Attic Insulation.............

[FinanceDude]

What's better for insulating:

1)Get the blown in stuff

2)Go buy some rolls of Owens Corning and lay them down yourself.......

Any advantages/disadvantages of either? Thanks................

 

[Brat]

The blown in stuff can be a pain if you need to do maintance work or if for some reason you want to replace it. Some of us sr members may remember that materials used in the blown in stuff turned out to be a problem and replacing it was a hassle. However, there may be areas in your attic where blown in is your only option. The blown in stuff rests on your ceiling.

You can easily pull back bats to work on wiring, check vents or whatever. Bats can be afixed to your roof joists or on the ceiling. If they are afixed to the roof joists you might be able to stilll use your attic.

Although bat insulation is more expensive I think it is worth it.

 

[BOBOT]

Also check this out, probably to augment the bat or blown-in. His site is good for all kinds of diy stuff.
http://www.dulley.com/docs/f411.htm

 

[Donzo]

Another problem with the blown in (cellulose) is that if you have a roof leak it will absorb water...alot of it and can cause a cave in - the bats will allow the water to mark the ceiling before you have a big heavy problem.
But the blown in is more efficient having no gaps

 

[FinanceDude]

Great info............I knew I could count on you guys.............

 

[OAG]

And do not forget the tax credit you can take on your taxes -- that along with the latest Home Depot or Lowes 10% credit or some other such sale on the stuff can lesson the cost about 25%. Also be sure not to push it too close to the roof at the eves -- need to leave some room for the air to move from outside up along the interior of the roof or you could get other problems.

 

[FinanceDude]

So, do I need to insulate the roof, or can I just use attic foil on the sloped parts, and put more on the floor in the attic?

Just wondering............and learning.............

 

[OAG]

No you do not need, nor do you want to, insulate the roof. Sorry if I was a bit misleading.... The insulation goes on the topside of the ceilings (flat part of the attic). What I was trying to get at was not to seal off the area at the eves as you need the air to circulate to preclude mositure from forming at the eves as that will cause problems with mildew and possibly ice forming (depending where you are at, temperture wise).

 

[FinanceDude]

No you do not need, nor do you want to, insulate the roof. Sorry if I was a bit misleading.... The insulation goes on the topside of the ceilings (flat part of the attic). What I was trying to get at was not to seal off the area at the eves as you need the air to circulate to preclude mositure from forming at the eves as that will cause problems with mildew and possibly ice forming (depending where you are at, temperture wise).

Thanks for all the help.........in the upper Midwest, so we have winter..........

 

[Sheryl]

How timely! My S.O. spent all last weekend removing damp, smelly, soggy blown in insulation, and putting in new batts.

It was damp, smelly and soggy because the bathroom fan was dumping wet air into it instead of being connected to the roof vent.

I would only use blown in for areas you can't get to with a batt - like the wall cavities of an old house.

Here is more than you want to know:

http://www.energystar.gov/ia/home_improvement/home_sealing/DIY_BW_100_dpi.pdf

 

[Brat]

The forum architect should be the one who gives the real scoop. It is my understanding that where you apply your insulation depends on your 'warm side'. If you use your attic for storage and you keep it warm you would attach bat insulation to the roof joists making sure that there is an air gap between the bat and the roof itself (air circulation mentioned by others), otherwise place it between the ceiling joists. You heating bill would be less if you don't heat the attic and place the bats above the ceiling. Less volume to heat and the posibility of using thicker (higher R value) bats.

 

[samclem]

Radiant barriers (foil, mylar, etc) are only minimally effective in a cold climate--generally they are not worth the trouble. It also needs to be open (not in contact with anything) on at least one side (if the foil is just sandwhiched inside other materials you don't have a radiant barrier). Lots of gimmicky radiant barrier snake oil out there, but for a home in the midwest I think you'd be wasting your time. The Dept of Energy web sites can tell you al you need to know.

Fiberglass (either in batts or loose-fill blow-in stuff) has a couple of problems. It really only maintains its stated R-value at very low differences in temperature (e.g. warm side at 70 deg, cool attic at 60 deg). Because air can move through it relatively freely (it's the same stuff cheap furnace filters are made of), convection currents start working at drawing heat out of it when the tep differences get big. When temps really dip down (0 deg), fiberglass insulaton can have as little as 50% of it's rated capacity for this reason. Also, fiberglass fibers do cause lung disease, so if you are working around the stuff, wear a good mask/respirator.

Cellulose blow in insulation has many advantages. It costs about 50% of what fiberglass costs, and the fibers are not hazardous. Because it is dense, it forms a barrier to air movement and convection--it keeps it's rated R-value regardless of temp difference. All the cellulose you can buy today is treated to inhibt mold growth and fire (the fire tests results are very impressive--boric acid is amazing stuff). It's also very environmentally friendly (made of ground up newspaper) and has much less embodied energy than fiberglass. It CAN hold a lot of water, which is a downside if you have a roof leak. If you've alrfeady got fiberglass batts or loose fill, adding just a few inches of celllose can make it much more efffective on cold days by cutting off the convection problem.

DW and I installed 15" of cellulose in our attic before last winter, it was a really good project. She was outside dumping the bales into the machine, I was upstairs in the attic blowing the insulation. Don't forget to add troughs for the soffit venting before you add the insulation (whichever type you add).

Good luck!

 

[Caroline]

This is great info! Since you guys are so good I'll throw a small spanner in the works and see how you do. Three words:

Knob and tube.

 

[samclem]

Three words for you:

Smoke and flame

I would be hesitant to add any kind of insulation near knob and tube.

Is it really still possible to get homeowners insurance with knob and tube "wiring"? My ins company demanded that I change out a fuse panel for circuit breakers.

 

[Brat]

Radiant barriers (foil, mylar, etc) break down with time, not worth the $$. Bat insulation is available with craft paper "barrier" and no barrier.

I still think bat is better but I agree it is not as cheap as blown-in. It hangs together like a pillow. If you place it in a celiling and need to check wiring, lighting, vents etc it is easy to lift off.

 

[Mr._johngalt]

Radiant barriers (foil, mylar, etc) break down with time, not worth the $$. Bat insulation is available with craft paper "barrier" and no barrier.

I still think bat is better but I agree it is not as cheap as blown-in. It hangs together like a pillow. If you place it in a celiling and need to check wiring, lighting, vents etc it is easy to lift off.

I find this thread kind of interesting even though I prefer to be boiled in my
own juices rather than do any sort of insulating around here. I've lived
here 5 years now and don't know what insulation exists in the attic
(never been up there). Suspect none. Anyway, I rely on thermostat
turnbacks (manual), small house size and unusual heating system design to hold down costs.

JG

 

[TargaDave]

Also, fiberglass fibers do cause lung disease, so if you are working around the stuff, wear a good mask/respirator.

Sam,
Where did you hear about lung disease from standard fiberglass insulation? Asbestos insullation for sure, but that has been off the market for ages.

BTW, one way to do troughs and cold side air gaps people are talking about is to just use foam rafter vent. Buy it at any building supply store. Pretty cheap and made to fit 16" oc rafter spacing. Just tack short strips (~3') of it to the underside of the roof ply between the rafters running up from the soffit. If you were doing a cathedral you would run the rafter vent from the soffit all the way up to the ridge vent.

 

[BUM]

I just got done replacing 2 bath fans. The blown in insul. blew everywhere. I'd like to get it blown out!

GO BATS

 

[samclem]

Fiberglass is clearly not in the same category as asbestos.

Here's what the American Lung Association says.
http://www.lungusa.org/site/pp.asp?c=dvLUK9O0E&b=35439


California classifies it as a potentil cancer causing agent. http://www.toolboxtopics.com/Gen%20Industry/Is%20Fiberglass%20a%20Health%20Hazard.htm

If you look at the web sites of personal injury lawyers you can get a real scare. I'd guess they are making a lot of money in claims related to fiberglass, but that is not the same as bulletproof scientific evidence.

There's a strong consensus that wearing a good dust mask (NIOSH 95 standard) is required when using the stuff.

Two other tips:
-- The foam soffit vent troughs work fine. If, however, you are insulating an attic with a low-slope roof, get the thin plastic ones instead. You won't want to crawl all the way to the eaves, and the plastic ones won't crack when you shove them into the gap. You only need one of these troughs approx every 5-6 bays.
-- If you are going to use blow-in insulation (cellulose or fiberglass), buya roll of fiberglass insulation and cut it into 1 foot lengths. Use these to fill gaps between the ceiling and the roof (except for the ones you put the trough vents in--see above) to stop the blow-in stuff from going into the soffits. If you have a low-slope roof, bring a broomstick up in the attic to help with placing these.

 

[Sheryl]

The forum architect should be the one who gives the real scoop. It is my understanding that where you apply your insulation depends on your 'warm side'. If you use your attic for storage and you keep it warm you would attach bat insulation to the roof joists making sure that there is an air gap between the bat and the roof itself (air circulation mentioned by others), otherwise place it between the ceiling joists. You heating bill would be less if you don't heat the attic and place the bats above the ceiling. Less volume to heat and the posibility of using thicker (higher R value) bats.

Sorry.... I quit reading this thread. Too much like w*rk. But, "what she said."

 

[riskadverse]

Sam,
Where did you hear about lung disease from standard fiberglass insulation? Asbestos insullation for sure, but that has been off the market for ages.

I believe that standard fiberglass insulation is very likely to cause lung disease. Asbestos was well known in the scientific community to be dangerous long before it was pulled off the market. Fiberfax (high temp fiberglass) was known to be dangerous back in the 70's and fiberglass was suspect as well. My conspiracy theory is that the use of fiberglass is too widespread to allow the problems to surface.

My house has no insulation.

 

[Sheryl]

I think if you inhale enough of anything, it will cause cancer. Yesterday I saw a guy on a job site cutting fiberglass railings with a chop saw. He was kneeling, bent over the saw, cutting one after the other, dust flying all around him - not even wearing a mask!! I didn't even want to slow down without holding my breath and he had probably been at it for hours. ACK!

 

[mb]

I believe that standard fiberglass insulation is very likely to cause lung disease. Asbestos was well known in the scientific community to be dangerous long before it was pulled off the market. Fiberfax (high temp fiberglass) was known to be dangerous back in the 70's and fiberglass was suspect as well. My conspiracy theory is that the use of fiberglass is too widespread to allow the problems to surface.

It probably doesn't do you any good but the risk is much less than asbestos for the following reason.

There is a particular problem with particles in the 0.1-1 micron particle diameter (The critical dimension is the diameter for fibers because short fibers align with the flud flow streamlines).

Particles larger than 1 micron tend to get caught in the respiratory track and never make it into the lungs.

The lungs actually have a mechanism for removing particles less than 0.1 micron and can therefore protect themselves.

But there is no natural defense for particles of 0.1-1 micron. They get into the lungs and stay there.

The diameter of asbestos fibers put them right in the problem area but if I recall the glass fibers in fiber glass tend to be 10 microns or greater.

Also crystalline materials are worse than amorphous materials.

But even given the above I wouldn't handle fiber glass insulation with out some kind of protection.

MB

 

[Brat]

But even given the above I wouldn't handle fiber glass insulation with out some kind of protection.

Absolutely!!! And don't forget goggles.

 

[lifeisgood]

Radiant barriers (foil, mylar, etc) break down with time, not worth the $$. Bat insulation is available with craft paper "barrier" and no barrier.

Amen. I've spent a bunch of hours hauling old foil out of the attic of a rental property; it all fell down under its own weight.

Warning: Make sure you look out for water piping in your attic; the more you insulate, the greater the risk of the pipes freezing. Like in the aforesaid property, where, in a tenant-less winter, the geyser ran for a month before Waterworks finally called to say "Yo, z'up?" $80,000 later....