Cavity wall insulation

Without the otherwise necessary air gap of at least 40 mm and without ventilation openings above and below - - As core insulation the full insulation between two masonry walls in two-shell exterior masonry (front and rear brickwork ), designs of curtain concrete slabs, building partitions or between rafters ( rafter insulation ) is called. In the processing of so-called " finger gap " (approx. 1 cm) remains.

For insulation in new construction solid materials such as rigid polyurethane foam can ( PUR / PIR), stone or mineral wool, extruded polystyrene foam ( XPS) Expanded polystyrene foam ( EPS) or bulk material can be used. For a subsequent core insulation is polyurethane -situ, rock or glass wool, Expanded polystyrene granules offer (EPS), Silicatleichtschaumgranulat ( SLS20 ) Blähperlite and airgel. The insulation must be durable water-repellent ( hydrophobic) and the standardized application of DIN 4108-10 (WZ = insulation of double-leaf walls, cavity wall insulation ) correspond. Normative of the shell distance is limited to 150 mm. Larger shell distances ( currently regulated to 200 mm) require cavity wall tie with building approval.

The reference values ​​of the energy (EnEV 2009) of U ≤ 0.28 W / m² K can already satisfy 0.035 W / m K at 10 cm core insulation of thermal conductivity. In order to meet the Passive House criteria ( U ≤ 0.15 W / m² K) are significantly better thermal insulation optionally in combination with increased shell distances required, eg 20 cm core insulation of thermal conductivity 0.032 W / m² K.

In a 1053 Kerndämmumg drainage holes in Fußpunktbereich the outer shell are to be arranged (5000 mm ² per 20 m² of wall surface ) according to DIN. In strictly observed, Brickwork no wear marks (ie no water outlet) from the drainage holes are in practice observed. In plaster facing shell drainage openings must be closed before plastering.

For the core insulation when building new flat insulating materials can be used.

Subsequent Cavity wall insulation in existing is possible with blow-in insulation or in-situ. The insulation material is thereby introduced through drilled holes in the outer wall. A distinction must be free-flowing and fibrous products. The installation of free-flowing products, such as EPS granulate, expanded perlite, Silicatleichtschaumgranulat and airgel, requires few and small injection holes. The materials are distributed very well in the hollow layers. Predestined, these products are for the insulation narrow hollow layers (up to 5 cm), for optimizing back-ventilated facades and post insulation of exposed aggregate concrete curtain walls with ventilated cavity wall insulation. Since it may occur through lungs, however, Riese, leaks should be identified prior to the measure by a fog machine and sealed. For larger hollow layers can fibrous products such as Stone and glass wool are used. These are cost-effective and interlock with each other and with the masonry. By giant lungs provide therefore no danger dar.

For the pros and cons of a subsequent core insulation in double-shell masonry ( Loose ) there are corresponding arguments:

Pro:

  • Applying a thermal insulation composite system to a hohlschichtiges Masonry is virtually ineffective
  • Inexpensive compared to subsequently externally applied insulation with facing ( (usually plaster, brick or wood); EIFS ), ie shorter payback periods
  • Short construction times, often for 1-2 days at a 1-2 family house
  • It is neither lost nor housing the optics of the house changes.

Cons:

  • The insulation thickness is limited to the width of the available space in the bivalve exterior masonry (eg 8 cm ), possibly should work with high performance insulating materials such as airgel or polyurethane -situ or in addition, an EIFS be installed
  • Thermal bridges such as window frames, wall anchors or masonry connections of the two -wall brickwork be better eliminated with EIFS, here should be given to the additional mounting an EIFS
  • Should there be an entry of water into the insulation layer, eg by rupture of a horizontal pipe in the wall, the drying will be difficult - especially when using mineral wool because of the capillary
  • On subsequent openings through the wall or masonry work is free flowing loose-fill insulation, such as EPS beads leak, so that the loose-fill insulation must then be partially replaced.
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