Thread: Installing Bat Insulation

Hello Folks:

I am in California and re-taking the ICC CA Residential Exam. A question on the exam in the CBC 2007 has had me puzzled. The question was "When installing batt insulation the vapor barrier side should be on the____?"
a. warm side
b. warm in winter side
c. cold in summer side
d. Living space.

I have found many opinions. Warm side, warm in winter side and living space. What I cannot find is the answer in the 2007 CBC. My answer was living space. Any suggestions? Working knowledge in the field and what the code describes are many time two different things.

Thanks

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Originally Posted by John Traina Jr.

The question was "When installing batt insulation the vapor barrier side should be on the____?"
b. warm in winter side
d. Living space.

b. warm in winter side - is the correct answer, however, if you think about it, the living space is going to be the "warm in winter side", but that is just a red herring answer ... b. warm in winter side.

Thank you. You are right it is a red herring. ICC questions... arghhhh~~ Where is it in the 2007 CBC?

Originally Posted by John Traina Jr.

Thank you. You are right it is a red herring. ICC questions... arghhhh~~ Where is it in the 2007 CBC?

I don't have the CBC, but it is *always* going to be the "warm in winter side".

But that is a *BAD QUESTION* as there *is no* "vapor barrier", the facing is a "vapor retarder".

There has been research which suggests that many areas, those which do not have a 9 month long winter, might be better served *with no* "vapor barrier" as, during the summer months, the vapor retarder may best be located on the exterior side, then, during the winter, the vapor retarder may best be located on the interior side - but ... as codes go, "warm in winter" side.

john,
the california energy code requires the vapor barrier be placed on the"conditioned side" (section 150 (g)) in climate zones 14 & 16 which takes in a large portion of the state.

Well that really sucks! You can't give the correct answer if it's not listed!

b, c, d are all the same. You have a 75% chance of getting it right!

Originally Posted by brian schmitt

john,
the california energy code requires the vapor barrier be placed on the"conditioned side" (section 150 (g)) in climate zones 14 & 16 which takes in a large portion of the state.

Brian,

What does the CBC say about it under insulation?

jerry,
the cbc does not say anything in regards to how to install insulation for energy efficiency. chapter 7 only mentions installation in regards to installation for fire related issues. it must be similar to your ibc chapter 7?

Brian,

I was thinking more like this from the 2006 IBC. (underlining is mine)

SECTION 1203
VENTILATION

1203.1 General.

Buildings shall be provided with natural ventilation
in accordance with Section 1203.4, or mechanical ventilation
in accordance with the International Mechanical Code.

1203.2 Attic spaces.

Enclosed attics and enclosed rafter spaces
formed where ceilings are applied directly to the underside of
roof framing members shall have cross ventilation for each
separate space by ventilating openings protected against the
entrance of rain and snow. Blocking and bridging shall be
arranged so as not to interfere with the movement of air. A minimum
of 1 inch (25 mm) of airspace shall be provided between
the insulation and the roof sheathing. The net free ventilating
area shall not be less than 1/150 of the area of the space ventilated,
with 50 percent of the required ventilating area provided
by ventilators located in the upper portion of the space to be
ventilated at least 3 feet (914 mm) above eave or cornice vents
with the balance of the required ventilation provided by eave or
cornice vents.

Exception:

The minimum required net free ventilating area
shall be 1/300 of the area of the space ventilated, provided a
vapor retarder having a transmission rate not exceeding 1
perm in accordance with ASTM E 96 is installed on the
warm side of the attic insulation and provided 50 percent of
the required ventilating area provided by ventilators located
in the upper portion of the space to be ventilated at least 3
feet (914 mm) above eave or cornice vents, with the balance
of the required ventilation provided by eave or cornice

vents.

I don't happen to have 2006 or 2009 IRC with me, but the 2000 IRC says:

R322.1 Moisture control.
In all framed walls, floors and roof/ceilings comprising elements of the building thermal envelope, a vapor retarder shall be installed on the warm–in–winter side of the insulation.

It looks liek that's the answer they were looking for.

Originally Posted by Steve Frederickson

I don't happen to have 2006 or 2009 IRC with me, but the 2000 IRC says:

R322.1 Moisture control.
In all framed walls, floors and roof/ceilings comprising elements of the building thermal envelope, a vapor retarder shall be installed on the warm–in–winter side of the insulation.

It looks liek that's the answer they were looking for.

In the 2006 IRC that section is:

R318.1 Moisture control.

In all framed walls, floors and roof/ceilings comprising elements of the building thermal envelope, a vapor retarder shall be installed on the warm in-winter side of the insulation.

However, the CBC, which is what was being tested on, does not have (as I understand it) a Residential Code yet, thus the information would have to come from the Building Code.

Which makes it a doubly bad question.

jerry,
that exception was introduced in the 2001 cbc in chapter 15 for attic ventilation. it applies to decreasing the required vented area by providing the vapor retarder but does not directly address insulation installment requirements for energy code compliance. i have allowed the exception for decreased ventilation area often. blown in insulation = no vapor retarder and no area decrease for ventilation. the answer to the op question would be the warm in winter side as you stated. i find it odd that icc has a calif residental cert when we have not adopted the irc. anything for a buck! it was a trick question with several correct answers. i'd challenge it.

Originally Posted by brian schmitt

i'd challenge it.

You can challenge it, just not easily done.

In the old days, you could write down on a piece of paper the questions you felt were incorrect or bad questions, then hand that in to the proctor when the test was over. When SBCCI reviewed those questioned questions, if the question was deemed to be a 'bad question', then everyone who took tests with that question on the test was given credit for having answered it correctly.

Now, you take the test on the computer at the test center, and you have a piece of paper to write problems on, do math on, etc., and, when done, all they do it take that piece of paper and, without looking at it, it goes into the trash to be shredded. I know, because I wasted some time noting some bad questions on the paper only to have them not even look at it and put it in the trash. When I asked about having noted bad questions on it and don't they at least send those to the ICC, they said 'Nope, it goes in the there and gets shredded. We don't even look at it.'

That makes it harder to challenge bad questions unless you fail and want to challenge your test score, but they do not make that easy to do either.

The testing process and challenge process used to be more user friendly for the test takers.

Gentlemen:

Thank you for all of your input. One thing to remember is that I was taking the 2007 California CBC Residential Building Inspector Exam. This exam has a (as of today) a 30 to 40 percent pass rate in So Cal (OC) area. The pain of it is, due to the newness of the exam, none of the schools in the area have a handle on the questions or due to the poor pass rate have decided not to teach the course (California Commerical and Residential Bld Inspector.)

I took the test again and failed. Again I received a 73 with 75 passing. All the questions on the exam changed except for three. It is my opinion that jumping between two volumes of books three inches thick, and ACI 318, I guess my memory will need to improve and I will have to memorize the books to pass. I know these books, however the format and way the questions are asked on the exam seem to get by me. The same question was on the exam regarding batt insulation so I know I got it right. However, I cannot find the answer in the 2007 CBC.

I called ICC Candidate line. Challenging is not an option if you know what it entails. This is hard to explain so I will try to explain step by step. It costs $50 to challenge. A challenge only occurs when you know you the question and/or the available answers A-D is wrong. If you answer the question, by guessing lets says and answer it correctly, then there is no challenge because you got the question correct. ICC will thank you for your time and send the question to thier engineers for review. You will not receive an answer back and you will not know what happened even if you call back and ask. If the question AND the answers available (A-D) are wrong, then they will re-evaluate your test and get back to you in about a month to give you your new curve test result. If it is 75 or better you pass. However, it is my opinion, if you are borderline, this is unlikely. It is my understanding ICC bases the test on a curve. How this is done is a mystery. Is the bad question thrown out? Is the curve based on 49 questions instead of 50? Is he question marked as correct and based on 50? It has been my experience so far it will be in ICC's favor.

For the California CBC Residential exam, you can only take CBC Vol 1 & 2, ACI 318 and a calculator into the test area. No paper or pens. They give you an erasable board and pen.

Originally Posted by John Traina Jr.

It is my understanding ICC bases the test on a curve.

Nope, no curve.

There are 50 questions, each worth 2 points ... sort of ... but basically yes, each worth 2 points.

You ask, then, how does one get a 73 when each question is worth 2 points, and the answer lines within that " ... sort of ... "

I have been told that some questions are considered more difficult than others are are worth 3 points, making an equal number of other questions worth 1 point. That is how one can get a 73 or a 75.

It used to be that each question was worth 2 points and you could not get that magical "75" to pass, you either got a "74" and did not pass, or you got a "76" and, being equal to or greater than "75", you passed - except that you never knew you got a "76" or a "98" - you got a "passed" score without getting your actual score.

Getting an odd number score is the give-a-way for that type of scoring.

Thus, the grading is not done on a curve, but the question value is done on a curve.

How many 1 pointers, 2 points (the vast majority), and 3 pointers there are probably varies with the test as each test is different.

For the California CBC Residential exam, you can only take CBC Vol 1 & 2, ACI 318 and a calculator into the test area. No paper or pens. They give you an erasable board and pen.

The key is not memorizing more, as the questions with exceptions would throw you off and you would miss them, but rather learning "where" in the books the information was. That is secret - tabs. Too many and you are wasting time going through them, not enough and you are wasting time trying to find what you want.

If you know where the answer should be, look there, otherwise start either with the Table of Contents or the Index. If your books are loose leaf, copy the Index and the Table of Contents, then add the second Index up at the front by the Table of Contents, and add the second ToC to the back by the Index. If you feel like make an extra copy of each, put them in the center with a tab at each. No need to waste time going to the front for the ToC, then to the back for the Index when you group them together, and one in the middle helps keep flipping to the front and the back to get to them.

How to tab? Tab some on the sides as usual, tab the tables or other information of your choice along the top. If you are adventuresome, tab some along the bottom, but be forewarned that those tabs will get damaged when the code book is set upright on its bottom. Also keep in mind that if you are going to tab the top and bottom, that when the book is laying down in front of you ... you can read the tabs on the bottom easier (as long as they are not damaged) than you can read the tabs on the top.

By splitting the tabs up in an orderly fashion you save looking through a bunch of non-applicable tabs to find the tab you want, it also reduces the number of tabs on the side and makes it easier to find and read the ones you do have there.

Are you taking the test on the computer at a testing center like Pearson Vue (formerly Promissor)?

My books are well tabbed and to tables and important stuff. I have my index tabbed as well.

Pearson Vue Ontario Ca.

I start plumbing tommorrow and still have to take the commerical bldg which at this point I am not fortified in confidence after taking the residential.

Originally Posted by John Traina Jr.

still have to take the commerical bldg which at this point I am not fortified in confidence after taking the residential.

I would schedule your residential retest for the morning and the commercial for the afternoon of the same day.

Why? Because you will likely find a lot of cross over between the two tests and you will be well versed in flipping through the books from the morning test to cruise through the afternoon test.

Just a suggestion.

Yes, I know that would be one killer day, but it may actually work to your advantage.

I cant take the residential test now for six months since I have failed it twice.

Thank you for your input.

I heard that batt. insulation installed on beach homes, (i'm talking 3 blocks from the ocean) will usually have insulation installed upside down under the house if the house is on stilts, to prevent stringing caused by the high moisture in the air. The paper backing would prevent the air from getting to the insulation.

My first question is, is this something you guys have seen, and second, if a sheathing has been installed over the insulation to prevent exposure, should the insulation have been reversed before the sheathing was installed?

The house was built in 1968.

Thanks,

Wes

Here is a picture of the area under the house where the insulation is installed, and a picture of the sheathing that is covering it.

Originally Posted by wes owens

I heard that batt. insulation installed on beach homes, (i'm talking 3 blocks from the ocean) will usually have insulation installed upside down under the house if the house is on stilts, to prevent stringing caused by the high moisture in the air. The paper backing would prevent the air from getting to the insulation.

That is the wrong way to install faced insulation and that should be rejected.

All that is going to happen is the moisture coming down from the house is going to collect on the facing as water ... as shown in your photo.

My first question is, is this something you guys have seen, and second, if a sheathing has been installed over the insulation to prevent exposure, should the insulation have been reversed before the sheathing was installed?

Install the insulation the proper way, facing toward the warm-in-winter side, then place netting under the insulation to keep the insulation up tight (without crushing the insulation) and to keep wind from getting to the insulation and damaging the insulation.

I would not put sheathing over it as that will serve as a second vapor retarder to a certain amount and collect condensed moisture on top of it ... as shown in your photo.

Hi Guys,

I was also confused today when I read the "Now that you've had a HOME inspection..." second edition - author (and I know this will start another line of replies) Ben Gromicko. Yes, that Ben. (the book was offered for free, so I'm checking it out - probably won't "buy" any more)

Page 41, Thermal Insulation.
....."If you live in a cold climate, the vapor barriers should be installed on the warm interior side of the wall. If you live in a warm climate, the vapor barrier should be installed on the exterior side of the wall."

That's when I found this thread. This is the first time I've read that the barrier should be on the exterior side.

Has anyone seen it installed this way? Would you write it up as incorrect?

Thanks.

Originally Posted by Dave Hill

Has anyone seen it installed this way? Would you write it up as incorrect?

Seen it and written it up.

I think they may have learned that the same place he did.

Actually, in many climates, NO vapor retarder is the 'best' was as there are times of the year when the vapor retarder is 'on the wrong side'.

However, when you get down to the purpose for the vapor retarder, you always want in on the living space side, which is best described as "warm in winter" as, in most uses, the moisture is produced by the occupants themselves and their living activities, and you want the moisture to be able to leave through the building, but not fast enough to collect within the building's structure.

If you live in a rainy area all year 'round, maybe you would need the vapor retarder on the exterior side, but, few, if any, places in the USA are rainy all year 'round, which means there are other times, plenty of other times, where you want the vapor retarder on the inside, or no vapor retarder at all.

How many places in the USA does it rain ALL YEAR ... 24/7/365? If you are in one, put the vapor barrier outside and exhaust the interior generated moisture to the outside.

BSI-015: Top Ten Dumb Things To Do In the South —
Here is a link to a Building Science article. Do your own research there for a better understanding of why vapor barriers are placed where they are and the difference in the perm rating. Vapor barriers on the inside of walls in warm humid climates is a dumb idea according to Dr. Joe L. There is a difference between vapor barriers and vapor retarders.

Originally Posted by Jim Luttrall

BSI-015: Top Ten Dumb Things To Do In the South —
Here is a link to a Building Science article. Do your own research there for a better understanding of why vapor barriers are placed where they are and the difference in the perm rating. Vapor barriers on the inside of walls in warm humid climates is a dumb idea according to Dr. Joe L. There is a difference between vapor barriers and vapor retarders.

Jim,

You will notice Dr. Joe is talking about vinyl wallpaper, which is almost effectively a "barrier" versus a vapor retarder on the insulation.

And, when you read more (as I know you have) of Dr. Joe's stuff and attend some of his seminars (I am sure you have) you will hear him debate whether or not there should even be a vapor barrier installed at all, for the reasons I discussed (I got much of that information from Dr. Joe and his seminars).

But ... if you are going to meet code ... and ... if you are going to install a vapor retarder WITHIN the walls ... versus installing vinyl wallpaper INSIDE ... you will want the vapor retarder on the heated side (warm in winter side), which is what is specified in the code.

Now, putting vinyl wallpaper on the INSIDE in ANY LOCATION, much less in the South, that's just dumb and asking for trouble.

The last houses I built, I met the requirements of an interior vapor retarder (notice the requirement is retarder, not barrier) by using Kraft paper backed batts on the interior surface but used foam with foil coating facing the brick veneer. Kept the interior of the wall dry summer and winter but in the very humid and hot north Texas summers, the walls could dry to the indoors. We did have cold winters, but were in a predominantly warm area with A/C running more than heat. A summer shower wetting the exterior brick walls can drive a significant amount of water into the walls, not as much as a hurricane, but a much more frequent occurrence.
I would highly recommend to everyone to get hold of any of the Building Science Corporation material. There is lots of free info on their web site but any of the Builder's Guide books are worth the money. I got the Hot-Dry & Mixed-Dry Climates edition for free at the last seminar of Dr. Joe Lstiburek that I attended. (See why I call him Dr. Joe?)
If anyone ever gets a chance to attend one of his talks in person, DO IT.

Originally Posted by Jim Luttrall

Dr. Joe Lstiburek that I attended. (See why I call him Dr. Joe?)

That's why we all call him Dr. Joe.

If anyone ever gets a chance to attend one of his talks in person, DO IT.

No only is Dr. Joe's seminar VERY educational, but Dr. Joe is not a dry boring speaker, he is animated and fun too. Makes learning FUN.

Originally Posted by Jerry Peck

Install the insulation the proper way, facing toward the warm-in-winter side, then place netting under the insulation to keep the insulation up tight (without crushing the insulation) and to keep wind from getting to the insulation and damaging the insulation.

It's worth repeating that the insulation needs to be 'tight' against the sub floor material (in this instance).
Down here the majority of hardwood flooring issues have poor insulation installation (with clips that fail to hold it up 'tight' against the sub floor) as a causal factor.

But I know ya'll know that!

My answer would also be living side....

Originally Posted by John Pignatore

My answer would also be living side....

John,

And you would have missed that question.

You need to be careful of red herring answers which they throw in there, the reason they put those answers in there is to catch those who are not thinking and knowing, but guessing, and if you miss too many of those questions, you fail the test.