Airtight construction and renovation in all weather conditions

Efficient sealing of unwanted gaps and seams

As energy performance requirements become increasingly stringent, the importance of airtight construction and renovation increases. For example, to increase thermal and acoustic comfort and to minimize heat losses. Following the example of spring and summer, autumn and winter are also good times to get started. For example, when working with the Zwaluw Hybriseal® 306 coating by Bostik, which is the only one in the market that can also be used on wet substrates. Moreover, the coating is immediately rainproof after spreading.

Sealing unwanted gaps and seams

With Bostik's Zwaluw® Airtight Building product range, all unwanted gaps and seams in a home or building can be efficiently sealed. “Thanks to the right measures, cold outside air can no longer enter our warm rooms undesirably, preventing cold and draft complaints,” says Nick Haring, Business Development Manager at Bostik. “Also, unwanted heat is no longer lost from inside to outside, resulting in substantial savings on energy bills. Moreover, thermal comfort is increased. Thanks to good functional connections and a watertight barrier on the outside of the building, vapor and moisture are prevented from entering the structure, resulting in annoying damage and health risks. And as an added bonus, insulating measures keep out noise from outside to inside.”

Even on wet surfaces

With Bostik's Zwaluw® Airtight Building product range the above advantages can be achieved both in summer and winter. For example, Zwaluw Hybriseal® 306 coating is the only coating in the market that can also be processed on wet substrates, keeping the work flow of airtight construction and renovation going. “Our hybrid sprayable and brushable Zwaluw Hybriseal® 306 coating is specifically designed to quickly and seamlessly seal seams and gaps between building materials. All year round and in all weather conditions,” says Herring. “The coating is also suitable for sealing air leaks and helps insulate buildings airtight. After spreading, the coating is immediately resistant to rain.”

Airtight solutions

There are three places in a home where the risk of air leaks is greatest: the floor, the window frames and the roof, Haring knows. “That's why it makes sense to address these areas first when renovating.” The approach is best started with a thorough inventory. “After all, an inventory must be made for each home to determine which measures can be implemented practically, effectively and with minimal structural intervention. Bostik can support this with a comprehensive site survey. We also have specific airtight solutions available for each detail of the home. For more information about airtight renovation, a comprehensive whitepaper can be found on our website.”

Facade

A compression band makes the joint between the frame and the wall impact rainproof. This keeps the primary water load out as much as possible. “A compression band is breathable, so any moisture does get out and does not accumulate in the structure,” Haring said. “With pre-cast concrete and masonry, expansion and connection joints occur. You finish these joints with a hybrid sealant, which stops the primary water load. To achieve the right ratio between joint depth and joint width, you can additionally use a back filler.”

Floor and roof

For airtight, waterproof and vapor-open connections between facade elements and support structures, Bostik offers airtight self-adhesive tapes. “These technical tapes are indoor airtight and vapor-impermeable, while the outdoor quality is both airtight, vapor-open and watertight,” Haring clarifies. “You seal the wall plate by using a flexible PUR on two sides. Then you finish this PUR on the inside with a Zwaluw Hybriseal® 306 coating.” 

You can also use flexible PUR foam or a good compression tape in the ridge connection. "For the roof/wall connection, an Airtight Tape Interior is additionally used. This tape is airtight and vapor-inhibiting and can be plastered over well, without primers. A polyurethane foam (PU foam) is suitable for air sealing and thermal insulation of joints around window frames and building structures among themselves, such as the joint between ceiling and wall."

Frame frames

The airtight sealing of structural frames can be done in several ways, says Haring. “The gap between the structural frame and the frame can be filled with Zwaluw Elast-O-Foam to restore the insulation break. In addition, this flexible PUR foam provides noise reduction on the frame. Then there are several options for proper air sealing, such as Zwaluw Hybriseal® 306 coating, Zwaluw Airtight Tape (vapor-open for the exterior) or Zwaluw Airtight Tape Interior (vapor-inhibiting for the interior).” 

No primer is required for bonding the tapes, he says. “In addition, the Zwaluw Airtight Tape is excellent for finishing the spider membranes at wood frame elements.” For complex window frames such as sliding doors, there is the airtight, vapor-permeable, waterproof and thermally insulating Zwaluw Airtight Foam Tape. “With these products you make joints easily air- and impact rain-tight,” he says.”

Glazing

Herring recommends that the joints between the windows and frames also be sealed airtight. For example, with a hybrid sealant. “This prevents the cold air from accessing the warm living spaces and allows even more comfortable, pleasant and energy-efficient living.”