Sign up to our newsletter

  • 1. Are there differences between a hanger bolt and the EJOT Solar Fastening Systems JA3 and JZ3?

    A hanger bolt looks very similar to the EJOT Solar Fastening Systems JA3 & JZ3. Nonetheless, there are important differences which indicate big advantages of the EJOT Solar Fastening Systems:

    1. The EJOT Solar Fastening is a complex system of
      -special screw for wood, steel or concrete applications 
      -setscrew with drive for mounting parts 
      -special and proven sealing elements

    EJOT solar fastening systems pic 1

    2. The screw length will be selected to work best with each individual project.


    The screw head is the preset depth (control) stop.
    Due to that the optimal intrusion depth into the substructure is always constant and not changeable allowing the necessary structural calculations.

    3. After installation the sealing system realizes a perfect waterproofing

    The sealing system EJOT ORKAN Storm Washer + sealing washer is used since decades for roof installations with trapezoidal profiles, insulated metal panels and corrugated metal profiles– and has proven to be a very reliable system.


    Photo: Metal roof with EJOT ORKAN Storm Washer

    4. The EJOT Solar Fastening Systems are fully quality controlled and have been approved by the DIBt (German Institute of Building Technology), whose standards are among the most rigorous in the world.

    The US market is currently establishing its own testing requirements for solar products. In the meantime, approval to use EJOT products can easily be obtained from local building authorities throughout the country as Alternate Materials, Design and Methods of Construction, IBC Section 104.11.  Together with our project-related initial sizings and technical data, this makes life a lot easier for specifiers and planners!


  • 2. Why don't I need three screw nuts for the installation?

    For a hanger bolt the third screw nut is necessary because it determines the intrusion depth into the substructure and thestop position for the sealing.

    The EJOT Solar Fastening Systems realize this stop position with its precisedefined depth (control) stop.


  • 3. Is the 'hanger bolt' technically approved by building authorities?

    No - Generally ‘hanger bolts’ do not have a technical approval!

    The good news – ‘The EJOT Solar Fastening System is NOT a hanger bolt!’

    A hanger bolt and the EJOT Solar Fastening Systems are looking very similar. In fact this is the reason why these products are often being confused with each other.

    Decisive is that the design of the EJOT Solar Fastening Systems differs from the hanger bolt with some fundamental characteristics. In fact this is the reason why the EJOT Solar Fastening System is the first fastening system for solar installations that was technically approved by building authorities in Germany.

    The translation of German Technical Approval of the EJOT Solar Fastening Systems JA3 & JZ3 (Z-14.4- 532) can be downloaded in the download section, as well as the respective technical data sheets. 

  • 4. How do I install the EJOT Solar Fastening Systems JA3 & JZ3?

    The EJOT Solar Fastening System has an internal drive (width across flats A/F 5mm) at the face side of the setscrew.
    With this drive the EJOT Solar Fastening System can be installed / uninstalled fast and easily without special tools.

    Considering the correct pre-drilling diameter (see topic: Determination of the pre-drilling diameter) the thread-forming screws will be installed fast and secure into the substructure.

    Retrofitting of existing roofs can be done fast and easily by replacing the existing roofing screws with EJOT Solar Fastenings Systems.

    The respective correct procedure is described in detail in the Installation Manual.

    Download Installation Manual.

    Link: Determination of the Pre-drilling Diameter.

  • 5. Why is an 8mm (5/16”) diameter used? Is that enough?

    The EJOT Solar Fastening System is offered as a standard product with a thread diameter of D = 8.0mm (5/16’’) for steel and wood substructures.

    The characteristics have been tested extensively and accurately for the fastening of racking systems for solar installations.

    With the technical approval of the EJOT Solar Fastening Systems JA3 & JZ3 you have the written confirmation of the performance, as well as the characteristic values for structural calculations. 

    Force Impacts on the EJOT Solar Fastening Systems

    Technical Approval of the EJOT Solar Fastening Systems JA3 & JZ3.

    Download Technical Approval.


  • 6. How does the fastening system bear the loads?

    The EJOT Solar Fastening System is anchored directly and securely into the substructure.

    Due to that the defined, static system can be calculated taking into account the external influences, e.g. module weight, wind suction, snow load, etc.

    Occurring forces, e.g. wind suction and module weight, are directly transfered via the EJOT Solar Fastening System into the substructure. As a result, the roof covering is not stressed through these influences.

    Shear forces will be absorbed due to the anchoring in the substructure and the bearing stress at the roof covering.  

  • 7. How do I specify the right fastening system for my application?

    We would like to support you in defining the optimal Solar Fastening System and the necessary sealing system for your project.

    You only need to download the questionnaire from the download area. Then send it completed to the e-mail address solar@atf-inc.com or fax +1 847-568-3713) and you will receive a proposal of the recommended EJOT Solar Fastening System setup for your individual project. 


    Download Questionnaire EJOT Solar Fastening Systems JA3 & JZ3.

  • 8. Which is the correct pre-drill diameter?

    Rule 1:
    In roof coverings with metal profiles or insulated metal panels the hole diameter in the roof profile and the substructure will be always drilled of the same size: 

    Rule 2:
    In a roof covering with fiber cement profiles the hole diameter in the corrugated profile will always be drilled bigger (11mm).


  • 9. Which materials are used for the EJOT Solar Fastening System?

    The EJOT Solar Fastening Systems complies with the requirements for the outdoor exposure.

    The materials are high-grade and designed for a high durability even under direct weather exposure.

  • 10. Does the JZ fastening system for steel applications have a full thread?

    The EJOT Solar Fastening with JZ thread is used to anchor in steel substructures. Starting with a length of L = 3.150’’ (80mm), the “screw” does not have a full thread.

    The length of the thread is always 2.520’’ (64mm).

    For dimensioning the screw length it needs to be considered that the steel substructure will always allow a full thread engagement. 

    Defining the recommended screw length (L) 

  • 11. What does thread-forming mean?

    To produce a thread in a hole, a profiled grooving, which follows a continuous convoluted screw line, is formed into the designated material.

    This shaping can be done through cutting or grooving.

    For the process of thread cutting in steel generally a tool or screw with cutting edge is used. During the cutting process chips are built, discharged and disposed. The microstructure is cut.

    In the thread-forming process screws with special thread geometries and appropriate thread flank hardness are used. The thread hereby is not cut but formed. Because of this deformation process, only a very small amount of abrasion at the joining surfaces is generated, instead of chips.

    During the installation in steel the hardness of the material in the thread is even slightly increased through a cold hardness increase in the joining.

    An additional advantage is the tolerance-free installation because the created female thread is copying the effective dimensions of the installed screw. For having no play between male and female thread the screw is mounted firmly and dynamically safe.     

    Thread-forming screws by EJOT, left to right:

    Formed thread in steel, JZ thread for steel, JA thread for wood.

  • 12. What about the watertightness?

    Sealing with the EJOT 'FZD' sealing element

    Fastening situation of a corrugated aluminum profile with
    EJOT 'FZD' sealing element.

    • Sealing element adapts to the surface
    •  Universal sealing solution for any kind of corrugated or
       trapezoidal metal profile roofings (crown should have a width of at least 1‘‘)
    •  Sealing element made of  EPDM
    •  Seals also on slightly rough surfaces



    EJOT ORKAN Storm Washer                                                                         
    For decades, a proven sealing system for fastening of metal profile roof coverings. Photograph shows fastening of a trapezoidal roofing profile with JT3 screw with EJOT ORKAN Storm Washer and sealing washer. 

    Recommended applications:

    •  Trapezoidal metal profiles (Steel/Aluminum)
    •  Corrugated metal profiles (Steel/Aluminum)
    •  Insulated Metal Panels (Steel/ Aluminum)
    •  EJOT ORKAN Storm Washers are available for many common metal profiles.

  • 13. Why is the EJOT ORKAN Storm Washer not delivered pre-assembled?

    When the EJOT Solar Fastening System is delivered in combination with the EJOT ORKAN Storm Washer, the Storm Washer is not pre-assembled on the screw – why is that? 

    Performing the installation, the EJOT ORKAN Storm Washer will be positioned on the pre-drilled profile sheet (please consider correct diameter). Due to that the washer acts as a joining template and at the same time is kept and fastened in the optimal position. This way the system achieves its reliable waterproofness.

    In case the EJOT ORKAN Storm Washer would have been pre-assembled to the screw before installation, it would hardly be possible to find the best mounting position on the profile during installation. A slight tilt of the EJOT Solar Fastening System could lead to a displacement or cant in the final positioning. The resulting gap could lead to leakage.

    To avoid these possible assembly errors the EJOT ORKAN Storm Washer is not delivered pre-assembled.


  • 14. The hole of the EJOT ORKAN Storm Washer is much too small – why is that?

    The hole diameter in the EJOT ORKAN Storm Washer is smaller than the EJOT Solar Fastening thread / shank diameter of the screw. Therefore the EJOT ORKAN Storm Washer cannot easily be attached – why?

    The EJOT ORKAN Storm Washer is always used with two sealing elements to provide the best sealing situation:

    1. Sealing washer

    2. EJOT ORKAN Storm Washer


    The sealing washer does have the function to create watertightness between the flat screw shank and the EJOT ORKAN Storm Washer.

    The EJOT ORKAN Storm Washer creates a secure sealing and load distribution by clamping on the metal profile.

    The tight fit between the screw shank into the hole of the EJOT ORKAN Storm Washer allows a free of play and improved sealing situation between screw and EJOT ORKAN Storm Washer.

    Due to this sophisticated and proven system the secure sealing can easily be realized for your projects, provided that the correct components and the correct installation have been applied.

  • 15. Which sealing system is the best for my application?

    The EJOT Solar Fastening Systems JA3 and JZ3 are designed for use in roof coverings with trapezoidal metal profiles, corrugated metal profiles, insulated metal panels and corrugated fiber cement panels. The following sealing systems are available: