Contacts

About PENOPLEX / Insulation of roofs / Inverted roofs

Inverted/protected membrane roofs are gaining popularity because they allow for a rational use of space in megalopolises: they can serves as parking lost, pedestrian zones, and green areas.

New York Motors, Moscow	Ploshchad Nezavisimosti, Kiev, Ukraine

In an inverted roof, the waterproof membrane is placed under a layer of insulation immediately on top of the concrete covering (the base of the roof). This structure was designed and implemented in construction with the introduction of a new generation of insulating materials – hard extruded foamed polystyrene, a thermal insulating material with evenly distributed enclosed cells, which does not absorb water, does not expand or shrink, has a high mechanical strength, chemical resistance, and does not decompose. These properties allow for placing it above a waterproof membrane and providing an additional protection for it.

When an insulating material is placed about a waterproof membrane, the membrane is protected from abrupt temperature changes, because its temperature is kept above water freezing point throughout the year. The insulation also protects the membrane from mechanical stress and UV rays.

Using PENOPLEX^® boards as insulant for inverted roofs offers:

• protection of roof from mechanical damaging;
• protection of waterproof membrane from abrupt temperature changes;
• quick installation in any weather;
• reliable protection from floods (heavy rains);
• lightweight roofing structures, because concrete coverings are not needed.

Another important property of PENOPLEX^® is that it does not decompose or facilitate growth of mold, which is especially relevant to inverted roofs, because the insulant is enclosed in a non-ventilated space.

Inverted roofs stimulates the use of flat roofs and lowers maintenance costs.

Designs of inverted roofs utilizing PENOPLEX^® boards is certified by the Gosstroy of Russia # ROOS RU.SR48.S00162, issued November 22, 2004.

Inverted roof with gravel loading

Underground garage, 10 Nakhimova Street, St.Petersburg

The waterproof membrane is laid immediately onto a concrete deck. PENOPLEX^® insulating boards are placed over the waterproof membrane as close to one another as possible. The use of a special "quarter" profiled edges of the boards completely eliminates cold bridges. Next, a filtering layer of geo-textile is installed on top of the layer of PENOPLEX^®.

For non-operated roofs, a layer of gravel loading (25/32 mm fraction) is installed. The thickness of the loading layer should be at least 50 mm (according to the design album, "Structures of Wall, Covers, and Floors with Insulation from PENOPLEX Extruded Foamed Polystyrene", code M 24.24/04).

Overlaid boards of geo-textile (filtering layer) along with a loading layer create a suitable protection from mechanical stress that may be cause by temporary flooding from heavy rain.

Gravel loading Protective (filtering) layer: canvas of synthetic fibers PENOPLEX® Waterproof membrane of bitumen rolls Lightweight concrete or cement and sand layer with a fall Slab of reinforced concrete

Roof accessible for pedestrians

Due to the fact that open areas are sparse in contemporary cityscapes, many residential and commercial buildings have roofs that are used as recreational zones. Inverted roofs are especially suitable for this application.

Sidewalk paving slabs are often used as a loading and protective layer. This layer is recommended to place over a layer of gravel loading (5–10 mm fractions), sand, or a mix of gravel and sand. The recommended minimal thickness for gravel loading is 30 mm.

This design of inverted roofs allows for combining pedestrian zones with zoned of regular gavel loading or green areas.

Sidewalk paving Sand Gravel of 10–20 mm fractions Filtering layer PENOPLEX® Waterproof membrane of bitumen rolls Cement and sand layer with a fall Slab of reinforced concrete

Green roof

All the advantages of inverted roofs are relevant for making green or garden roofs.

The following materials will go on top of a layer of insulation:

• filtering layer (geo-textile)
• drainage layer (for example, large gravel or expanded perlite)
• filtering layer
• soil substrate

You should choose special plants that are suitable for green roofs.

The main advantage of inverted green roofs is their mechanical protection of the waterproof membrane created by a layer of insulant when laying a soil substrate and planting.

Growing medium Root barrier Drainage element from gravel of 10–20 mm fractions Filtering layer (geo-textile) PENOPLEX® Waterproof membrane of bitumen rolls Cement and sand layer with a fall Slab of reinforced concrete

Roofs available for traffic

Ice Rink, St.Petersburg

Yet another economic reasoning to use inverted roofs is creating parking lots on flat roofs of public, commercial, and residential buildings. This allows for utilizing precious space, especially in megalopolises, where parking areas are difficult to find.

Protecting the waterproof membrane of flat roofs available for traffic becomes especially relevant.

Depending on the design of a roof and its projected load, different thicknesses of PENOPLEX^® boards should be used. A layer of gravel loading with a thickness of no less than 30 mm should be placed between insulating boards and paving (solid or slabs of reinforced concrete) on top of the filtering layer.

Before using concrete roofing, you should place a separation layer (construction cardboard, for example) to protect gravel from construction water. Statistic calculations should be performed to choose the specifications for the concrete layer.

When placing concrete on top of PENOPLEX^® insulation always use a separation layer (polyethylene film, for example) to protect the seems between insulant boards from concrete compound fluids.

Sidewalk paving Sand Polyethylene film PENOPLEX® Waterproof membrane of bitumen rolls Cement and sand layer with a fall Slab of reinforced concrete

Considerations for designing inverted roofs with protected membrane

• PENOPLEX^® sheetd should be used within the recommended temperature range (Table 1). If exposed to temperatures outside the specified range for a long time, the boards may change in size or their mechanical and insulating properties irreversibly.
• When choosing adhesives, check with the instructions that come with them and make sure they are suitable for use with polystyrene.
• PENOPLEX^® boards have increased chemical resistance to many construction materials: bitumen mixes, water-based agents not containing thinners for protecting wood, lime, cement, etc.
• Some organic compounds (including water-based agents containing thinners for protecting wood, bitumen and its derivatives, paint thinners, and other widely used thinners: acetone, ethylacetate, petroleum toluene, etc.) may cause softening and shrinkage of extruded foamed polystyrenes.
• PENOPLEX^® extruded foamed polystyrene does not decompose under normal circumstances and is not hazardous to nature or people, which is proven by the accompanying test certificates.