It is well known that roofs, especially pitched roofs, but also the walls of buildings are thermally insulated by means of the application of mineral wool products or other heat insulation materials between rafters and/or beams. When this is done, it is generally necessary to cover these materials with a plastic foil to act as a vapour barrier and con- stitute an air-tight covering. On the other hand, local passages have also to be provided in order to permit leads, cables and pipes to pass through the foil. It is therefore neces- sary for such passages of pipes through vapour barrier foils or roofing felts to be ap- propriately sealed. It is a common practice to use adhesive or sealing tapes for this pur- pose.

Such sealing tapes are usually formed on a plastic base, especially made of plastic ma- terial on a butyl rubber base. This material confers self-adhesive properties upon the sealing tape, so that for the purposes of storage and use a foil is normally applied to overlie and cover the sealing tape on both sides. Known sealing tapes for making good the passages of pipes through vapour barrier foils are thus covered by a plastic and in most cases transparent foil applied to one side, while the other and opposite side of the tape is covered by a peel-off foil that is perforated at the centre, siliconized transfer pa- per for example, which prevents successive layers of the tape from sticking to each other when the tape is wound onto a roll. When the sealing tape is used, it is generally folded along the middle and one half of the peel-off foil is then removed; thereafter the longitudinal half from which the foil has been removed is manually formed into a ro- sette, the other half of the peel-off foil is removed and the sealing tape is then made to adhere to the pipe with this longitudinal half. To this end the user will previously have prepared a section of the sealing tape having a length corresponding to the pipe circum- ference airwaference. At the time the tape is made to stick to the pipe, the previously formed rosette is also pressed against the vapour barrier foil and made to adhere to it.

Since the longitudinal half of the tape that does not stick to the barrel jacket of the pipe extends in a more or less radial direction therefrom, this means that the area of contact with the vapour barrier foil is larger than the original area of the tape, so that the tape must first be stretched in this area. This is possible when the chosen sealing tape is made of plastic material on a butyl rubber base, because these tapes have a substantial component of plastic material, so that the sealing tape, following the radial extension, can be appropriately stretched in the radial direction. In actual practice, however, the known sealing tapes are associated with the drawback that, given the multi-layer structure of the sealing tape, which consists of carrier and foil, the stretching is ad- versely affected by the existence of tensions and deformations, which have the effect that the adhesion of the sealing tape to the vapour barrier foil and the barrel jacket of the pipe may come apart at least over part of the area. This is due, above all, to the fact that especially the plastic foil will tend to warp and form folds, so that the deformable sealing tape will become detached from the vapour barrier foil in at least some sec- tions. Local leaks may therefore form, especially in the area of such warps and folds, so that the vapour barrier will no longer be airtight. Furthermore, the crumpled and/or folded sealing tape will give rise to a poor appearance and convey the impression of poor and careless workmanship in creating and sealing the passage of the pipe through the vapour barrier foil. Lastly, the adhesive capacity of the longitudinal half formed into a rosette will be adversely affected when this longitudinal half without a peel-off foil is manually stretched.

The present invention therefore sets out to introduce some simple measures that will render possible the reliable sealing of the passages of pipes through vapour barrier foils and the like, while yet keeping the actual application extremely simple.

According to the invention, this aim is achieved by means of the features set out in the characterizing part of Claim 1 hereinbelow, while useful further developments of the invention are characterized by the features described in the various dependent claims.

In accordance with the invention, given a sealing tape that is formed on a butyl or an acrylic base, especially on a butyl rubber base, said base being covered on one side by a plastic foil that serves as carrier foil and on the opposite side by a peel-off foil, said carrier foil being made to be stretchable and this in such a manner as to enable the car- rier foil to follow the enlargement and/or stretching of the section of the sealing tape that-in order to make said sealing tape adhere to the flat vapour barrier foil-is bent in the manner of a flange, that is to say, the carrier foil is enabled to follow the stretched state that has to be attained if the sealing tape is to adhere to the flat vapour barrier foil and, what is more, will permanently maintain this adhesion. This prevents the warping of the carrier foil and the formation of folds and this, in turn, not only con- fers an unobjectionable appearance upon the sealed passage, but also prevents the stretched sealing tape from becoming detached from the vapour barrier foil, thus pre- venting even a partial and autonomous peeling in the absence of external influences. In a very simple manner it thus becomes possible to assure a reliable and permanent seal even in the case of very complex pipe passages.

To this end it will be helpful not only if a tape with plastoelastic characteristics and a high plastic component is used as sealing tape and, further, if the stretching capacity of the carrier foil matches the stretching capacity of the sealing tape, especially if it is made equal to it.

Preferably the stretchable carrier foil will be made of plastic material, especially trans- parent plastic material and, preferably, of polyamide.

In a particularly appropriate embodiment of the invention the carrier foil is designed for a predetermined thickness, which will be in the range between 15 and 30, um, espe- cially between 17 and 20, um, and preferably of the order of 20 ym. Such a design of the protective foil assures that the stretching capacity of the protective foil will be in line will be in line with the stretching capacity of the sealing tape, so that it will perma- nently follow the latter when it is radially enlarged while it is being made to adhere to the vapour barrier foil. Such a design makes it possible for the adhesive or sealing tape to be appropriately stretchable even when it is stretched in combination with the carrier foil on one side and will not tear even when it is stretched up 100%. Preferably sealing tape and carrier foil will here be designed for a stretching capacity in the range between 50 and 100%, especially between 70 and 80%. To this end it may be advantageous if the carrier foil is at least half-sidedly creped in the longitudinal direction.

It is of practical importance to provide the peel-off foil of the sealing tape and/or the carrier foil with perforations or appropriate subdivisions in the longitudinal direction of the sealing tape, because this will make it possible for the sealing tape to be folded and appropriately pre-stretched on one side. The sealing tape does not have to be stretched when it is made to adhere to the pipe jacket, but this becomes necessary in the case of the remaining part of the sealing tape, which is bent away from the pipe jacket in the manner of a flange, and that is the reason why a one-sided elongation or pre-stretching of the sealing tape is advantageous.

In an advantageous embodiment of the invention the sealing tape is provided with a carrier foil made of polyamide that has a coating on a butyl or acrylic base, especially a butyl rubber base. In yet another embodiment the sealing tape can be provided with reinforcement inlays to increase its tear resistance. The incorporation of checker- pattern inserts will be particularly suitable for this purpose. To this end the material and the form of the checker pattern will be so chosen as to enable it to follow the stretching process.

In a practical and advantageous embodiment the sealing tape will be designed to have a thickness in the range between about 1.5 and 3 mm, and preferably about 2 mm. It is now proposed to describe a preferred embodiment of the invention with the help of the single figure attached hereto, which, albeit in a purely schematic form, illustrates a pipe passage through a vapour barrier foil.

In this figure the reference number 1 designates a cylindrical pipe that passes through a vapour barrier foil 2, the passage being sealed and rendered air-tight by means of a sealing tape 3. The longitudinal half of sealing tape 3 designated by the reference num- ber 4 is laid around the barrel jacket of the pipe 1 and made to adhere firmly to said barrel jacket, while the lower longitudinal half of the tape, which in the figure is desig- nated by 5, is bent outwards from the barrel jacket in the manner of a flange and ad- heres to the vapour barrier foil 2. To this end it is evident that the lower longitudinal half 5 must be appropriately enlarged in order to be able to follow sealing tape section 4, which is laid around the barrel jacket of the pipe, and the radial stretching outwards and away from the barrel jacket. In this case the outer surface of sealing tape 3 that can be seen in the figure is covered by a carrier foil 6, which will be advantageously made of polyamide and, more particularly, transparent polyamide and be designed to have a thickness of 20 um. The sealing tape itself has a thickness of about 2 mm For the purposes of practical use the sealing tape is made available wound onto a roll, where the side of the sealing tape opposite to the carrier foil is covered by a peel-off foil to protect its adhesive surface, though this peel-off foil is not shown in the figure.

When the sealing tape is actually to be applied, the user first detaches a length of seal- ing tape corresponding to the circumference of pipe 1 and then folds it more or less in the area of the centre of the sealing tape, so that the part indicated in the figure by the reference number 4 is made to adhere to the barrel jacket and the folded part 5 is made to adhere the vapour barrier foil 2.