Manufacturers

Bosig

Connection and sealing tapes

Items: 4
Categories: 4
Headquarters: Gingen an der Fils, Germany

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Adhesive Tapes & Films 4 Window Sealing Tape & Membrane 3 Sealing Windows & Doors 3 Butyl & Bitumen Tape 1

About Bosig

BOSIG is a manufacturer from Gingen an der Fils that develops sealing and connection systems for windows, façades and roofs. We stock the part of the range needed at the building-body connection: the Inside butyl window sealing tape for the inner level, the Fasatan Eco EPDM connection tape for the outer level, the Windfix film adhesive – and, with Rooflex, a self-adhesive butyl-aluminium tape that takes the place of the classic lead flashing on the roof.

Rooflex instead of lead: the roof connection without heavy metal

Where a roof meets a rising wall, a chimney or a roof window, the connection has to follow the tile profile – and for exactly that, lead was the means of choice for decades: it can be beaten into every wave and stays there. A butyl-aluminium tape achieves the same through a stretchable aluminium insert, but does without heavy metal and weighs a fraction.

Self-adhesive means: no second fixing. According to the product data, Bosig Rooflex is self-adhesive and UV-resistant, does without lead and other heavy metals and is considerably lighter than a classic lead flashing. It is supplied in roof tile colours, so that the connection does not stand out in the roof's appearance; the roll measures 280 millimetres × 5 metres. The substrate must be dry, dust-free and load-bearing – no self-adhesive tape holds on damp or mossy tile, regardless of the manufacturer.

The sequence at the roof connection remains the same as with lead: the tape is applied from the bottom upwards, each strip overlapping the one beneath so that water runs over the overlap and not into it. At the wall it is taken up and bonded in at the top into a joint or under a profile – a tape that ends freely at the top leads water behind the connection. In cold weather butyl also needs warmth: below about five degrees it only adheres hesitantly, and contact pressure alone does not produce adhesion.

Selection guide: which Bosig product for which place?

The overview arranges the Bosig range we stock by the place on the building. The details in the last column come from the product data of the respective article.

Bosig range at Baustoff-Held, arranged by installation location
Product	Base	Purpose	Special feature
Bosig Inside window sealing tape	Butyl rubber on fleece	inner level at the window connection	Fleece backing can be plastered over · split release paper · 2 × 10 m
Fasatan Eco EPDM	EPDM	outer level at the window connection	Vapour-permeable · 0.6 mm thick · B2 · eight widths
Bosig Windfix film adhesive	Acrylate dispersion	Bonding fleece and sealing films	Weatherproof for the outer connection · white, application visible
Bosig Rooflex	Butyl with aluminium insert	Roof connection to wall, chimney, dormer	Lead-free · UV-resistant · in roof tile colours · 280 mm × 5 m

The fleece backing decides whether the plaster holds

A sealing tape at the window connection is in many cases later plastered or skim-coated over. A smooth film gives the plaster no grip – it tears off at the edge or comes away as a shell. That is why the tapes intended for this carry a fleece layer: a rough, open fibre layer into which the plaster mechanically grips.

Plasterable is a property of the backing, not of the adhesive. According to the product data, the Bosig Inside window sealing tape is full-surface butyl rubber on a fleece backing that can be plastered and skim-coated over; the split release paper makes alignment easier, because first one half and then the other is exposed. The Duo version additionally carries a 20-millimetre adhesive strip at the front, with which the free edge is fixed to the frame before the plaster goes on.

What tradespeople use Bosig for

Forming window connections airtight on the inside
Plastering and skim-coating over connection tapes
Closing window connections vapour-permeably on the outside
Bonding sealing films to the building body
Sealing roof connections at walls and chimneys
Connecting dormers and roof windows so that they carry water
Replacing lead flashings with lead-free tapes
Letting residual construction moisture dry out to the outside

Bosig product families

Bosig Inside window sealing tape, two rolls of 10 metres — **Inside** – butyl on fleece

Roll of Fasatan Eco window connection tape made of EPDM — **Fasatan Eco** – EPDM, 0.6 mm

Bosig Windfix film adhesive, white, in a 600 ml bag — **Windfix** – film adhesive

Roll of Bosig Rooflex butyl-aluminium connection tape — **Rooflex** – roof connection without lead

Good to know

Based in Gingen an der Fils. BOSIG GmbH is located at Brunnenstraße 75-77 in 73333 Gingen and is entered in the commercial register at Ulm.
Butyl does not cure. It stays permanently plastic and therefore seals even when components move slightly. The price for this: once bonded, it can no longer be cleanly released and repositioned.
EPDM stays elastic. The synthetic rubber absorbs movement, is ageing-resistant and, at 0.6 millimetres, so thin that it hardly adds bulk in the connection – important when the joint is tightly dimensioned anyway.
Vapour-permeable on the outside is not a contradiction. The outer level is meant to keep driving rain out and at the same time let moisture out of the joint. That is exactly what Fasatan Eco is designed for, according to the product data.
The adhesive shows where it sits. Windfix is coloured white – you can see during the work which stretch has already been given adhesive. On a grey wall that is worth more than it sounds.
Source of the company information: bosig.de, legal notice, retrieved on 17 September 2026.

Frequently asked questions about Bosig

Which tape belongs on the inside, which on the outside?

On the inside the tighter level, which keeps the humid room air out of the connection joint – the Inside window sealing tape made of butyl on fleece is intended for this. On the outside the vapour-permeable level, which keeps driving rain out and still lets moisture dry out; Fasatan Eco made of EPDM is intended for this. If the levels are swapped, moisture collects in the joint instead of drying out.

Can I use Rooflex instead of lead?

According to the product data, Rooflex is intended for exactly this: self-adhesive, without lead and other heavy metals, considerably lighter and available in roof tile colours. Whether it is the suitable solution in an individual case depends on the connection detail, the roof pitch and local requirements – that is decided by the execution planning, not the roll of tape. The substrate must be dry, clean and load-bearing.

Can I plaster over the sealing tape?

If it has a fleece backing, yes – the plaster grips into the open fibre layer. According to the product data, the Inside window sealing tape can expressly be plastered and skim-coated over. On a smooth film, by contrast, plaster does not hold; it tears off at the edge or comes away as a shell. The binding information is given in the technical data sheet of the respective tape.

How do I apply the tape straight?

Via the split release paper. With the Inside window sealing tape, only one half is exposed and applied first; as long as the second half is still covered, the strip can be aligned. Only then is the rest peeled off and pressed down. With butyl tapes this is important because they can no longer be corrected after pressing down – butyl sticks immediately and permanently.