Fiberglass Batt vs. Blown-in Insulation?

[Gary Fowler]

I think if you were not too worried about insulation from cold creeping in and is mainly for noise abatement, I would go with the cheapest material to install. When I had my new house built, I went with bats between the rafters then 14" of blown in FG so I have all the areas sealed and have at least R21 insulation plus the reflective board on the roof. We dont have to worry about -40 temps as it rarely gets below +20 but the summer time heat reaches over 100F so I mainly insulate for keeping out the heat. All my interior rooms are insulated in the walls for sound using FG bat. It works really well, I cant even hear the wife yelling at me from another room. I dont know how well it will work for ceiling / floor like you have with walking noise as most of the sound I would think would travel thru the joist and sheetrock and then transmit on down. Insulation will stop some of the voice noise I would think.

 

[Iplayfarmer]

... I cant even hear the wife yelling at me from another room.

Thank you for giving me even more motivation to insulate. Maybe I'll consider insulating any walls interior walls, too.

 

[PA hayseed]

My house is quite old and I moved it a couple of years ago. I redid all the elctrical, plumbing, added central air etc. I put bats up. I don't notice a bit of difference in the sound levels. On the side where I added the addition, put up bats and drywalled over that, I don't notice much in the way of noise from there. Part of me thinks that the HVAC (forced air furnace) is carrying sound to the second floor from the basement. I added insualtion to all of the metal ductwork (I forget the term for them but I think they are either takeoffs or boots), and my main trunk and lines are insulated. I can still hear things on the second floor from the basement, but it isn't very loud.

I thought I would throw that out there for your consideration. Since I added the insulation to the old side floors, the upstairs floors are now a little colder, but the basement is warmer. I have a pellet stove that I use to heat the basement, it is only supposed to heat about 1000 sq ft, but it keeps about all 2000 sq ft warm enough to exercise in with the insulation in place. I also use it for other stuff and it is good enough.

One thing that people often overlook with fiberglass bats is that it CAN be compressed. If you take R-18 and compress it into a space meant for r-13, you actually wind up with an R-15 rating. Don't take my word for it, go online and research that tidbit yourself. I will tell you that it is hard to find that information, because everyone believes that you should never compress fiberglass. Additionally, I like bats for tight fits. Rip the strips up and tuck away. Some blow in stuff sticks and builds out without filling the cavity completely (with pipes or other lines in the way). All in all, if I were doing it all over again, I would go with sprayfoam. I used blow in in my attic, and there are issues there too, but overall it is decent.

I'm done here, too much information/rambling.

 

[pat32rf]

If your old house is like mine, you will be farther ahead to spend the time sealing around the outside rim joists while you have access. Either have it sprayed (there are DIY kits) or caulk the seams, then stuff fiberglass and seal it with 6mil poly vapour seal, using tape and sealant.
Four inch batts of roxul between the 8" floor joists will cut the sound and give a fire barrier but an extra layer of drywall on metal strapping on the ceiling will probably accomplish the same thing.
We spent the past couple years working (and researching) on our project. Now we heat 1600sq ft (plus basement)for $75/month during the heating season (geothermal). The best result is the fact that our house is now comfortable with a thermostat setting of 60deg. Google has lots of info on the proper way to make a big difference in making your house efficient but you MUST look after humidity control as part of the big picture. In our case we had drafts in the winter AND a cold clammy basement in the summer, with condensation on the concrete floor.

 

[charlz]

What has me confused right now is that I can get the blow-in stuff installed cheaper than I can buy the batt to do it myself. That has me wondering what the trade-offs are to the cheaper blown in insulation.

I just had my floors insulated and ran into the same thing, getting it installed was cheaper than I could buy the materials Only thing I could think of was they buy it in bulk and maybe straight from the manufacture so get a big price break.

BTW There is a tax credit if you get it done by the end of the year:

Federal Tax Credits for Energy Efficiency : ENERGY STAR

 

[Iplayfarmer]

...BTW There is a tax credit if you get it done by the end of the year:

Federal Tax Credits for Energy Efficiency : ENERGY STAR

I know, but that's just not going to happen. I thought about trying to get it done in time for the tax credit, but I just don't have time to do it right. I still have to re-do some of the upstairs electrical, I have ventilation ducts to install, and I have some plumbing to finish up. Add to that the fact that I'm doing it in my free time between work, volunteering with the fire Department, and serving as the planning and zoning commission chairman. Plus, Christmas time is always busy.

I do think I can get some assistance through my power company, though. That's another advantage to having the guy come and install his stuff... He knows all of the credits and incentives that are out there.

 

[charlz]

I do think I can get some assistance through my power company, though. That's another advantage to having the guy come and install his stuff... He knows all of the credits and incentives that are out there.

Yes, they do consider it to be 'placed in service' not when you purchased it.

The power company rebate is just for attic insulation:

Idaho Power - Energy Efficiency - Residential - Programs - Home Improvement Program