With the fischer injection mortar FIS EM Plus for bonding in wood, fischer offers an innovative solution for timber construction. In an initial project, the company Holzbau Bögerl GmbH used the fischer FIS EM Plus epoxy mortar in conjunction with FIS A anchor rods to connect glulam columns along the length of five storeys of a new building.
In a new six-storey building, five timber-framed upper storeys rise above the reinforced concrete supporting structure of the ground floor. Their columns and beams are made of glulam. The ceilings are made of cross-laminated timber.
To create the longitudinal connection between the glulam columns and the next columns on the floor above, the contractor Holzbau Bögerl GmbH (Breitenbrunn) used fischer FIS EM Plus 390 S together with FIS A anchor rods for bonding in the timber. The cross-section of the supports is 2 x 240 x 480 mm as double supports. The “allgemeine Bauartgenehmigung” (general type approval (aBG)) / “allgemeine bauaufsichtliche Zulassung” (general building authority approval (abZ)), which fischer obtained for the injection mortar in combination with system components in March 2024, provides security. "The expansion of the application area of our FIS EM Plus injection mortar to include bonding in wood opens up completely new perspectives for us," emphasizes Johannes Zähringer, Developer Business Unit Chemistry. "The innovative system solution enables the transfer of high loads and a wide range of applications for timber construction. Our FIS EM Plus is used in conjunction with FIS A anchor rods or our new FIS IG internally threaded anchors to connect load-bearing glulam components made of spruce, fir or pinewood."
To date, approximately 100 cartridges of FIS EM Plus 390 S have been installed in the new building together with approximately 320 FIS A M12 x 1,000 8.8 anchor rods and around 1,900 DD-E M12 and DD-S M12 centring clips each. The mortar was injected using the by-pass injection method approved for the application, in which the borehole was filled from the bottom of the borehole using a transverse borehole. The carpenters carried out half of the grouting in the factory and half on the construction site. By-pass injection made it possible to fill the deep drill holes and, together with the FIS A M12 x 1,000 8.8 anchor rods, create an anchoring depth that guarantees a high load-bearing capacity of the connections.
Bonding on construction sites is unusual, but posed no problem in the prevailing weather conditions. The Fraunhofer Institute for Wood Research, Wilhelm-Klauditz-Institut WKI (Fraunhofer WKI, for short) in Braunschweig certified the carpenters at Holzbau Bögerl GmbH in advance of the installation by organizing a special training course at short notice and also monitored the correct execution on the construction site. Each fastening point was documented in detail by the installer, with the wood moisture, ambient temperature and other relevant data being recorded. Adhesive samples were also taken from each batch.
In the construction project, fischer FAZ II Plus bolt anchors in diameter 16 were also used to fasten steel brackets to the reinforced concrete wall of the solid core, which are required as supports for the cross-laminated timber ceiling elements.
"A contractor needs a certificate of suitability for bonding steel parts to wood," emphasizes Daniel Heiß, the fischer application engineer in charge of the project. "Together with our specialist dealer, Friedrich Dorner GmbH from Thalmässing, we were able to provide the timber construction company with expert advice on prequalification and other requirements." Philipp Creuzberger, who helped oversee the project on behalf of the fischer Chemicals division, adds: "In addition to the right system solution, we impressed the timber builders with our services and expert advice and are happy to continue to support them until the project is successfully completed."
Following the granting of the abZ/aBG for gluing steel rods into timber components in March 2024, the system was able to successfully demonstrate its advantages for the first time in a reference project. The system has now also received an ETA (ETA-19/0657) for approval-compliant use in other countries.
The built-in solution
The fischer injection system FIS EM Plus for gluing in FIS A anchor rods or flush-bonded FIS IG internally threaded anchors enables the transfer of high loads and a wide range of applications for timber engineering. Load-bearing glulam components (made of spruce, fir or pinewood) can be securely and permanently connected with the system solution. Two components can also be connected at the construction site.
An extensive range of accessories and system components made of galvanised steel and stainless steel enable numerous connections and reinforcements in timber both indoors and outdoors in conjunction with the FIS EM Plus. The FIS A anchor rods can be used in M6 to M30 with variable anchoring depths and FIS IG internally threaded anchors with an internal thread in M8 to M20. Concrete ribbed steel with a diameter of 6 to 32 mm is also approved. By offering the innovative internal thread solution, fischer offers the possibility of realising fixing points that are flush with the surface. This makes an important contribution to safe and efficient transport. The risk of bending protruding anchor rods is avoided and the transport surface can be optimally utilised by the component. The use of the FIS IG with the FIS EM Plus is - like the connection using glued-in anchor rods - a detachable connection. However, the internally threaded anchor can be removed flush with the surface and the fixing point can therefore be easily reused. This is generally ideal for temporary fixings, but also for angled, detachable connections where a threaded rod could make disassembly difficult or impossible. The injection mortar FIS EM Plus is available in different container sizes with a content of 390 ml, 585 ml and 1,500 ml - each suitable for the respective application and requirements. The extensive range of accessories also includes the DD-E/DD-S centring clips for centring anchor rods and internally threaded anchors, injection aids, extension hoses, manual and battery-operated injection devices and much more. A comprehensive range of accessories for cleaning drill holes is also available, such as blowers and brushes.
Timber components can also be joined invisibly with the system solution. This opens up new design possibilities for architecturally appealing connections. Invisible fixing points do not interrupt the uniform appearance and original character of the timber surface.
