Blown-in insulation: Baffled about Baffles

[Ashyukun]

As per the thread down a bit, I'm hoping and planning on blowing insulation in my attics this weekend since it has almost none at the moment, so I'm working this week on getting them prepped and ready for it.

One thing I definitely need to do from my reading is to install baffles so there will still be air flow through the attic from bottom to top. What I'm not so sure about is just how MANY I need. It makes perfect sense that there would be baffles where there are soffit vents to allow a path for the air- but only the upper attic HAS vents, the lower has none that I can see. I've also seen it said that there should be baffles on ALL of the rafters- which admittedly scares me a bit because it will take a LONG time to put up that many if this is the case.

So, I'm hoping others who have done this can enlighten me a bit about putting up baffles. Thanks!

[zolotiyeruki]

One alternative to the plastic baffles is to get some inexpensive styrofoam sheets, plastic sheets, mdf panels, or something similar, and run them along the underside of the rafters around the bottom of the attic.  That will leave a nice big air gap between the rafters and between the sheathing and your styrofoam/plastic/mdf.

[OOBER]

I just got done with this a couple of months ago and struggled with this question myself.

I ended up buying a whole stack of the plastic baffles then sticking one anywhere that it would fit (anywhere there wasn't an obstruction)

Figured more vents was better than less vents. I also tried not to pack the insulation in so tight around the vented edges especially where there weren't plastic baffles. Filled all air gaps with expanding foam before blowing in the insulation (I was amazed at how many air holes/issues I found while doing this). Went from ~6" of insulation to ~18". So far it has been working great and we have already noticed a HUGE difference. Our House is actually bearable in the summer.

Here are some pictures:



Notice how I had to skip a couple of spots where the chimney and crossmembers were.









Do yourself a favor and get the "L77" product from a real local distributor instead of the pink junk from home depot. Same manufacturer, but there is a big difference in quality between the two. I used L77 on my house. Went to my FIL's house and used the remaining bags until we ran out. Had to go to Home Depot and pick up some more of the normal stuff and in addition to it being more expensive the quality wasn't nearly as good (not as fluffy and much more granular). Do some research on the L77 product, even the manufacturer states that it is better. I think they just stock the home stores with the low quality stuff because inexperienced people don't know any better.

[Shawn J]

I installed baffles in the spring, will be blowing in the insulation this fall. I wouldn't skimp on the baffles. Just put them between every rafter, they aren't very expensive.

Don't forget to air seal your attic before you starting installing the insulation.

[Ashyukun]

Thanks for the great info & pictures! My wife eventually pointed out that I should just call her home-builder Dad and pick his brain on this stuff, and I did- and he concurred that EVERY bay needed to be baffled if possible. I got the lower attic baffled and air-sealed as best I could yesterday, and have what I need to (hopefully...) get the upper attic baffled this afternoon/evening. NOT a fun task- and today's will be even less fun since it will be hotter and harder to move around in the shorter upper attic- but I need to get it done.

Still going back and forth between using cellulose or fiberglass. Both my father-in-law and brother-in-law who work in home construction have said that cellulose is the more common and bigger bang for the buck, but my helper swears by fiberglass for the houses he's insulated in the past. Unfortuntely, I've not had any luck in finding the L77 insulation here on short notice- so I'm leaning toward the cellulose.

[Shawn J]

Cellulose will compress over time but has a better R-value per inch.
Fiberglass will not compress but has less R-valule per inch.
Cellulose is also itch free!!!!!

I will be using cellulose once the weather cools down. I should have started the project in the winter so I could have finished it but waited too long. The heat has put a stop on the progress because its an unbearable 120 degrees up there.

[Ashyukun]

Yeah- on the cellulose the FiL said to blow about 15" of it and it will settle to about 13".

I'd LOVE to not be doing this in the middle of summer, but the upper level of the house is really unbearable at this point and with finishing setting things up and unpacking we'll likely be using it a lot more so it will hopefully be worth the time spent up in the heat there to make the house itself much more livable for the rest of the time we're there (and cheaper to cool/heat).

[OOBER]

Cellulose is also itch free!!!!!

The new blown in fiberglass is pretty much itch free also. I was practically rolling in it for 2 days straight while I did my and my FIL's attics.

Long sleeves/pants, gloves, a respirator (I used a 3M style 6000 series with P100 filters, the whole setup is only ~$20-$30), safety glasses, and a headlamp are pretty much required.

Having experienced them both I would DEFINITELY recommend L77 over the Home Depot L38. This is the distributor that I got it from: http://www.idi-insulation.com/. They have locations all over the country. Just go in and say "with my 10% off Lowes/Home Depot coupon I can get insulation for XX.xx a bag, can you match/beat it?" I did the same and got a pretty big discount. I ended up paying $28.00 a bag for the L77 which if I remember correctly the L77 bags are actually bigger and have more in them also. Currently at Home Depot the lower quality stuff is $35.45.

ProPink L77 Brochure: http://insulation.owenscorning.com/assets/0/428/429/440/9f5a9d05-9916-434a-90f5-dfba4c04bc8c.pdf

L77 @ $28.00 * 20 bags = $560 (free machine rental with insulation purchase @ IDI Distributors)
L38 @ $35.45 * 20 bags = $709 (free machine rental with insulation purchase @ Home Depot/Lowes)

I got an official quote before I started that was ~$3,000. Through learning from the guy that was quoting it, YouTube, and help from the distributor, I did it myself to an even higher R value than I was quoted for ~$1000. I did way too much research on it and have confidence that it was done correctly and will last a long time.

This forum is about saving money and buying smart. Yes it is easier and faster to go to Home Depot, but it is smarter and cheaper to do it the way the pros do.

[Ashyukun]

I ended up going with the Cellulose and blowing in 40 bags of it (they're about 1/3 the size of fiberglass bags). Was pretty painless all told. If I'd had a larger window of time to get everything together I might have gone with the L77 fiberglass, but I just didn't have the time to track it down. The cellulose though has already made a considerable difference on the temps on the top floor, so I'm happy with it. Kind of wish I'd put down even more- but if I decided to do that I just need to get the blower and more bags and go for it since all the hard prep work was already done.

Now I just need to put in soffit vents on the lower attic so it vents properly (for probably the first time in the house's 50 year existence...). And actually hunt down the right circuit so I can provide power to the outlet I installed in the ceiling before blowing in the insulation.

[OOBER]

I ended up going with the Cellulose and blowing in 40 bags of it (they're about 1/3 the size of fiberglass bags). Was pretty painless all told. If I'd had a larger window of time to get everything together I might have gone with the L77 fiberglass, but I just didn't have the time to track it down. The cellulose though has already made a considerable difference on the temps on the top floor, so I'm happy with it. Kind of wish I'd put down even more- but if I decided to do that I just need to get the blower and more bags and go for it since all the hard prep work was already done.

Now I just need to put in soffit vents on the lower attic so it vents properly (for probably the first time in the house's 50 year existence...). And actually hunt down the right circuit so I can provide power to the outlet I installed in the ceiling before blowing in the insulation.

Congrats! In the end it doesn't much matter which product you picked. The important part is that both of the products work and that you completed the project while saving ~$1000's of dollars by doing it yourself.