Terry F. Brewer & Associates

619 Mercury Ave., Suite 108

Duncanville, Texas 75137

(972) 298-3525  Fax (972) 298-3521    


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IECC FAQ       



  IECC Frequently Asked Questions                                  

bulletR=8 or R=6 Attic Duct work is the question? Who is right after Jan. 22, 2006? Answer Link

bullet Texas Senate Bill 5 & A&M Energy Systems Laboratory Link

bullet New framing details needed for Energy Efficient designs Link


No not use 2x6 cathedral framing. Both the IRC and the IECC will permit limited construction of roof/ceiling assemblies (cathedral) with R-22 batt (R-19 with REScheck trade off) insulation. The batt insulation must be separated from the roof decking with a 1-inch air gap for ventilation.  Link to more information.

bullet Alterations or change in Occupancy what do I do? Help!!!! Link   Refer to pages 6,7 and 8

bulletWe can perform HVA/C design per Manual-J and ASHRAE 90.1

bullet"Just over-size the HVAC system!   BAD IDEA!

With the new IECC code, air infiltration is being reduced, requiring less need for HVAC over-design. Over-sizing can increase utility costs by 15% and will also increase the amount of humidity,  moisture and mold problems. Humidity will cause a cold, clammy feeling in the summer. Short cycling of AC will increase the room to room temperature variation by 5 degrees.

We can provide computer Manual J designs, providing room by room CFM flow and unit sizing so contractors can get "apples to apples" bids. Link Manual J design fees

bulletSuspended Ceilings and the Energy Code From "Setting the Standard" (2)

Does Insulation Draped Above the Suspended Ceiling Satisfy Energy Code Requirements?

Suspended ceiling

No. Insulation installed in a suspended ceiling does not meet the infiltration requirements of the International Energy Conservation Code (IECC). When the insulation is on the suspended ceiling, the ceiling is defined as part of the building envelope. This requires that it be air-sealed like any other envelope component:

IECC, Section 802.3.2 Sealing the Building Envelope: Openings and penetrations in the building envelope shall be sealed with caulking materials or closed with gasketing systems compatible with the construction materials and location. Joints and seams shall be sealed in the same manner or taped or covered with a moisture vapor-permeable wrapping material. Sealing materials spanning joints between construction materials shall allow for expansion and contraction of the construction material.

ASHRAE 90.1-1999 also prohibits the insulated suspended ceiling from being part of the building thermal envelope for compliance (Section

What can be done to meet code?

Insulate and seal the exterior roof and show compliance with the roof assembly as part of the building envelope component. The drop-down ceiling can remain as an interior ceiling, but no credit will be given for batt insulation draped above the suspended ceiling.

How can I show compliance for an office space within a warehouse?

If the warehouse is heated only to prevent freezing or is considered an unconditioned space, the office should be treated as a "building within a building." This means the ceiling of the office space would be part of the "building within a building" envelope and should be insulated and sealed as described above. Interior walls (walls separating the office from the warehouse only) and exterior walls of the office space also will require insulation and sealing.

(2)"Setting the Standard" is published by the Building Energy Codes Program of the U.S. Department of Energy Office. Link to this article.

ACCA Manual J Software: