“Weil Jedes Detail Zahlt”

“Every Detail Counts”

Good airtightness on a roof or wall can be achieved by ensuring a “Synergie” between design and execution and by trying to ensure that there are two airtight layers present:

• Internal Airtight Layer (for example a Vapour control layer)
• External windtight layer (for example a highly breathable membrane)

The weak points are not large surfaces but all the interruptions and openings in the roof or wall. The rule of thumb is that if you were to go around the graphic design of the house with a pencil, every time you lift the pencil is a potential air leakage point, such as conduits, waste and soil pipes and ducts, pipes for solar systems, window and door frames. The key is to totally seal these air leakage points:

• Vapour control layers, barriers and breathable membranes should be sealed at their joints using Multi Tape
• Large pipes, conduits and roof windows should be sealed on the outside using butyl tapes, such as Coll Flexi, to the breathable membranes and to the vapour control layer on the inside using Multi Tape
• The internal walls of timberframe houses should be sealed at their joints with acrylic adhesive tape Multi Tape, butyl tape or sealants in cartridge containers
• Door and window frames should be sealed with elastic expanding foam, and or compression tapes and sealing tape around their perimeters where they meet the wall or subframe. You can choose Synergie Full Adhesive Window Tape, with full waterproof adhesive, where the tape is to plastered on smooth blockwork or choose FI-D Window tape where the blockwork is rough and you need to adhere the tape to the substrate with acrylic adhesive, Synergie Acrylic Adhesive or in damp conditions our Synergie MSP MS Polymer Adhesive and Sealant. Both tapes, once fully adhered, can be plastered over

Kiwa GmbH issue the Conformity Certificates which attest that “all provisions concerning the attestation of factory production control are applied”, in accordance to the Harmonised EU Norms;

• EN13859 – 1:2014 – which covers Breathable Roof Sarking Membranes
• EN13859 – 2:2014 – which covers Breathable House Wrap Membranes
• EN 13984:2013  – which covers AVCLs (Airtight Vapour Control Layers)

To produce each category of product, Synwer GmbH sources the best quality, most durable, European manufactured, raw materials, including PP (Polypropylene) Spunbond non-woven fleeces of different thicknesses and weights, PP foils, PE (polyethylene) foils, PUR (polyurethane) foils, PA (polyamid) foils, PET (polyester spunbond) foils and Coex foils. Each foil has its own Sd-value. The Sd-value of an external roofing membrane, timber-frame house-wrap or airtightness vapour control layer, is a measurement of the “Resistance to the migration of water vapour” of that material.

Membranes that are generally exposed to the weather during construction (roofing membranes typically) will have very low Sd-values, usually Sd 0.02m. This means that the material used, although completely water tight (meeting W1 water-tightness) is very “vapour open”, or “breathable”, allowing very quick migration of any water vapour (that may build up on the underside of the material, due to condensation mainly), from the inside to the outside of the sarking membrane. This is known as the “open diffusion” properties of that material. On the other hand, as you move closer to Sd 100m, the material in question becomes more “vapour tight”, significantly slowing down the rate/speed of migration of the water vapour from the inside to the outside.

Although they manufacture many different membranes at Synwer GmbH, the specific products, that Ostman Thermal Ltd. stock and distribute are as follows;

(i) Windtight Exterior Products

• “Superior Line” SL155 Breathable Monolithic Roof Sarking Membrane, is the next generation of Superior Performance vapour permeable underlays. Head SL155 is a three-ply diffusion-open sarking membrane with the latest monolithic technology. The latest state of art is a three-layer combination of
• an upper protective layer of water-repellant, UV-stabilised, anti-slip, polypropylene PP spunbond fleece (with outdoor exposure up to 6 months),
• Central membrane; an inner functional film which is a UV10 Bikom PUR film (unique to Synwer GmbH) that is monolithic, diffusion-open, driving rain-proof as well as UV and heat resistant.
• and a lower protective layer of PP, high-quality, UV resistant.
• SL155 is 100% completely airtight, is 155g/m2 in weight, and has an Sd-value of Sd 0.07m.
• Monolithic films are the newest, most modern functional foils, that do not contain microporous pores for the transfer of water vapour. Instead, the monolithic, pore-free foils actively transport moisture to the outside. Only a minimal partial vapour pressure gradient is required for this transport of moisture (water vapour). The more it is, the faster the diffusion resistance of the foil decreases, ie. the more diffusion-open the foil becomes. The monolithic foil ensures special protection against driving rain because there are no pores. However, the PUR (polyurethane) foil still has moisture-variable properties to allow for open diffusion to occur, but still ensure 100% airtightness, with all of these characteristics in full compliance with CE EN 13859-1/2. The Monolithic PUR film is 15 times more durable than the standard microporous membranes.

• “Eurostandard Line” Head Wall 120, which is a three-layer, highly diffusion open sarking membrane that meets all the requirements of the various applicable European Standards for tearing forces and rainproof sub roofs and wall façade applications. The three-layer, diffusion open, wind seal, sarking membrane is a combination of
• an upper protective layer of water-repellant, UV-stabilised PP (polypropylene) fleece,
• an inner Microporous functional film of PP (polypropylene foil),
• and a lower protective layer of PP (polypropylene).
• Head Wall 120 is completely 100% airtight, is 120g/m2 in weight, and it’s Sd-value is Sd 0.02m.
• The inner functional foil is made of polypropylene as a closed foil. The material of this foil is diffusion-tight in its original state. In order to create a diffusion-open/breathable sarking membrane, calcium carbonate is added and stretched in the production of the PP film to form micro pores. These three-ply films are then subjected to the “thermobonded” process, with high temperature more than 140 deg. C with high pressure, in a technologically very complex and specially established production process to finish with a rain-proof, wind-proof, airtight, vapour diffusion-open sarking membrane, in compliance with CE EN 13859-2.
• The attached FIW Munich Certificate is a test of the breather membranes that Synwer GmbH produce with microporous polypropylene foils

(ii) Two Airtight Vapour Control Layers

The airtight layer is located on the inside of the “building envelope”. At Ostman Thermal, we currently stock two Airtight Vapour Control Layers (AVCLs);

(i)  Synergie Sd Variable, (Intelligent/Active) Airtight Vapour Control Layer
(ii) Synergie Sd Fixed, Sd2, Airtight Vapour Control Layer

(i) “Synergie Sd Variable Sd 0.2m – Sd 20m Airtight Vapour Control Layer (AVCL)’’ is a two-layer, moisture-variable performance, fully 100% airtight, vapour control layer. Variable Sd AVCLs can change their vapour permeable characteristics based on the vapour pressure gradient, or Relative Humidity (RH) surrounding/in close proximity to the membrane. The two-layer Sd Variable membrane has an upper functional foil film in PA (polyamid). This film is a special kind of plastic that reacts to the humidity in the air and the temperature differentials between outside and inside. The PA film remains completely airtight, while the micropores of the film can increase (open) or decrease (close) their size to allow the passage of water vapour molecules, which are many, many times smaller than air molecules. Vapour can pass through, but air cannot pass. The lower support layer is PET (polyester spunbond). In the summertime, there is relatively higher RH, and the functional PA foil is “open” vapour permeable, operating at the lower spectrum of Sd0.2, and is very breathable, while in the winter, there is lower RH and the functional PA foil becomes more vapour “tight”, as it operates closer to the upper limit of Sd20. In the long run, over a few years, this ability to act as a barrier in winter and a breathable membrane in summer, helps to protect the building from structural damage caused by excessive moisture trapped in the building fabric.

The Synergie Sd Variable membrane is ideally suited to flat roof make-ups which are not adequately ventilated or diffusion “vapour tight” towards the outside. The Synergie Sd Variable membrane is also suitable in new build where excessive moisture accumulation has occurred during the initial construction phase of the building process, such as Timber-frame, where timber elements and/or thermal insulation has suffered an unplanned wetting.

(ii) Synergie Sd Fixed AVCL, Sd2/100, is a two-layer, translucent airtight vapour control layer with an Sd value of 2m and is 100gramme/m2 in weight. It is manufactured as a combination of an upper protective layer of water-repellent, UV-stabilised, completely 100% airtight, polypropylene spunbound fleece and on the underside, the functional film, slightly diffusible (allowing slow vapour diffusion) polypropylene film. With its optimum fixed Sd value, Sd2m, this fully 100% airtight VCL is perfectly suitable for the underside of ceilings in most pitched roof applications, where breathable roofing membranes (with typical Sd values of Sd 0.02) are incorporated, as they are diffusion open to the outside.

The decision on which airtight vapour control layer to choose in a warm roof (lived-in attic space) or cold roof detail (with the AVCL fitted, say, for instance, at first floor ceiling level) is often made on the basis of a simple principle or “rule of thumb”, which states that a roof or wall construction should, in relation to water vapour migration, be “tighter on the inside than on the outside”. But just how much tighter should the ACVL be? Another simple “rule of thumb” states that “10 times more diffusion-proof on the inside than on the outside is optimal”.  If the roofing membrane on site is “vapour open” and has an Sd-value of Sd0.2m then the Synergie Sd2.0m is 100 times higher Sd than the Sd-value of the external roofing membrane. This is perfect, as any vapour molecules that can pass slowly through the Sd2.0 membrane will easily be dealt with by the Sd0.02 vapour open properties of the pitched roof sarking membrane, ensuring that no build-up of condensation on the underside of the roofing membrane will occur. Both membranes are vapour permeable and allow for natural open diffusion to occur.

To summarise, the Sd2/100 AVCL is a 100% completely airtight membrane with a “Resistance to Penetration of Air” of less than 0.002m3/(m2h/50Pa) and as outlined above, performs as a Vapour Control Layer with a declared Sd-value, or “water vapour transmission rate” of Sd2.0m, as per the attached Technical Data Sheet (TDS), dated 28^th July 2020, and the Declaration of Performance (DoP), dated 15^th July 2020.

The Synergie Sd Variable and Sd2/100 AVCLs are fully EU CPR compliant, are CE Marked and are airtight vapour control layer construction products, “fit for their intended use”, and “manufactured in strict accordance with the applicable EU harmonised technical specification DIN EN 13984: 2013-05 Plastic and rubber vapour control layers – Definitions and characteristics.”

All membranes produced by Synwer GmbH are manufactured under the strict supervision of the EU notified body, Kiwa GmbH, who carry out the annual audits and issue the Conformity Certificates each year. Synwer GmbH also use the testing services of Technical University Berlin & FIW Munich.

Synergie Membrane Tape 60mm is an adhesive tape on PE treated paper coated highly adhesive acrylic glue for internal use. The tape has been specifically produced for bonding Synergie vapour control layers with the purpose of providing a seal against air, wind, vapour and noise on interuptions in roofs and/or walls. It can also be used for internal sealing of OSB boards in timberframe construction. On surfaces to be bonded, make sure they are free from dust and moisture. Cut the tape to the desired length, remove the protective liner and lay the adhesive tape onto the overlap of the membrane, then press firmly along the length of the tape with the Pressing Roller so that the adhesive bonds properly.

Synergie Coll Flexi is available in 100mm width and is a highly flexible butyl adhesive tape. It is totally hand malleable and permanently elastic, can be pressed down by hand then rolled in flat with the Pressing Roller. Once properly adhered it has very strong adhesion properties and mostly works without the need to prime the surface. It is ideal for use as a permanent seal both inside and outside at all penetrations in the building structure.