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Penetrations

Penetration flashings for fully supported metal roof cladding must be installed by the roofing contractor only, and other trades must not cut any hole in fully supported metal roof or wall cladding.

Penetration flashings used in conjunction with fully supported metal roof cladding require specialist detailing. The details for weathering penetrations in fully supported roof cladding that are included in this section should be read in conjunction with section 8.0. penetrations.

The back curb of the flashing upslope from the penetration should be installed under the roof panels, and the front apron of the flashing should be installed over the roof panels.

 

Front Curb

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Back Curb

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The designer is responsible for coordinating the penetration location to be sure that a penetration will not coincide with the panel seams.

When the penetration is less than 50% of the width of a panel, the hole can be weathered by using a fabricated flashing made by forming an upstand by soldering, welding or sealing.

Small pipe penetrations that can be installed within the width of the individual roof panel can be weathered using an EPDM proprietary flashing as described in Collar or Boot Flashings These are not the preferred option as the expected life of these flashings is unlikely to equal that of non-ferrous fully supported roof cladding. Shop fabricated flashings may require a conical metal rain collar or a 'Chinese hat' to provide sufficient movement if the pipe is sleeved or insulated.

Large penetrations are more complex and require additional considerations during design and installation.

Regardless of the penetration size, weatherproofing should be achieved without relying solely on sealant and independent movement of panel and penetration should be allowed for.

When the penetration width is over 600 mm the panel ribs should be stopped short of the upslope face of the curb, so that water can flow past the ends of the ribs and not be trapped against the curb.

Large penetrations that require flashing through the panel ribs and are over 600 mm wide should be factory manufactured to a cricket design as described in section 15.8.

Flues should be terminated at a sufficient height above a metal roof and discharged in such a manner as to ensure that concentrated flue gases do not come in contact with the cladding.
Dormer windows, chimneys, vents and other penetrations projecting through the roof can impede drainage and require special design. (see Dormer Junctions)
The majority of flashings are made from fully annealed or dead soft metal, but where rigidity or a straight line is required, only half-hard grades of material should be used.

 

Clause: 
015_004_009_004_000_000_000_000_000
Clause Number: 
15.4.9.4
/cop/other-products/standing-seam-cladding#penetrations
Revision Category: 
0 - Clause Removed
Revision Detail: 

Clause removed during a comprehensive revision of Standing Seam Cladding.

Draft Clause: 
014_004_009_004_000_000_000_000_000