraziamento allo Studio GSG di Bagnoregio e a Mario Mecarelli per le fotografie utilizzate.
Si ringrazia inoltre chi direttamente o indirettamente contribuisce alla realizzazione dell'evento ed un grazie particolare va a tutta la comunità di Vetriolo che da anni partecipa sentitamente alla Rappresentazione del Venerdì Santo.

 

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