The most recent product innovation in the Ontop range is the Iso-block. This allows a fully sealed passage of metal flue through floors and/or roofs, while fire safety remains absolutely guaranteed!

An unique construction means that all warmth stays indoors with significant energy savings. The Iso-block is therefore perfectly suitable for use in passive houses.

Up until now a choice had to be made with chimneys: ventilation for fire safety purposes, or "plugging" the space at passages with a fire risk. This is certainly no unimaginable danger with increasingly thicker (insulated) roofs. The Iso-block also solves the dilemma of a passage breaking through the moisture-retarding layer whereby condensation problems can occur.

The Iso-block enables the home to be finished totally sealed, with the moisture-retarding layer being left intact and fire safety maintained. The Iso-block can be used to completely seal a chimney which leads through roofs or floors in just about all construction situations.

The Iso-block is compact and lightweight, which makes it easy to work with. Various accessories are available to complete the passage outdoor and indoor.

After the assembly, the Iso-block is easy to finish.