# Adding attic insulation and cutting soffits a DIY job?



## Sammy (Mar 11, 2007)

Most big box stores will loan you the blower for free for a day if you buy "X" amount of bags of blown in. 

Best to have a helper feeding the machine while your blowing it in the attic. And have all of your soffit protectors in place so they dont get covered with the insulation. Make sure you have the appropriate mask protection for what your blowing. 

Some stores run rebates in the fall /winter too you may still be able to get in on. 

Cutting the vents in should be no problem either.


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## Ed the Roofer (Jan 27, 2007)

I need dimension of the footprint of the house tp give you an accurate assessment. Measure from end of soffits all the way around. It does not have to be exact, just close.

What other dimension is the 32" soffit? Is it a 2" or 3" continuous strip? Is it 32" X 16" rectangular?

The 3 mushroom style roof exhaust vents regardless of any dimensions, are at least only 1/3rd to 1/6th of what you will need after you calculate the NFVA required. With the dimensions provfided, I can do that for you very easily.

The insulation blowers are sometimes provided for free and sometimes you have to pay a small rental fee.

You need 2 people as stated before.

Do not block the egress to the soffit overhangs or cover and block the air passage flow from the soffit vents. What R-Value does your area require?

If your shingle roof is already curling, they will not get better now, just by perfecting or improving the ventilation flowage.

Time to budget for a new roof in one to two years and add 100 % intake venyilation along all eave edge soffits and a continuous ridge vent on the ridges.

Ed


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## the roofing god (Aug 2, 2007)

It`s probably better to run raftermate and solid rolls of r-30 unfaced insulation(after sealing pipes etc,)than to put blown insulation in,blown tends to settle,also you need to make sure any high hat lighting fixtures are marked IS(insulated)before insulating over them,be very careful as insulating things wrong can lead to fire


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## joasis (May 28, 2006)

the roofing god said:


> It`s probably better to run raftermate and solid rolls of r-30 unfaced insulation(after sealing pipes etc,)than to put blown insulation in,blown tends to settle,also you need to make sure any high hat lighting fixtures are marked IS(insulated)before insulating over them,be very careful as insulating things wrong can lead to fire


Unfaced fiberglass is absolutely worthless as insulation. It is a myth that fiberglass is a quality insulation medium....all it does it slow the transfer of heat, since it actually has no inherent air barrier qualities. The kraft faced fiberglass at least has a barrier to air transmission. 

Anyone who doesn't believe this, do some research online. 

Cellulose can settle, and become "tighter"......without loosing it's characteristics or ability to be effective.....that myth is still being put out by Owens Corning, makers of the pink stuff.


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## Ed the Roofer (Jan 27, 2007)

Joasis,

Would the JM version which has the plastic wrap on the insulation be better than the kraft paper versions?

On the kraft paper, it is only on the bottom side, which should be as a vapor barrier, (but, since their is a seam that does not get taped, I doubt its effectiveness throughout.), and the plastic wrapped is completely encapsulated.

If you know, could you explain which would be better.

Ed


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## joasis (May 28, 2006)

The full wrapped version of fiberglass is more effective, since it "traps" air, and dead air provides the insulation properties. 

Somewhere, I have a hard copy (don't know about online) of a test conducted by a tech school, where they built two identical wall sections......both were sheeted and finished to the exterior, and caulked and sealed. Drywall on the interior. One with fiberglass, one with nothing, and guess what? The heat loss was nearly identical. This study was done to prove the effectiveness of sealing the envelope, not necessarily the insulation, and the results were surprising. They are supposed to do a similar study with cellulose and fiberglass, and we know how that one will turn out. 

When my son went to the training school at Fiberlite to get the certification for blowing insulation, they used a simple heat box to demonstrate the effectiveness of cellulose.....and I bet everyone has seen the heat boxes at home shows, usually demonstrating foam insulation. Even rock wool is better then fiberglass. Made a believer out of me, and it is cost effective. 

I think some of the reluctance we see with cellulose is people have had the older/non treated and dusty stuff blown, and if your attic isn't sealed up, it can "sift" down through openings around ceiling boxes.....the cure is to wet blow the attics...the corn starch base cellulose is treated with is a natural or green product glue, that can make the cellulose "set up", and also hold down the dust. Same way we blow the walls. Since it is "glued", it doesn't settle. Another myth that I hear from builders is that wet blowing "traps" the moisture in the wall....well...if you rocked it too quickly after it was blown, I can see that, but we wait 48 hours before rocking, and it works great...it also is borate treated, and mold resistant.....win win situation. Lack of understanding is why people are reluctant.....kind of like ICF home technology....tradition resists change.


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## the roofing god (Aug 2, 2007)

NOT AS FAMILIAR W/CELLULOSE.but the original insulation has a vapor barrier to it,and if the unfaced is installed tightly it should add good r-value,do you have a link to something there joasis or are you just going on hearsay--around here I see them chop the raw fiberglass in the machines to blow it in,and that doesn`t seem so great


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## joasis (May 28, 2006)

Like this hearsay? #5 Blown in Cellulose vs Fiberglass Insulation Air Infiltration







Blown in cellulose insulation is 2-3 times denser than fiberglass insulation. Studies comparing Blown in cellulose insulation Vs fiberglass insulation show that cellulose insulation was 38% tighter and required 26% less energy. A Princeton University study shows, a group of homes with blown in cellulose insulation in the walls had an average of 24.5% reduction of air infiltration compared to fiberglass insulation, with only the walls insulated. A similar study, the Leominster MA Housing Project for the Elderly found that, a building with blown in cellulose insulation compared to a building with R-13 fiberglass batt insulation in the walls and R-38 fiberglass batt insulation in the ceiling, had 40% lower leakage. However, when it comes to air infiltration, sheathing and drywall are better air barriers than any cavity insulation. Air infiltration barriers such as high-density polyethylene membranes are installed for this specific purpose.


Full Text:http://www.rvalue.net/page5.html

Hard to beat tradition...there is a ton of stuff out there, just clicks away. BTW, blown fiberglass is just as useless as the batts.


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## the roofing god (Aug 2, 2007)

WELL There ya go!,mr hay is one of the most respected authorities on the subject,and his closed cell foam insulation is purported to be up to 30% better insulating than icynene foam,which will make fiberglass and cellulose a thing of the past ,good to see you Tom :thumbup:


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## ShortEdged (Dec 23, 2007)

Soffit vents,
Has anyone heard of a code change (in Texas anyway) that Soffit vents are not to be placed above windows?


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## the roofing god (Aug 2, 2007)

NO BUT i DON`T SEE WHY IT WOULD,WINDOWS HAVE A SOLID WOOD HEADER ABOVE THEM,SOFFIT VENTS VENT THE ATTIC SPACE,PROPERLY DONE ABOVE THE EXISTING INSULATION


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## ShortEdged (Dec 23, 2007)

the roofing god said:


> NO BUT i DON`T SEE WHY IT WOULD,WINDOWS HAVE A SOLID WOOD HEADER ABOVE THEM,SOFFIT VENTS VENT THE ATTIC SPACE,PROPERLY DONE ABOVE THE EXISTING INSULATION


Are you yelling at me? I guess I should not believe everything a contractor says.


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## Ed the Roofer (Jan 27, 2007)

ShortEdged said:


> Soffit vents,
> Has anyone heard of a code change (in Texas anyway) that Soffit vents are not to be placed above windows?


 
I haven't heard of this and I will try to look up why that would be a something to be considered in the first place.

At first guess, if true, I would be thinking about condensation being brought in through the soffit vents above a wall that is blocked off by the window blocking. Would there be a need to transfer wall moisture upwards into the attic? Why would the elimination of the soffit vent above the window make a difference?

I'll see if I can come up with something later this week. I'm not going into the office until Wednesday.

Ed


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## the roofing god (Aug 2, 2007)

At first guess, if true, I would be thinking about condensation being brought in through the soffit vents above a wall that is blocked off by the window blocking. Would there be a need to transfer wall moisture upwards into the attic? Why would the elimination of the soffit vent above the window make a difference?

I'll see if I can come up with something later this week. I'm not going into the office until Wednesday.

Ed
That wouldn`t be an issue as the window is insulated separately,the venting would be the same as the rest of the attic-TRG


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## pesphoto (May 2, 2007)

I just insulated my attic 2 days ago. Used the blow in cellulose from Home Depot. The blower was a free rental since i bought enough of the stuff(20 bags). I acually had some left over and they took it back and refunded my credit card and still didnt charge me a rental fee. I too need to have some soffits installed at some point.


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