Duct Insulation

[Frank T]

Under the 2009 codes in PA

I have a home built on full foundation (ICF foundation) with duct runs in basement area. The duct insulation is a R 4.3 and there is no heat in basement area. The floor system is not insulated either.

Can I still use the R4.3 or do I need to bump up to R6 since the basement is not heated.

 

[jar546]

What is the insulation value of the ICF foundation? How much of it is basement? Are there any areas where the foundation is <50% below grade such as a walk out basement?

If the basement becomes part of the thermal envelope then no insulated duct is required at all. It is only if the basement is completely outside of the thermal envelope that it needs to be R6

it has nothing to do with whether or not the basement is heated, nothing at all. It's either part of the thermal envelope or it is not. If it is not, you can't heat it anyway, not even cut in a supply register at all.

 

[Frank T]

R-value of walls is suppose to be R-22.

The way I am reading the following is that the basement is not conditioned space so the envelope would need to start at floor system of home or the basement area would need to be conditioned.

NII03.2 Ducts.

NII03.2.1 Insulation. Supply ducts in attics shall be insulated

to a minimum ofR-8. All other ducts shall be insulated

to a minimum of R-6.

Exception: Ducts or portions thereof located completely

inside the building thermal envelope.

BUILDING THERMAL ENVELOPE. The basement walls,

exterior walls, floor, roof and any other building element that

enclose conditioned spaces.

CONDITIONED SPACE. For energy purposes, space within

a building that is provided with heating and/or cooling equipment or

systems capable of maintaining, through design or heat

loss/gain, 50°F (IO°C) during the heating season and 85°F

(29°C) during the cooling season, or communicates directly

with a conditioned space. For mechanical purposes, an area,

room or space being heated or cooled by any equipment or

appliance.

CONDITIONED AREA. That area within a building provided

with heating and/or cooling systems or appliances capable

of maintaining, through design or heat loss/gain, 68°F

(20°C) during the heating season and/or 80°F (27°C) during

the cooling season, or has a fixed opening directly adjacent to a

conditioned area.

 

[tmurray]

If there is no insulation within the floor system the basement would become part of the conditioned space. It will be heated by conduction from above.

 

[jar546]

If the basement walls are R22 then they meet the energy code anywhere in PA. My guess is that they will not insulate the floor either so it sounds like your basement is in the thermal envelope so you can use R-0 if you want.

 

[steveray]

BUILDING THERMAL ENVELOPE. The basement walls,

exterior walls, floor, roof and any other building element that

enclose conditioned spaces.

If it is not conditioned....it is not part of the thermal envelope.....R6

 

[mtlogcabin]

402.2.7 Basement walls.

Walls associated with conditioned basements shall be insulated from the top of the basement wall down to 10 feet (3048 mm) below grade or to the basement floor, whichever is less. Walls associated with unconditioned basements shall meet this requirement unless the floor overhead is insulated in accordance with Sections 402.1.1 and 402.2.6.

It is an ICF basement. I believe it meets the requirement of being within the building thermal envelope.

CONDITIONED AREA. That area within a building provided

with heating and/or cooling systems or appliances capable

of maintaining, through design or heat loss/gain, 68°F

(20°C) during the heating season and/or 80°F (27°C) during

the cooling season, or has a fixed opening directly adjacent to a

conditioned area.

Leave the door off leading to the basement

 

[steveray]

, or has a fixed opening directly adjacent to a

conditioned area.

Leave the door off leading to the basement

That might get you there....

 

[fatboy]

Looks like you are new to posting on the forum, a heart welcome to you Frank T!

 

[Frank T]

This is from 2009 IECC Commentary 402.1 General (Prescriptive).

A space is conditioned if it is heated or cooled directly; communicates directly with a conditioned space; or where a space is indirectly supplied with heating, cooling or both through uninsulated walls, floors or uninsulated ducts or HVAC piping.

So I guess that the R4.3 meets code requirement as the ICF is part of building thermal envelope.

Thanks for everyone replies!