OT- Attic insulation help

scfa99 · Dec 23, 2005

I know this is off topic but it is heat related and you all are a knowledgeable bunch.

I have an 18 year house and want to make sure all the heat my QF 7100 is kicking out is not flying up through the attic. Attic has batt insulation appears to be R 13 or 19 can't tell since its matted down alot. I have about 7.5" between 2nd floor ceiling and top of attic beam. My region says r49 now is the standard, i don't know if i can get it that high but would like something in the R30ish range.

So if i assume that i currently have R19 which is matted down and depending on area has about 1-3" of a gap from the top of the insulation to the beam. I plan to fill in the gaps with cellulose insulation to the top of the beam. This will fill in all gaps and also get all of the insulation to the top of the beams consistantly. So with the existing and cellulose i should have an R value of R3 per inch so about R20-21.

Then I plan on rolling batts of R-19 (criss crossing the existing) over top the beams and current insulation. I will use batts without the backing since the original already has this. This should get me up to R39-40 range. Part of the reason why i'm going with this approach is that I do have some storage space up there and also want the ability to be able to get to areas up there if needed (wiring, repairs, mouse traps etc). So i do have some plywood up there and figure i will just lay the batts over them and if i need to access it i will just move the batts out of the way. So here come the questions:

Is my plan sound?

Should i install R25 instead of the R19?

Since I'm not doing a ton of cellulose can i install/spread by hand and not use a blower? Any tips on doing this and how to spread?

If the existing insulation is blackened i've read that you should remove and seal any gaps that air is coming through. What should I use to seal it? Expanding foam? I dont think caulk will hold up long term.

Areas where there is plywood, will adding the batts over it help insulate?

They sell rolled insulation with a platic covering to help prevent itchyness, the platic is perforated to allow airflow. Should i be concerned with it building up moisture over time?

Thanks any help, tips, advice or links to other helpful forums will be appreciated.

vgrund · Dec 23, 2005

First, congratulations for insulating.

I strongly urge you use blown cellulose for all of the insulation you add. It is easier to install (IMO) and a more efficient insulator due the monolithic nature of the product (no gaps). Yes you can't roll it out of the way for attic projects, but how often do you plan to do this anyway?

With regard to R values, more is obviously better although the economies usually break down above R-49. Also with cellulose one must consider the weight of the product.

Expanding foam is appropriate and more economical for larger gaps. For smaller gaps use acrylic caulk fortified with silicone which will last a very long time or, if you don't mind spending more money, pure silicone will last even longer. I use silicone a lot for air sealing since it can handle heat around ducts (400 degrees for regular silicone, 500 degrees for RTV). Many experts recommend mastic for duct sealing but it is such a messy proposition and I've had no problems with pure silicone caulk.

Victor

roac · Dec 23, 2005

What I would add to what has been said is to wait until Jan 1 when federal tax incentives take effect. Ditch the extra storage, buy an outside storage building. The money saved in utility bills will pay for that. I bought a bag of cellulose insulation once with the hope of hand spreading, two words, forget it. That stuff is compacted into the bags and comes out clumpy. I agree with others to blow cellulose and with purchase from HD or Lowes you get a free rental of the blower. Is there a vapor barrier installed? This could be in the form of plastic sheet laid on the floor of the attic or could be even attached to old insulation. With a proper vapor barrier installed air leaks would be sealed once insulation was blown on it.

SeanD · Dec 23, 2005

Blown in insulation certainly has it's advantages with (relative) ease of installation and being able to get in every nook and cranny, but.....I was very surprised when I went up into my son's attic. He has loose, blown in insulation and vents in both ends of the attic. The wind blowing into the vents and through the attic had actually caused the insulation to drift - just like a snow drift. Instead of having a uniform 15" of insulation throughout the attic some places were 24" while others were 6". We smoothed it out and 2 months later it was the same! I think our next step will be to smooth it one last time and put batts of fiberglass on top to hold it in place.

joshuaviktor · Dec 23, 2005

Can I add a question to this?

I have an old attic with HUGE wide board flooring. There is what looks like 3 inch fiberglasss from god knows when in there, but there's at least 3-4 inches of space in the attic floor. Can I use the blown in stuff, and just blow it into the attic floor? This would let me NOT rip up big freaking boards with square nails in them (square nails are almost impossible to get out.)

If so, any suggestions. I've never used blown in insulation. Like, how do you know when there's enough in there?

Thanks,

Joshua

velvetfoot · Dec 23, 2005

How does one navigate up there with hall that insulation? Any tricks?

roac · Dec 23, 2005

You blow it in the gap til it comes out, I would remove all the old too. If you blow insulation in, you don't have to carry it up. The blower sits downstairs, wife or friend keeps the beast fed with cellulose and you have the hose up in the attic directing the flow...

SeanD · Dec 23, 2005

Hoy Smokes, Joshua! If you only have 3" insulation in your attic stop everything else and start insulating your attic. Nothing you do will give you a more immediate, faster return on your investment.

roac · Dec 23, 2005

velvetfoot,

Are you asking how to install or how to walk through the deep snow drifts? If the latter then, very very carefully... Try and find a beam going the same way you want to go and from there put your foot down very slowly and methodically.

velvetfoot · Dec 24, 2005

I've been navigating the current attic fairly well (to place mouse traps), but the edges of the batts show where the truss is. I guess you'd step very gingerly, using the exposed part of the trusses as a guide. You'd compress the top layer with your feet though. I've read of bringing up some plywood platforms to bridge the trusses but then you'd be compressing it too. Does it (fiberglass) bounce back?

elkimmeg · Dec 24, 2005

Like any other topic each has pluses and minuses. Blown in has ease ot placement great coverage not itchy but use a respirator and mask. Down side it sometimes gets where it should not like in the eves blocking eves ventilation. A real pain if you ever remodel. Cut one hole in a ceiling and you will know exactly what I an talking about. Makes walking up there and storage a real problem.
Fiber glass more prone to air leakage ichy, plastic wrapped has made it more tollerable. Any additional insulation benifits will be imediately felt if your existing insulation is less than r19 Even at 19 one should be considering adding an additional r19. Even unfaced 13 or r15 would be a vast improvement. Fiberglass make remodeling mush easier just roll it out of the away Someone mentioned walking around on ceiling joist is quite dangerous. What I do is bring up some short boards or planks. that I move from place to place to walk on. Even if it crushes down the fiber glass the fiberglass will return back to it's dept somewhat once removed. As for storage why not place 2/6 under the plywood raising it and insulate under it. Yes one can blow it in under boards from each side and even blow in inches over the boards or lay bats there as well. Do not forget to insulate the attic pull down stairs or hatchway huge heat loss area

roac · Dec 24, 2005

SeanD said:
Blown in insulation certainly has it's advantages with (relative) ease of installation and being able to get in every nook and cranny, but.....I was very surprised when I went up into my son's attic. He has loose, blown in insulation and vents in both ends of the attic. The wind blowing into the vents and through the attic had actually caused the insulation to drift - just like a snow drift. Instead of having a uniform 15" of insulation throughout the attic some places were 24" while others were 6". We smoothed it out and 2 months later it was the same! I think our next step will be to smooth it one last time and putbatt of fiberglass on top to hold it in place.

SeanD,

That's an interesting problem. He obviously has blown fiberglass vs. blown cellulose. Cellulose is a much heavier product that actually settles some after time. I don't think cellulose would blow around that much.

Elk,

Sounds like if you think you may do some ceiling work in the future that it would be worth doing the first layer of attic insulation in an R13 rolled batt and then blow over that with up to R49. That way you should have less fall through. By the way... don't go to the cocoon website (cellulose provider forHD and lowes) they show the product being blown in by a guy walking on rafters. Their own directions say make a platform...

scfa99 · Dec 27, 2005

Thanks for all the tips, there are many things i didn't consider.

Sandor · Dec 28, 2005

I noticed that you said the current insulation has blackened.

If that is the case, that is mold growing on the insulation due to high moisture levels.

Ventilation should be addressed before adding any insulation.

elkimmeg · Dec 28, 2005

Great point If blackened by an air leak around a light fixture that could be dust or dirt accululation over a period of time.
All too many attics only have small gable end vents, nowhere enought ventilation. If you have signs of mold or mildew on your roof plywood or on your insulation, putting more up there, this problem does not go away Actually you just agrevated the problem.
As Sandor said better address the ventalation issue first. Since hot air rised ridge vents installed correctly do a decent job.
Actually in the codes it is spelled out the minium ventilation requirement for the attic space. So much cubic vollume requires x cubic ventilation . I will have to look that up to be more precise

scfa99 · Dec 28, 2005

Thanks,

We just did a roof in the fall and added ridge vents, i also cleared the existing insulation back from the soffits. So hopefully that along with the passive vents should be enough.

elkimmeg · Dec 28, 2005

Sounds like you should be ok. Wise move clearing the sofit vents and adding the ridge vent

joshuaviktor · Dec 28, 2005

In my house, you can actually look out along the side of the roof (perpendicular joints), and see sunlight. My realtor told me to make sure we didn't obstruct the soffits when we insulated. I laughed and pointed at the wall. She looked and said I think you have plenty of ventilation.

franktank232 · Dec 29, 2005

I'm new...heres what my attic looks like (3bd Ranch in S WI)...add more?

elkimmeg · Dec 29, 2005

I would use a rake and smooth out what you have BTW how thick is the average now. How well is your attic ventilated? Are the sofit vent pluged up with the blown insulation? I did not see styrofoam vent shields to protect the blown insulation from filling the sofit area. I have seen what high wind can do with this insulation. It can pile it up like snow drifts. even fills the sofits, That"s another reason the styrofoam vent shields are required

scfa99 · Dec 30, 2005

Just a follow up on the post about sealing up the attic door area. You can make your own but i decided to go with the product on this site for 29 bucks. http://www.batticdoor.com/ I wrapped in R30 and it has a good seal. When standing at the top of the attic steps after closing it you can feel the heat accumulate instantly. Just thought i'd pass it along. they also have some sort of chimmney flu pillow for those of you with open fireplaces.

the dryer vent thing looks interesting not sure if would work. not sure that plastic will keep the cold out.

up next soffit baffles, sealing up any leaks and then rolling out the r25 encapsolated crisscross over the existing. i'm going to skip the cellulose since it sounds like you can't spread by hand. lowe's only gives a free rental if you buy over 20 bags.

drizler · Dec 31, 2005

And if you go to crawling around up there on loose moveable boards remember one thing. Make sure you don't crawl or walk past the end of the last support joist. You might come down much faster than you went up. Remember Chevy Chase in Christmas Vacation. I put a couple bags of that cellulose in my attic to try it out. No way far too messy to deal with. Bite the bullet and roll some bats up there. Wear a dust mask and all will be fine. If you get that paper insulation anywhere near your entrance hatch you will be reminded of it forever. Every time you open that hatch..................

vgrund · Jan 1, 2006

Driz said:
And if you go to crawling around up there on loose moveable boards remember one thing. Make sure you don't crawl or walk past the end of the last support joist. You might come down much faster than you went up. Remember Chevy Chase in Christmas Vacation.

In my last neighborhood, one of my neighbors did exactly that. Walking on the outer edge of a board, it flew up and sent him flying down. The board wacked him in the can in the early part of the journey which, I might add, occured over a 19' ceiling. Luckily his crotch squarely landed on a joist, stopping his fall.

Notably, he subsequently fathered a child so I guess it worked out.

Victor

BrotherBart · Jan 1, 2006

vgrund said:
Driz said:

And if you go to crawling around up there on loose moveable boards remember one thing. Make sure you don't crawl or walk past the end of the last support joist. You might come down much faster than you went up. Remember Chevy Chase in Christmas Vacation.

Click to expand...

In my last neighborhood, one of my neighbors did exactly that. Walking on the outer edge of a board, it flew up and sent him flying down. The board wacked him in the can in the early part of the journey which, I might add, occured over a 19' ceiling. Luckily his crotch squarely landed on a joist, stopping his fall. Notably, he subsequently fathered a child so I guess it worked out.

Victor

That is how I ended up laying on the garage floor surrounded by busted pieces of sheetrock in my last house.

When we sold the house the real estate agent asked about the new piece of sheetrock in the garage ceiling. I just growled at her.

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