BMC SPP-LL

PVC Membrane Protected Roofing System (Loose Laid)


Download PDF

Description:

This roofing assembly consist of thermoplastic PVC membrane loosely laid over the lightweight foam concrete screed & a separation layer, covered by extruded polystyrene insulation board followed by another separation layer and finishing of pre-cast concrete pavers or gravel.

Features and Benefits:

■    The membrane is maintained at a nearly constant temperature, close to the temperature of the building's interior; this minimizes the stresses on the membrane by reducing the harmful effects of thermal cycling and excessive heat.

■    The waterproofing membrane is protected from weathering, foot traffic and other types of physical abuse - both during and after construction.

■    Allow year-round construction since the roof is waterproofed first, then insulated.

■    Permit easily removal and re-installation of the ballast and insulation for making repairs or for constructing additional stories. In addition, a protected membrane roof provides an environmentally preferred option to reuse the insulation.

■    Allow for a range of ballast options - stones, precast paving slabs, green roof, interlocking stone or concrete - depending on use and aesthetic considerations.

■    Eliminate the need for a separate vapor retarder.

 

Installation Guidelines:

Lightweight foam cellular screed laid to falls and cross falls (minimum 1% slope) trowel-applied smoothly finish. Mix design shall be in accordance with manufacturer recommendation.

Concrete upstands shall be dry, clean and smoothly finished; CMU (concrete Masonry Units) upstands must be properly plastered smoothly finished.

Separation Layer:

Apply a layer of non-woven geotextile separation layer with minimum of 100mm wide overlaps, loosely laid, above the prepared substrates, minimum of 50mm wide overlaps to the adjacent sheets.

Membrane Placement:

The PVC membrane shall be loose laid over the geotextile layer. The roof perimeter has to be fixed mechanically to keep the membrane in place.

Overlap seams are welded by electric hot air welding equipment, such as manual hot air welding machines and pressure rollers or automatic hot air welding machines with controlled hot air temperature.

Welding parameters including temperature, machine speed, air flow, pressure and machine settings must be evaluated, adapted

and checked on site according to the type of equipment and the climatic situation prior to welding.

The effective width of welded overlaps by hot air should be minimum of 20mm.

The seams must be mechanically tested with seam probing method to ensure the integrity / completion of the weld. Any imperfections must be rectified by hot air welding.

Membrane Termination:

Upper ends of membrane shall be terminated above roof finishing level (minimum 150mm) using extruded aluminum termination pressure bar, mechanically fastened at 300 O.C., and completely sealed with mastic sealant.

Water Test:

The water test can be done with flood testing. Minimum water head level and duration of the water test as per project requirements and engineer's instruction must be followed.

Plug the drains and provide necessary barriers to contain flood water to avoid pressure and damage the membrane.

Removal of water and cleaning/drying of the tested area must be done after the water test is completed.

Thermal Insulation:

Apply extruded polystyrene rigid board thermal insulation, loose laid with rebated edges over the completed and water tested waterproofing membrane system.

Separation Layer:

Apply a layer of non-woven geotextile separation layer with minimum of 100mm wide overlaps, loosely laid, above the installed waterproofing membrane, minimum of 50mm wide overlaps to the adjacent sheets.

Finishing Items:

Application of finishing items above the separation layer (i.e.: Pre­cast Concrete Pavers / Gravels) shall be provided & installed as project specification requirements.

Storage Conditions:

Products must be stored in their original packaging under cool and dry conditions. They must be protected from direct sunlight & rain.

Criteria

System Property

Membrane

Membrane Type

Polyvinyl Chloride (PVC)

Application Type

Loose Laid

Thickness Options

1.2mm / 1.5mm / 1.6mm / 2.0mm

Roll Size (W x L)

2m x (20m / 25m)

Insulation

Insulation Type

Extruded Polystyrene Insulation Board

Density Options (kg/m3)

32-35/36 / 40 / 45 / 48

Thickness

Variable, As Per Project Requirements

Separation Layer

Separation Layer Options

Non-Woven Polyester or Polypropylene Geotextiles / Polyethylene Sheets

Separation Layer Density

Options

Variable, As per Project Requirements

Finishing

Finishing’s Options

Pre-cast Concrete Pavers / Gravel