What is a Fly Roof? How To Build a Flying Roof

Part of: "Best Ways To Cool Your Home."

A fly roof (or flying roof) functions as a parasol by blocking sun or other weather without trapping heated air in or against the main structure.

Another function is to vent the interior of the structure, such as a fly roof over industrial "smoke stacks" or the more familiar chimney cap (rain cap) on residential homes. A fly roof is like a chimney cap over the entire house.

The fly roof can use heat convection, solar chimney effects, stack effects, venturi effects, and evaporative cooling (e.g. swamp cooler, a.k.a. desert cooler) as part of an air-conditioning system.

You can get a partial effect by installing radiant barriers under the roof, insulating below the attic floor, and installing attic vents. Imagine if the entire attic walls were vents or screens.

A "double roof" essentially uses a fly roof, sometimes to create ducting between parallel roofs.

A Fly roof can be permanent or temporary (seasonal), rigid or flexible, parallel to an underlying roof or not parallel. You can make the fly roof a “carport” over the house, a tarp suspended over the main structure, or a retractable "window shade."

Here are some fly roofs and a retractable roof:

Ancient Egyptian fly-roof air-conditioner in 2600 BC Egypt (Cheops 1 ship used a wet canvas over the wooden frame to create solar-heat-powered evaporative cooling):

Huge suspension-cable flying roof in Lisbon, Portugal:

Carport-style self-supporting fly roof near Newcastle, Australia:

Large chimney cap in Massachusetts, USA:

Stainless steel chimney cap:

Copper chimney cap:

Masonry chimney cap:

Flying roof framing:

Retractable wheeled roof for an observatory: