Hi,
My attic has 2x6 joists. The (ancient) fiberglass insulation between the joists appears to be matted down to about 2" thick.

Do I rip it out and replace with 6" thick batts and add more above that?
Or do I leave it, add 4" batts, and add more above that?

All opinions appreciated.
Regards,
Theodore.

wrote:
Hi,
My attic has 2x6 joists. The (ancient) fiberglass insulation between
the joists appears to be matted down to about 2" thick.

Do I rip it out and replace with 6" thick batts and add more above
that?
Or do I leave it, add 4" batts, and add more above that?

All opinions appreciated.

I have no idea where you are, but up north, thay are using a lot more than 6"
these days. I filled the joist space, then did another thick layer over that
(R30??).

On 5/17/2014 12:33 AM, wrote:
Hi,
My attic has 2x6 joists. The (ancient) fiberglass insulation between the joists appears to be matted down to about 2" thick.

Do I rip it out and replace with 6" thick batts and add more above that?
Or do I leave it, add 4" batts, and add more above that?

All opinions appreciated.
Regards,
Theodore.

I've worked with blown cellulose, once. Seemed
to do OK. I'd add more, over the top. Either
blown cellulose, or more fiberglass.


--
..
Christopher A. Young
Learn about Jesus
www.lds.org
..

On Saturday, May 17, 2014 6:58:05 AM UTC-4, Stormin Mormon wrote:
On 5/17/2014 12:33 AM, wrote:

Hi,

My attic has 2x6 joists. The (ancient) fiberglass insulation between the joists appears to be matted down to about 2" thick.



Do I rip it out and replace with 6" thick batts and add more above that?

Or do I leave it, add 4" batts, and add more above that?



All opinions appreciated.

Regards,

Theodore.



I've worked with blown cellulose, once. Seemed

to do OK. I'd add more, over the top. Either

blown cellulose, or more fiberglass.



Unless height is an issue, I'd just add on top of what's
there, probably use batts. As Bob said, 6" isn't much,for
most of the USA in winter, R30 is the minimum. That's 9 1/2"
thick. The original should have a vapor barrier and if you
use batts, then it should not have a vapor barrier.

On Fri, 16 May 2014 22:26:53 -0700, "Bob F"
wrote:

wrote:
Hi,
My attic has 2x6 joists. The (ancient) fiberglass insulation between
the joists appears to be matted down to about 2" thick.

Do I rip it out and replace with 6" thick batts and add more above
that?
Or do I leave it, add 4" batts, and add more above that?

All opinions appreciated.

I have no idea where you are, but up north, thay are using a lot more than 6"
these days. I filled the joist space, then did another thick layer over that
(R30??).

He DID say he was going to add more above.
Matted down insulation has poor insulation value. I'd remove the old
first - and be tempted to have a spray insulation applied (about 2
inches) to act also as a vapour barrier and then fill with blown
insulation above that.

On Saturday, May 17, 2014 11:13:59 AM UTC-4, wrote:
On Fri, 16 May 2014 22:26:53 -0700, "Bob F"

wrote:



wrote:

Hi,

My attic has 2x6 joists. The (ancient) fiberglass insulation between

the joists appears to be matted down to about 2" thick.



Do I rip it out and replace with 6" thick batts and add more above

that?

Or do I leave it, add 4" batts, and add more above that?



All opinions appreciated.



I have no idea where you are, but up north, thay are using a lot more than 6"

these days. I filled the joist space, then did another thick layer over that

(R30??).



He DID say he was going to add more above.

I missed that. I guess enough insulation to fill it up
to the level of the top of the joists, then loose cellulose
gives the best energy solution. I wonder what the energy difference
is if you use just thick batts? There would be some gaps
between them, ie between joists, which would cut down the
performance. Topping it with blown-in would be better from
that standpoint. Only thing about blown-in I don't like is
that if you have to do some work, eg find an electric, phone,
CATV etc cable, it's going to be a pain in the ass. But I
guess you don't have to do that very often.



Matted down insulation has poor insulation value. I'd remove the old

first - and be tempted to have a spray insulation applied (about 2

inches) to act also as a vapour barrier and then fill with blown

insulation above that.

Sounds like unnecessary complication to me. I agree if it's matted,
it has low R value, but so what? It's still greater than zero, and
if you put what you intend to put on top of it, you have the new plus
whatever is existing. A little more insulation and you avoid the
work and disposal, etc of ripping the old stuff out.

trader_4 wrote:
On Saturday, May 17, 2014 11:13:59 AM UTC-4, wrote:
On Fri, 16 May 2014 22:26:53 -0700, "Bob F"

wrote:



wrote:

Hi,

My attic has 2x6 joists. The (ancient) fiberglass insulation between

the joists appears to be matted down to about 2" thick.



Do I rip it out and replace with 6" thick batts and add more above

that?

Or do I leave it, add 4" batts, and add more above that?



All opinions appreciated.



I have no idea where you are, but up north, thay are using a lot more than 6"

these days. I filled the joist space, then did another thick layer over that

(R30??).



He DID say he was going to add more above.

I missed that. I guess enough insulation to fill it up
to the level of the top of the joists, then loose cellulose
gives the best energy solution. I wonder what the energy difference
is if you use just thick batts? There would be some gaps
between them, ie between joists, which would cut down the
performance. Topping it with blown-in would be better from
that standpoint. Only thing about blown-in I don't like is
that if you have to do some work, eg find an electric, phone,
CATV etc cable, it's going to be a pain in the ass. But I
guess you don't have to do that very often.



Matted down insulation has poor insulation value. I'd remove the old

first - and be tempted to have a spray insulation applied (about 2

inches) to act also as a vapour barrier and then fill with blown

insulation above that.

Sounds like unnecessary complication to me. I agree if it's matted,
it has low R value, but so what? It's still greater than zero, and
if you put what you intend to put on top of it, you have the new plus
whatever is existing. A little more insulation and you avoid the
work and disposal, etc of ripping the old stuff out.

Hi,
My question is how come it matted down? Moisture problem one time or
another? I want to make sure about this. Is there vapor barrier under
neath?
If all is good, I'd just add more insulation by any means. Here it is
R60 in the attic.

On 5/17/2014 11:04 AM, Tony Hwang wrote:
trader_4 wrote:
On Saturday, May 17, 2014 11:13:59 AM UTC-4, wrote:
On Fri, 16 May 2014 22:26:53 -0700, "Bob F"

wrote:



wrote:

Hi,

My attic has 2x6 joists. The (ancient) fiberglass insulation between

the joists appears to be matted down to about 2" thick.



Do I rip it out and replace with 6" thick batts and add more above

that?

Or do I leave it, add 4" batts, and add more above that?



All opinions appreciated.



I have no idea where you are, but up north, thay are using a lot
more than 6"

these days. I filled the joist space, then did another thick layer
over that

(R30??).



He DID say he was going to add more above.

I missed that. I guess enough insulation to fill it up
to the level of the top of the joists, then loose cellulose
gives the best energy solution. I wonder what the energy difference
is if you use just thick batts? There would be some gaps
between them, ie between joists, which would cut down the
performance. Topping it with blown-in would be better from
that standpoint. Only thing about blown-in I don't like is
that if you have to do some work, eg find an electric, phone,
CATV etc cable, it's going to be a pain in the ass. But I
guess you don't have to do that very often.



Matted down insulation has poor insulation value. I'd remove the old

first - and be tempted to have a spray insulation applied (about 2

inches) to act also as a vapour barrier and then fill with blown

insulation above that.

Sounds like unnecessary complication to me. I agree if it's matted,
it has low R value, but so what? It's still greater than zero, and
if you put what you intend to put on top of it, you have the new plus
whatever is existing. A little more insulation and you avoid the
work and disposal, etc of ripping the old stuff out.

Hi,
My question is how come it matted down? Moisture problem one time or
another? I want to make sure about this. Is there vapor barrier under
neath?
If all is good, I'd just add more insulation by any means. Here it is
R60 in the attic.

If it's like my attic it's dust piled up over the decades. I think, when
I finally get the funds together, I'm going to have old insulation left
in place with cellulose blown over it. With vaulted ceiling it's
probably the best solution. Back in '83, when they built my house, they
used some kind of rock wool insulation. Seems to work okay, but I'm sure
it's not anywhere near present standards.

Hi.
House is in lower New York State.
Existing batts have been matted down over their apparent 60+year life in the attic.
I find fiberglass batts much easier to deal with than blown cellulose, so I'll stick with them.
I guess I'll leave the existing and just place more on top!

On Friday, May 16, 2014 11:33:48 PM UTC-5, wrote:
Hi, My attic has 2x6 joists. The (ancient) fiberglass insulation between the joists appears to be matted down to about 2" thick. Do I rip it out and replace with 6" thick batts and add more above that? Or do I leave it, add 4" batts, and add more above that? All opinions appreciated. Regards, Theodore.

Any bats added above the joists should be placed at right angles to the direction of the original bats to ensure there are no accidental "chimneys".

On 5/17/2014 1:10 PM, wrote:
....

Existing batts have been matted down over their apparent 60+year
life in the attic.
....
I guess I'll leave the existing and just place more on top!

As long as they're not completely full of dirt as can happen here in the
High Plains over that period...we took over 2" of accumulated dirt out
of the attic of the house here (built in '15/'16). Most was from the
"Dirty 30's" but I'm sure a fair amount also accumulated during the
other really bad period of the 50's...

--

On Sat, 17 May 2014 10:04:11 -0600, Tony Hwang
wrote:

trader_4 wrote:
On Saturday, May 17, 2014 11:13:59 AM UTC-4, wrote:
On Fri, 16 May 2014 22:26:53 -0700, "Bob F"

wrote:



wrote:

Hi,

My attic has 2x6 joists. The (ancient) fiberglass insulation between

the joists appears to be matted down to about 2" thick.



Do I rip it out and replace with 6" thick batts and add more above

that?

Or do I leave it, add 4" batts, and add more above that?



All opinions appreciated.



I have no idea where you are, but up north, thay are using a lot more than 6"

these days. I filled the joist space, then did another thick layer over that

(R30??).



He DID say he was going to add more above.

I missed that. I guess enough insulation to fill it up
to the level of the top of the joists, then loose cellulose
gives the best energy solution. I wonder what the energy difference
is if you use just thick batts? There would be some gaps
between them, ie between joists, which would cut down the
performance. Topping it with blown-in would be better from
that standpoint. Only thing about blown-in I don't like is
that if you have to do some work, eg find an electric, phone,
CATV etc cable, it's going to be a pain in the ass. But I
guess you don't have to do that very often.



Matted down insulation has poor insulation value. I'd remove the old

first - and be tempted to have a spray insulation applied (about 2

inches) to act also as a vapour barrier and then fill with blown

insulation above that.

Sounds like unnecessary complication to me. I agree if it's matted,
it has low R value, but so what? It's still greater than zero, and
if you put what you intend to put on top of it, you have the new plus
whatever is existing. A little more insulation and you avoid the
work and disposal, etc of ripping the old stuff out.

Hi,
My question is how come it matted down? Moisture problem one time or
another? I want to make sure about this. Is there vapor barrier under
neath?
If all is good, I'd just add more insulation by any means. Here it is
R60 in the attic.
There SHOULD be vapour barrier under it, but you can almost guarantee
it is not uninterupted if it IS there - which is why I would seriously
consider removing what is there and having a thin coat of spray foal
installed before filling it with cellulose or fiberglass.

On Sat, 17 May 2014 12:02:44 -0500, gonjah wrote:

On 5/17/2014 11:04 AM, Tony Hwang wrote:
trader_4 wrote:
On Saturday, May 17, 2014 11:13:59 AM UTC-4, wrote:
On Fri, 16 May 2014 22:26:53 -0700, "Bob F"

wrote:



wrote:

Hi,

My attic has 2x6 joists. The (ancient) fiberglass insulation between

the joists appears to be matted down to about 2" thick.



Do I rip it out and replace with 6" thick batts and add more above

that?

Or do I leave it, add 4" batts, and add more above that?



All opinions appreciated.



I have no idea where you are, but up north, thay are using a lot
more than 6"

these days. I filled the joist space, then did another thick layer
over that

(R30??).



He DID say he was going to add more above.

I missed that. I guess enough insulation to fill it up
to the level of the top of the joists, then loose cellulose
gives the best energy solution. I wonder what the energy difference
is if you use just thick batts? There would be some gaps
between them, ie between joists, which would cut down the
performance. Topping it with blown-in would be better from
that standpoint. Only thing about blown-in I don't like is
that if you have to do some work, eg find an electric, phone,
CATV etc cable, it's going to be a pain in the ass. But I
guess you don't have to do that very often.



Matted down insulation has poor insulation value. I'd remove the old

first - and be tempted to have a spray insulation applied (about 2

inches) to act also as a vapour barrier and then fill with blown

insulation above that.

Sounds like unnecessary complication to me. I agree if it's matted,
it has low R value, but so what? It's still greater than zero, and
if you put what you intend to put on top of it, you have the new plus
whatever is existing. A little more insulation and you avoid the
work and disposal, etc of ripping the old stuff out.

Hi,
My question is how come it matted down? Moisture problem one time or
another? I want to make sure about this. Is there vapor barrier under
neath?
If all is good, I'd just add more insulation by any means. Here it is
R60 in the attic.

If it's like my attic it's dust piled up over the decades. I think, when
I finally get the funds together, I'm going to have old insulation left
in place with cellulose blown over it. With vaulted ceiling it's
probably the best solution. Back in '83, when they built my house, they
used some kind of rock wool insulation. Seems to work okay, but I'm sure
it's not anywhere near present standards.
Roxul is still about the best insulation you can buy - it does not
absorb water, it does not support mold, or mice.

On Saturday, May 17, 2014 6:45:47 PM UTC-4, wrote:
On Sat, 17 May 2014 10:04:11 -0600, Tony Hwang

wrote:



trader_4 wrote:

On Saturday, May 17, 2014 11:13:59 AM UTC-4, wrote:

On Fri, 16 May 2014 22:26:53 -0700, "Bob F"



wrote:







wrote:



Hi,



My attic has 2x6 joists. The (ancient) fiberglass insulation between



the joists appears to be matted down to about 2" thick.







Do I rip it out and replace with 6" thick batts and add more above



that?



Or do I leave it, add 4" batts, and add more above that?







All opinions appreciated.







I have no idea where you are, but up north, thay are using a lot more than 6"



these days. I filled the joist space, then did another thick layer over that



(R30??).







He DID say he was going to add more above.



I missed that. I guess enough insulation to fill it up

to the level of the top of the joists, then loose cellulose

gives the best energy solution. I wonder what the energy difference

is if you use just thick batts? There would be some gaps

between them, ie between joists, which would cut down the

performance. Topping it with blown-in would be better from

that standpoint. Only thing about blown-in I don't like is

that if you have to do some work, eg find an electric, phone,

CATV etc cable, it's going to be a pain in the ass. But I

guess you don't have to do that very often.







Matted down insulation has poor insulation value. I'd remove the old



first - and be tempted to have a spray insulation applied (about 2



inches) to act also as a vapour barrier and then fill with blown



insulation above that.



Sounds like unnecessary complication to me. I agree if it's matted,

it has low R value, but so what? It's still greater than zero, and

if you put what you intend to put on top of it, you have the new plus

whatever is existing. A little more insulation and you avoid the

work and disposal, etc of ripping the old stuff out.



Hi,

My question is how come it matted down? Moisture problem one time or

another? I want to make sure about this. Is there vapor barrier under

neath?

If all is good, I'd just add more insulation by any means. Here it is

R60 in the attic.

There SHOULD be vapour barrier under it, but you can almost guarantee

it is not uninterupted if it IS there - which is why I would seriously

consider removing what is there and having a thin coat of spray foal

installed before filling it with cellulose or fiberglass.


Let's say it has the typical vapor barrier similar houses would have.
What is going to happen that is so bad, from just adding more insulation?
If this house isn't experiencing any problems related to moisture passing
through the vapor barrier that is there, what's the compelling need to
rip out the existing insulation and do spray foam?

The house I'm living in, I'm sure the vapor barrier isn't perfect.
It isn't perfect in new construction either. But I'm not seeing
any problems from it. And if the OP doesn't have problems, I'm
not seeing the necessity of the rip out and spraying in foam.

On 5/17/2014 5:48 PM, wrote:
On Sat, 17 May 2014 12:02:44 -0500, gonjah wrote:

On 5/17/2014 11:04 AM, Tony Hwang wrote:
trader_4 wrote:
On Saturday, May 17, 2014 11:13:59 AM UTC-4, wrote:
On Fri, 16 May 2014 22:26:53 -0700, "Bob F"

wrote:



wrote:

Hi,

My attic has 2x6 joists. The (ancient) fiberglass insulation between

the joists appears to be matted down to about 2" thick.



Do I rip it out and replace with 6" thick batts and add more above

that?

Or do I leave it, add 4" batts, and add more above that?



All opinions appreciated.



I have no idea where you are, but up north, thay are using a lot
more than 6"

these days. I filled the joist space, then did another thick layer
over that

(R30??).



He DID say he was going to add more above.

I missed that. I guess enough insulation to fill it up
to the level of the top of the joists, then loose cellulose
gives the best energy solution. I wonder what the energy difference
is if you use just thick batts? There would be some gaps
between them, ie between joists, which would cut down the
performance. Topping it with blown-in would be better from
that standpoint. Only thing about blown-in I don't like is
that if you have to do some work, eg find an electric, phone,
CATV etc cable, it's going to be a pain in the ass. But I
guess you don't have to do that very often.



Matted down insulation has poor insulation value. I'd remove the old

first - and be tempted to have a spray insulation applied (about 2

inches) to act also as a vapour barrier and then fill with blown

insulation above that.

Sounds like unnecessary complication to me. I agree if it's matted,
it has low R value, but so what? It's still greater than zero, and
if you put what you intend to put on top of it, you have the new plus
whatever is existing. A little more insulation and you avoid the
work and disposal, etc of ripping the old stuff out.

Hi,
My question is how come it matted down? Moisture problem one time or
another? I want to make sure about this. Is there vapor barrier under
neath?
If all is good, I'd just add more insulation by any means. Here it is
R60 in the attic.

If it's like my attic it's dust piled up over the decades. I think, when
I finally get the funds together, I'm going to have old insulation left
in place with cellulose blown over it. With vaulted ceiling it's
probably the best solution. Back in '83, when they built my house, they
used some kind of rock wool insulation. Seems to work okay, but I'm sure
it's not anywhere near present standards.
Roxul is still about the best insulation you can buy - it does not
absorb water, it does not support mold, or mice.

That's nice to know. I have vaulted ceiling in well over 50% of my house
and access to some areas of the attic requires a contortionist.

Tony Hwang wrote:
Hi,
My question is how come it matted down? Moisture problem one time or
another? I want to make sure about this. Is there vapor barrier under
neath?
If all is good, I'd just add more insulation by any means. Here it is
R60 in the attic.

My guess would be that it started as no more than R-11 insulation, so it really
didn't matt down all that much.

wrote:
Roxul is still about the best insulation you can buy - it does not
absorb water, it does not support mold, or mice.

And it is much more resistant to high temps than fiberglass or cellulose.

trader_4 wrote:
Let's say it has the typical vapor barrier similar houses would have.
What is going to happen that is so bad, from just adding more
insulation? If this house isn't experiencing any problems related to
moisture passing through the vapor barrier that is there, what's the
compelling need to rip out the existing insulation and do spray foam?

The house I'm living in, I'm sure the vapor barrier isn't perfect.
It isn't perfect in new construction either. But I'm not seeing
any problems from it. And if the OP doesn't have problems, I'm
not seeing the necessity of the rip out and spraying in foam.

If it doesn't have a vapor barrier, that could cause it to matt down. It would
at least be worth pulling up a bit of the old insullation and checking for a
good vapor barrier.

wrote:
On Friday, May 16, 2014 11:33:48 PM UTC-5, wrote:
Hi, My attic has 2x6 joists. The (ancient) fiberglass insulation
between the joists appears to be matted down to about 2" thick. Do I
rip it out and replace with 6" thick batts and add more above that?
Or do I leave it, add 4" batts, and add more above that? All
opinions appreciated. Regards, Theodore.

Any bats added above the joists should be placed at right angles to
the direction of the original bats to ensure there are no accidental
"chimneys".

That's how I did it. I also built raised walkway above the final insulation
level first. so I can get in there without walking on the new insullation. Just
2 - 2x6's about 6" apart on supports nailed to the joists down the middle of the
attic spaces. Makes it a lot easier to fix wiring, atc. The nice thing about
insulation batts is they make it much easiers to expose the wiring if you need
to work on it.