Swingman wrote:


Basically, unvented roofs with clay or concrete tile shingles and R-19
insulation or greater; and vented roof systems, with mechanical
equipment and ductwork within the conditioned space, and R-19 or greater
ceiling insulation, perform the best in the Southwest.

If the AC ductwork and air handlers must be located in the attic spaces,
then go with a design that incorporates an unvented roof, creating a
conditioned attic space for the mechanical equipment.

I find that very interesting.
My attic currently has no venting whatsoever. It had a power vent which
did not work.
Good thing, as there were no other vents in the attic at all, so I guess
it would have pulled air from the house.

Here's the situation:

1500 sq ft home in North Texas DFW
Hot, with high humidity
Attic space is less than half the floor space, due to vaulted ceilings
HVAC ducts are the accordion-style hoses in the attic.
Insulation is older loose rock wool.
Roof is painted metal over asphalt shingles.
Almost all the attic space is shaded by overhanging tree branches.
Soffit space with attic exposure is approximately 10 feet.

Is it OK to leave this unvented?

If I do vent it, I'll probably use a power vent and add a gable vent at
the other end of the attic. I may also make it an operable vent, and
add a 2nd operable vent into the living space to use it as a whole-house
fan. Any reason that won't work? I realize I would need a
tight-sealing grille into the living space.

Suggestions welcome.