[Greenbuilding] [BULK] Re: Insulation, windows, siding...oh my! (Take 2)

[Lawrence Lile]

I'd also say your fiberglass supplier was a bit biased.

60% recycled fiberglass, versus 100% recycled cellulose - no contest

Cellulose is slightly higher R-per inch.

Fiberglass is made with high temperature kilns, cellulose is made with a hammermill with a small electric motor.

Despite what he may maintain, fiberglass allows more infiltration and convection inside the wall. I have seen demonstrations of this, with two plexiglass-covered walls, and smoke introduced into the cavity.  The smoke rises and flows throught eh fiberglass cavity, not through the other cavity.

Blown in fiberglass probably beats Batts, which depending on the installer are either tight fitting and space-filling, or gappy and fulla holes - I don't like fiberglass batts at all.

Fiberglass is more dangerous to breathe than cellulose, more itchy on the skin, and may (depending on the research this week) be a carcinogen.  Cellulose, not so much, although a dust mask is still needed while installing it.

With wet-spray cellulose, you can SEE what you are insulating. It is installed before the sheetrock goes on.  With fiberglass, you must fill a cavity, and HOPE that there are no voids or cross-pipes blocking the fill. Did it really pack tight under the electrical outlets? Who knows.

Cellulose, despite his assertions, does not pack down if properly installed at high densities.  Poorly installed cellulose might pack down, both technologies depend on the skill of the installer.  Properly installed cellulose doesn't settle.

Cellulose is typically manufactured locally (depending on your area) whereas fiberglass is trucked in from who knows where. In my area, to add PC to Green, the closest manufacturer is a Woman owned business, and she is very knowledgable about cellulose, having installed it for 30 years, when we've talked.  Try calling up the boss of Owens-Corning and having a chat?

For my nickel, cellulose is a very Green choice.

> -----Original Message-----
> From: greenbuilding-bounces at listserv.repp.org [mailto:greenbuilding-
> bounces at listserv.repp.org] On Behalf Of Justin Close
> Sent: Wednesday, April 23, 2008 4:14 PM
> To: Benjamin Pratt
> Cc: Greenbuilding at listserv.repp.org
> Subject: [BULK] Re: [Greenbuilding] Insulation, windows, siding...oh
> my! (Take 2)
> Importance: Low
>
> Thanks for the reply, Ben.
>
> Yes, we have over hangs.  I think that we would still insulate the
> attic
> fully (no room to overblow at the edges, as you mention further on, so
> remove and replace is probably how it would go).
>
> We just had one of the folks we asked for estimates have a look at
> things, and he was saying that they use a blown fiberglass for both
> walls and attic.  He said that it was 60% recycled glass.  He was
> poo-pooing cellulose as being full of chemicals, settling, wet-blown
> stuff would shrink after it dried, etc.  (We are thinking of opening
> the
> stud bays and so I was asking about a blown in product while the bays
> were open, instead of a drop in filler.)  Does anyone have any comments
> on that style (blown in) fiber glass?  He was also talking about only
> shooting for a 10% air infiltration rate (blower test before and after,
> but their final target flow is square footage * .10).
>
> We have the EnergyTrust of Oregon coming to do an energy audit, but I
> don't think that they are going to go as far doing infrared scans.  A
> shame, I suppose, but it is free.
>
> I have thought that a metal roof would be a good idea as well, but it
> is
> the cost that is probably going to nix that.  We don't plan on being
> here for a long time, but who knows how things will end up.  :)
>
> I love the idea of a solar water heater, and would like to go that
> route, but that initial cost is a big barrier, especially in the face
> of
> doing all this other stuff.
>
> Thanks again,
> Justin
>
> Benjamin Pratt wrote:
> > Justin:
> > A caveat--I am just a homeowner too who joined this list around two
> > years ago and got hooked on green architecture. But I am also a
> design
> > professor (although not an architect) so I've been able to learn
> > fairly quickly. There are certainly much more knowledgeable people on
> > this list, but I will give your answers to some of your questions.
> >
> > 1. I looked into putting foam under my new roof---fairly worthless
> > because the thermal envelop will most likely be broken where the roof
> > meets the wall--especially if you have overhangs.
> >
> > 2. I ended-up getting an energy audit--including an infrared scan, of
> > my house. well worth it--especially since it was subsidized by the
> > energy company (it was ($100US for the works) and is tax deductible
> >
> > 3. Cellulose is by far the best and most cost effective solution in
> > your situation. you can have the old stuff sucked out or removed, but
> > if you have the space, the cellulose can be blown on top of the old
> > stuff with no loss of it's effectiveness. I think you'd be surprised
> > how cheap it is (much cheaper than the foam you'd put on your roof)
> >
> > 4. windows and doors have the lowest rate of return compared to other
> > measures. The main problem with older windows issue is leakage, not
> > r-value. Caulk is cheap. However, if you want new windows and doors,
> > I'd look on cragslist. it may be worth it to buy ones with slightly
> > different sizes, depending on your exterior siding and trim. I put in
> > a craigslist window--slightly narrower than the opening, and filled,
> > the gap with insulation and covered it with wider trim.
> >
> > 5. If you are going to be in the house a long tim--consider a steel
> > roof. it wil pay itself back since it lasts 3 times logner than
> > asphalt. It is also, by far, the greener choice. On a house like
> > yours, it may not be twice as expensive, and you culd use the
> simplest
> > style roof.
> >
> > 6. Also, this would be a great time to consider a solar water heater
> >
> > 7. If you want to talk, i could call you on my commute, but i have no
> > more time to write.....
> >
> > Ben
> >
> >
>
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