Passive House institute presents paper on case of modular window assembly system

Airtightness drastically reduces E and S levels and increases the quality of the building envelope and the entire construction. Soudal, renowned manufacturer of quality products in the field of insulation and sealing, offers various solutions for achieving a good level of airtightness with the liquid membranes Soudatight and the innovative intelligent modular window mounting system SoudaFrame SWI. Both products were recently awarded Passive House certification. 

A solid layer of insulation is indispensable to meet stringent energy performance requirements. For optimal thermal effect, windows are best installed at the height of that insulation layer.

"A thicker insulation layer usually also results in better insulation values, but that also means that the distance between the window and the load-bearing wall increases," says product manager Steven Van Orshaegen. "The greater the cantilever, the larger and stronger the metal window anchors must be or the more anchors must be used, but that also increases thermal conductivity and the risk of thermal bridges. To prevent this, we developed SoudaFrame SWI, an intelligent modular assembly system with L-profiles that guarantees a perfectly insulated and airtight window assembly while reducing installation time."

Intelligent modular window mounting system

SoudaFrame SWI is ideally suited for exterior wall insulation systems (ETICS) and ventilated facade systems, where the interior wall is erected first and only then the insulation and facade finish are installed.

This frame is made of glass fiber reinforced plastic (GRP), a high-strength, lightweight material with high load-bearing (up to almost 800 kg/m) and insulating capacity. When the window is installed in the insulation plane, the isotherms run straight through insulation and window, achieving significantly better heat loss scores at the wall-window transition (psi values). 

"In addition, we wanted to get rid of the cumbersome, often complex sealing methods involved in using window anchors. The frame, available in four sizes, can be assembled both in the workshop and on site and then mounted as a single unit on the wall using a high initial adhesion hybrid adhesive, Soudaseal SWI. This leaves the installer's hands free to further fully secure the pre-frame with a few bolts. Unique spring clips guarantee a uniform joint between pre- and window frame. Even before the start of project construction, the exact amount of product needed to seal the window connections can be calculated," explains the product manager.

"After the window frame is screwed directly into the SoudaFrame SWI frame, the clips can be removed and the opening can be filled and sealed and finished with Flexifoam, a flexible PU foam, and with our liquid Soudatight membranes."

Passive House certification

With Soudatight, Soudal offers a series of high-quality polymer pastes that, once dry, form a completely seamless and elastic membrane, ideal for the airtight and vapor barrier finishing of penetrations, window, floor-wall, wall-ceiling and roof connections. The fiber-reinforced Soudatight LQ is applied by brush, the SP version airless sprayed. 

"Both versions of our airtightness membrane have recently become Passive House-certified components," Van Orshaegen informs. "But there is more, because as of now the SoudaFrame SWI pre-frame system also carries the Passive House certification even for three different climate zones, namely cold-moderate, cold and warm-moderate. It is the first time that a component has been tested and passed the criteria of different climate zones of the Passive House institute. They found the case so interesting that they wrote a paper on it, which was presented at the 24th International Passive House Conference in late September."