Rules of Bituminous Membrane

Rules for correctly laying membrane

Waterproofing Membrane

Laying out the sheets

Before laying, the rolls must be unrolled and aligned to layout the overlaps between the sheets. The sheets must then be rolled up again to proceed with the flame welding.

The end-to-end overlaps of the waterproof sheets must not be arranged along a single line but must always alternate.

The sheets must be arranged with overlaps as in tiling a roof, i.e. always starting the overlaps at the drains or the downpipes.

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Lateral and end overlaps

Lateral: These are the joints that run in the direction of the length of the sheets. They must be welded with great care until a trickle of melted mixture about 1 cm wide can be seen coming out along the line of the overlap. The lateral overlaps must have a width of not less than 10 cm.

End: This refers to the joint along the shorter side of the sheet. This too is a point that requires close attention. The membrane must be melted until mastic runs out in the process of overlapping. The overlapped part should be not less than 15 cm wide.

Bitumen Coating Steel

45° cut at end overlap

At the end overlap, a corner of the membrane measuring 10 cm per side must be cut off at an angle of 45°.

Sheets reinforced only with polyester non-woven fabric laid in semi-adhesion, in proximity to the end overlap, must be glued to the substrate at complete adhesion for a strip at least one meter wide.

The bonding operations will be facilitated if the sheets are wound around a rigid plastic tube (HDPE, ø 12 cm, length 97 cm) which will prevent ovalisation of the roll during laying, particularly in summer. At the same time, the pressure exerted on the roll will be uniformly discharged over the entire contact surface with the support, also facilitating the release of the melted mixture along the overlap lines, ensuring that the membrane is perfectly welded

 

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Application

Connecting the membrane to the substrate must be carried out as follows:

Double layer of membrane

Double layer of membrane

If laying a second layer is specified, it must be laid so as to straddle the overlap of the previous layer and must be bonded at complete adhesion.

The burner flame must also heat the membrane already laid.

Always starting the overlaps at the drains or the downpipes.

Rood Waterproofing

End overlap of mineral-coated membrane

At the end overlaps the mineral-coated surface must be heated with certain persistence so that melting consequently takes place over an area corresponding to the width of the overlap, with consequent melting of the bituminous mastic underneath.

Once the membrane compound which will form the overlap has been melted, this will enable the two edges to be welded perfectly.

How to select a waterproofing membrane?

Check for the following properties of the membrane: