Helpful? 0

I have a gable roof with a gable vent in front, but there is now a cathedral addition

In south Mississippi, I have a gable roof with a gable vent in front, but there is now a cathedral addition in the rear, so there is no longer a rear gable vent. No ridge vent, no soffitt vents. It is an unconditioned attic with HVAC ductwork. The air handler is in a closet below the ceiling. The fresh air intake is located in the ceiling of the front porch which is a cantilever.

I have two registers going from the original rear gable wall into the new addition which is split into two equal rooms, each 14'x16'.

How do I create a satisfactory envelope?

Do I do a floor, wall, ceiling in the original structure, and leave the HVAC ducts unconditioned, or can I use open cell, or 1" polyiso sheets on the undersides of the rafters for a roof envelope?

Asked by roger steinbrink
Posted Thu, 06/19/2014 - 08:56
Edited Thu, 06/19/2014 - 09:37

Tags:

1 Answer

Select your preferred way to display the comments and click "Save settings" to activate your changes.
1.
Helpful? 0

Roger,
If you have attic ductwork, the best approach is to move the insulation to the sloped roof assembly, so that you convert your vented unconditioned attic to an unvented conditioned attic.

This article should answer your questions: Creating a Conditioned Attic.

For more information on why it is important to address this issue, you might want to read Keeping Ducts Indoors.

Answered by Martin Holladay, GBA Advisor
Posted Thu, 06/19/2014 - 09:40
Edited Thu, 06/19/2014 - 09:42.

Other Questions in General questions

Calculating how much air needed to even out temps for minisplit

In Mechanicals | Asked by Tom Frisch | Oct 23, 14

How do deviations in average winter temperature affect energy consumption?

In Energy efficiency and durability | Asked by norm farwell | Oct 24, 14

Flat roof insulation

In Energy efficiency and durability | Asked by Angela M | Nov 22, 13

Roof insulation

In GBA Pro help | Asked by Steven Clark | Oct 24, 14
Register for a free account and join the conversation


Get a free account and join the conversation!
Become a GBA PRO!