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Do you also take care of the waterproofing detail of the roof penetration?
Monkeytoe supplies the appropriately sized Dektite boot with our Stub leg kits, which should be installed by the main roofing contractor at the time of roof install. This typically means that the leg stubs are installed before the roof itself. On a retrofit project, if there is an existing roofing contractor then we recommend they be engaged to install the boots.
If there are no roofers currently on the job then Monkeytoe can engage one for you.
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Do the penetrations through the roof require a flashing detail?
This will depend on the roofing type being used on the building. The standard manufacturer’s flashing detail should be used for a Ø250 round penetration using a Dektite boot. Backtray flashings may be required for some profiles and not for others.
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Is the Xbeam a watertight unit?
The beam is manufactured as a sealed unit, however some penetrations are made for connection to the beam. Where required, these can be sealed using neoprene washers or an appropriate silicone sealant.
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Are there any concerns about dissimilar metals at hub portal connections, such as between zinc bolts, aluminium structures and steel beams? Are there any risks of galvanic corrosion?
In short, no. Where these connections are made inside a building, there are no concerns. For galvanic corrosion to occur, an electrolyte must be present to complete the electrical circuit. This should not be happening inside a building often enough for corrosion to happen. As an added precaution, however, Monkeytoe recommend using a lanolin moisture/corrosion inhibitor spray at the time of install to prevent any moisture from being trapped during construction.
We have chosen zinc bolts for this application as they are more compatible with aluminium than galvanised fasteners are, and they maintain compatibility with the steel structure. Where this connection occurs in a weather-exposed area, isolation will be provided between all dissimilar metals to mitigate and prevent corrosion. This will typically be a thin rubber or hard plastic layer, but in some situations a specialised coating may be used.
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Does Monkeytoe engineer and certify from portal up?
Monkeytoe will engineer from our connection point upwards, including the fasteners used. If we are providing the leg stubs, then this will be from the portal up (but not the portal itself). If we are mounting to support legs that are supplied by others, our engineering will cover from our connection upwards. Monkeytoe can assist with the design requirements for the legs in this case.
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Monkeytoe’s aluminium is designed to AS/NZS1164 (Aluminium structures). How is carbon fibre covered?
This is covered by a combination of physical testing as per AS/NZ 1170.0 Appendix B, as well as reference to the European composites code where applicable.
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Where and how is carbon fibre incorporated into the Xbeam?
Carbon fibre is fixed into the top and bottom flange cavity of the beams in the form of ‘Spar Caps’ by use of a structural acrylic adhesive.
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What glues or adhesive are used to fix extrusions together, and what testing have these undergone?
We started with over 50 different potential options and narrowed these down over a period of more than six months, with various tests and discussions with adhesive chemists. We conducted hundreds of lap shear tests at temperatures ranging from below ambient to up to +200°C in order to select our adhesives.
The aluminium-aluminium bonding is achieved with a high temperature capable adhesive that has been specially formulated for us by Bondchem in the UK. The carbon fibre-aluminium bonding is done with a Bondchem structural acrylic. We also have other equivalent options that have been tested and that can be substituted if needed.
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What testing has been completed for structural integrity in fire situations?
We’ve designed and tested to a range of parameters, and we’re currently working with fire engineers to look into additional fire capabilities using intumescent paints.
The aluminium bonds are designed to withstand at least 200°C for an extended duration. This covers scenarios where a fire-rated roof can emit a radiant temperature of up to 180°C for a specified duration.
In our adhesive lapshear testing to date, we’ve actually observed this particular bond increasing in strength with increases in temperature thanks to the nature of the specifically formulated product. We’ve tested this up to 220°C.
Beyond this temperature, it’s possible the aluminium bonding may fail, and that the system would be relying on the bond friction and the connecting bracketry only. We’ve tested this scenario with all bonds failed and the beam loaded to 1.5x its designed shear load held overnight, without observing a catastrophic integrity failure. So pretty successful, we think.
Above 300-350°C the aluminium itself will degrade in performance and reach expected failure.
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Is the XBEAM unit watertight?
While the Xbeam is watertight along the main length, the end caps aren’t a sealed fit. We are now looking at making the entire beams watertight by using a waterproofing foam in the ends of the cavities before installing the end caps.
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Do you have the Fire resistance properties of these beams, such as the FLR Ratings?
Currently we do not have any fire rating capability with these beams, though this is something we’re working on currently with fire engineering companies in Australia. This will take some time to complete.
As above, our design & testing to date has been around the beam maintaining structural integrity when exposed to 180°C+ radiant temperatures (based on the allowable radiant temperatures through a fire rated roof/wall).
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How did we go about getting the capacities from the Xbeam? Was this through testing?
The properties and capacities of the Xbeam are both calculated and verified by FEA & physical testing to determine its performance under a range of stresses.
