Want to get an idea of how your attic insulation compares to your neighbors? Step outside a few days after a snowstorm and check out your roof. Does it seem to have about the same snowpack on it as your neighbors (facing the same direction)? If your roof has less than your neighbors, it may be time to insulate! Either way, pop your head up into your attic and see what type and how much insulation you have. There should be a certificate left by the installer stating how much insulation was installed and its R-Value. Stick a ruler in the itch and note the "settled" depth of your insulation. If it is less than a foot you should consider adding more.
About a year and a half ago I bought a hundred year old home in Salt Lake. It is double wall brick construction (no wall insulation), about 900 sf on the main floor and has 14 windows on the ground level. I love the light! It was one of the main attractions for me.
Most of the windows are insulated glass except for three big windows in the living room, they are fixed glass with storm windows. I will eventually swap these out for modern, clad wood windows (Pella!) when I can budget for them so one of the first things I did after buying the house was add attic insulation.
I know I'm losing a lot of energy through these old walls but the fix requires providing insulation space either on the inside or outside of the walls. Pricey and involved either way.
It had about 10" of cellulose insulation, about R30 , pretty common in the valley but not near enough. So I went to homedepot.com and checked for cellulose insulation. They have a handy calculator to help you figure out how much you need based on the square footage of your attic and the depth of insulation you want. I ordered enough bags to bring my attic insulation to R-60, the maximum value available with cellulose insulation.
I rented a blower and got a buddy to give me a hand. I recommend that you insulate in the Spring or Fall because your attic can get bloody hot in the summer and very cold in the winter. Before insulating, fix any issues with your roof, swap cooler ducting, plumbing vents, etc. I knew I was going to insulate so before I did I added the recessed lighting in my living room.
Now, swimming around in insulation is dusty work so I wore a Tyvek suit, googles and a good dust mask. Cellulose is not as itchy as fiberglass but you want to wear good protection. I also cut 12" by 8' strips of OSB sheathing to give me something to walk on as I worked. And yes, just like in the cartoons it is possible to step through your ceiling so be careful of where you place your feet!
My attic access is outside through a door in the gable end and that made it easier than dragging the hose through your house. The plan was to start at the furthest point from the access and work my way out. I had marked the depth of the insulation on the attic framing to guide me. My starting point was over my bedroom, which was an addition added after the home was built. Fortunately the builder had left a gap in the sheathing so I was able to crawl through it into the space. The framing only gave me about two feet of headroom so I laid there on my belly and waited for Stephen to start feeding the hopper with bags of insulation.
Both of us being contractors, we did not watch the instruction video first as suggested by the rental guy and this turned out to be a mistake. I laid there for about 20 minutes waiting for the insulation to flow, it would spit about a handful and then nothing. I finally left the hose there and crawled out to see what was going on. Stephen was frantically forcing wads of itch into the hopper with a stick trying to get things flowing. What they tell you in the video is to break up each bag of cellulose before adding it to the hopper. That makes quite a mess as the cellulose goes everywhere when you break it up. Next time around I would break it up in a clean garbage can and feed the hopper from there.
After a couple of hours the work was complete and I admired the sea of new cellulose in my attic. I'm not sure how much energy I saved because this was my first winter in the home but I now have a much higher insulation value up there! And I have snow on my roof longer than most other houses on my street.