I want to upgrade my attic insulation. I have 2x6 beams and old
unfaced R13-R19 fiberglass batts up there. I want to add R38 on top of
the existing insulation. I am in San Jose, CA.

I can do cellulose, which will give me uniform coverage and is the
least expensive option. But I've heard it's very dusty (even after
it's done, my furnace hot air ducts runs in the attic), not easy to
deal with if I need to go up the attic and do something, and boric
acid/ink may give off bad VOC.

I can do blown-in fiberglass, but how do I ensure the contractor won't
fluff the insulation? I am also not fond of the idea of lose
fiberglass floating around in the attic. They may get sucked into the
furnace duct and gets into the house.

I can do fiberglass rolls. Less chance of lose fiber floating around,
and R38 is R38. But it may not insulate as well as blown-in since it's
layed on top of my existing insulation and the coverage won't be as
uniform as blown-in. But advantage is I can move it out if I need to
go up and do something.

I am leaning toward the 3rd option. Assume the contractor does a
decent job, will it provide adequate insulation? Between a reasonably
installed (ie, average, not perfect) batt vs blown-in cellulose, how
does the fiberglass batt compare? If it's 80% as good, then I think I
am fine with it...

Thanks!

Raymond

wrote in message
...
I want to upgrade my attic insulation. I have 2x6 beams and old
unfaced R13-R19 fiberglass batts up there. I want to add R38 on top of
the existing insulation. I am in San Jose, CA.

I can do cellulose, which will give me uniform coverage and is the
least expensive option. But I've heard it's very dusty (even after
it's done, my furnace hot air ducts runs in the attic), not easy to
deal with if I need to go up the attic and do something, and boric
acid/ink may give off bad VOC.

I can do blown-in fiberglass, but how do I ensure the contractor won't
fluff the insulation? I am also not fond of the idea of lose
fiberglass floating around in the attic. They may get sucked into the
furnace duct and gets into the house.

I can do fiberglass rolls. Less chance of lose fiber floating around,
and R38 is R38. But it may not insulate as well as blown-in since it's
layed on top of my existing insulation and the coverage won't be as
uniform as blown-in. But advantage is I can move it out if I need to
go up and do something.

I am leaning toward the 3rd option. Assume the contractor does a
decent job, will it provide adequate insulation? Between a reasonably
installed (ie, average, not perfect) batt vs blown-in cellulose, how
does the fiberglass batt compare? If it's 80% as good, then I think I
am fine with it...

I went for the batts. It is great to be able to move them aside to add a wire or
whatever. I did it myself. It probably took 3-4 hours.

As far as insulation value, if you place them carefully together, fiberglass
should be fine. And it doesn't settle over time like the blown in cellulose I
put in my previous house.

Bob

a. cellulose is the best option.
b. how could the fiberglass get 'sucked' into the furnace ducts? do you
have an open return air vent in your attic?
c. cellulose is the best option

www.centralfiber.com for some good reading.


steve


wrote in message
...
I want to upgrade my attic insulation. I have 2x6 beams and old
unfaced R13-R19 fiberglass batts up there. I want to add R38 on top of
the existing insulation. I am in San Jose, CA.

I can do cellulose, which will give me uniform coverage and is the
least expensive option. But I've heard it's very dusty (even after
it's done, my furnace hot air ducts runs in the attic), not easy to
deal with if I need to go up the attic and do something, and boric
acid/ink may give off bad VOC.

I can do blown-in fiberglass, but how do I ensure the contractor won't
fluff the insulation? I am also not fond of the idea of lose
fiberglass floating around in the attic. They may get sucked into the
furnace duct and gets into the house.

I can do fiberglass rolls. Less chance of lose fiber floating around,
and R38 is R38. But it may not insulate as well as blown-in since it's
layed on top of my existing insulation and the coverage won't be as
uniform as blown-in. But advantage is I can move it out if I need to
go up and do something.

I am leaning toward the 3rd option. Assume the contractor does a
decent job, will it provide adequate insulation? Between a reasonably
installed (ie, average, not perfect) batt vs blown-in cellulose, how
does the fiberglass batt compare? If it's 80% as good, then I think I
am fine with it...

Thanks!

Raymond

If he has it blown in there with a water spray (ie: stabilized blow) it
won't move and it won't settle.

s


"Joseph Meehan" wrote in message
...
I would go for the cellulose. It tends to seal better. As for the
dust, that is only a problem if you are up there or if you have leaky
returns. The supply side will not pull any dust in and frankly if there
is nothing to move the stuff, I don't see there being a dust problem, once
it is in.

how about closed cell expanding foam ? R6 per inch.

pricey but great insulator

I thought there was all kinds of controversary about that stuff. Moisture
wicking, offgassing, etc. Or am i thinking of another product?

s
(not to mention, you'd never pull a wire through it) LOL!


wrote in message
ps.com...
how about closed cell expanding foam ? R6 per inch.

pricey but great insulator

On Thu, 1 Nov 2007 19:43:24 -0700, "Bob F"
wrote:
wrote in message
...
I want to upgrade my attic insulation. I have 2x6 beams and old
unfaced R13-R19 fiberglass batts up there. I want to add R38 on top of
the existing insulation. I am in San Jose, CA.
[cut]
I went for the batts. It is great to be able to move them aside to add a wire or
whatever. I did it myself. It probably took 3-4 hours.

As far as insulation value, if you place them carefully together, fiberglass
should be fine. And it doesn't settle over time like the blown in cellulose I
put in my previous house.

Why aren't you considering icynene or polyurethane for maximum
insulation?

"KLS" wrote in message
...
On Thu, 1 Nov 2007 19:43:24 -0700, "Bob F"
wrote:
wrote in message
...
I want to upgrade my attic insulation. I have 2x6 beams and old
unfaced R13-R19 fiberglass batts up there. I want to add R38 on top of
the existing insulation. I am in San Jose, CA.
[cut]
I went for the batts. It is great to be able to move them aside to add a wire
or
whatever. I did it myself. It probably took 3-4 hours.

As far as insulation value, if you place them carefully together, fiberglass
should be fine. And it doesn't settle over time like the blown in cellulose I
put in my previous house.

Why aren't you considering icynene or polyurethane for maximum
insulation?

Because it would cost way more for the same insulation level, It's difficult to
install also. Foams only make sense for me if there is not space enough for
conventional insulations. Also, it would make re-working things in the space
very difficult.

Bob

On Nov 1, 4:23 pm, wrote:
I want to upgrade my attic insulation. I have 2x6 beams and old
unfaced R13-R19 fiberglass batts up there. I want to add R38 on top of
the existing insulation. I am in San Jose, CA.

I can do cellulose, which will give me uniform coverage and is the
least expensive option. But I've heard it's very dusty (even after
it's done, my furnace hot air ducts runs in the attic), not easy to
deal with if I need to go up the attic and do something, and boric
acid/ink may give off bad VOC.

I can do blown-in fiberglass, but how do I ensure the contractor won't
fluff the insulation? I am also not fond of the idea of lose
fiberglass floating around in the attic. They may get sucked into the
furnace duct and gets into the house.

I can do fiberglass rolls. Less chance of lose fiber floating around,
and R38 is R38. But it may not insulate as well as blown-in since it's
layed on top of my existing insulation and the coverage won't be as
uniform as blown-in. But advantage is I can move it out if I need to
go up and do something.

I am leaning toward the 3rd option. Assume the contractor does a
decent job, will it provide adequate insulation? Between a reasonably
installed (ie, average, not perfect) batt vs blown-in cellulose, how
does the fiberglass batt compare? If it's 80% as good, then I think I
am fine with it...

Thanks!

Raymond

Ray-

fiberglass rolls at 90 deg to current rolls...keep clear of roof
underside & allow for eave to ridge venting
Any gaps between the layersis just more dead air space...free
insulation.

btw are you adding R-19 to get up to R-38 total or adding R-38?

San Jose is a pretty mild climate so R-38 total should be plenty.

I'm in Orange County & I put R-30 in 1980; fiberglass rolls that I
just rolled back to do some attic work

The R-30 works pretty good for me but the old house is not as tight as
it could be due to other issues.

IMO blow-in cellulose is good stuff, it works but its a mess if you
ever need to revisit the attic. I hate it!

My parent's house has blow-in cellulose & it's been keeping the place
warm for ~30 years.

cheers
Bob

Thanks everyone for the reply!

fiberglass rolls at 90 deg to current rolls...keep clear of roof
underside & allow for eave to ridge venting
Any gaps between the layersis just more dead air space...free
insulation.

Ok I will keep that in mind and make sure the contractor does this.

btw are you adding R-19 to get up to R-38 total or adding R-38?

I am adding R38 on top of existing stuff, which is probably R13.

San Jose is a pretty mild climate so R-38 total should be plenty.

The contractor said the cost difference between R38 and R30 is minimal
compare to the cost of the job, so I am just going to go max and
install R38.

Thanks!

Raymond

According to KLS :

Why aren't you considering icynene or polyurethane for maximum
insulation?

They cost more than cellulose or fiberglass, and installing
the stuff on top of existing non-rigid insulation is silly.
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
It's not just anyone who gets a Starship Cruiser class named after them.

According to :
The contractor said the cost difference between R38 and R30 is minimal
compare to the cost of the job, so I am just going to go max and
install R38.

Ask your contractor if he can do rockwool (eg: Roxul).

Generally it's the same price as fiberglass, but is slightly
superior in all respects. Particularly that it's a lot less
picky and less likely to blow around. Can be blown or used as batts.
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
It's not just anyone who gets a Starship Cruiser class named after them.

Chris Lewis wrote:

Ask your contractor if he can do rockwool (eg: Roxul).

Generally it's the same price as fiberglass, but is slightly
superior in all respects. Particularly that it's a lot less
picky and less likely to blow around. Can be blown or used as batts.

Can you elaborate on why it's slightly superior? Thanks!

Raymond

According to :
Chris Lewis wrote:

Ask your contractor if he can do rockwool (eg: Roxul).

Generally it's the same price as fiberglass, but is slightly
superior in all respects. Particularly that it's a lot less
picky and less likely to blow around. Can be blown or used as batts.

Can you elaborate on why it's slightly superior? Thanks!

I'm speaking of Roxul here, I'm not familiar with other brands.
The Roxul product is manufactured under license from a European
company IIRC, and is somewhat different than the (much older)
forms of rock wool I've encountered.

Roxul is quite popular in Canada and I believe it's becoming
more popular in the US.

The R value is slightly higher than fiberglass (R21.5 vs R20 I
think for 5.5" batts).

It's heavier, and is a better sound barrier.

The fibers are larger and heavier, doesn't "fly" as much during
installation (no clouds of fine particles), and isn't so "picky".
Eg: you won't be breathing the stuff nor itching for days nor finding
it stuck/embedded in everything. Easier to cut. It's much more
pleasant to work with.

[As long as you're not working overhead, it's reasonable to install
rockwool without gloves/skin/breathing/eye protection.]

Even fiberglass will sog/permanently pack down to a certain extent
with moisture. Rock wool won't pack down, and sheds water quicker.

While fiberglass isn't flammable, the binders are, and the stuff melts
fairly readily. Rockwool has no binders, and the melt point is
considerably higher. Rockwool is thus considerably more fire resistant
than fiberglass.

Here (Roxul is big in Canada), the price per square foot is
usually identical to fiberglass. Most people who try Roxul won't
go back to fiberglass. We had roof insulation upgraded with
blown in (shredded batts) Roxul, and there was virtually _no_
dust anywhere, and I wouldn't think of using anything else. I've
also helped insulate a church extension (about 500 square feet)
with batts, and it was much nicer than previous fiberglass jobs.

About the only drawback to rockwool is that it doesn't compress
as much as fiberglass, so your order will consume more shipping/
storage space.

I have no relationship to the Roxul company, other than as a
satisfied customer ;-)
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
It's not just anyone who gets a Starship Cruiser class named after them.

Chris Lewis wrote:

Roxul is quite popular in Canada and I believe it's becoming
more popular in the US.

The R value is slightly higher than fiberglass (R21.5 vs R20 I
think for 5.5" batts).

It's heavier, and is a better sound barrier.

Sounds good. About the weight, I have standard 1/2" ceiling sheetrock.
Will the weight be an issue? If I go with batts, it will be resting on
the wood beams which should be fine, but if I go with blown-in, then
the weight might rest on the ceiling. Just don't want a sagged
ceiling, not to mention this is an earthquake area. Ho much heavier is
it compare to fiberglass and cellulose?

If I go with blown-in, how difficult will it be to move them aside to
do some work? I like the fire resistent and moisture resistent
property.

Thanks!

Raymond

According to :
Chris Lewis wrote:

Roxul is quite popular in Canada and I believe it's becoming
more popular in the US.

The R value is slightly higher than fiberglass (R21.5 vs R20 I
think for 5.5" batts).

It's heavier, and is a better sound barrier.

Sounds good. About the weight, I have standard 1/2" ceiling sheetrock.
Will the weight be an issue?

No. It's still mostly air ;-)

If I go with batts, it will be resting on
the wood beams which should be fine, but if I go with blown-in, then
the weight might rest on the ceiling. Just don't want a sagged
ceiling, not to mention this is an earthquake area. Ho much heavier is
it compare to fiberglass and cellulose?

Roxul is spun mining slag, fiberglass is spun glass. Slag is slighty
heavier than glass, and the fibers are fatter, but it's still mostly
air. A roxul batt is probably less than 50% heavier than a fiberglass
batt.

If I go with blown-in, how difficult will it be to move them aside to
do some work? I like the fire resistent and moisture resistent
property.

You just push it out of the way. Because of its higher weight and fiber
size it won't produce a vast cloud of flying fibers like fiberglass
does.
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
It's not just anyone who gets a Starship Cruiser class named after them.

On Nov 6, 8:40 am, (Chris Lewis) wrote:

Rockwool has no binders

Roxul's Rock Wool Insulation MSDS, available on their Web site,
contradicts this, saying that it contains one to six percent "Cured
Urea Extended Phenolic Formaldehyde Binder." The binder undergoes
"thermal decomposition" above 200 degrees Celsius, releasing the usual
suspects as gases. "Acrid smoke may be generated during a fire."

http://www.roxul.com/graphics/RX-NA/...xul%20Material
%20Safety%20Data%20Sheet%2004-1-071.pdf

--Eric Smith

According to Eric S. Smith: Left-Field Marshal :
On Nov 6, 8:40 am, (Chris Lewis) wrote:

Rockwool has no binders

Roxul's Rock Wool Insulation MSDS, available on their Web site,
contradicts this, saying that it contains one to six percent "Cured
Urea Extended Phenolic Formaldehyde Binder." The binder undergoes
"thermal decomposition" above 200 degrees Celsius, releasing the usual
suspects as gases. "Acrid smoke may be generated during a fire."

http://www.roxul.com/graphics/RX-NA/...xul%20Material
%20Safety%20Data%20Sheet%2004-1-071.pdf

Odd. I have done simplistic burn tests of both fiberglass
and Roxul - "try to light with a lighter". Fiberglass burns briefly,
gives off smoke, and melts. The Roxul glowed red, and that's all it
did. I've seen a video of a similar test with a propane torch with
similar results, and Roxul's fire resistance over fiberglass is
touted as one of the advantages.

Tho, the latter could be it slows down fire spread in building structures,
not that it doesn't emit something in a fire.

Formulation change? Different product? Brain damage?

Dunno ;-)
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
It's not just anyone who gets a Starship Cruiser class named after them.

Here's the video of trying to burn properly treated cellulose.

click on the big burn link at : http://www.cocooninsulation.com/homeowners/


steve


"Chris Lewis" wrote in message
...
According to Eric S. Smith: Left-Field Marshal :
On Nov 6, 8:40 am, (Chris Lewis) wrote:

Rockwool has no binders

Roxul's Rock Wool Insulation MSDS, available on their Web site,
contradicts this, saying that it contains one to six percent "Cured
Urea Extended Phenolic Formaldehyde Binder." The binder undergoes
"thermal decomposition" above 200 degrees Celsius, releasing the usual
suspects as gases. "Acrid smoke may be generated during a fire."

http://www.roxul.com/graphics/RX-NA/...xul%20Material
%20Safety%20Data%20Sheet%2004-1-071.pdf

Odd. I have done simplistic burn tests of both fiberglass
and Roxul - "try to light with a lighter". Fiberglass burns briefly,
gives off smoke, and melts. The Roxul glowed red, and that's all it
did. I've seen a video of a similar test with a propane torch with
similar results, and Roxul's fire resistance over fiberglass is
touted as one of the advantages.

Tho, the latter could be it slows down fire spread in building structures,
not that it doesn't emit something in a fire.

Formulation change? Different product? Brain damage?

Dunno ;-)
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
It's not just anyone who gets a Starship Cruiser class named after them.

According to Steve Barker :
Here's the video of trying to burn properly treated cellulose.

click on the big burn link at : http://www.cocooninsulation.com/homeowners/

It's an interesting video. But what must be remembered is that
that's just one manufacturer's test (not all cellulose is created
equal) shown as a marketing tool, and secondly, I'm not altogether
convinced that those fires were that representative of typical fire
behaviour in a real building structure. Eg: real buildings will
have hotter fires than that.
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
It's not just anyone who gets a Starship Cruiser class named after them.

hotter than a propane torch point blank eh? well alrighty then..... i
think not.

s


"Chris Lewis" wrote in message
...
It's an interesting video. But what must be remembered is that
that's just one manufacturer's test (not all cellulose is created
equal) shown as a marketing tool, and secondly, I'm not altogether
convinced that those fires were that representative of typical fire
behaviour in a real building structure. Eg: real buildings will
have hotter fires than that.
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
It's not just anyone who gets a Starship Cruiser class named after them.

According to Steve Barker :
hotter than a propane torch point blank eh? well alrighty then..... i
think not.

They used a propane torch to start those fires. It's _not_
representative of conditions _during_ the fires.

Those buildings were "open" structures (openings instead of doors
and windows), and didn't seem to have any interior wall coverings
like drywall. These were representative of insulated sheds. Not
houses.

Houses aren't built like sheds. People generally don't insulate
sheds either. Fire pattern is rather different in enclosed spaces
with drywall.
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
It's not just anyone who gets a Starship Cruiser class named after them.

I was referring to later on in the video where the guy has a hand full of it
and puts the torch to it in his hand.

s


"Chris Lewis" wrote in message
...
According to Steve Barker :
hotter than a propane torch point blank eh? well alrighty then..... i
think not.

They used a propane torch to start those fires. It's _not_
representative of conditions _during_ the fires.

Those buildings were "open" structures (openings instead of doors
and windows), and didn't seem to have any interior wall coverings
like drywall. These were representative of insulated sheds. Not
houses.

Houses aren't built like sheds. People generally don't insulate
sheds either. Fire pattern is rather different in enclosed spaces
with drywall.
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
It's not just anyone who gets a Starship Cruiser class named after them.