What is a "doghouse" on a roof, and how do I flash duct penetrating the side of it?

A Doghouse is a vertical sheet metal enclosure built on a roof to house large horizontal duct transitions entering the side of a mechanical penthouse or building wall.

['A Doghouse is a vertical sheet metal enclosure built on a roof to house large horizontal duct transitions entering the side of a mechanical penthouse or building wall.', 'To flash it, install an overhanging counter-flashing hood (shingle-style) above the duct penetration point. Run the lower sheet metal edges out over the roofing membrane so water sheds away from the opening like an umbrella canopy.']

Stop if

• Use this as training guidance. The foreman, approved drawings, project specs, manufacturer installation instructions, employer safety policy, and AHJ/code requirements always control the final answer.

Steps

• A Doghouse is a vertical sheet metal enclosure built on a roof to house large horizontal duct transitions entering the side of a mechanical penthouse or building wall.
• To flash it, install an overhanging counter-flashing hood (shingle-style) above the duct penetration point. Run the lower sheet metal edges out over the roofing membrane so water sheds...

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