2009 IECC help

[TimNY]

Trying to get up to date on the new energy code we'll be using here.

Does anybody have any recommended reference material? I looked at iccsafe and there are 4 different books on the 2009 IECC that look like they might be good.

I am trying to figure out a few things:

"an air barrier extends behind [electric] boxes or air sealed type boxes are used"-- in the case of boxes on the interior side of exterior walls, this would not apply, correct? I interpret this to mean boxes on the exterior side of exterior walls (ie for exterior receptacles or exterior wall fixtures) would need to be sealed.

"an air barrier is installed at any exposed edge of insulation"-- this is *edge*, right? ie in the case of insulation in a floor above an unconditioned basement, an air barrier would not be required on the underside of the insulation?

"an air barrier is required behind tubs and showers on exterior walls"-- ok, i get this.. but is an air barrier required between a room and the exterior wall anywhere else?

thanks in advance,

Tim

 

[Architect1281]

TimNY

Mass has been doing air barriers for a while and we stole them in 07 to stretch the commercial code

this site has some suggested datailing for commercial and is pretty darn useful.

http://www.mass.gov/?pageID=eopsterminal&L=4&L0=Home&L1=Consumer+Protection+%26+Business+Licensing&L2=License+Type+by+Business+Area&L3=Construction+Supervisor+License&sid=Eeops&b=terminalcontent&f=dps_inf_bbrs_sample_detail&csid=Eeops

rather than re-invent the wheel on residential I place my air barrier and vapor retarder right behing the drywall in the houses

with 6 mil taped poly and wrtap the electrical with

A- Ice and Water barrier - sticky and no air or moisture

or

B - Intumescent rated wrap like I spec in commercial rated penetrations

that and lots of sealant at mechanical and plumbinmg penetrations as well.

if you have an external box and the air barrier is inside thats not an air barrier penetration but I treat those similar as a

Water resistant barrirer penetration

 

[TimNY]

Well, I got the 2009 IECC WOrkbook today.. not good for much.. except starting the fireplace maybe. Guide to Performing Energy Inspections is backordered.. hopefully that will be better.

I don't have my books, but in my cranium I believe the air barrier is on the outside and the vapor barrier is on the inside (if required). Maybe I am missing something blatantly obvious, but I don't see where an air barrier is required on the inside, except behind the tub.

Perhaps it is common knowledge to those 'in the know', but from reading the code I don't see it.

EDIT: in rereading your post, I see you place the air barrier on the inside.. again no books now but I assume the code does not dictate where the air barrier is locate in the assembly? Must read more on Monday..

 

[Robert Ellenberg]

air barrier resources

Tim,

Google the Building Sciencce Corp. They have a lot of good instructive bullentins etc. available on their website you can search and are considered just about the best/most knowledgable in this stuff. Green Building Advisor website is another good one to search.

 

[TimNY]

ok, so it's been a week and this is still the most recent thread in the Residential Energy forum

Next question.. Table N1102.4.2 "Air-permeable insulation is inside of an air barrier."

I see some online documents depicting some type of air barrier on the outside of kneewalls (ie on the side of the kneewall facing the soffits) to fulfill this requirement.

My question is if insulation is required to be "inside" an air barrier, how can ceiling insulation be left exposed in a ventilated attic? Conincidentally, the same images that display the sheathing on the backside of the kneewall also shows the insulation between the ceiling and attic exposed to the open air in the space between the kneewall and the soffit.

Scratching head... Got 2 books on the 2009 IECC and neither one is much help.

 

[Francis Vineyard]

My question is if insulation is required to be "inside" an air barrier, how can ceiling insulation be left exposed in a ventilated attic? Conincidentally, the same images that display the sheathing on the backside of the kneewall also shows the insulation between the ceiling and attic exposed to the open air in the space between the kneewall and the soffit.

Scratching head... Got 2 books on the 2009 IECC and neither one is much help.

Tim,

The air barrier is place directly on the interior side of the building thermal envelope. This explains the requirement for behind the tub/shower, above drop ceilings, inside chases and at the rim boards along the exterior wall insulation. Penetrations of floors, walls and ceiling interior of the thermal envelope need not be sealed, only where the penetrating items are at the thermal barrier; for example through the top plate or bottom plate inside an interior wall. Draft stopping in these locations is to be air-impermeable.

I agree the articles and guidelines showing an air barrier on the exterior side of the insulation at knee walls is not clearly stated IMO, however “wind-wash baffles” between the joist below the knee walls, cantilevered floors and offset floors is the “air barrier is installed at any exposed edge of floor.”

Some other questions are;

Where are the wind wash baffles (air barrier) above the knee wall listed?

How is the garage not covered by the other items that required it to be mentioned?

 

[TimNY]

Yeah very confusing. I don't see anywhere that says an air barrier needs to be in any particular location, other than behind tubs and showers. The only reference I see to any location is in the Table where it states "insulation is inside an air barrier"

I have visited buildingscience.com and they talk of an interior or exterior air barrier, and the disadvantages/advantages of both. Which leads me to believe there is no prescriptive location.

Tyvek is an air barrier; if you seal the seams and caulk the penetrations, I don't see what would require any other barrier except in the case of kneewalls, since the Tyvek would not extend to that area.

I think the best scenario is exterior AND interior air barriers, but that's not a requirement.

 

[Francis Vineyard]

Building science articles are best practices and guidelines. Since not all weather resistive barriers are air barriers I deduct that IRC is prescribing an assembly that takes into consideration the thermal envelope may not have and not required to have an air barrier on the exterior side. The air barrier on the "inside of the permeable insulation" would be better stated the “interior” side.

A little more guidance would be welcomed.

 

[Francis Vineyard]

It appears if implementing the blower door test option the air barrier can be chosen to seal air leakage coming in or going out of the building thermal envelope. Spray foam insulation puts the air barrier location in the middle.

The other option is the visual inspection of items listed in Table 402.4.2

HVAC ducts outside the thermal envelope leakage test are mandatory in both instances.

"the discussion about interior and exterior air barriers resembles the debate over how many angels can dance on the head of a pin. Here, most energy experts lament that “American homes don’t yet have a single air barrier; two air barriers are a far-off dream.” Posted 7/16/2010

http://www.greenbuildingadvisor.com/blogs/dept/musings/one-air-barrier-or-two

"The IRC requires all sources of infiltration to be 'caulked, gasketed, weatherstripped, or otherwise sealed with an air barrier material, suitable film, or solid material.' The code does not include any exceptions. In other words, there is no such thing as a legal crack or air leak.

"Unfortunately, the requirements of Section N1102.4 are rarely enforced, and as a result, many new American homes — especially fiberglass-insulated homes — perform poorly."

So, that sums up the story for the 2006 IRC. The latest version of the code, the 2009 IRC, has upped the ante. It has retained the air sealing requirements found in the 2006 IRC, while adding additional requirements.

In Section N1102.4.2, the 2009 IRC gives builders two options: either have a third-party inspector verify completion of an air-barrier checklist (shown in Table N1102.4.2), or perform a blower-door test to confirm that the home's air leakage is less than 7 ach50 (a low bar, but better than no bar at all).

http://www.greenbuildingadvisor.com/blogs/dept/musings/questions-and-answers-about-air-barriers

 

[TimNY]

Thanks, Francis.

The topic seems about as clear as mud.

I just inspected a small addition. Prior to installing the insulation, every joint in the framing was caulked. They caulked the seams in the plywood sheathing, they caulked where the sheathing met the top/bottom plates.. heck they caulked between the jack and king studs and between the double top plates.

So, they are using the sheathing and framing as the air barrier. Acceptable or no? I think as long as I can see that all possible points of infiltration have been sealed, it complies.

I do have the benefit of knowing this is what they are doing for LEED in a neighboring jurisdiction and it is passing fine.

 

[NH09]

We have also been struggling with the 2009 IECC here in New Hampshire, which went into effect on 4/1/10. For new structures we have opted for the third party testing option; prior to the CO being issued we require documentation from the test agency stating the structure complies with the 2009 IECC (they perform the duct tightness test and blower door test), we no longer perform insulation inspections on new homes. I don't know how many other NH towns do this, but it seems to be working ok for us. In regards to additions, we visually inspect according to 09 IECC requirements but give some leeway on older homes.

402.4.2.1 Testing option.

Building envelope tightness and insulation installation shall be considered acceptable when tested air leakage is less than seven air changes per hour (ACH) when tested with a blower door at a pressure of 33.5 psf (50 Pa). Testing shall occur after rough in and after installation of penetrations of the building envelope, including penetrations for utilities, plumbing, electrical, ventilation and combustion appliances.

 

[ewenme]

One of the confusing aspects of the 2009 IECC is the change in definitions and use of familiar terms: vapor barrier has gone away, and in its place is air barrier. Also, you'll find air permeable insulation [which is fiberglass] which allows movement of air, however small, and thereby loss of heat. One term that is not in the IECC is "six sided insulation" but it is used in other standards and prgrams. The exterior walls of conditioned homes involves six sided insulation: between the studs and the base and top plates, and the sheathing/drywall there are six surfaces that can be attributed with preventing air passage. Those are the air barriers. The knee walls on bonus trusses need this same effectiveness but it has not been required in the past. Putting sheathing on the back of the knee-wall improves the performance of the bonus rooms, both for heating and cooling. HVAC contractors are finding diminished call-backs for poor performance when six-sided insulation is required. The other big deal in the 2009 IECC is sealing. The only warning I give to contractors and homeowners is that when we tighten the building envelope we inrease the necessity for controlled ventilation: fresh air! No one wants a house with stale air, but sometimes the owners disable the air intake fans because 'it's expensive.' The commercial requirement for bringing in tempered air speaks to that issue, and it may find its way into the residential requirements eventually.

 

[JMORRISON]

Here are a couple links. These are WA State Energy Code but there is useful info.

http://www.energy.wsu.edu/BuildingEfficiency/EnergyCode.aspx

http://www.energy.wsu.edu/Documents/BFG%20Chapter%205-Jan2011.pdf

 

[TimNY]

Thanks for the links and info.

I continue to re-read Chapter 11 and I still can't make sense of a lot of it. I think it is still very much a work-in-progress. I just hope the same folks who did the safety glazing section don't get a hold of it!