EP0208246A1

EP0208246A1 - Ventilated insulating of hollow spaces

Info

Publication number: EP0208246A1
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: 1987-01-14
Anticipated expiration: 2006-07-02
Also published as: DK304885D0; DK151820B; DK304885A; ATE51049T1; DE3669555D1; EP0208246B1

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 orderto ventilate undesirable humidity in the building structures.

Description

The present invention relates to a thermally insulating material suited for being deposited and filling out hollow spaces and is of the kind disclosed in the preamble of claim 1. The invention also relates to a 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 like in the case of plast foams, in other cases the porous system is open like in the case of mineral wool.
An open porous 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 insulating layer, und such vapour must be removed or ventilated irregardless 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 insulation material as well as for the sake of the keeping qualities of the structures that such in itself undesirable and for various reasons existing aqueous vapour may diffuse through the insulation and then subsequently be let out into the open through ventilating slots or the like.
Aqueous vapour arise 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 vapour membranes and the occurence 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 a re-insulation.
Several publications relating to insulation material for filling out hollow spaces, for instance by blowing, are known.
From Norwegian "utlegningsskrift" no. 147 554 someglass fiber bodies in the shape of sticks are known, the cross section of which is preferably rhombic, quadrangular or triangular, in which sticks the fibers are oriented in layers in order to impart to the sticks a tendency of dividing up themselves at many places along their length transversely to their longitudinal direction.
From DAS 2811 004 a method for producing small balls or bodies of spherical shape is known, said balls or bodies being formed by introducing loose fibers into a cyclone.
From Canadian Patent No. 1116 994 a method for producing cubes from glass fiber material bonded with a binding agent is known, which cubes are delaminated by means of particular devices, see for instance lines 3 - 7 on page 8.
From US Patent No. 2618 817 a method for dividing a glass wool mat into columns is known, and in which these columns are cut off by a rotating knife and blown into a hollow space.
Common for these publications is the tendency of trying to solve the problem of making the materials pack well. Either this is done by letting bigger regular pieces delaminate in such a way that the small or thin parts of these regular pieces fill out the hollow spaces between the bigger regular pieces, or by producing regular pieces from a material with a very low density, the regular pieces then becoming soft and fluffy which entails a good packing.
The specific weight or the densities mentioned in the above publications are all within a very low range, viz. from approx. 5 to 20 kg/m³.
Thus, it appears that previously it has been 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 big enough for removing the humidity occurring.
This is probably best seen from the increasing number of damages to houses and structures after re-insulation.
The actual errors are due to missing or permeable vapour membranes, permeable walls or roof constructions, penetrating humidity from the foundation or the like, but the damages do not get really visible until a renewed insulating to bigger insulation thickness is carried out 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 thermally insulating qualities.
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 blowing in the material in the hollow spaces in buildings exactly the random packing is attained. The requirements as to rigidity and strength of the bodies are thus only that they must be able to resist the influence from the air-borne transportation and the packing in the hollow space without essentially breaking or disfiguring. The open structure of the packed material allows a ventilation of the hollow space, so that aqueous vapour apart from diffusing through the insulation pieces themselves can be ventilated through the hollow spaces between the individual regular pieces.
Particularly risky re-insulation jobs may be re-insulation of for instance the service space in foundations, similar service space constructions facing the ground or concrete layers covering the ground and 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 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 ℓ for instance will be 10-20-30-40-50-60 or 70 times as big as the air permeability figure Y, 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 being pressed into a rigid shape and dried, they may be produced by moulding a wet fibrous mass or plastics foam, by extrusion or by other known methods for producing bodies of a regular, rigid shape.
The bodies to be used are shaped in such a way that they will not pack densely. A preferred shape according to the invention is a hexaedric body, i.e. shaped as a cube or box, the length and width of which is not a multiplum of height.
By way of example may be mentioned bodies, in which the dimensions L x W x H for instance are 25 x 15 x 10, 40 x 35 x 25 or 80 x 60 x 35 mm.
If the pieces aremade 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 the direction in which the risk of delamination of mineral wool products are biggest, which gives a very high degree of rigidity and regularity of the bodies.
When the bodies 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 3 3 be from 20 to 80 kg/m , and preferably from 30 to 50 kg/m³.
To illucidate the difference between conventional insulating layers and insulating layers according to the invention, the only figure of the drawing shows diagrammatically the ℓ-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 figured with the dimensionaly of m4/hN for conventionally produced rock wool products is within the range from L= 0.02 to ℓ = 0.8, the t-value being marked as a function of the density. By way of comparison it is shown that an insulating example of bodies with regular and rigid shape and having the dimensions 35 x 40 x 25 and a density of 50 kg/m³after being blown in will have a ℓ-value of 4.5 m4/hN. From the diagram can be seen that a conventional insulation with a density of 50 kg/m³ has a. ℓ-value of 0.18 m4/hN, which makes the air permeability of the insulation layer according to the invention 25 times as big as in the case of a conventional insulation.
In a test air velocities of approx.1-2 m/h has been measured with horisontal 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.
By natural draught conditions is in this connection understood a free wind affecting the construction on the outside and having a velocity of 3-5 m/sec., and that the construction has been provided with ventilation openings to the outside as common in service spaces in foundations.

Claims

₁. Thermally insulating material suited for being deposited in and filling out hollow spaces, for instance by way of blowing, characterized in that the material consists of regular and substantially rigid pieces open to moisture diffusion, the air permeability figure being within the range of 0.8 to 15 m4/hN.

2. Thermally insulating material according to claim 1, characterized in that the drop of pressure through the material deposited is within the range of 0.01 to 0.03 mm VS/m.

3. Thermally insulating material according to claim 1, characterized in that the air velocity through the insulating material is within the range of 0.5 to 5 m/h during natural draught conditions.

4. Thermally insulating material according to any of the preceding claims, characterized in that it consists of mineral wool having a density after depositing from 15 to 8_{0 k}g/_m ³ _.

₅. Thermal insulation of hollow spaces in building structures such as service spaces in foundations and built-up roofs by blowing into the hollow space a granulate insulating material, characterized in that the material consists of regular pieces of a rigid insulating material which is open to moisture diffusion, the material being randomly and loosely packed in the hollow spaces, substantially without deformation of the pieces of insulating material.

6. Thermal insulation according to claim 5, characterized in that the pieces are hexaedric bodies of mineral wool with bonded fibres and with a specific weight of 30 kg/m - 80 _kg_/m ³ _.

7. Thermal insulation according to claim 6, cha-racterized in that the dimensions of the bodies are such that the height does not form a multiple of the other dimensions.

8. Thermal insulation according to claim 6, cha-racterized in that the air permeability figure ℓ is 0.8 - 15 m4/hN.