Bulk insulation - the uncomplicated form of cavity insulation

Bulk insulation can be done if there is an open area or a readily accessible cavity. In practice, it plays a role especially for the thermal insulation of the top floor ceiling.

Like a blow-in insulation, a bulk insulation with loose insulation materials is made. The insulating material is poured on the areas to be insulated. Optionally, the insulation layer is additionally compacted to improve the insulation performance and the pressure stability.

Bulk deposits - efficient and cost-effective

A bulk insulation is as powerful as a thermal insulation with insulation boards, mats or felts. It is an easy to implement and very cost effective process. The costs for the pure thermal insulation (without floor construction or outer cladding) are essentially identical to the financial expense for a blow-in insulation. Bulk deposits are suitable both for new buildings and for the energetic renovation of older houses.

Table 1: Costs of bulk insulation *)

house areaCost per m2 (EUR)
Insulation of the top floor ceiling15 – 25
Floor insulation including basement floor15 – 25

*) These costs are average values ​​and refer to a thermal insulation according to the minimum requirements of the EnEV 2014 as well as with common insulants (mineral wool, polystyrene, cellulose).

Tips & Tricks

Bulk deposits require an open area or cavity for the introduction of the insulation material. In a walk-in bulk insulation, the cavity for the insulation layer and a mounting plane for the floor construction / the outer panel can be created by slat constructions or prefabricated insulation systems.

Areas of application for a bulk insulation

Bulk deposits can be used everywhere where easily accessible cavities are available. Such cavities may be, for example, the unused / non-accessible crawl space of a building or the compartments between the load-bearing beams of the top floor ceiling. This requirement for a bulk insulation can also be created by appropriate constructions. So far, such constructions mostly consist of wooden blades and are manufactured individually. In the building materials trade, however, there are now also prefabricated systems that serve to produce a Dämmraum for Schüttdämmungen or Einblasdämmungen. An example of this is the "isofloc Edition" barker - for the insulation of the top floor slab or the roof pitches, the manufacturer also provides all the components necessary for producing a robust, usable floor and an optimal wall cladding with free choice of insulation.

Insulation of the top floor ceiling

Most frequently, bulk insulation is used to insulate the top floor. They can be made as non-accessible or walk-in insulation, in the second case must also be the structure of a floor. Bulk deposits are suitable for concrete as well as for beamed ceilings. They also compensate for uneven surfaces. Under such an insulation - ie directly on the floor slab - a vapor barrier or vapor barrier is laid to protect the insulating layer from penetrating water vapor from the warmer building interior.

Non-accessible structures

The thermal insulation of the top floor ceiling in an unused and hardly ever attic can be made as non-walkable construction. For this purpose, the insulating material is poured as a closed layer on the entire ceiling surface. Further work steps are not required. It may be necessary to set up some paths for maintenance on the insulation layer.

Walk-in constructions

In a walk-in floor structure in the attic, the bulk insulation is introduced either in a Dämmraum-construction or in the compartments of the supporting beams, which also serve as a mounting level for the floor structure. If the insulation material does not provide the desired sound insulation sufficiently, an additional impact sound insulation can be made.

Other house areas

Floor insulation by a bulk insulation follow the same principle. In a non-accessible crawlspace, they are introduced as a loose insulating layer, otherwise they are part of an insulated floor construction. In other areas of the building, bulk insulation is rather uncommon, in façade or roof constructions loose insulating materials are introduced through blown insulation. Due to their high load-bearing capacity, bulk skimmed glass granules are sometimes used as additional insulation for perimeter insulation or flat roof insulation.

Insulating materials for pourable insulation

Suitable insulation materials for bulk insulation are all materials which are available as granules or fibers. These include mineral wool (stone and glass wool), EPS / polystyrene granules, perlite, expanded clay, foam glass, but also natural insulating materials - such as cellulose, wood fibers, hemp, cork and reeds.

Table 2: Selected insulation materials for pourable insulation

insulationThermal conductivity (W / mK)Minimum insulation thickness (cm)Cost / m2 (EUR)
mineral wool0,032 – 0,0401410 – 20
EPS / Styrofoam0,035 – 0,045145 – 20
perlite0,04 – 0,072020 – 45
expanded clay0,1 – 0,187218 EUR / 50 l
foam glass0,04 – 0,051640 – 60
cellulose0,04 – 0,0451610 – 20
wood fiber0,04 – 0,0551840 – 50
Hemp / flax0,04 – 0,04515/1610 – 30

Specifications of EnEV 2014

The height / thickness of the bed depends on the insulation used. In accordance with the minimum requirements of the Energy Saving Ordinance (EnEV) 2014, the thermal insulation in living areas must achieve at least a heat transfer coefficient (U-value) of 0.24 W / m2K. However, many home builders improve the energy efficiency of their home with more efficient insulation, thus also optimizing the summer heat insulation and sound insulation of the building. Public funding through a loan or construction subsidy from KfW is possible if the EnEV requirements are undercut and the efficiency of the insulation solution is proven by a professional energy assessment.

Tips & Tricks

Commonly used insulation materials for bulk material are mineral wool, EPS / polystyrene granules, expanded clay and perlite. However, many natural insulating materials are suitable for this type of insulation. Their advantages are also a very good sound and heat protection and the highly permeable structure of the insulation.

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