Any architects on this ng from southern Louisiana? Would like to discuss
insulation in walls vs. attic. I suggest a 30R for attic and only 11R for
walls (4"). There is a myth out there that walls need to be 6" to give
southern walls adequate insulation. Crock of grits! I bump into someone
who keeps this myth going every now and then (like now - client - who
happens to be an engineer who thinks he knows more than God).
Thanks. The R values are close to what I suggest in my plans. Minimum R11
(I think I'll go up to the 13, however) in the wall and I'll stick with my
R30 vs. R20 in my attics. This gives me something to show the guy. :)
The Building Science guys know their stuff. They've approached it all
from a physics standpoint - what really happens and how can you really
build it. 99% of the time, I do what they recommend. It's really hard
to go wrong with it...
Note that they recommend using rigid at the perimeter wall... Something
you don't see everyday, usually.
I have worked on a project where the owner requested "Blue Wood" for the
What I understand is the "blue" is a coating that preserves the wood,
prevents the wood from mold and the like. It doesn't
have anything to do with the insulation. If you know that felt or other
building paper wasn't used over the 'blue' then it must do
both, building paper and a wood preservative.
I know if you search "Blue Wood" with Google's you will find out exactly was
We have fiberglass in the framing, then 3/4" blue foam (string board at the
corners) and Tyvek over that, then the brick (hardi-plank on the second
storey). I'd like mroe insualtion in the attic, tho'. We have the blown-
in kind but I'd like to put somnething over that, maybe the thick rigid
THat's a good idea, I prob ought to check into setting something up
*before* anything like that happens...
How much does it save? I mean, both up-front, *and* including what one
has to gothrough to remedy all the eventual problems...?
It increasingly seems to me that most "savings", really aren't...
Those the tips re: the batting are excellent. I wouldn't have thought to
do any of that. In a hot wet climate, does the paper go upwards, or
does it face down (where the ceilings are)? I know I could aks the sales
doodz at Home Depot or Lowe's, but I don't trust them to know...
One thing for sure, to work with fiberglass, I would get one of those
disposable hooded body suits, face mask, gloves, and so on - fiberglass
is great as insualtion, but it is also nasty if it gets into your skin or
Hard part will be clambering over all of the ducting - it's flexible, but
it's everywhere (and I'm not as limber as I used to be, more like lumber,
Oh, yeah... smart idea!
I'm assuming I would have to get some of those styrofoam forms that you
insert between the studs (of the roof) to be sure that the insualtion
doesn't cover the soffets.
BTW, what do you think of putting nylon door/window screening over the
soffits, on the inside, to block bees and whatnot? I don't know whether
the holes (we have hardi-plank soffets) are small enough to keepout bees.
ANyhoo, thanks for the practical tips. I feel like I ought to send you
Actually, there isn't as much cross-bracing as I'd expect - it's mostly
taken up by flexible insualted ducting tubes. At least, the one
I'd have to plan it pretty carefully; laying the batting under the
ducting will also be a challenge. It will definitely take planning.
There is only one way into the topmost area, which is the pull-down
ladder in the upstairs landing area. The area over teh garage is easy,
thre is a mini-door - literally, it's framed and had a doorknob and so
on. The water heater is in that area. no insulation since it's over the
garage, but I'll eventually put something down so as to keep teh base-
plate area of the "extra room" warmer. Right now, the room seems to me
to get hotter and colder than it ought to, which I think might be
affecting the master bath underneath it.
THe other side of the extra room only has some silly screw-in square of
painted plywood - I'd like to eventually put a mini-door there as well,
because there is potential storage space, plus I'd liek to be able to
check the area periodically.
I guess I'd have to look at the blown stuff, too, and see how high it's
So it should cost about $350 (after tax) for the material itself. Not
too bad, but takes planning.
I'd prob have them deliver it, actually. I can't fit too much in my
little old Saturn sedan <L!> Also wouldn't want fiberglass bits left in
THat's the case with most things, so makes sense.
Good idea re: the plywood. It's not a bad idea to have some on hand for
generalized cutting, too.
Got those ;) I found some "heavy duty" ones at Lowe's, which are good
for any'n'all projects that require kneeling. I think they're a good
investment - if one has knee problems, they mitigate those, and if one
does not have knee problems, it's one way to keep from getting them.
Yeah, esp. given the humidity here (Houston is the 5th most humid city in
the US, IIRC).
I'm not as worried re: heat loss (it got up to 78 degrees yesterday - the
A/C kicked on...), as I am with the longevity, "blowiness", and other
problems with the blown-in junk.
((ALthough I do wonder whether the rising heat from the uninsulated attic
rea over the garage for most of the year is part of what makes the extra
room so hot - there is batting on the room's walls, buit the garage faces
South, so the sun beats down on it for most of the day.))
Ideally, I'd consider boarding-over the attic, first to keep teh
insulation in place and so on, second to provide a place to walk so I can
periodically check through the attic. Trying to balance on the beams is
really tricky for me.
All in all, tho', the main thnig is that, if I do this again (have a
place built by either a developer or, *hopefully* int he future, custom),
I'm definitely going to ask about options other than this blown-in crap.
If it costs extra, or if I have to go buy it myself and put it in before
the ducting goes in, so be it. THis blown-in stuff in IMO just something
that is expedient and cheap as peanut shells for the builder, and a
future big pain in the bucket for the buyer...
I know that the walls don't need 6" of insulation in southern Louisiana.
This pdf gives me something to show the guy. We did all the heat gain/heat
loss calucations in college with brick/stone wall, stucco wall and siding ad
Why is more insualtion bad?
I lived in a place here (Houston area) with low insualtion, and this place
(decent insulation). I could feel the heat (and January chill) through the
walls in the other place, feel lots less here. Main loss ia the windows -
double-paned, but the sumbass aluminum frames radiate like mad - had great
ones in Canada, wish I could recall what type/brand they were (that was
1993, so I've forgotten).
Air-conditioning is a lot more expensive than heat, so it always mystifies
me that people think you need less insulation in a hot (esp a hot and
extremely humid) climate.
YOu might call it a myth, but personally, I'd take more/better insulation
over less insulation ANY day.
I also got tech-shield and tyvek. I guess that, in your book, that makes
me an even bigger idiot. I'm not an engineer and I certainly don't think
I know more than God, OTOH, I *do* know what my energy bills say, or more
to the point, *don't* say.
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