HELUZ vapour-impermeable pass-through piece
Feb 6, 2019
It prevents moisture condensation, it meets the fire-prevention standard and it reduces thermal losses of the roof structure
HELUZ vapour-impermeable pass-through piece for brick chimneys brings three benefits
HELUZ has begun to supply a new vapour-impermeable piece made of Foamglass foam that attaches a vapour-permeable foil within the roof structure securely to a brick chimney body. The HELUZ vapour-impermeable piece, made of Foamglass boards 50 mm thick, brings three benefits: it is not diffusional, it prevents dew point formation and it prevents moisture condensation. It also represents a thermal insulating solution that prevents heat from escaping round the chimney as it is directly connected to it. And this direct connection can be made due to the fact that the Foamglass boards are non-flammable. According to ČSN 734201, the solid-fuel chimney body must be at least 50 mm away from flammable materials. The HELUZ non-flammable vapour-impermeable pass-through piece for brick chimneys bridges safely this required five-millimetre gap between the vapour-permeable foil and the chimney and thus completes the roof vapour-permeable system.
The new HELUZ vapour-permeable pass-through piece for brick chimneys is made of foam glass boards, 50 mm thick (height of 500 mm, 450 mm or 850 mm). The Foamglass boards are glued, using installation tools, to the chimney body at the desired location of the pass-through piece and, after that, they form a vapour-impermeable, non-flammable and dimensionally stable pass-through sized 500 x 500 mm (or 500 x 900 mm).
All kinds of solutions have been replaced by a system component according to the standard
“According to ČSN 734201, the solid-fuel chimney body must be at least 50 mm away from flammable materials.” says Jan Míchal, technical advisor to HELUZ Technical Adviser, and continues: “A chimney pass-through has been dealt in complicated ways or sometimes not at all. In the event that the investor installs a composite roofing system, i.e. a vapour-permeable foil, mineral insulation, laths, counter-laths and roof tiles, so if they wanted to obtain the regulatory five-centimetre gap, there was a gap between the foil and the chimney that caused unnecessary losses of air, i.e. heat, and heat loss calculations of the roof shell did not yield good results. And they could lose subsidies. Or if someone glued a vapour-permeable foil directly to a chimney, chimneysweepers did not like this because the foil had no test certificate allowing it to be in direct contact with the chimney body. Notwithstanding the fact that the temperature of the chimney body is variable, so the vapour-permeable foil did not hold to it and came unstuck. That is why HELUZ has created this 50-millimetre foam-glass barrier, a construction piece that can come into direct contact with the chimney body, while maintaining the safety five-centimetre gap and the foil sticks to this barrier because it is glued with heat-resistant cement.”
The HELUZ vapour-impermeable pass-through piece for brick chimneys brings three benefits
1/ It prevents moisture condensation because Foamglass is not diffusional, i.e. it prevents the formation of dew point, a phenomenon that would lead to the condensation of water vapour, moisture condensation and mould formation.
2/ It complies with fire-prevention standard because Foamglass is non-flammable, a thickness of 50 mm, so it forms the required gap between the chimney body and combustible material – a vapour-permeable foil.
3/ It reduces heat loss because it completes a roof system with insulation by direct connection to a chimney so that warm air does not escape around the chimney.
Installation of HELUZ vapour-impermeable pass-through piece for brick chimneys:
Place a mounting strap around the chimney using plastic staples at the bottom of the pass-through piece. Push plastic corners behind it; they will hold the pass-through piece until the cement hardens.
Apply heat-resistant cement to the surface of the boards in a wave-like fashion. Apply it similarly to the faces (edges) of the boards to be glued to each other.
Place the boards on plastic corners and glue them to the chimney and to each other to create the desired pass-through around the chimney.
Tie the four glued boards around the chimney tightly with the supplied strap. Prior to final tying, place additional plastic corners on the board edges to protect the boards from damage.
After the cement has hardened (at least 3 hours at 15 °C), remove the two straps carefully and smoothen up any inaccuracies to create a perfectly smooth surface.
Fill all the joints of the boards (vertical and horizontal ones) and the joints of the boards with the chimney shell, both from the underside and the top side, with cement to ensure that the cement layer is not interrupted all around the pass-through circumference.