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Posted by ransley on October 30, 2008, 7:22 am
> > On Tue, 28 Oct 2008 07:00:19 -0700 (PDT), Raider Bill
> > >> FYI, I happen to know the house is in Tennessee.
> > >> > Dont know where the house is, but here in Texas, South East Texas,=
I dont
> > >> > go hog wild with the foam, house and the attic needs to breath, if=
you
> > >> > seal one up that tight, think of a fresh air return added to your =
HVAC
> > >> > system, to positive presure the house, and get some fresh outside =
air in
> > >> > there, cause we dont live in our refridgetors, we keep food in the=
m. but
> > >> > to seal up so tight is not the best way to go, when I say not best=
way, I
> > >> > am talking healthy way as well.
quoted text -
> > >> - Show quoted text -
> > >Doug is right Athens. =A0tenn.Good memory!
> > >Sorry I posted and ran =A0I'm back up here and internet and cell is ve=
ry
> > >spotty at best.
> > >I'm freezing my butt off. Icf sure is a great insulater as it has
> > >retained all the cold.
> > >I like the idea of foaming the ceiling then blowing in some cellouse
> > >on tp.
> > >But what about condensation in the summer from the the metal roof?
> > >To vent or not to vent....... that is the question?
> > That question was answered by almost everyone-- you *must* vent.
> > Period, not two ways about it.
> > Now, why do you feel you need foam? Why not just cellouse?
> Loose fill cellulose does nothing to stop air/moisture movement from
> the living space up to the attic - the primary source of problems with
> winter moisture buildup in attics. 2-3" of high density spray foam
> seals everything up, greatly, greatly reducing the opportunity for
> moisture to get into the attic and drastically reduce the chance for
> any moisture damage up there during the winter.
> During the summer, the moisture drive is from the outside air. The
> metal roof cools rapidly and condensation forms under it if there is
> any moisture between the metal roof and the underlying sheathing so
> there must be a moisture impervious layer between the metal roof and
> the sheathing as well as room for ventilation between the metal and
> the sheathing to avoid moisture entrapment.- Hide quoted text -
> - Show quoted text -
Even a 1/4 inch of foam or sheet plastic works, a better reason is
fiberglass and cellulose loose R value as it gets very cold, near 0 it
might be 20% less R value. Fiberglass and cellulose settle easily 10%.
But many foams can go bad and deteriorate if not painted
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Posted by Astro on November 2, 2008, 7:27 am
> > > On Tue, 28 Oct 2008 07:00:19 -0700 (PDT), Raider Bill
> > > >> FYI, I happen to know the house is in Tennessee.
> > > >> > Dont know where the house is, but here in Texas, South East Texa=
s, I dont
> > > >> > go hog wild with the foam, house and the attic needs to breath, =
if you
> > > >> > seal one up that tight, think of a fresh air return added to you=
r HVAC
> > > >> > system, to positive presure the house, and get some fresh outsid=
e air in
> > > >> > there, cause we dont live in our refridgetors, we keep food in t=
hem. but
> > > >> > to seal up so tight is not the best way to go, when I say not be=
st way, I
> > > >> > am talking healthy way as well.
de quoted text -
> > > >> - Show quoted text -
> > > >Doug is right Athens. =A0tenn.Good memory!
> > > >Sorry I posted and ran =A0I'm back up here and internet and cell is =
very
> > > >spotty at best.
> > > >I'm freezing my butt off. Icf sure is a great insulater as it has
> > > >retained all the cold.
> > > >I like the idea of foaming the ceiling then blowing in some cellouse
> > > >on tp.
> > > >But what about condensation in the summer from the the metal roof?
> > > >To vent or not to vent....... that is the question?
> > > That question was answered by almost everyone-- you *must* vent.
> > > Period, not two ways about it.
> > > Now, why do you feel you need foam? Why not just cellouse?
> > Loose fill cellulose does nothing to stop air/moisture movement from
> > the living space up to the attic - the primary source of problems with
> > winter moisture buildup in attics. 2-3" of high density spray foam
> > seals everything up, greatly, greatly reducing the opportunity for
> > moisture to get into the attic and drastically reduce the chance for
> > any moisture damage up there during the winter.
> > During the summer, the moisture drive is from the outside air. The
> > metal roof cools rapidly and condensation forms under it if there is
> > any moisture between the metal roof and the underlying sheathing so
> > there must be a moisture impervious layer between the metal roof and
> > the sheathing as well as room for ventilation between the metal and
> > the sheathing to avoid moisture entrapment.- Hide quoted text -
> > - Show quoted text -
> Even a 1/4 inch of foam or sheet plastic works, a better reason is
> fiberglass and cellulose loose R value as it gets very cold, near 0 it
> might be 20% less R value. Fiberglass and cellulose settle easily 10%.
> But many foams can go bad and deteriorate if not painted
All foams are somewhat vapor permeable. 1/4" of foam, even high
density polyurethane, is quite permeable. Perm rating is non-linear.
At 1", it is 2.6. A thin coat would block bulk air movement however,
which would be good for most houses and could be a compromise. But
better to use at least 3" everywhere.
See: http://www.fomo.com/resources/technical-bulletins/Moisture-Vapor-Trans=
mission.aspx
Cellulose increases R-value with decreasing temperatures:
http://www.foam-tech.com/theory/rvaluedrift.htm
Settling not such a problem with cellulose as thermal performance
doesn't vary much with density as it does with fiberglass. It will
still decrease, but not a big deal since you applying lots of it -
12-15" typically ..
Foams only go bad if exposed to UV. Not much UV gets through shingles
and roofs :-)
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|
Posted by ransley on November 2, 2008, 7:50 am
> > > > On Tue, 28 Oct 2008 07:00:19 -0700 (PDT), Raider Bill
> > > > >> FYI, I happen to know the house is in Tennessee.
> > > > >> > Dont know where the house is, but here in Texas, South East Te=
xas, I dont
> > > > >> > go hog wild with the foam, house and the attic needs to breath=
, if you
> > > > >> > seal one up that tight, think of a fresh air return added to y=
our HVAC
> > > > >> > system, to positive presure the house, and get some fresh outs=
ide air in
> > > > >> > there, cause we dont live in our refridgetors, we keep food in=
them. but
> > > > >> > to seal up so tight is not the best way to go, when I say not =
best way, I
> > > > >> > am talking healthy way as well.
Hide quoted text -
> > > > >> - Show quoted text -
> > > > >Doug is right Athens. =A0tenn.Good memory!
> > > > >Sorry I posted and ran =A0I'm back up here and internet and cell i=
s very
> > > > >spotty at best.
> > > > >I'm freezing my butt off. Icf sure is a great insulater as it has
> > > > >retained all the cold.
> > > > >I like the idea of foaming the ceiling then blowing in some cellou=
se
> > > > >on tp.
> > > > >But what about condensation in the summer from the the metal roof?
> > > > >To vent or not to vent....... that is the question?
> > > > That question was answered by almost everyone-- you *must* vent.
> > > > Period, not two ways about it.
> > > > Now, why do you feel you need foam? Why not just cellouse?
> > > Loose fill cellulose does nothing to stop air/moisture movement from
> > > the living space up to the attic - the primary source of problems wit=
h
> > > winter moisture buildup in attics. 2-3" of high density spray foam
> > > seals everything up, greatly, greatly reducing the opportunity for
> > > moisture to get into the attic and drastically reduce the chance for
> > > any moisture damage up there during the winter.
> > > During the summer, the moisture drive is from the outside air. The
> > > metal roof cools rapidly and condensation forms under it if there is
> > > any moisture between the metal roof and the underlying sheathing so
> > > there must be a moisture impervious layer between the metal roof and
> > > the sheathing as well as room for ventilation between the metal and
> > > the sheathing to avoid moisture entrapment.- Hide quoted text -
> > > - Show quoted text -
> > Even a 1/4 inch of foam or sheet plastic works, a better reason is
> > fiberglass and cellulose loose R value as it gets very cold, near 0 it
> > might be 20% less R value. Fiberglass and cellulose settle easily 10%.
> > But many foams can go bad and deteriorate if not painted
> All foams are somewhat vapor permeable. 1/4" of foam, even high
> density polyurethane, is quite permeable. Perm rating is non-linear.
> At 1", it is 2.6. A thin coat would block bulk air movement however,
> which would be good for most houses and could be a compromise. But
> better to use at least 3" everywhere.
> See:http://www.fomo.com/resources/technical-bulletins/Moisture-Vapor-Tran=
...
> Cellulose increases R-value with decreasing temperatures:http://www.foam-=
tech.com/theory/rvaluedrift.htm
> Settling not such a problem with cellulose as thermal performance
> doesn't vary much with density as it does with fiberglass. It will
> still decrease, but not a big deal since you applying lots of it -
> 12-15" typically ..
> Foams only go bad if exposed to UV. Not much UV gets through shingles
> and roofs :-)- Hide quoted text -
> - Show quoted text -
Uffi foam once banned and now back in some use turns to powder in
sealed walls, Have foams been around long enough to really know what
will happen?
Cellulose that I have seen disentegrates over years, its just
newspaper, and any roof leak makes it worthless, Cellolose settles is
alot.
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Posted by Steve Barker DLT on November 2, 2008, 9:30 am
Contrary to popular belief, modern, properly installed cellulose insulation
does not settle.
s
Cellulose increases R-value with decreasing temperatures:
http://www.foam-tech.com/theory/rvaluedrift.htm
Settling not such a problem with cellulose as thermal performance
doesn't vary much with density as it does with fiberglass. It will
still decrease, but not a big deal since you applying lots of it -
12-15" typically ..
Foams only go bad if exposed to UV. Not much UV gets through shingles
and roofs :-)
|
|
Posted by ransley on November 2, 2008, 2:24 pm
On Nov 2, 8:30=A0am, "Steve Barker DLT"
> Contrary to popular belief, modern, properly installed cellulose insulati=
on
> does not settle.
> s
> Cellulose increases R-value with decreasing temperatures:http://www.foam-=
tech.com/theory/rvaluedrift.htm
> Settling not such a problem with cellulose as thermal performance
> doesn't vary much with density as it does with fiberglass. It will
> still decrease, but not a big deal since you applying lots of it -
> 12-15" typically ..
> Foams only go bad if exposed to UV. Not much UV gets through shingles
> and roofs :-)
Expain why, even fiberglass batts settle mine did, its like saying
water doesnt evaporate.
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Page 4 of 5 < 1 2 3 > last >>
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