We priced traditional Fiberglass batts, assure R blown fiberglass and foam. We are going with the blown fiberglass and tight house sealing including zip sheathing and lots of can foam at the important places. I could not justify the extra $8000 for foam over the blown fiberglass. I would suggest getting quotes for all and deciding at that point. We have friends who moved into their new 7000 sq ft 1.5 story and they insulated with foam. Their power bills are regularly $150-200/ month. Pretty doggone good!

Central SC is so mild that foam does not payoff.

Best payoff is keeping ducts in conditioned space which does not require foam - just proper planning.

Rigid foam on the walls is a reasonable choice - at least a better one than spray foam.

We have a bedroom above the garage and no foam and no problem.

Nothing beats foam in the garage ceiling. Until I started using it, rooms above were cold in the winter, hot in the summer. Foam is also a good idea in the rim joist areas, as much for its air-sealing ability as insulating values.

I'm in a cold zone that, like many other cold zones, reaches mid 30s C. on humid summer days.

rigid foam sheating for walls.
tape seams seal holes.
conventional insulation in walls
air tight drywall approach to interior walls.

spray foam for roofline.
depth is dependent on type of foam
and code requirements in your location.
keep in mind that actual R-values are what
count, not quanitive or K-values.

spray foam on roofline
unless equipment & ducts are in
living space below attic.
which is pretty uncommon unfortunately.
but if your designer has designed the
house with ducts inside living space..then
foam the attic floor. and give your
designer a bonus for saving you money.

best of luck

Once you put foamboard on the exterior of your home in a mixed climate zone, such as South Carolina, you have to plan on the wall drying largely to the inside. So it's essential to have low permeance materials to the interior--no poly, no vinyl wallpapers. Be sure this is allowed in your area. For further info see here.

*****
recessed lights th[r]oughout the house.

Just use "ICAT (insulation contact, air tight) rated" pots and you can safely pile on all the insulation you want. [updated at energy raters suggestion.]

This post was edited by worthy on Sun, Dec 2, 12 at 11:44

Thanks for the suggestions and info. Can someone explain where you put duct work in a conditioned or semi-conditioned space? Ours was in the attic in the last house and I completely understand how inefficient that was. Our heating and AC bills were awful. I'm just having trouble imagining where it should go.

Here's a brief article on ducts from buildingscience.com:

http://www.greenbuildingadvisor.com/blogs/dept/musings/keeping-ducts-indoors

When we installed central air in my existing
home we planned ducts in the living/conditioned
space. with the layout of my house it wasn't too
difficult.
it all depends on if you'll have access to all
rooms to build fur downs for ducts.
in my case, I sacrificed half of my linen
closet to house the air handler unit. return air
is below ahu. supply plenum is at top of
closet with ducts run through fur downs to
supply all rooms.

lexmom..you'd have to post layout with location
of heating system. moving the heating system
& ducts inside the living space is the best.
the means you'd have to have a centrally located
place to house the heating system & returns
along with space for supply plenun & supply ducts.
if you paint the fur downs the same color as
the walls..they don't stand out. you can also
do a tray ceiling design to hide ducts.

nice article virgil. if we could just get
designers & architects to design with
ducts & heating system inside cond space..
it would start homeowners out with a big
savings.

best of luck.

worthy- your link is broken. I'd love to read the info if you can fix the link for us. Thanks!

I built a 2 story on pilings with the ducts in between the two floors. There were some ducts under the house but at least it wasn't the attic and could be well sealed.

A sealed crawl is semi conditioned and a fine choice in SC.

We have a basement+ 2 stories and most of the ductwork is between the basement and 1st story. There is ductwork for the second floor in an unconditioned attic.

My A/C bill this year was around $250 for the summer for 5000 sqft. I'd guess that $100 of that was for the 2nd floor so ductwork in the attic is not necessarily horrible but you are a little warmer than us (central NC). I still think foaming the roof line is a dubious proposition since ours would have been $10k - all to chase 15% of $100 a year...

a better choice that IC lights are ICAT
IC recessed cans have holes in the housing
surround these holes with insulation & you
have pathway for both attic air & insulation
particles to enter the house.

Insulation Contact Air Tight recessed lights
are about $10 more per contractors pack of 6.
to retrofit one IC can to air tight insert
(baffle) will cost $12-$15 each.

invest in ICAT. one IC recessed light leaks
enough air into the house to de-rate the insulation
around it in 1 st ft area.

if you do a search at buildingscience.com
for perfect wall construction for all climates
you'll see that foam sheating to exteior
is recommended. not using vinyl wall papers
or enamel paints is always a good idea.

putting equipment and ducts in semi conditioned
attic is a good upgrade. solves a lot of
issues..like the wrong recessed lights (IC instead of ICAT)
open thermal bypasses and the holes in the
ceiling to attic that are seldom sealed.
payback is usually within 8-10 years, benefits
are long term.

spray foam insulation in walls..long payback
& qc issues. putting enough inches to meet code
isanother issue. payback for foaming walls can
exceed 25 years.

best of luck.

worthy- your link is broken

Thanks. (I always figured based on responses that no one ever reads them!) Now it works.

David,

I thought I posted a response this morning, but apparently it did not take.

Can you please post the specs of your envelope and how you handled your HVAC and ducts. We are building (I think) in Knoxville and trying to figure out exterior sheathing, rigid foam, insulation, ducting, etc. I really trust the builder that we will use if we build, but I question some of his thoughts on these issues. I figure it is easier just to spec it and let him build it.

We are building a basement with 2500 on first floor, 1000-1500 finished initially on second and 1500 or so to be finished at some point in the future in the basement. Basement will be media room, exercise room, bedroom and rec room.

Thanks in advance.

Thanks for all of the replies and links to info. I'm learning that there's much more to building a house than picking out cabinets and granite. :) I'm trying to learn as much as I can so that I can ask the right questions of my builder. The builder is going to quote the option of foaming the roof deck and I'll certainly ask about putting the duct work and air handler in a conditioned space instead. Not sure if a picture of the exterior eleveation helps but here it is.

Would like to get some education & feedback on this: our HVAC & ducting in what will be conditioned & seal crawl space:

Any issues we should be questioning?

I'm in a situation very similar to shouldibuild in Knoxville. Our new house will be in the very southwestern corner of NC, in the town of Murphy. We're on the tip top of a 2500' high mountain, and won't have much natural protection from anything - especially will have LOTS of WIND. It's a basement walkout; main level is 2600 sf, cathedral or other type raised ceilings; basement level is 2000 sf, mostly dug into the slope.
Opinions?? Thanks!!

I'm in a situation very similar to shouldibuild in Knoxville. Our new house will be in the very southwestern corner of NC, in the town of Murphy. We're on the tip top of a 2500' high mountain, and won't have much natural protection from anything - especially will have LOTS of WIND. It's a basement walkout; main level is 2600 sf, cathedral or other type raised ceilings; basement level is 2000 sf, mostly dug into the slope.
Opinions?? Thanks!!

Jowens, I do not have anything to add yet, but I glad you resurrected this thread. I have been investigating putting our second story on floor trusses to keep the ducts out of the attic. The plan did not call for floor trusses so it will require some rearranging. Quite frankly, that seems to be adding to the cost such that I cannot see the payback from any energy efficiency making sense. We have talked about double wrapping the ducts for a R-16 wrap and with them barried in the attic insulation, I hope I am fine.

Does anyone have any thoughts on this?

double wrapping ducts puts two vapor barriers on ductwork, where there should be only one.
burying ducts works in some climates, is yours is one?
then burying ductwork is a better option than double
wrapping ducts.

make sure that ducts are mastic sealed, returns are air tight & supply boxes are sealed to penetrations into living space.

pbx2
pretty duct runs, nice strating nicely strapped. in pic 1.
is there a vapor barrier on the ground?
what is that in pic2? dampered intake?
couldn't duct be routed so that it doesn't dip down?
crawlspace is completely sealed?
again...mastic seal not caulk, duct or foil tapes.
paint on mastic or mastic tape. long lasting seal.

best of luck all.

I'm the OP and we decided (today actually), to go ahead and foam the roofline. I was completely wrong about the amount of attic and space behind the kneedwalls. There is a TON, some of it is even large walk-in spaces! So much storage space that I've asked my builder to close off some of the access doors they have because there is just too much. BTW, code does require access but they will access through the space from other areas. There is a lot of roof area so I was pleased that the quote was only 6,700. I think we will see this as a good investment. The builder says the price has come down considerably in the last five years. Now we have to consider whether it's best to keep the savings from the smaller unit we need now (about $1200) or upgrade the 13 SEER to a higher SEER. Anyone with advice on that?

We are right at the beginning of a huge transition in our country's housing stock related to performance and health.

Build your house the old way (probably local code minimum) and you will get a home with average energy costs and perhaps more importantly, un-healthy Indoor Air Quality IAQ. Build your house the new way (IECC 2012) and you will get a cost-effective energy efficient home with dramatically better IAQ.

Insulation is important along with the other things discussed in this thread. The two topics that deserve more light are 1. Airtightness (as measured by blower door test). 2. Fresh Outdoor Air Introduction with mechanical ventilation.

Meeting the minimum requirements of the International Energy Code IECC 2012 is a cost-effective path to low- energy bills and healthy indoor air. Individual opinions and anecdotal evidence can be helpful but meeting these minimum guidelines is ones best bet for those results.

Building with deep floor trusses is an easy way to get ducts into conditioned space. Even better, hang the trusses from the wall to reduce air leaks and thermal bridging.

jowens751, Murphy is beautiful. Its in building climate zone 4 but personally, I would build to Zone 5 minimums due to your exposure. I would also go for less than 1.5 ACH50 on the blower door test. International code is currently at 3 ACH50 for zones 4 and above but Iam pretty sure the 2015 version will be much closer to 1.5 so try to stay ahead of history if possible.

Airtightness is much easier to measure than real world R value and it has a much bigger impact on energy costs.

Insulative sheathing (foam being most affordable and popular option) is practically required in the new energy code for Zones 3 and up. Open cell foam for cavity insulation has become cost competitive with densepack cellulose in many areas and blocks air movement better. Find out your local climate zone and see what the minimum energy codes (future laws) require in Table 402.1.1 of the IECC 2012.

lexmomof3, I would probably upgrade but might want to cross post to HVAC forum. SEER ratings are rarely accurate as they depend on different Compressors, Air Handlers and duct install. In other words, a 12 could be outperforming a 16 but thats usually an exception. Probably more important is to get a variable speed or two stage unit to better handle de-humidification.

well well lexmomof3,
took 4 months, but you got here!

upgrade from minimum efficiency produced.
your best investment with the longest payback
& savings is conservation.
correctly sizing the hvac system & upgrading
effeiciecy is the right thing to do.
GET A LOAD CALC.
after all the decisions you don't want to
lose out of comfort & affordability at the
hvac stage. this is the one piece of equipment
that effects everyday comfort & the biggest
comsumer of electricity in your home.

if you are all electric. heat pump.
once you get into 15 seer variable speed
units are available. vs air handlers do great
at controlling rh.
if gas, 90+ for your foamed attic.
a/c side 15 seer.

I find the 'sweet spot' of savings & efficiency
to be 15 t0 17 SEER.
even with ductwork in semi conditioned space,
mastic seal of everything. no duct tape no foil tapes.
returns air tight. make sure this is in bids,
and inspect to be sure you get what you've
requested & paid for.
remember low man on the job runs ducts. make
them take the time to size & install correctly
then seal so that the air goes into living space.
you aren't sizing to condition the attic.

have bids give good (14 seer)
better 15-17 seer
best 17+ seer bids.
then compare pricing & features.
instead of wifi tstat which seem to be the rage
now as apricy upgrade go programable & set
it & leave it alone. put your $$ in the efficiency.

over the years I've seen a lot of folks build
a lot of homes. some get it and put the $$ in the
things you don't see, others build for show
& use minimum specs.
the former have low utility bills & comfort.
the latter have uncomfortable expensive show
places that the later spend thousands trying
to remediate.

go for it now. its cheaper in the long run.
best of luck.

LOL energy_rater_la, yes, it took me awhile to get here. Mostly because I was told by several that our climate was ideal for a good roi. Anyway, we're going to foam and I'll get at least a 14 SEER but we'll get bids on higher SEER units as well.

Upstairs is electric heat and downstairs is gas if that makes a difference.

look at the advantages of 15 as compared to 14 seer.

will downstairs gas furnace be in attic with
electric furnace? if so, it will need to be 90+%
you might want to compare heat pump for
upstairs as opposed to electric strip.
elec strip is very expensive way to heat.

general thinking is gas heat from first
floor will rise to reduce runtime of elec strip
of second floor. depending upon layout this
is partly true. but still, my $40 jan heat pump
bill as opposed to my sisters $150 elec strip
heat is a huge difference.
I'd look into heat pump for upstairs as opposed
to elec strip.

best of luck.

I'll check into adding the heatpump to the upstairs too. The equipment for the upstairs is in the attic that we're foaming. The equipment for the downstairs is in the crawlspace. I don't think the builder planed to seal the crawlspace but I'm not sure. I'm checking into that. As for heat rising, the layout isn't really conductive to that as I've closed off the two story foyer so there is limited open ceiling for the warm air to get to the second floor.

so, is the crawspace open?
cirttters are pretty distructive to ducts.
rip flex apart and tear insulation off hard duct.

or is the crawlspace critter tight?

just wondering.

The crawlspace is not open but also not planned per the contract to be sealed and conditioned. It is concrete block surrounded by brick with access doors and vents covered with a mesh. This is how it was in our last house and I crawled around under there from time to time as we stored some kids outdoor toys and other tools under there as well as I had to search for a leak one time. It was vented and there was a black plastic covering the dirt but clean and certainly no critters under there other than spiders and such. I'm sure this is what is planned for our new house. Most of the house sits pretty high off of the ground (3-5 feet) but there is one area that is probably closer to 2 ft (min. code). The builder says that he has heard some information about sealing the crawlspace but hasn't done it. I am very surprised because he is a custom builder and does higher-end homes. He said that he is foaming the roof deck in 8 out of 10 homes he builds but has not done ANY sealed crawlspaces and crawlspaces are the norm in our location. Very few houses have basements and slabs are not allowed in many subdivisions. He is going to talk to his insulation guy about it.

With ductwork out of the equation and code minimum insulation levels, ventilated crawlspaces are usually much worse than ventilated attics.

I'd just like to counter the NG furnace downstairs and heat pump upstairs argument. I have/had that and I ran ducts from the NG furnace to upstairs to remediate.

The only time the heat pump is not ideal is overnight (in our climate) and that is when you need heat upstairs. I didn't like heating downstairs overnight just to keep the upstairs from running.

An NG furnace doesn't cost much - I'd put one on each floor (although I do think you are quite a bit warmer than me).

My utility is converting to a TOU-D rate which means a few things but means you pay for your highest peak usage for 15 minutes in a month. So if you have a 10kw strip fire up in Jan for 20 minutes, you pay a demand charge of $3.75 per kw - or $38 that month. If you just had NG, that charge would be much smaller.

You may never have this rate but it maybe the future in your area also. We have Progress Energy (now Duke) which operates in SC. Their focus is on avoiding building new plants which means they need to temper the peak demand. A lot of that peak is actually winter time at 6 am when everyone's electric strips kick in. I was looking at another utility who had their all time peak in December 2011 and that was NC coast which is a little warmer than inland.

If you have Progress Energy - PVs put you in TOU-D. EVs also push you towards TOU-D. They want more people in TOU-D...

"It is concrete block surrounded by brick with access doors and vents covered with a mesh. "

keeping cats & critters out of crawlspaces will keep
ducts intact for the most part. you may have mice,
but could always put poison out..as long as only
mice get to it.

are ducts hard pipe? if so, the hard pipe ducting will
keep any critters out of the duct itself, but insulation
will still be attractive to them.

here is a little hardpipe duct 101:
hard pipe lasts, but is very leaky. once insulated the leaks will still be there, just not acessable.

the way hard ducts are installed is long round pieces of metal that snap together. then are screwed together, and 90 degree ells are screwed on to make turns, these attach to supply boxes in floors and the other end of the duct is screwed to the take off collar on the supply plenum.

each of these sections, from the first longitutal snap together seam to the last connection to duct collar & supply bos, should be well screwed..mininum of 3 screws per connection,

then they are mastic sealed.not duct or foil but
paint on mastic or mastic tape.
most codes dictate mastic be painted on 'nickle thick'.
not just a dab, not duct or foil tape, but mastic.
you NEVER want to have to address this again.

making sure that this is done as install is ongoing is
something you may have to do. too often the homeowner
pays for it...but never checks to see it is done.

I usually take one day to install & mastic, let mastic dry
& the next day, wrap the ducts with R-8 ductwrap.

there is a method for the wrap also. it is cut to fit,
wrapped around the duct, stapled ..two rows of duct
staples followed by duct wrap tape (fsk tape). again..
not duct or foil tapes. fsk tape. I usually staple fsk down
on both sides. stapels are cheap.

ductwrap when properly done, and kept away from critters, & water will last a long time.

you see why hard duct is more expensive than flex.

how are the floors being insulated?
3" closed cell foam...after ducts are installed?

have you gotten used to one thing leading to
a dozen more details to oversee yet? LOL!

best of luck.