Mounting and sealing in one operation

A sealing system that enables prefabricated construction

Prefabricated construction is seen as one of the solutions to our housing shortage. After all, it allows faster and cheaper construction without sacrificing consistent, high construction quality. While all parts are produced with extreme care in the factory, the foundation can already be started on site. "By prefabricating, fewer skilled hands are needed on site," says Claus den Dunnen, Sales Manager at Celdex. "It also reduces failure costs and makes building in the factory safer. In combination with good air sealing, requirements such as BENG, Zero-Meter and BREEAM-NL can be excellently met."

More flex housing, 15 large-scale construction sites, faster conversion of offices, more direction and tighter rules. These are the main proposals of Minister of Housing and Spatial Planning (VRO) Hugo de Jonge to combat the housing shortage. Through 2030, De Jonge wants to build some 900,000 homes, of which at least two-thirds must be affordable rental and owner-occupied housing. The most acute problems are to be solved by putting up 15,000 prefab homes a year. "Celdex has seen the prefabricated construction trend coming for some time and has extensively surveyed the needs and challenges in this area," Den Dunnen said. "Among other things, this has led to our Seal4Prefab concept, with which we provide construction stakeholders with all the essential building blocks to achieve and demonstrate the desired performance in airtight construction."

4 principles

Seal4Prefab consists of four principles: an air seal on the inside, an insulating middle seal, a driving rain seal on the outside and is suitable for prefabrication. "All products that are part of Seal4Prefab are suitable for sealing horizontal and vertical connection seams of precast building elements," Den Dunnen said. "The sealing system offers processors and occupants important advantages. For example, Seal4Prefab boasts demonstrable quality in durability, air and driving rain tightness. It is economically attractive because of the processing that saves time and reduces failure costs. Seal4Prefab is also circular because the sealing products are demountable and reusable. It provides the necessary speed during construction: assembly and sealing are done in one operation."

Successful projects

Seal4Prefab has already been successfully applied in several projects. A good example is De Kwekerij project in Utrecht, Phase 2, which consists of six colorful residential towers with 244 rental units. Machiels Building Solutions is the producer of the colorful HSB facade elements. "After production at the factory, the HSB elements are coated with Celdex sealing products," Den Dunnen said. "Pre-Seal M on the inside provides air sealing and insulation, while EPDM Soft on the outside prevents the penetration of driving rain. Because these 'dry' sealing products can be applied prefabricated in the factory, considerable application time is saved on the construction site. Assembly rates increased during the project to as much as one complete tower per week."

A current reference project for Seal4Prefab is Wonderwoods in Utrecht. Commissioned by building consortium Wonderwoods VOF (Kondor Wessels Amsterdam | Boele & van Eesteren), Westo produces insulated concrete sandwich elements for both sustainable towers. Pre-Seal LF here provides the air seal and insulation on the inside, while EPDM Soft forms the driving rain seal on the outside. In addition, Butyl tape 70S is used as a water barrier for the sandwich elements. The custom-made EPDM Cuffs complete the total sealing system.

Preparation and engineering

Important parts of Celdex Seal4Prefab are knowledge transfer and quality assurance, but also proper preparation and engineering. "Based on, for example, the best requirements and building drawings, we give advice on the best fitting sealing products and (prefab) assembly," says Den Dunnen. "For example, how is water management handled? And air tightness? What performance is demanded? Where are the critical points? What tolerances do HSB, frame and concrete frame manufacturers expect? Are we dealing with uniform joint dimensions and/or can this be realized? But also: which assembly sequence is best to follow, for an optimal result? If desired, we can test materials in advance in a critical building detail for air and driving rain tightness. We can also issue a performance guarantee for this." 

Toolbox meeting

Before moving on to precast production, Celdex organizes a toolbox meeting for the processors. "Before assembly begins, a toolbox meeting is also set up for the precast assemblers, focusing in particular on inspection and repair in the event of unexpected transport damage. All processes are carefully recorded in partial reports, which together produce a single report for private quality assurance."  

https://celdex.nl/