From: cox@cadence.com (Henry Cox; x6410)
Subject: SUMMARY: Insulation - retrofit an old house
Organization: Cadence Design Systems/CAE Div, Lowell MA
Date: Sun, 16 Aug 1992 04:24:26 GMT


A couple of weeks ago I requested information regarding installing
insulation in an old house.  The following is a (more or less
chronological collation of the responsed I got, both email and posted.
(Name removed, just in case someone didn't want to be cited.)

Thanks to everyone who responded.  And to anyone who feels like adding
something - I'm still here and still interested.

(Things heated up rather a lot at work in the meantime, so we have not
decided what to do yet - still plenty of time for you to get your
$0.02 in!)

					Henry

PS:  This is rather long - you might want to hit "n" (or whatever)
now... 


------------------------------------------------------------

(email)

In article <COX.92Aug4181712@acae206.acae206> you write:
>
>My wife and I recently purchased an older (~50 years) house.
>Unfortunately, it was built in the days of cheap energy, and has
>virtually no insulation in the walls or attic -

Tell me about it. My house is 137... 

> or anywhere else, for that matter.  We would like to do something 
> about that.
>
>Materials:
>
>We have gotten two quotes for blown cellulose.  According to them,
>cellulose is better because:
>	- it does not burn (impregnated with boric acid)
>	- mice, etc. will not nest in it (boric acid again) - they
>	  will nest in fibreglass
>	- termites, etc. don't like the flavor and won't eat it
>	- it is nontoxic - children and pets who do eat it may feel
>	  ill, but won't die.
>
>One guy selling blown fibreglass was also in.  What a surprise, he
>thinks fibreglass is best:
>	- it won't burn (contradicted by the cellulose folks)
>	- it does not settle as much (?)
>	- if it gets wet, it will dry out and continue to function.
>	  Cellulose won't
>	- termites, etc. can't eat it

The guy that owned our house before us blew in cellulose. My experience
with these two (when I replace an inside wall I replace the cellulose
with fiberglass batts): The cellulose does settle (a lot of the upstairs
rooms do not have insulation because it has settled downstairs). The
cellulose is not flamable (I think fiberglass is).

>
>Rock wool does not appear to be an option - no one here seems to sell
>it.  

I do not think it is made any more.

>Fibreglass batts are not a good option even in the attic (it has
>a floor which I am not eager to take up).

Another option (although I do not know what it would cost) is to have
a foam insulation blown in.  You know, it is that stuff that comes out
as a foam, it then swells and hardens. An advantage with it is that
I do not think you need a vapor barrier.

>
>What, if anything, is done about a vapor barrier in this kind of
>situation?  One option may be that the builder was religious in
>carefully installing foil-faced/foil-backed (both sides) kraft paper
>everywhere - presumably because it was "scientific" (radiant heat
>loss, etc.).  With any luck, insulation blown from the exterior will
>crush it up against the interior wall.

I bet you that the builder did not do that. In this case I think there
is only two ways to get a vapor barrier (1) paint the interior walls
with a paint that acts as a vapor barrier (not the most effective way)
or (2) tear out all of the inside walls and install the vapor barrier
(I don't think you want to do that).

>
>
>The house:
>
>... is a two-story colonial with sloped ceilings on the second floor.
>Total area of walls, slopes, and attic is ~2400 sq. ft.  In most
>places, the walls are 6 inches thick (they used a _lot_ of wood).
>
>The exterior is 8" clapboard.  New clapboard seems to run about
>$0.80/ft. 
>
>It has a concrete block foundataion and a full (unfinished) basement.
>What should I do for basement insulation?  (I intend to use it as a
>workshop.) 
>
>Heat is forced hot water by gas.  The boiler is very old and may need
>to be replaced in a few years.  (On the other hand, it may outlast us
>all.) 
>
>
>The cost:
>
>The fibreglass quote is not in yet.  The other two were for $975 and
>$1950, respectively.  Is this reasonable? 

Quite a difference...

>
>The price difference concerns me - what could one be doing that the
>other isn't?  (Aside from making a hefty profit.) 
>	- the expensive guy will give a written guarantee that all is
>	  well and will come back if he missed something.  I believe
>	  that he will also reinstall clapboards (replace ones that
>	  get broken, etc.) 
>
>A potential cost-saving option is to try to do it ourselves.  Is this
>a good idea?  (Both cost and effort required are factors.)
>

You can rent the necessary equipment, but it will take time - since 
you don't do it for a living you will have to learn as you go (this is
what I am doing with other projects on my house - and my wife cannot
understand why it takes me so long to finish a job).

>
>The summary:
>
>All told, my question to the net.collective.wisdom is: what should we
>know?  what questions should we be asking?  what was your experience?
>what did it cost?  Would you do it again?, etc.  etc.  Also, if you
>happen to live in the Boston area and know someone you would
>recommend/stay away from, please let me know.
>

My only suggestion - no matter which type you go with: DO NOT let them
drill holes in your clapboards to blow the stuff in. There are two
other ways that they can do it (1) remove strategic clapboards or
(2) go into the interior of the house and drill holes in the 
plaster/drywall (which can then be patched).  The previous owner who
blew insulation into my house just drilled holes. The house looks
pretty stupid with all of these little white plastic plugs in the
clapboards. So, as I repaint the houes (stripping off the multiple
layers of paint and re-painting) I am either replacing clapboards
(if they have too many of those little plugs) or putting wood plugs
in and sanding them down to hide the holes.

Good luck

------------------------------------------------------------

(email) 

We were in much the same situation with our house ('cept it's a lot
smaller).  We ended up blowing cellulose ourselves.  

I tried burning some cellulose and it wouldn't; it sort of melts and 
blackens, but that's it.  Cellulose does settle though, and does pack 
& become less effective if it gets wet, and doesn't have as great an 
R value as does fiberglass.  If I had it to do over I'd go for fiberglass.

If money is a problem consider doing it yourself.  Our outside paint
is about shot anyway so we pried off the top row of clapboards, as well
as a row under the windows, and blew it in.  The materials are really
pretty cheap (I think we spent $75 but we weren't starting from a
completely insulation-free house, and ours is only 1200 sq. feet).
The place that sells you the insulation should also have blowers 
available.

-------------------------------------------------------------- 

(My reply)

> We were in much the same situation with our house ('cept it's a lot
> smaller).  We ended up blowing cellulose ourselves.  

Actually, the house isn't that large - about 1900 ft^2, not including
the basement.  It has an odd footprint, though (lots of bends and
corners), which result in a very large surface area.  (Apparently, the
surface area of most 3000 ft^2 houses is less than 2000 ft^2 - our
house is way off the curve.)

> I tried burning some cellulose and it wouldn't; it sort of melts and 
> blackens, but that's it.  Cellulose does settle though, and does pack 
> & become less effective if it gets wet, and doesn't have as great an 
> R value as does fiberglass.  If I had it to do over I'd go for
> fiberglass.

Any other reasons to go for fibreglass aside from R/inch?  (I still
have not found definitive unbaised figures for R/inch of cellulose vs.
fibreglass - the manufacturer of each says that theirs is the best.
They use different test methods, though.).  I was also told that
fibreglass is much more difficult to blow in - the equipment is much
more expensive and harder to use, although the raw material costs
about the same as cellulose.

> If money is a problem consider doing it yourself.  Our outside paint
> is about shot anyway so we pried off the top row of clapboards, as well
> as a row under the windows, and blew it in.  The materials are really
> pretty cheap (I think we spent $75 but we weren't starting from a
> completely insulation-free house, and ours is only 1200 sq. feet).
> The place that sells you the insulation should also have blowers 
> available.

Our paint is also shot - we would like to insulate before we repaint.
How difficult was it to blow the stuff in?  Did you probe the walls to
find obstructions, drill extra holes, etc. to prevent voids?  The
second floor of the house is ~16 ft. from the ground - will this be a
problem?  (I'm not wild about heights.)

Thanks for the information. I will post a summary when it looks like
everyone who is going to respond has done so.


------------------------------------------------------------

(reply to reply)

>> with these two (when I replace an inside wall I replace the cellulose
>> with fiberglass batts): The cellulose does settle (a lot of the upstairs
>> rooms do not have insulation because it has settled downstairs). The
>> cellulose is not flamable (I think fiberglass is).
>
>Any opinions?  Is the settling due to lack of care in installation, or
>something that is bound to happen?  How long did it take to settle?
>(Some installers will come back to fill voids - voids can be detected
>by an infrared scan in winter.)

I think it is bound to happen. How long? well I assume that the previous
owner did the job about 10 years ago (he did it himself, so there was no
installer to come back and fill any voids).

>
>>>Rock wool does not appear to be an option - no one here seems to sell
>>>it.  
>
>>I do not think it is made any more.
>
>I think you are right - at least that what the insulation folks around
>here say.   However, I have seen mention of it several times on the
>net, so I thought I would throw it in.
>
>> Another option (although I do not know what it would cost) is to have
>> a foam insulation blown in.  You know, it is that stuff that comes out
>> as a foam, it then swells and hardens. An advantage with it is that
>> I do not think you need a vapor barrier.
>
>Do you know the names of any manufacturers?  I would like to check
>into foam, but haven't found anyone who does it in this area.  The
>manufacturer might be able to give me some, or tell me if it is
>something I can do myself.
>

Sorry I cannot help. I went to a local home improvement show once (about
four years ago) and there was a company there who did that kind of work, 
but I didn't pursue it because I would have had to take out the cellulose
before they could have blown that stuff in.

>> My only suggestion - no matter which type you go with: DO NOT let them
>> drill holes in your clapboards to blow the stuff in. There are two
>> other ways that they can do it (1) remove strategic clapboards or
>> (2) go into the interior of the house and drill holes in the 
>> plaster/drywall (which can then be patched).  The previous owner who
>> blew insulation into my house just drilled holes. The house looks
>> pretty stupid with all of these little white plastic plugs in the
>> clapboards. So, as I repaint the houes (stripping off the multiple
>> layers of paint and re-painting) I am either replacing clapboards
>> (if they have too many of those little plugs) or putting wood plugs
>> in and sanding them down to hide the holes.
>
>We are going to try removing the clapboards - like you, I think it
>will look funny if holes are drilled directly in the clapboards.  The
>only problem there is that they aren't easy to get off without
>breaking them (double nailed in a lot of places, including with those
>little triangular clapboard nails)
>

Since our house is so old the clapboards are nailed with cut nails. The
procedure I use is as follows:  Using a pry bar work your way under the
clapboard you want to remvoe. Work it out enough to get a blade under the
board (hardware stores have these little handles that hold hacksaw
blades) cut all of the nails holding the board in question. Next, do the
same thing with the board above the board in question. Then the board
you want to remove should be able to be pulled out. When you are done putting
in the insulation, you put the clapboard in and re-nail it.  The thing I am
not sure about is how you go about picking the proper clapboard to remove.
Due to fire stops, and cross members in the walls, you may have trouble 
and need to take off more than one per wall.

Yes, it is still possible to crack the board. But, if it was my house, I 
would rather replace an occasional clapboard than have those stupid little
holes. Just my opinion.

------------------------------------------------------------
(email)

This isn't exactly an answer to your post, but it is something to 
investigate.  I have heard that knob-and-tube wiring (which you probably have)
is not rated for use in an insulated space.  It might get too hot which
could be a safety problem.  I don't know if this is true but please find
out before you insulate.

------------------------------------------------------------

(My reply to a message I seem to have misplaced)

> The guy that owned our house before us blew in cellulose. My experience
> with these two (when I replace an inside wall I replace the cellulose
> with fiberglass batts): The cellulose does settle (a lot of the upstairs
> rooms do not have insulation because it has settled downstairs). The
> cellulose is not flamable (I think fiberglass is).

Any opinions?  Is the settling due to lack of care in installation, or
something that is bound to happen?  How long did it take to settle?
(Some installers will come back to fill voids - voids can be detected
by an infrared scan in winter.)

>>Rock wool does not appear to be an option - no one here seems to sell
>>it.  

>I do not think it is made any more.

I think you are right - at least that what the insulation folks around
here say.   However, I have seen mention of it several times on the
net, so I thought I would throw it in.

> Another option (although I do not know what it would cost) is to have
> a foam insulation blown in.  You know, it is that stuff that comes out
> as a foam, it then swells and hardens. An advantage with it is that
> I do not think you need a vapor barrier.

Do you know the names of any manufacturers?  I would like to check
into foam, but haven't found anyone who does it in this area.  The
manufacturer might be able to give me some, or tell me if it is
something I can do myself.

>>What, if anything, is done about a vapor barrier in this kind of
>>situation?  One option may be that the builder was religious in
>>carefully installing foil-faced/foil-backed (both sides) kraft paper
>>everywhere - presumably because it was "scientific" (radiant heat
>>loss, etc.).  With any luck, insulation blown from the exterior will
>>crush it up against the interior wall.

>I bet you that the builder did not do that. In this case I think there
>is only two ways to get a vapor barrier (1) paint the interior walls
>with a paint that acts as a vapor barrier (not the most effective way)
>or (2) tear out all of the inside walls and install the vapor barrier
>(I don't think you want to do that).

We have had to tear out and replace a couple of interior walls
(previous owner did _no_ maintainance for 20 years - consequently, the
front entry was literally falling down and the plaster on the bathroom
walls was rotted out due to moisture.  Everywhere we look we find the
foil.  We are looking into the interior paint option.  You are right -
having taken out a couple of walls, I don't want to do any more (very
messy, nasty job.)

>>A potential cost-saving option is to try to do it ourselves.  Is this
>>a good idea?  (Both cost and effort required are factors.)

>You can rent the necessary equipment, but it will take time - since 
>you don't do it for a living you will have to learn as you go (this is
>what I am doing with other projects on my house - and my wife cannot
>understand why it takes me so long to finish a job).

That's what we are doing too - as you say - it takes a lot longer when
you do it yourself.  My concern is that it may both take longer and
end up worse than if I hire someone - also, it may not be worth my
time.  

There were a couple of bags of cellulose in our attic when we moved in
- it looks like a previous owner started the job and then quit (only
about a third of the attic was completed).  I'm not sure if it was
because the job was unpleasant/difficult, or because that's just the
way he did things.  (Judging by the entry and bathroom, the latter is
quite possible!)

> My only suggestion - no matter which type you go with: DO NOT let them
> drill holes in your clapboards to blow the stuff in. There are two
> other ways that they can do it (1) remove strategic clapboards or
> (2) go into the interior of the house and drill holes in the 
> plaster/drywall (which can then be patched).  The previous owner who
> blew insulation into my house just drilled holes. The house looks
> pretty stupid with all of these little white plastic plugs in the
> clapboards. So, as I repaint the houes (stripping off the multiple
> layers of paint and re-painting) I am either replacing clapboards
> (if they have too many of those little plugs) or putting wood plugs
> in and sanding them down to hide the holes.

We are going to try removing the clapboards - like you, I think it
will look funny if holes are drilled directly in the clapboards.  The
only problem there is that they aren't easy to get off without
breaking them (double nailed in a lot of places, including with those
little triangular clapboard nails)

------------------------------------------------------------

(email)

In article <COX.92Aug4181712@acae206.acae206> you write:
>
>The cost:
>
>The fibreglass quote is not in yet.  The other two were for $975 and
>$1950, respectively.  Is this reasonable? 

Hmm,  BOTH prices sound very cheap to me.  I just paid 400.00 just to
have the floor insulated with R19 fiberglass (my house is only 1100 sqft).
We are insulating the ducts ourselves but are buying the materials 
through the contractor (about 300.00 for duct wrap, tape and some new 
flexible ducting--we are replacing some of the ducts outright, it's easier).
The last time I insulated an attic (another 1100 sqft house) with fiberglass
batts the cost was 250.00.  So, that 975.00 figure of yours to insulate
an entire, huge, house sounds very low.  Removing clapboards to blow
in insulation is a very time-consuming (ie. labor-intensive ie. expensive)
job.  Many older houses have wood sheathing under the clapboards which
must have holes drilled into it.  My parent's house (in NH) did.  It
looked like a giant purple martin birdhouse by the time the insulators
were done drilling holes into it!

------------------------------------------------------------

(email)

Well, you are going to get lots of responses, I'm sure.  Personally, we just
had 12 inches of fiberglass blown in our attic on top of 3 inches of
cellulose that used to be 6 inches of cellulose...I would never use cellulose,
myself.  While it is a lot easier to be in the attic with it, it does settle
a lot more than fiberglass, and is also heavier.  We have fiberglass batts
in the wall, but there is no vapor barrier anywhere in the house that I
know of.  I believe that the builder must be of the "houses got to breathe"
school.  However, it was 100 degrees on Sunday, and our house stayed in
the 70's, so we must be doing something right...

Anyway, there are a couple of issues here.  In addition to using fiberglass
insulation, make sure that your attic(s) are adequately ventilated...ours
weren't, so we had to add a bunch of venting, including ridge and hip vents,
and some eyebrow vents, and even vented one unvented space into another
vented space to help the moisture that our lack of vapor barriers allows to
get into the attic travel to go outside.

As far as vapor barriers go, if you have no vapor barrier in the wall (it
should be on the inside side of the wall, not the exterior), you can use
the vapor barrier paints to create one.  We will probably eventually do that,
but we don't need to paint yet, so it can wait till we do.

As far as basement insulation goes, I would use rigid foam board.  But before
I put up insulation, I would be as sure as I can be that the walls of the
basement don't leak.  When insulation gets wet, unless it is closed-cell
rigid board, the insulation will soak up water, which reduces its insulating
value to very little.  The alternative here is to build a framework of
2x4's on the basement walls to hold fiberglass batts, but I wouldn't do
that.  It would be expensive, time consuming, and also would not perform as
well in damp conditions.  Fixing moisture in basements is a whole other
subject.

Blowing in insulation is not something that I would do myself, but that is
just me.  I don't want to have to work with loose fiberglass, nor in 120
degrees in an attic.  To have the 12 inches of fiberglass blown in cost
$500 (the attic space was 1000 sq.ft.), and we are expecting a $100 rebate
as well.   So $400 is really not very much to pay a professional.

Any other questions, feel free to ask.  I have lots of insulation experience.


------------------------------------------------------------

(Posted response)

In article <COX.92Aug4181712@acae206.acae206> cox@acae206.acae206 (Henry Cox; x6410) writes:

   My wife and I recently purchased an older (~50 years) house.  ...
   built in the days of cheap energy, and has virtually no insulation
   in the walls or attic - or anywhere else, for that matter....

I was just reading this chapter in the book Renovation, by Michael
Litchfield (which I recommend for this project and any future projects
on your house; see review below).

Litchfield recommends starting with (1) below and working up to (5),
in order of cost-effectiveness.  I think this list is in the correct
order; check the book.  My comments afterwards.

	1. Weatherstrip doors and windows; caulk frames (exterior).
		This is cheap and easy to do.
	2. Insulate attic.
		This is a bit more money (but not much), and easy to do.
	3. Improve windows (storm windows, double glazing, etc.)
		This is a lot of money, but it's where you lose the
		most heat.  If you don't have storm windows, install
		them.  Double and triple glazing, on the other hand,
		is not particularly cost-effective.  Litchfield
		recommends insulating shutters, which are moderately
		priced and very effective, but also very ugly unless
		designed together with the house.
	4. Improve heating system efficiency.
		It sounds as though this might be worth doing in your
		case.  Do you have an objective measure of how bad
		your efficiency is?  It may just need adjustment, or a
		new burner.
	5. Insulate walls.
		This is at the bottom of the list because it is
		expensive (as you found), and has less impact than the
		other steps.

   What, if anything, is done about a vapor barrier...? ...the builder
   was religious in carefully installing foil-faced/foil-backed (both
   sides) kraft paper everywhere...

I wonder if that kraft paper might not actually PREVENT the blown-in
insulation from getting blown in properly.  By the way, the standard
recommendation on checking a blown-in job is to have the contractor
keep the empty bags, and count them.  Make sure he has blown in the
necessary amount.  Half-filled cavities aren't terribly useful.

Anyway, the other possibility is to repaint the interior walls with a
vapor-barrier paint.  There are several around; I happen to be
familiar with Pratt & Lambert's Lyt-All Double-Duty Primer.

   It has a concrete block foundataion and a full (unfinished) basement.
   What should I do for basement insulation?...

Since you want to heat the basement, don't insulate the basement
ceiling.  Instead, you can install rigid insulating panels against the
basement walls.  Note also that air infiltration around the top of the
foundation (under the sill plate) is a major heat loser.  Be sure to
caulk that.

In any case, before doing major work, have an energy audit done to see
where your energy dollars are actually going, and what the most
cost-effective steps are.  You may be surprised to find that wall
insulation is of very low priority....  Around here, the utilities
will send an inspector "for free" to do an energy audit.

------------------------------------------------------------

(Posted response)

In article <COX.92Aug4181712@acae206.acae206> cox@cadence.com writes:
> On cellulose -
>	- it does not burn (impregnated with boric acid)

I wouldn't want something acidic in my walls.

> On fiberglass -
>	- it won't burn (contradicted by the cellulose folks)

It won't.

>	- it does not settle as much (?)

True, but both will settle. Settling 3 or 4" in an 8' wall is not uncommon.

>	- if it gets wet, it will dry out and continue to function.
>	  Cellulose won't
>	- termites, etc. can't eat it

Again, he's right.

>Rock wool does not appear to be an option - no one here seems to sell
>it.  Fibreglass batts are not a good option even in the attic (it has
>a floor which I am not eager to take up).

You *don't* want rock wool. Fibreglass is much better.

>What, if anything, is done about a vapor barrier in this kind of
>situation?  One option may be that the builder was religious in
>carefully installing foil-faced/foil-backed (both sides) kraft paper
>everywhere - presumably because it was "scientific" (radiant heat
>loss, etc.).  With any luck, insulation blown from the exterior will
>crush it up against the interior wall.

Don't count on this. The insulation has to stay sort of fluffy (lots
of tiny air pockets) to do it's job. Properly installed, it's not going
to put much pressure on anything.

>It has a concrete block foundataion and a full (unfinished) basement.
>What should I do for basement insulation?  (I intend to use it as a
>workshop.) 

What I have done in similar situations is the glue up furring strips
with foam panel insulation directly to the block and then nail on sheet
rock or an insulting panel board. The foam panels only have a R value of
about 3, so this may not be worth it to you.

>A potential cost-saving option is to try to do it ourselves.  Is this
>a good idea?  (Both cost and effort required are factors.)

I wouldn't, if I were in your position. That's exactly the case, by the
way. My house is newer (sheet rock walls), but has only the vapor barrier
you mention. I took up the floor in my attic an laid batts, and I'm
removing the rock from the outside walls, installing fibreglass, and
putting up new rock. That's only a little more work than trying to smooth
out the existing rock with spackling compound (in my case). Since your
place must have the old lathe and plaster walls, this is not an option
for you.

To summarize: I place a great deal of importance on the honesty of
  people I hire. The cellulose installer says that fibreglass burns,
  I have always heard differently. I would verify this with the local
  Fire Department. If FG doesn't burn, I would put in FG; you can't
  trust the cellulose installer.

-----------------------------------------------------------------------

(Posted response) 

>>You *don't* want rock wool. Fibreglass is much better.
>
>Why?

The stuff I'm familiar with is heavier and denser and produces a lower
"R" value than fibreglass. I'm told that there's also a greater risk
of silicosis, though this is usually only a problem for the installer.
As far as I know, its only advantage over FG is that it is more suitable
for feeding through a blower.

In the areas in which I worked commercially, people pretty much quit
installing rock wool when fibreglass hit the market. You don't usually
see it in Southern houses built after 1960.

>How can I prove I am not crazy to people who are?

Why should you? Who cares what a nut thinks?

-----------------------------------------------------------------------

(Posted response)

>> On cellulose -
>>	- it does not burn (impregnated with boric acid)

>I wouldn't want something acidic in my walls.

It's dry and inert.  Though, given a hot enough fire, it'll eventually
burn.  It's not acidic when dry.

>> On fiberglass -
>>	- it won't burn (contradicted by the cellulose folks)

>It won't.

Fiberglass melts at relatively low temperatures, and the binders burn and
give off noxious fumes.  Try it.  You won't like it.

>>	- it does not settle as much (?)

>True, but both will settle. Settling 3 or 4" in an 8' wall is not uncommon.

Rockwool settles hardly at all.

>>	- if it gets wet, it will dry out and continue to function.
>>	  Cellulose won't

Depends.  Supposedly some forms of cellulose won't sog, and will recover
partially.  Fiberglass will sog, and lose *some* of it's value.  Rockwool
doesn't.

>>Rock wool does not appear to be an option - no one here seems to sell
>>it.  Fibreglass batts are not a good option even in the attic (it has
>>a floor which I am not eager to take up).

>You *don't* want rock wool. Fibreglass is much better.

Rock wool is far superior in every aspect.  Higher R value, won't
sag or pack, denser (better sound insulation), easier to cut, much less
of a breathing or eye hazard, no sog etc. etc.  I've used both rock wool
and fiberglass, the latter quite extensively.  I'll never go back
to fiberglass now.

Besides, with a little looking, you can frequently find rock wool
cheaper than fiberglass.

>To summarize: I place a great deal of importance on the honesty of
>  people I hire. The cellulose installer says that fibreglass burns,
>  I have always heard differently. I would verify this with the local
>  Fire Department. If FG doesn't burn, I would put in FG; you can't
>  trust the cellulose installer.

Rock wool! ;-)

Rock wool is also environmentally friendly - produced from mine slag... ;-)

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(Posted response)

>Fiberglass melts at relatively low temperatures, and the binders burn and
>give off noxious fumes.  Try it.  You won't like it.

I have tried it (in a fire barrel). The paper backing did burn, but we
didn't notice anything noxious about it. The glass itself didn't melt
completely, but it did sort of crumple up. This was a typical wood fire.
Although temps in house fires may get considerably higher, I wouldn't
say it "melts at relatively low temperatures" myself.

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(posted response)

|> 
|> >Fiberglass melts at relatively low temperatures, and the binders burn and
|> >give off noxious fumes.  Try it.  You won't like it.
|> 
|> I have tried it (in a fire barrel). The paper backing did burn, but we
|> didn't notice anything noxious about it. The glass itself didn't melt
|> completely, but it did sort of crumple up. This was a typical wood fire.
|> Although temps in house fires may get considerably higher, I wouldn't
|> say it "melts at relatively low temperatures" myself.
|> 
|> George Patterson -  | part of it feels pain. Be very sure, though, that

We saw a fire video at work, and they said many household substances give
off toxic gases well before they begin burning.  Paint, furniture, wood
finish, etc. (probably fiberglass as well).  This is often the cause of
death.  Also these gases cause explosions when the ambient temperature reaches
the flash point, this is often the cause of fire spreading quickly through
a structure.

Myself, I wouldn't get near burning fiberglass if I knew about it.

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(Posted)

>>Fiberglass melts at relatively low temperatures, and the binders burn and
>>give off noxious fumes.  Try it.  You won't like it.

>I have tried it (in a fire barrel). The paper backing did burn, but we
>didn't notice anything noxious about it. The glass itself didn't melt
>completely, but it did sort of crumple up. This was a typical wood fire.
>Although temps in house fires may get considerably higher, I wouldn't
>say it "melts at relatively low temperatures" myself.

[Copy of something I mailed, cc'd to some other people]:

Fiberglass is indeed made out of glass fibers.  Ie: silicon dioxide.
However, the fibers are bound together by a flammable binder - in fact,
a glue.  (This is *unfaced* batts)  You probably wouldn't have noticed
anything particularly noxious in a fire barrel in free air - heck,
I don't even notice burning plastic or styrofoam.  But in enclosed spaces...

This is why, for example, fiberglass is not permitted in direct contact with
flues for things like water heaters and stoves.  Rock wool is permitted, as
well as vermiculite for direct contact with hot flues.  (vermiculite is
"popped" mica).  Even without the binders, fiberglass melts long before
rock wool or vermiculite.

I have numerous references to this.  One of the more practical ones discusses
how to build solar panels.  The solar panels are built with a fiberglass
"underplate" to prevent heat radiating out the back.  The book goes to great
lengths to make absolutely certain that you "bake" the fiberglass.  You
see, "unbaked" fiberglass will outgas when heated up inside the solar
panel.  The outgassing will coat the glass sheet over the front of the
solar panel and reduce the efficiency of the unit.  "Baking" consists
of sticking the batt in an oven, and baking at 400F for 20 minutes.  With
good ventilation...

Rock wool, on the other hand, doesn't need binders at all, and has nothing
to outgas or burn.

As far as the different characteristics of fiberglass versus rock wool, try
an experiment.  Take a small wad of fiberglass, and hold a butane lighter
under it.  It flames up for a while while the binder burns off, then it
melts.

With rockwool, *nothing* happens.  Might glow red, but that's it.  Propane
torches won't melt it either.

If I remember rightly, fiberglass slags at ~1000F, and rock wool doesn't
slag til 3500F.  Comparatively speaking, 1000F is a lot lower than 3500F.

While it's certainly true that if the temperature of the wall hits 1000F
it's gone anyways, but the rock wool will retain its shape much longer,
and retard flame spread much better.  In a floor, for example, rockwool
would delay flamethrough longer than fiberglass.

When fiberglass gets wet, it deforms (sags), and drys relatively slowly.
Not all of the sag will go away when it drys.  Water just runs right
through rock wool without changing its shape at all.

In addition to the above characteristics, rock wool also has higher
R value per inch than fiberglass, is nicer to handle/install, will
stay up - even between 24" floor joists - on its own, and is better sound
proofing.  Even as a shredded and blown insulation, it's better than
fiberglass, for it won't pack, and won't fly around like fiberglass
does when you have to walk in the attic.

I'll *never* go back to fiberglass.

Someone was referring to the rock wool of 20 years or so ago.  
Ie: lower R value than fiberglass.

This is not the same stuff as I'm referring to.  The stuff I use, one trade
name being "Roxul plus" (made in Guelph, Ontario, Canada) is a new
manufacturing technique, originally developed in Europe, licensed within
the last 5 years or so to the Guelph company and I believe another company
in the US.  Roxul is higher R value than fiberglass.  Ie: 5.5" of Roxul is
R21.5 - fiberglass 5.5" is R20.  Not an enormous percentage, but still better -
especially if you can get good prices on Roxul.

You just have to try both at the same time.  Like we just did on a church
extension.  We used Roxul for the floors (footings, not basement), exterior walls
and ceiling.  Fiberglass for interior walls for sound proofing (somebody
contributed a few bags of spare stuff).  There is no comparison.  Rock wool
is superior in every respect.  It was cheaper than fiberglass too.

It's instructive to see the results of a rockwool job and fiberglass job
in the same building.  With the very same installers, the rock wool was a
solid, uniform thickness, no gap wall.  The fiberglass was rumpled,
compacted, had gaps etc.

The two disadvantages are that you get fewer batts per bag, and the bags
are heavier.  On a square-foot basis, the price is about the same, and
you can get somebody else to lift the bags... ;-).

I saw one amusing pair of ads.  One was from Roxul:
	- higher R value than fiberglass
	- won't sag as much as fiberglass
	...

The one from the fiberglass pink people on the facing page said:

	- has a high R value too
	- doesn't sag as bad as cellulose...

Somehow the fiberglass people just couldn't come up with anything
that they beat rock wool in.  But they tried to give the impression...

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(Posted response)

>However, the fibers are bound together by a flammable binder - in fact,
>a glue.  (This is *unfaced* batts)  You probably wouldn't have noticed
>anything particularly noxious in a fire barrel in free air - heck,
>I don't even notice burning plastic or styrofoam.  But in enclosed spaces...

Nit-picking - Blown in fg wouldn't have this, I suppose.

>Someone was referring to the rock wool of 20 years or so ago.  
>Ie: lower R value than fiberglass.

That was me.

>This is not the same stuff as I'm referring to.  The stuff I use, one trade
>name being "Roxul plus" (made in Guelph, Ontario, Canada) is a new
>manufacturing technique, originally developed in Europe, licensed within
>the last 5 years or so to the Guelph company and I believe another company
>in the US.  Roxul is higher R value than fiberglass.  Ie: 5.5" of Roxul is
>R21.5 - fiberglass 5.5" is R20.  Not an enormous percentage, but still better -
>especially if you can get good prices on Roxul.

Ok, I'm convinced. Now. Does this stuff come in something like the rolls
that fg comes in? I still have quite a few walls to do in my place.

-----------------------------------------------------------------------

(Posted) 

>>However, the fibers are bound together by a flammable binder - in fact,
>>a glue.  (This is *unfaced* batts)  You probably wouldn't have noticed
>>anything particularly noxious in a fire barrel in free air - heck,
>>I don't even notice burning plastic or styrofoam.  But in enclosed spaces...

>Nit-picking - Blown in fg wouldn't have this, I suppose.

It usually does.  Have you ever watched them do it?  They fire up a big
shredder/blower, and feed batts into it.  Without the binders, fiberglass
would be even more of a breathing hazard than it is now.

>Ok, I'm convinced. Now. Does this stuff come in something like the rolls
>that fg comes in? I still have quite a few walls to do in my place.

I've not seen Roxul in rolls.  Only batts.  Any of 8 (or so) standard sizes.
However, the stuff is rigid enough that you can piece together what you need
>from batt bits without any trouble.  Unlike fiberglass that packs too much -
yes you can do it, but the results aren't as good without more effort.

------------------------------------------------------------

(Email)
I just had blown-in cellulose added over blown-in fiberglass.  Cost 
for 2400 sqft of 7 inch depth (to bring R value up to 39) was $950.
Blown-in cellulose was recommended over the top of fiberglass to reduce
settling of the fiberglass.   The cellulose had a small amount of
glue binder and was blown in slightly wet - claimed that this helped
the cellulose hold its position and reduced settling.  My attic is
strussed so job was not easy.  Also had an attic fan installed at
same time.  So far I have noticed that the house (ranch style) stays
cooler.
Best of luck,

------------------------------------------------------------

(email)

>
>My wife and I recently purchased an older (~50 years) house.
>Unfortunately, it was built in the days of cheap energy, and has
>virtually no insulation in the walls or attic - or anywhere else, for
>that matter.  We would like to do something about that.
>
>
>Materials:
>
>We have gotten two quotes for blown cellulose.  According to them,
>cellulose is better because:
>	- it does not burn (impregnated with boric acid)

See below.

>	- mice, etc. will not nest in it (boric acid again) - they
>	  will nest in fibreglass
>	- termites, etc. don't like the flavor and won't eat it
>	- it is nontoxic - children and pets who do eat it may feel
>	  ill, but won't die.
>
>One guy selling blown fibreglass was also in.  What a surprise, he
>thinks fibreglass is best:
>	- it won't burn (contradicted by the cellulose folks)

The glass won't burn but the paper backing may.

>	- it does not settle as much (?)

True, based on our experience.

>	- if it gets wet, it will dry out and continue to function.

Also true, based on experience.

>	  Cellulose won't

Probably true, based on experience.

>	- termites, etc. can't eat it

True.

Hmmm.  Methinks that the cellulose salesman is full of it.

We moved into a house that had treated cellulose blown into the attic.
I was curious so I tested some of it for flammability.  The stuff does
burn but will not sustain a flame - in other words, I can light it
with a flame and it will flame briefly, then turn into glowing embers
and soon will extinguish.  I don't consider it to be a significant
fire hazard.

I would go with the fiberglass myself, purely because the pitch
seems to be honest.

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