Attic Insulation Advive Wanted

[Oil Changer]

My home was built in 1961. It has the original attic insulation with the kraft-faced backing. This existing insulation is compressed to about 4" but otherwise servicable.

I have ruled out blown-in insulation.

My questions:

1. Should I leave the existing insulation and place non-backed insulation over it (i.e. R-11), the roll out the non-backed R-38 in the opposite direction. Or...

2. Remove the existing 50 y/o insulation and replace with kraft-faced R-19 which would fill the joist, and then roll out the non-backed R-38 over that.

Code is R-49. Would like to have R-60. I have the money to cover the entire attic using option #2 at R-49. Option #1 would allow for R-60 (or close enough because there would be compression).

I'm all ears.

(Looking for advice, not advive!

)

 

[saberz]

Pretty good read from a site that specializes in it:

http://www.everguardinsulation.com/pages/removal.html

Quote:
Insulation Removal

Many homeowners inquire about removing the old insulation from their attic, rarely is this necessary. The only time we recommend removing old insulation is when the insulation has been fire damaged, water damaged or heavily infested with rodents.

Most homes have some old or "existing" attic insulation already in their attic. Typically we just add more insulation to what you already have in order to bring the attic up to an R-30 or R-38 rating. The existing insulation may be dusty, filled with old roofing debris and look quite tattered, but it's just old material; it doesn't contain asbestos nor contain anything that wouldn't be rendered safe once new and fresh material is installed over it. Also, there's no chemical interaction or problem with mixing various insulation materials either. We actually can save you money by using your existing insulation as a base and installing enough additional material over it to bring the attic up to R-30 or R-38.

 

[Oil Changer]

Thanks for the link!

 

[ARCOgraphite]

Where th ecarft backing is youll get moisture condensate there. Think about it

 

[bepperb]

The paper backing is (or at least was) acting as a moisture barrier. I would inspect that. If it's still sound, leave it in there. If it's not, pull everything and put a vapor barrier down (over each joist, yes) then put unbacked between the joists, then perpendicular.

50 year old house is probably loose enough to not have mold issues even in the attic, but I wouldn't want to take that chance.

 

[Oil Changer]

All the existing insulation is sound. No mold, pest, rodent, or water issues.

From everthing I read, the proper way to lay attic insulation is to use kraft-back with the backing facing the heated room, which would be the ceiling of the heated living space below. That is code. That is what I have now. I just need more.

If I am to leave the existing, I would not need to buy any insulation with the kraft-backing (which is your moisture/vapor barrier). This savings would allow me to add greater R value.

 

[mpvue]

Originally Posted By: Oil Changer
All the existing insulation is sound. No mold, pest, rodent, or water issues.

From everthing I read, the proper way to lay attic insulation is to use kraft-back with the backing facing the heated room, which would be the ceiling of the heated living space below. That is code. That is what I have now. I just need more.

If I am to leave the existing, I would not need to buy any insulation with the kraft-backing (which is your moisture/vapor barrier). This savings would allow me to add greater R value.

I would just get the thickest unfaced I could afford and lay it perpendicular to the existing. done.

 

[ARCOgraphite]

With the craft facing the heated room you are good to go! No decision required. Easy job now. Just roll out new non backed insulation over existing. IMPORTANT Dont crowd/layover the soffit vents area though - that air has to circulate. Is the Govent still giving energy credit for the insulation? I was able to deduct some new thermal E windows and insulation 2 years ago.

 

[Oil Changer]

Originally Posted By: bepperb
The paper backing is (or at least was) acting as a moisture barrier. I would inspect that. If it's still sound, leave it in there. If it's not, pull everything and put a vapor barrier down (over each joist, yes) then put unbacked between the joists, then perpendicular.

50 year old house is probably loose enough to not have mold issues even in the attic, but I wouldn't want to take that chance.


Wow! I am all about doing things the right way the first time Especially when it is my house we are talking about) but that would be ALOT of work. I have an unfinshed attic. I can almost stand upright in the very middle. Most of this work will be done on my belly. Nails stick through like a pin cushion covering every inch of the interior attic space.

The work involved in putting down sheets of vapor barrier just makes me say, WOW!

I laugh when I go to these websites that shows these guys standing up in well lit attic spaces having a great 'ole time putting in insulation. Not at this house! When I start in the farthest corners, there will barely be room for my body. Lift my head to high, I will impale myself.

Besides, I believe there is vapor barrior between the ceiling (plaster) and the attic "floor" (the sheeting that backs the ceiling).

All the DIY and manufacturer sites sy to put kraft-backed insulation down between the joists, the non-backed perpendicular to the joists.

 

[Oil Changer]

Originally Posted By: mpvue
Originally Posted By: Oil Changer
All the existing insulation is sound. No mold, pest, rodent, or water issues.

From everthing I read, the proper way to lay attic insulation is to use kraft-back with the backing facing the heated room, which would be the ceiling of the heated living space below. That is code. That is what I have now. I just need more.

If I am to leave the existing, I would not need to buy any insulation with the kraft-backing (which is your moisture/vapor barrier). This savings would allow me to add greater R value.

I would just get the thickest unfaced I could afford and lay it perpendicular to the existing. done.


That would be great but the existing insulation is compressed to the point of uselessness. It would look like a wave pool when I was done and I'm looking for maximum efficiency.

I don't mind the extra work and I get $400 off whatever I spend so buyng extra to up the R value to the max w/o getting stupid is what I want.

 

[Oil Changer]

Originally Posted By: ARCOgraphite
With the craft facing the heated room you are good to go! No decision required. Easy job now. Just roll out new non backed insulation over existing. IMPORTANT Dont crowd/layover the soffit vents area though - that air has to circulate. Is the Govent still giving energy credit for the insulation? I was able to deduct some new thermal E windows and insulation 2 years ago.


I think that is what I'm going to do. I just found out within the last couple of days that it is pefectly acceptable to lay the non-backed insulation over the existing (which does have the backing faced down towards the heated space).

I assumed I had to remove the existing. Now that I know that I do not, I'm going to put non-backed R-11 to lay over the existing. This represents a huge cost savings over buying the kraft-backed R-19 (not to mention the work involved removing/disposing of the original). This will put the insulation slightly higer than the tops of the joists. Gravity will take care of that over time, plus (and most importantly) I'm going to lay the non-backed R-38 perpendicular on top of that.

This will be light-years better than what is existing, and put me real close to the maximum recommended R-60 and well over the minimum recommended R-49 (accounting for compression).

Soffit vents/attic ventalation is a non-issue. My home has 30" overhangs. The vents are located well outside the framing for the exterior walls. This is one of the reasons I did not want to blow in insulation. I would have to go back and clean all the overspray out of that area. Batts are easier in my case.

The last day for the tax credit was 12/31/11. Story of my life.

 

[Kestas]

Originally Posted By: Oil Changer
I just found out within the last couple of days that it is pefectly acceptable to lay the non-backed insulation over the existing (which does have the backing faced down towards the heated space).

You seem to be on track for doing it right. If you do end up laying additional insulation that has backing, you could score the backing open down the center with a utility knife and lay it with the backing on top. I've done this with no issues.

 

[opus1]

Originally Posted By: mpvue
.....I would just get the thickest unfaced I could afford and lay it perpendicular to the existing. done.
This.

Technically that's what my builder did when I upgraded the attic insulation, but they used blown-in over the standard, between the joist batts.

 

[sleddriver]

1. Yes
2. No

However, I would advise that you spend some time sealing all electrical, plumbing, kitchen, bath & dryer vent, & gas line penetrations in your wall top plates with either acrylic caulk or expanding foam BEFORE adding additional insulation. Further, you could also use pink/blue foamboard to seal off any open fir-down cavities to prevent cold air from sinking down in there and chilling interior walls.

Remember fiberglass/rock wool/cellulose won't stop airflow. If any air does flow through it, its insulation value is greatly reduced. Furthermore, in your area, you don't want warm, humid air rising into your attic where it'll meet cold air and condense to liquid. You need a cold attic to prevent ice dams from forming as well.

I did this sealing work & fluffing the insulation last Jan. and it really made a difference.

Look on Fine Homebuildings site for videos of Mike Guertin explaining this. Excellent info.

BTW, an easy way to clear any blown-in insulation from soffit vents is to use a leaf blower from outdoors.

 

[RTexasF]

Why is it that blown in insulation won't work for you? We had 1' blown into the attic of our 40 year old one story and the difference in the electricity bill (all electric home) was a $90 drop the first month. The savings paid for the insulation in less than a year and the house "felt better" if that makes any sense.

 

[Oil Changer]

Originally Posted By: sleddriver
1. Yes
2. No

However, I would advise that you spend some time sealing all electrical, plumbing, kitchen, bath & dryer vent, & gas line penetrations in your wall top plates with either acrylic caulk or expanding foam BEFORE adding additional insulation. Further, you could also use pink/blue foamboard to seal off any open fir-down cavities to prevent cold air from sinking down in there and chilling interior walls.

Remember fiberglass/rock wool/cellulose won't stop airflow. If any air does flow through it, its insulation value is greatly reduced. Furthermore, in your area, you don't want warm, humid air rising into your attic where it'll meet cold air and condense to liquid. You need a cold attic to prevent ice dams from forming as well.

I did this sealing work & fluffing the insulation last Jan. and it really made a difference.

Look on Fine Homebuildings site for videos of Mike Guertin explaining this. Excellent info.

BTW, an easy way to clear any blown-in insulation from soffit vents is to use a leaf blower from outdoors.


Great advice. Great post. Thank you.

 

[Oil Changer]

Originally Posted By: RTexasF
Why is it that blown in insulation won't work for you? We had 1' blown into the attic of our 40 year old one story and the difference in the electricity bill (all electric home) was a $90 drop the first month. The savings paid for the insulation in less than a year and the house "felt better" if that makes any sense.


I weighed the +/- of both.

Don't want to lug the machine back and forth.

Don't want to mess with the hose.

Don't want to rush the job just to get the machine back on time.

Don't want to recruit help.

I think batts will be better overall for me.

There's more but you get the idea.

There's nothing wrong with the blown-in stuff, it has its merits and I'm glad it worked for you. But I'm going to stick with the rolls. Just going with my gut.

 

[INTJ]

I'll chime in maybe something that many are unaware with blown in cellulose.

When the temp starts to drop below freezing, the fibre glass batts or blown fibre/glass will fall way behind in performance when compared to blown cellulose.

Air currents start to rise in the fiber glass and it convects out the envelope. It allows much more heat loss and the colder you are the worse the effect. The loss is not linear, and around zero, you would see a difference in 20 percent between the two. R -value is R-value, but it is apples to oranges when going cold. Above freezing both are on equal footing, but you'll need more fibre glass than cellulose, thus more fill and greater cost.

We put/blown a r-22's worth of cellulose over existing double r-11 batts in 2x6 ceiling joist cavities in our attic. The first batt was Kraft faced down, the second was unfaced. It was the Pink Panther brand, and said "new" with a picture of a guy with horned rim glasses rolling it out.

40% less NG.

 

[doitmyself]

Oil Changer,

there's lots of info on You Tube also. Here is one showing exactly what you propose to do...fill the joists, lay perpendicular over that: HA HA, nice open attic!


What I have learned over the years is that proper ventilation is VERY IMPORTANT. Especially as you add more insulation, the attic will become cooler (winter), adding to the possibility of moisture accumulation/condensation...leading to mold or other problems.

In my link above, you can see how you can still plug up the soffit ventilation if you are not careful.

I "think" the rule of thumb is a minimum of 1sq. ft. ventilation to 300 sq. ft. floor/ceiling area. It should be split 1/2 in the eave and 1/2 in the ridge or gable.

Again, attic ventilation is often over looked! Keep an eye on yours after insulation is completed.

AND.....DON'T STEP THROUGH THE CEILING!!!!!!

 

[bepperb]

Convection currents and air movement are a problem with Fiberglass, but my understanding is that with batts it's much less of an issue that with lightweight loose fill fiberglass. At least that's the fiberglass manufacturers stance.

Really, you're going to want to do this as easily and inexpensively as possible. It's easy to advise you to get all the existing out of there and spray in a foot of foam. It's not as fun to actually do that and then pay for it. Best of luck. I think you're on the right track. Unfortunately actually doing it is a pain, at least it was in our 1946 cape cod.

We also had seriously lacking attic ventilation which didn't get fixed until we reroofed. In a house this age that was an afterthought at best. Our house actually had a flap to block the gable vents. Not quite sure what season that was for?