As winter is fast approaching and my 1948-built (new to me though) house is insufficiently insulated, the quickest and easiest way to remedy this appears to be adding some insulation to the attic. There’s already some old blown insulation up there (not much more than 6 inches though I’d guess), so I figured I could lay down some fiberglass batts and throw a bag of the new blown stuff around and be covered.
I’m wondering how much I really need though. At the store, the guy was recommending the R12 (45$ for ~130 sq. ft.), but after he said new houses have R40 I got a bag of R28 (50$, 60 sq. ft.) for the edges also (as well as the bag of loose-fill stuff). At work now, some co-workers are recommending I go with R28 all over.
I haven’t started yet, and I’ll have to go back for more regardless, so I guess my questions are: how much extra insulation should I be adding, where should it be going (right to the edges?), and if I use more in some places, should it be in the middle or the edges? (My house doesn’t have soffits, if that makes a difference).
An R value of 40 is good. More is generaly better. Don’t go crazy with it. Your ceiling could have a value of 1000 but that doesn’t do much good if your windows and walls are only good for 12.
Since you do not have soffit vents I asume you have gable vents. For your roof to maintain good health you want it’s tempiture to remain the same as the outside or as close as possible. So while your piling up insulation make sure the eves remain vented ie don’t shove insilation between the rafter beams leave that open for airflow.
Use the loose blown type to fill to the top of the rafters.
Then lay bats across the rafters to cover the entire space. The better the insulation the higher the cost.
You might want to check on the side wall and underfloor insulation while you are at it.
Get a couple of quotes. We found it was essentially the same cost to have a guy blow it in for us, than it would be for us to purchase the material at retail.
We had a man come in and blow in insulation from 4" to 10" (loose cellulose) to bring the (1973) house up to code. Mostly I am apalled that it took me 7 years in the house to realise how bad the insulation in the attic was.
Thanks for the replies - now I know why my roof vents are there too.
I’ll see about getting some quotes while I find a ladder to borrow, but given that this is Edmonton and if you can actually find someone to do anything for you, it’ll cost twice as much as 5 years ago, I think I’ll end up doing it myself.
Next GQ: How do I fix the hole in my ceiling where I fell through it?
If you are working with batts, don’t use the kind with a vapor barrier (paper or foil on one side) when you are adding to existing insulation. You’ll get condensation where you don’t want it.
In a 1948 attic, the blown in stuff may be asbestos, and that’s a whole 'nother category of hazard and precaution. In any case, dust will be thick, and even fiber glass or cellulose are things you don’t want to breathe. Get a serious filter mask, and be covered from toes to neck. No cheating, this is important.
One of my co-workers worked for a few years as an insulation blower. He said the number of bags you use may be twice as many, for the depth, depending on whether you blow it fluffy or solid. Ask about technique when you rent the blower.
Take some boards with you to kneel or stand on. If you fall through, that’s a drywall or plaster question, and I can’t help you with that.
If you’re going to do the blown insulation, the two cents’ worth from the viewpoint of the Wife who had to stand there being supportive while Hubby and his brother “did” the insulation on our house: Hire someone. Really.
It took probably three times as long as it would have taken someone who knew what they were doing, plus we wouldn’t have had insulation blobs and fuzzies floating around the house for months afterward, plus we wouldn’t have ended up with about six big bags of excess insulation that even as we speak, 15 years later, are quietly rotting out in the garage. I mean, whaddaya DO with that stuff?