EP0208246B1

EP0208246B1 - Ventilated insulating of hollow spaces

Info

Publication number: EP0208246B1
Application number: EP86108984A
Authority: EP
Inventors: Ian Cridland
Original assignee: Rockwool International AS
Current assignee: Rockwool AS
Priority date: 1985-07-04
Filing date: 1986-07-02
Publication date: 1990-03-14
Anticipated expiration: 2006-07-02
Also published as: DK151820B; DK304885A; DK304885D0; DE3669555D1; ATE51049T1; EP0208246A1

Abstract

Thermally insulating material suited for filling out and being deposited in hollow spaces in buildings, which material consists of regular and substantially rigid pieces open to moisture diffusion, said pieces ensuring, due to their loose packing, a certain passage of air through the material under normal ventilating conditions in order to ventilate undesirable humidity in the building structures.

Description

The present invention relates to a thermally insulating material suitable for being deposited and filling out hollow spaces is of the kind disclosed in the preamble of Claim 1. The invention also relates to thermal insulation of hollow spaces in building structures, such as service spaces in foundations and built-up roofs.
Most thermally insulating materials are porous and contain considerable amounts of relatively static air. In certain cases the porous system is closed as in the case of plastic foams, in other cases the porous system is open as in the case of mineral wool.
An open porus system offers the advantage that aqueous vapour may diffuse through the insulating layer. Aqueous vapour may be present in and around an insulating layer, something which is unfortunate and damaging to the insulating quality of the layer, thus such vapour must be removed or ventilated regardless of the reason for its presence. An increasing content of aqueous vapour in an insulating material means a decreasing insulating quality of the material, the thermal conducting quality of the insulating material increasing with increasing humidity.
Consequently, it is of vital importance both for the sake of the insulating quality of the insulating material as well as for the sake of the keeping qualities of the structure that such, in itself undesirable and for various reasons existing, aqueous vapour is able to diffuse through the insulation and can then be subsequently let out into the open through ventilating slots or the like.
Aqueous vapour arises in building constructions for many different and well-known reasons. By way of example constructional errors and inadequate workmanship may be mentioned. Examples of the latter may be permeable vapor membranes and the occurrence of humidity in the- foundation wall. The last-mentioned examples frequently occur both in comparatively new houses as well as in old ones, and it is one of the objects of the present invention to be able to remedy such errors without harming the buildings, at the same time reducing the thermal loss by re-insulation.
Several publications relating to insulation material used for filling out hollow spaces, for instance by blowing, are known.
From Norwegian "utleningsskrift" no. 147554 elongate glass fibre bodies are known, the cross section of which is preferably rhombic, quadrangular or triangular, in which bodies the fibres are oriented in layers in order to impart the bodies a tendency to divide themselves up at many places along their length transversely to their longitudinal direction. This specification discloses an alternative to traditional methods for manufacturing a granulate material which may be introduced into cavities in a building construction to provide thermal insulation. In order to obtain an optimum insulation the granules should be small and easy to deform so that they can pack closely and evenly, take the shape of the cavity, and ensure that no empty spaces are left. The columns of mineral wool cut from the mat have their largest dimension perpendicular to the main directions of the fibres, which, owing to the way in which they are layed is generally directed in the plane of the mat.
The known insulation material is based on the fact that the columns have a pronounced tendency to delaminate, mainly because of the directions of the fibre, but also because of harsh treatment from the cutting process. After delaminating the mineral fibres will be present in small flakes of varying thickness. These flakes, which are thin and soft, will pack into an almost homogeneous filling in the cavity leaving no empty spaces for ventilation. A material according to NO-B-147 554 will have after being blown into a cavity, a permeability figure in the range of 0.02-0.8, and this will prevent an effective ventilation of the cavity to remove any vapour condensation.
From DE-AS 28 11 004 a method is known for producing small balls or bodies of spherical shape which are formed by introducing loose fibres into a cyclone.
From Canadian Patent No. 1,116,994 a method is known, for producing cubes from glass fibre material bonded with a binding agent which cubes are delaminated by means of particular devices, see for instance lines 3-7 on page 8.
From US Patent No. 2,618,817 a method is known for dividing a glass wool mat into columns, and in which the columns are cut off by a rotating knife and blown into a hollow space.
Common in these publications is the tendency of trying to solve the problem of making the materials pack well. Either this is done by allowing the bigger and regular pieces to delaminate in such a way that the delaminated flakes of these regular pieces fill out the hollow spaces between the bigger and regular pieces, or by producing regular pieces from a material with a very low density, the regular pieces then becoming soft and fluffy which results in a good packing.
The specific weights or densities mentioned in the above publications are all within a very low range, viz. from approx. 5 to 20 kg/m³.
Previously one has tried to produce regular pieces which first and foremost packed well in order to obtain the best possible insulating quality. On the other hand, the ability to ventilate undesirable aqueous vapour seems to be considerably limited. In the cases where humidity has been ascertained in a structure and in those cases where experience has shown that humidity is often likely to occur, the natural convection in conventional insulating materials is not great enough to remove the occurring humidity.
This is probably best seen from the increasing damage to houses and structures after re-insulation.
The actual errors are due to missing or permeable vapor membranes, permeable walls or roof constructions, penetrating humidity from the foundation or the like, but the damages is not apparent until insulation is renewed to a bigger insulation thickness and a too tightly packed insulation material is used.
The object of the present invention according to Claim 1 is to ensure an increased ventilation through the insulation layers at the expense of a slight reduction of the thermal insulation quality.
The invention is characterized by the subject matter of the characterizing clause of Claim 1.
The invention is based on the fact that uniform and regularly shaped bodies when randomly packed will form a structure having many open and mutually interconnected interspaces. When such a material is blown into the hollow spaces in buildings exactly this random packing is attained. The only requirements for rigidity and strength of the bodies are thus that they are able to resist the influence of air-borne transportation and of packing in hollow spaces without essentially breaking up or disfiguring. The open structure of the packed material allows ventilation of the hollow space, such that aqueous vapour, apart from diffusing through the insulation pieces themselves, can be ventilated through the hollow spaces between the individual regular pieces.
Previously damaging re-insulation jobs may now be undertaken with such a material, for instance the re-insulation of service spaces in foundations, similar service space constructions facing the ground or concrete layers covering the ground, and of built-up roofs.
By carefully selecting the outer mutual dimensions of the individual regular pieces and by carefully selecting the size of the regular pieces, in this connection perhaps by mixing differently shaped regular pieces and by selecting the density of the material, it is possible to produce insulation layers, in which the air permeability figure I for instance will be 10-20-30-40-50-60 or 70 times as big as the air permeability figure I for a conventional insulation.
The regular pieces may be produced in several ways and they may have any imaginable shape. They may for instance be cut from conventionally produced insulation plates, they may be made from a carded fibrous material, which after the admixture of a bonding agent is pressed into a rigid shape and dried, they may be produced by moulding a wet fibrous mass or plastic foam, by extrusion or by other known methods for producing bodies of a regular, rigid shape.
The pieces to be used are shaped in such a way that they do not pack densely. In this respect the length and width of the piece is not allowed to be a multiple of its height. A preferred shape according to the invention is a hexaedric body, i.e. shaped as a cube or box.
By way of example may be mentioned pieces, in which the dimensions LxWxH for instance are 25x15x10, 40x35x25 or 80x60x35 mm.
If the pieces are made by cutting from a conventional insulation plate of mineral wool, they are cut in such a way that the L and W dimensions are in the plane of the plate and the H dimension corresponds to the thickness of the plate. By doing this the smallest dimension (=H) is placed in a direction in which the risk of delamination of mineral wool products are biggest, which results in a very high degree of rigidity and regularity of the pieces.
When the pieces are made from mineral wool, densities of from 20 to 120 kg/m³ can be used, and preferably a density of about 50-70 kg/m³. The relative density or specific weight (the weight of the insulation material after having been blown in and after having been deposited). will then be from 20 to 80 kg/m³, and preferably from 30 to 50 kg/m³.
To elucidate the difference between conventional insulating layers and insulating layers according to the invention, the only figure of the application shows diagrammatically the I-values for mineral wool made of rock wool fibers. The diagram is known from Rockwool A/S's Insulating Manual, 2nd edition.
From the drawing can be seen that the air permeability figure I with the dimensions of m4/ hN is within the range from I=0.02 to 1=0.8 for conventionally produced rock wool products the I-value being marked as a function of the density. By way of comparison, the figure shows that an example of insulation comprising pieces of regular and rigid shape and having the dimensions 35x40x25 and a density of 50 kg/m³ will have a I-value of 4.5 m4/hN after being blown in. From the diagram can be seen that a conventional insulation with a density of 50 kg/m³ has a I-value of 0.18 m4/hN, which makes the air permeability of the insulation layer according to the invention almost 25 times as big as in the case of a conventional insulation.
In a test air velocities of approx. 1-2 m/h have been measured with horizontal insulating layers according to the invention at a drop of pressure through the insulation of 0.015-0.025 mm VS/m and natural draught conditions.
In this connection, natural draught conditions is understood to be a free wind affecting the construction on the outside and having a velocity of 3-5 m/sec., and wherein the construction is provided with ventilation openings to the outside as common in service spaces in foundations.

Claims

1. Thermally insulating material suitable for being deposited in and filling out hollow spaces, for instance by way of blowing, said material comprising regular pieces cut from a mineral wool mat open to moisture diffusion, characterized in that the pieces are cut from a mineral wool mat containing a bonding agent in such a quantity that the pieces are rigid, the dimensioning of the pieces being such that their height does not form a multiple of their width or length and that the air permeability figure I of the deposited material is within the range of 0.8 to 15 m⁴/hN and the pressure drop through the material under normal draught conditions is within the range of 0.01-0.03 mm/WC/m.

2. Thermal insulation material according to Claim 1, characterized in that the pieces are hexaedric bodies and that the specific weight of the material after being deposited is 15 to 80 kg/ _m ³ _.

3. Thermal insulation of hollow spaces in building structures, such as service spaces in foundations and built-up roofs, into which an insulation material is introduced by blowing, which material comprises a granular material cut from a mineral wool mat, which material is open to moisture diffusion characterized in that the material consists of regular and rigid pieces of a mineral wool with a specific weight of 30-80 kg/m³, the fibres of which are bonded with a binding agent, the pieces, being so dimensioned that their height does not form a multiple of their width or length and being loosely and randomly packed in the hollow spaces, substantially without deformation of the bodies, and in that ventilation openings are provided to the outside of the building structure.