Often I go into attics and see that people have put in extra insulation. They usually make two mistakes - they use the wrong kind of insulation and install it wrong, OR it is put in the wrong direction.
The purpose of insulation is to provide a thermal barrier. The amount of insulation gives it a resistance value, commonly called the R-value. The more R-value, the better the thermal resistance.
Heat seeks cold. Heat can go up or DOWN to seek this cold. So in an attic space, the insulation is there to keep the heat out of the house in the summer and inside the house in the winter. That is as simply put as possible.
Lesson over...
Often people add insulation to an attic, as I said. And often it can be done better.
The initial reaction to this picture is that the vapor retarder is backwards.
A vapor retarder can be plastic, foil or paper and is attached to insulation to use it in certain applications where moisture needs to be kept out of a space. The exterior walls of your house likely have the insulation you see here, with the paper facing the interior of the house.
To be effective, the vapor retarder should be on the "warm" side. While on a scale of 1-10, with 10 being real bad, this application here is probably a 7 or so. It might even retain some moisture underneath and contribute to molds on the ceiling drywall.
Effectively placed, this insulation should be upside down, with the paper TOUCHING THE DRYWALL. But here it is laid over the previous stuff that was there. Not the best way.
If you add insulation to your attic, it would be most effective if:
1. The desired number of extra inches is blown in over the existing insulation. For fiberglass, a good rule of thumb is an additional R-value of 3 for every inch or so of blown in. In new homes in VA they are putting in R-38 now (until recently the recommended value was R-30). The "super-insulated" houses have R-48 here!
A cellulose insulation, derived from chewed up newspaper and treated with boric acid so bugs won't eat it, is also a very effective "top coat" over what is there. It has a slightly higher R-value per inch, so less depth is needed.
2. If you add rolled, or batt, fiberglass, rolling it the opposite direction of the trusses, at a 90 degree angle, is best practice. This helps seal up any gaps or holes in the layer underneath. Everywhere must be covered.
3. Be certain not to place the insulation so close to the edge of the roof that it covers the soffit vents, if there are any. Ventilation is ESSENTIAL to this space above.
SO WHILE THIS EFFORT ABOVE IS A GOOD EFFORT, IT IS DEFINITELY A HOMEOWNER JOB!
My recommendation: BIG HINT -- measure the length and width of your space. Determine the number of inches of insulation you want. The hardware store can tell you how many bags or rolls of insulation you will need to pull that off. You can wait to buy it when it is on sale.
If you employ a company to add the insulation for you, when they are done, BE SURE they used the number of rolls or bags they have "estimated" you would need! The price of your job was based on that! Hint, hint, wink, wink...
P.s. Until the end of the year there is a tax credit for extra insulation added to your home. And it is something you can do yourself. Keep that in mind!
Jay Markanich Real Estate Inspections, LLC 
Based in Bristow, serving all of Northern Virginia.
Office (703) 330-6388 Cell (703) 585-7560
OOPS!!! Seems like I have seen that a few times...
Say it ain't so Michael! Yeah, for sure. This is one of the most common homeowner mistakes. We see it haphazardly done too, with new stuff here and there! Like that will help...
Jay, just curious what climate zone you are in there?
Hey Charlie - where you been boy? For gardening Zone 6. Is that what you mean? Our average annual low is 0 - 10 degrees. What'r you in? I ask you because for sure my son wouldn't know!
Maritime climate here Jay, I just wasn't sure whether your area was considered hot climate or cold climate. With those temperatures I would say you fall in cold climate :)
And, interestingly, just south of me, in Richmond, they are definitely a Zone 7. Here we are right on the eastern edge of the Blue Ridge Mountains, and the garden centers all say to consider us Zone 6 because of the mountain influences.
What is the insulation R-value recommendation where you are?
R-38 roof and R-19 sidewalls minimum----required
Do you think people do this because they do not like the itchy feel from the other side so they make sure that the paper side faces them? Just wondering....
As I ask around, R-38 seems to be the national minimum standard now. I don't see too many 6" side walls here though. But that would be fine with me! The more the merrier...
I don't think so Kathryn. When you lay that stuff, it kicks up a lot of fibers and dust. I think they just don't know which way is up, so to speak!
Thanks Jay,
I've done it wrong at least once. If you have blown in insulation on the ceiling and you use the type of insulation shown in the picture tacked to the roof joyces that would be correct wouldn't it?
Bob
No Bob. You don't want to tack anything to the roof sheathing or in between the trusses.
Jay, do they use exterior foam to get up to the R-19?
On new construction I never see it. Sometimes when people replace siding it is used, but only on the jobs that replace it all at once. That 1/2" stuff is only an additional R-1 or 2 right? New construction is OSB with the plastic wrap, or the masonite board (which they call "structural" (! HA!) ) with the foil on the outside. The only places I see the 6" stud work is on tall balloon walls, like around the front door, which holds heavy windows and such. Next time I get a chance I will look to see if that cavity is entirely filled with insulation or if the still use the R-13 thickness.
Seems odd---even zone 5 requires R-19 typically----there might be ways around the requirement but I doubt that most people would want less windows etc.
The windows are often so poorly insulated on new construction that I wonder why they use the low E's!
That is a big point of contention on my pre-drywall inspections! Along with not stapling insulation...
Mr Jay,
You are getting a dose of Mr Charles being obstinatacated. You now see why I have to keep him in line.
Nutsy
I'm a big fan of using just about anything besides fiberglass batts in attics. I've never seen fiberglass batts properly installed in an attic; some installations are certainly better than others, but that stuff is almost impossible to install properly. There are always little gaps all over the place that add up to exponential heat loss.
The best attic insulation method I've seen is where they start with 1 1/2" of spray foam to completely seal up the lid, then add loose fill on top. This method should completely eliminate any attic bypasses.
Nutsy - in our Zone 6 things are as they are. Maybe in Zone 5 to our north things are as Charlie sees them where he is. South of us in Zone 7 I just don't know! But I might be obfusticatated...
Ruebs - thought you'd be stopping by! I have never seen the combo of a small layer of foam (I assume you mean open cell - I have never seen closed cell here in any context) and insulation. But I think the best insulations are blown cellulose because they don't draw heat from the house below 10 degrees F as does fiberglass. You're right, batts are hard to get really right...
Our requirements here in CT R-19 walls, R - 38 ceilings. Up until recently this was not a uniform code for the state. The coastal areas were R - 13 & R - 30 respectively.
Jay - Good tips and a reminder to DIYers that just adding insulation isn't enough. Adding it properly is the key to increasing R-value. But then, that's just another reason we need home inspectors.
Jim - it could be the walls are suggested R-19 here, but so far I have not seen it. The 38 in the attic is common now.
John - hence the post! I, and Jim above you, and Charlie above that, all see this DIY stuff, which is, as I said, OK, but not properly done and not as effective as it could be.
Jay, after spending a hot summer day helping my brother blow insulation in his house.....I would GLADLY pay a companly to blos insulation in my house!
Always learn something from the pros! The simple things that we sooo not think about!
Damon - I would too! Just make sure they blow in the amount they say they will blow in!
Chris - that's what AR is all about! And we try to be instructive around here...
We had this conversation....and there was a considerable difference in the prices we got...for the same thing....and some recommendations of a million...ok.....more inches than necessary....on our way to a warmer winter !
I was wondering when you would see this! I put this up partially for you, but I did not know how far along you were with things.
More is generally better, but you can reach the point where additional benefit is minimal - diminishing returns so to speak (business/econ term). If you went to R-42 or R-48 you would be fine and experience a dramatic difference in winter. The cost of doing that would not be so great, as I remember you saying you had R-30. To gain the new amount you need 10-12" of blown fiberglass or 8-10" blown cellulose.
Be sure not to cover any soffit vents, if you have them.
Good luck S&D! Don't forget your tax credit.
Jay - I'm actually referring to closed-cell foam. After 1 1/2", it qualifies as a vapor barrier. This method does get expensive though; I agree, straight cellulose would be the next best thing.
Closed cell is HIGHLY NOT recommended in our climate Reuben. It gets too hot here, and humid, for too long to make that an effective product. I thought maybe that is what you were referring to. People here see Mike Holmes use that all the time on TV, and ask about it. It works in Canada, and Minnesooooota. But not here.
Mr Jay,
I do not believe, do you, that you are being obstinatacated. I believe that only Mr Charles does that.
Nutsy
And, Nutsy, I can see that you know which side is up!
Had to reblog this one...so many times we see insulation not properly put in!! Thanks for the lesson.
It is often Jen, and that's usually because people are trying to upgrade it themselves without knowledge. And thanks for the reblog!
Jay, I am sure there are many homes with this issue. Thanks for educating us.
There really are Chris. And while some additional insulation may be better than none, it still is not an effective application and can do damage!
Good advice for home owners. Thanks for sharing!
Some advice and hopefully a lesson Roy.