U Bracket for Metal Roof

The U type bracket is the connecting part between the roof sheet metal and the aluminium bar on which the panels sit. It looks like a stirrup: it has a base that rests on the sheet metal and two vertical wings to which the rail is fixed. Without it, on a metal roof the rail would have nothing to be fixed to.

The wings have holes or a vertical slot, so the rail can be raised or lowered by a few millimetres during installation, which is useful because no roof covering is perfectly flat, and the row of panels must come out straight. Fixing is done with self-drilling screws provided with an EPDM rubber washer, which is squeezed when tightened and seals the hole, and additionally butyl tape can be applied under the bracket base. The screws are always driven into the crest of the corrugation, that is into the upper part of the wave, not into the valley, where the water runs. The solution is chosen when the smallest possible number of penetrations of the covering is sought.

U type bracket (stirrup) of aluminium or stainless steel, materials galvanically compatible with aluminium rails and with A2 stainless steel tightening elements. Fixing with self-drilling or self-tapping screws with an EPDM sealing washer, into the crest of the corrugation of the trapezoidal sheet, of the corrugated sheet or of the sandwich panel; the connection with the rail is achieved through a bolt and nut, with height adjustment. The number of brackets and their spacing are established by calculation, depending on the wind and snow loads, the thickness of the sheet and the width of the crest.

Who it suits

Suitable for industrial halls, workshops and agricultural buildings with a trapezoidal sheet or sandwich panel covering, where the number of roof penetrations must be kept to a minimum.

Terms explained

• Crest of the corrugation: The upper part of the sheet wave, the only place where holes are drilled, because water does not pool there.
• EPDM washer: The rubber gasket under the screw head, which is squeezed when tightened and closes the hole in the sheet.
• Galvanic compatibility: The choice of metals that do not corrode each other when they touch and get wet.

Technical specifications

Recommended applications

• Fixing aluminium rails on hall roofs of trapezoidal sheet
• Roofs of sandwich panels, where fixing is done in the upper corrugation
• Compensating the unevenness of the metal covering when installing the rails
• PV installations on agricultural and industrial buildings with a metal covering

Technical details

Generic product — standard specifications

The U type bracket is the connecting part between the metal roof covering and the load-bearing rail of the photovoltaic system. It has the shape of a stirrup, with a seating base drilled for the screws fixing into the sheet and with vertical wings provided with holes or a vertical slot for coupling the rail, which allows height adjustment during installation and the compensation of the covering's unevenness.

The brackets are usually made of extruded aluminium or of stainless steel, materials galvanically compatible with aluminium rails and with A2 stainless steel tightening elements. Fixing on the roof is done with self-drilling or self-tapping screws with an EPDM sealing washer, screwed into the crest of the corrugation of the trapezoidal sheet or into the sandwich panel; the compressed EPDM washer seals the penetration, and additionally butyl tape can be applied under the bracket base.

The number of brackets and their spacing are established by calculation, depending on the wind and snow loads, the thickness of the sheet and the width of the crest. The solution is preferred where a short rail across the whole width of the corrugation is not wanted and where the aim is to minimise the number of penetrations of the covering.