Izolvent

The substrate should meet the following requirements:
- dry substrate (concrete in an air-dry condition, without any visible traces of moisture or darkening caused by moisture),
- clean substrate (the surface of the concrete is free of loose fractions, dust, oil stains, grease and other impurities),
- smooth substrate (local unevenness and cavities in the surface of concrete do not exceed ± 5 mm),
- even substrate (the gaps between the surface of the substrate and a 4 m long batten placed on the concrete substrate do not exceed 10 mm).

Before installing NEXLER Izolvent bituminous felt, it is recommended to prime the substrate with solvent-based bitumen products, e.g. NEXLER Penetrator G7 or water-based bitumen products, e.g. NEXLER BITFLEX Primer, and to perforate the existing membrane layers in which moisture is trapped. The number of holes is approximately 10 per 1 m² of ventilated area.

The product should not raise any objections. The roll should be evenly rolled, without kinks.

If it is necessary to make the covering at low ambient temperatures, it is recommended to store the rolls in heated rooms at a temperature of not less than +18°C for 24 hours before installation.

During acceptance, the following should be checked:
- correctness of installation along with the top-layer bituminous felt,
- correctness of sealing of the ventilation chimneys.

Lay the NEXLER Izolvent bituminous felt loosely, with an overlap of approx. 3 cm, on the existing, cleaned and primed bituminous felt with the vents arranged in place. The substrate must be mechanically resistant, and free from any loose dirt, greasy stains or water.
The NEXLER Izolvent bituminous felt is used together with a torch-applied bituminous felt to install a roofing retrofitting solution which can evacuate the moisture trapped in the existing roof covering. Before welding the top-layer bituminous felt, e.g. NEXLER PREMIUM PYE PV250 S53H, it is recommended to prime the old bitumen coating. The recommended top-layer bituminous felt, NEXLER PREMIUM PYE PV250 S53H is an SBS elastomer modified membrane - with its bitumen compound type, the bituminous felt can be properly welded to the substrate through the holes in the NEXLER Izolvent ventilated bituminous felt. 
The number of ventilation chimneys to be installed depends on the dampness of the existing roof (usually 1 chimney is used approx. every 50 m²). Do not place any ventilation chimneys at the lowest section of the roof slope.
Do not lay the NEXLER Izolvent ventilated bituminous felt within approx. 50 cm of the eaves, roof edges, chimney stacks, structural expansion joints, drain gutters, or roof drains, because these areas need the torch-applied capping sheet to be bonded with its entire surface.

Before use, please read the application details in the product's Technical Data Sheet.