ASM Cylindrical Penetration (Split Panel Flashing)

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ASM Cylindrical Penetration (Split Panel Flashing)

Division D - Construction Details

ASM | Cylindrical Penetration (Split Panel Flashing) ( Article and Article

Notice to Reader
Images used in a Construction Detail are representative and not prescriptive, and are not necessarily drawn to scale. They are intended to support the related Standard (Ref. Division A, Article

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ASM Details

ASM 11.1.2 Pipe Flashing, Split Panel.jpg

Print Sheet Under Revision


(1) Deck overlay
Required for continuous support of the underlayment when the deck is not suitable.
(2) Underlayment
The type of underlay required is determined by roof slope.
(3) Insulation
Offset and stagger layers 300 mm (12").
(4) Vapour-permeable separation membrane
Installed over insulation and required on all insulated Architectural Sheet Metal Roof Systems. The material must be located between the insulation and metal panels/ventilation material.
(5) Ventilation beneath panels
A ventilation space is required on slopes less than 1:3; entangled mesh (shown) may be used as void fill. The ventilation space facilitates drying as condensation forms on the underside of the metal panels.
(6) Bearing plate
Only thermally non-conductive clips or bars passing through the insulation assembly, or mechanically fastened bearing plates, may be used to secure and support insulation panels, or provide support for panel clips.
(7) Architectural metal panel clip
(8) Architectural metal roof panel (lower)
Lower, installed prior to the pipe flashing, cut hole large enough to allow for movement. Extend 400 mm (16") upslope beyond the pipe.
(9) Overlap area of lower panel
Penetration flashing is mounted here, set in an acceptable sealant.
(10) Spaced Cleat
Discontinuous cleats (to permit drainage), set in accepted caulking, spaced 50 mm (2") and fastened with compatible non-corrosive flat head screws.
(11) Sealant
(12) Architectural metal roof panel (upper)
Installed after penetration flashing. Cut hole for pipe penetration and turn lower panel end under to hook onto cleat.
(13) Protrusion Flashing
Flange set in two continuous beads of accepted caulking.
(14) Sealant
Applied around base of penetration flashing.
(15) Settlement Cap
Material must match flashing material.


(A) Acceptable Deck

NOTE: See the Standard for additional requirements.

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