Insulation - new construction

kaiser715

kaiser715

Doing hard time
Joined
Jun 1, 2006
Location
7, Pocket, NC
Looking to build....2700sqft single level over crawlspace.

Going brick veneer....most all the builders we've talked to are saying just go 2x4 walls and R/15. Have 2x6 R19 in current house (vinyl sided). Electric bill runs about $75 fall and spring, 125 to 140 summer and winter for 1200sf. I let wife set thermostat where she wants it.

Worth it to go 2x6 with brick veneer?? Blue foam board between for a thermal break?

What do y'all think is the tipping point around here for more insulation vs. potential savings?

Going heat pump with either heat strips or propane burner for supplemental.
 
Brick does nothing for insulated value. Price the 2x4 studs vs 2x6 studs and plates to make your decision. I do lumber take-offs on mostly custom homes and am seeing a lot more 2x6 ext walls used as well as conditioned crawls.

I never see foam spec'd on the exterior, just house wrap. You could also consider tech shield for the roof sheathing. It is OSB with a foil surface on the inside face. The attic is where most heat transfer takes place.
 
Windows and doors are where most of the thermal loss in a house is. So if your house has alot of large windows 2x6 walls with r19 isnt going to make a huge difference cause your still going to loose alot threw windows
 
Do a conditioned crawlspace, during new construction is the perfect time. It might not help a huge amount with energy bills (but it will help) but it will really help control humidity and cause a lot less problems if you're going to have wood floors. Do the research, I would never do anything else than a conditioned crawlspace for a new home.
 
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Fabrik8 said:
Do a conditioned crawlspace, during new construction is the perfect time. It might not help a huge amount with energy bills (but it will help) but it will really help control humidity and cause a lot less problems if you'rengoing to have wood floors. Do the research, I would never do anything else than a conditioned crawlspace for a new home.
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The BEST thing for hardwood floors.
 
Fabrik8 said:
Do a conditioned crawlspace, during new construction is the perfect time. It might not help a huge amount with energy bills (but it will help) but it will really help control humidity and cause a lot less problems if you'rengoing to have wood floors. Do the research, I would never do anything else than a conditioned crawlspace for a new home.
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We had our crawl space done last year and I can say I've noticed a huge difference in the comfort. Our in home humidity levels have stayed below 55% without a dehumidifier even on the swampiest days. Our hardwood floors were swollen and cupped before but have since leveled back out. I'm still going to replace them because they are loose now. We keep our thermostat set a lil higher now because it feels cooler. I know I sound like a commercial but this was seriously the best thing we could have done! Next is re-insulating the attic. Our house is approximately 1600sf with 2x6 walls our power bill stays under 200 now, including our garage and apt. above it.
 
Fabrik8 said:
Do a conditioned crawlspace, during new construction is the perfect time. It might not help a huge amount with energy bills (but it will help) but it will really help control humidity and cause a lot less problems if you'rengoing to have wood floors. Do the research, I would never do anything else than a conditioned crawlspace for a new home.
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Yep, going to do it. That was going to be one of my next questions here, what y'all thought about them. Builders here aren't doing any, but are open to doing it. Most say not much additional cost, a wash to a couple or three grand...one said it would add 25-35k. Guess who I won't use?
 
One builder mentioned doing a "Mooney wall"...I was surprised, as i had read up on them on I thick buildingscience.com. ... little more labor and material, but not as bad as some other high insulated wall systems. He has never done one, but intrigued by the concept.
 
I'd do continuous insulation in the air space before I did 2x6 studs. Increase the air space and do an inch or two of rigid over the air barrier.

Two inches of polyisocyanurate in the cavity, and you don't need batts. Hardest part for a homeowner is going to be coordinating the jamb details at the windows and doors.
 
2x6 is the way to go. It just makes for a much better finished product. A house framed with 2x6 just feels better, if that makes any sense. R-15 would be the minimum for that area of the state. The cost difference between 15 and 19 is probably negligible at best when looking at the total cost of construction.

I've only seen one conditioned crawl since I've been here. Taylorbuilt Homes out of Winston Salem did it. It was really quite nice, done well. This was a fairly large house on the 18th tee box of Old North State so I think there was some money there.
 
I'd bet you can do an inch of rigid and R13 batts cheaper than you can do R19 batts, not counting the additional framing cost, jamb extensions, etc. And you'd have a higher effective R value on the assembly.
 
I'm a huge fan of open cell spray foam. Probably because I used to install it and was the spray guy. I'd reserve that more for the attic though. However I have shot many a interior walls and ceilings with it.
 
Put the most insulation where there is the biggest temperature difference. Start with attic put in as much you can even if you have raise floor if you have storage there. Radiant foil barriers are great if they have an air space to work. Open cell or fiberglass need dry air to perform properly. If you raise the moisture 1 and 1/2 percent in fiberglass insulation the R value decreases 36 percent. Next insulate walls. I built my house in 1989 and used 2 x4 studs with fiberglass batts but I also put 3/4 insulation board ( closed cell ) with foil face on the out side and another layer on the inside of the exterior walls. I considered 2x6 studs since I built my dads house that way. Pricing extension jambs for windows and doors vs R value I did 2x4. There are 3 different types of crawl spaces under the NC code. Vented, closed and conditioned. I would do the closed and use the the cheapest insulation. There is very little temperature difference in a closed type so very little or no insulation is needed but some is required by code.
 
Foil barriers and foil faced sheathing make me nervous. They act as a vapor barrier and a condensation plane. Really easy to cause yourself all sorts of issues.

In our climate, you do not want to have any vapor barriers in the wall or roof/ceiling assemblies. INCLUDING KRAFT PAPER!! Your batt insulation should all be unfaced. The air barrier should be installed outboard of the insulation and should be vapor permeable.
 
The folks at LP say their product is vented. Looks like nothing more than a bunch of pinholes in the foil. They do have their advertising down. Quoting a house right now with it. Oh, and a conditioned crawl and 2x6 ext framing.

2700sf is a pretty big single story. I'm going to guess you'll have lots of attic.

Keep in mind that if you have a nasty cut up hip roof, you will have more waste because the pieces can't be flipped like regular OSB.
 
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broncosbybart said:
2700sf is a pretty big single story. I'm going to guess you'll have lots of attic.
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This is our house to grow old in. Plan would be to downsize in 25 years depending on health (late 70's then...too much land to take care of then). Want it all single story. Also want to max out ceiling insulation, so no attic storage. Have storage room figured into floor plan for "attic" stuff (large walk-in closet off hallway).

All on one level maybe not quite as energy efficient as two story stacked...but does allow to make up for some of it in increased insulation overhead. Plus, around here 2 story means 2 heat pumps. (something like a 2 and a 2.5 ton vs. a 4 ton)...more $ up front, maintenance, eventual replacement, etc...

House is in kind of a "T" shape...3 gable ends... Back section about 38Dx54W, front leg of the T about 24Dx38W, with an 8' shed roof over porch on 3 sides. Part of the back section taken up by 12x18 screen room.

2756 right now...I am working now on the plans to squeeze out some space, shooting for 2650 sq.ft. 2700 will be easy...that last 50sqft not so easy.
 
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broncosbybart said:
The folks at LP say their product is vented. Looks like nothing more than a bunch of pinholes in the foil.
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I'm not sure that's enough. Can you find a published perm rating? I can't.

If you want to get into fancier roof assemblies, rigid insulation sandwiched between layers of sheathing is a better (and proven) way to go.
 
If you've got the money upfront during construction, I can get you the number of a guy that designs home insulation plans and HVAC. You build it his way, to his specifications and he will guarantee you that your power bill will not be over $XX.XX a month. Of course that depends on the size, but to put it in relation He did a house for one of the Nascar drivers (or somedamnbody like that) and it was a 6000sqt house. He said it wouldn't be over $100/month to heat or cool. He was right. I've heard this from 2 different sources that don't even know each other. one use to work for him, the other is a contractor Supplier who knows all the builders and architects in the area. this guy was Energy Star before there was Energy Star.

It won't be cheap up front, but pays back in savings.
 
mbalbritton said:
If you've got the money upfront during construction, I can get you the number of a guy that designs home insulation plans and HVAC. You build it his way, to his specifications and he will guarantee you that your power bill will not be over $XX.XX a month. Of course that depends on the size, but to put it in relation He did a house for one of the Nascar drivers (or somedamnbody like that) and it was a 6000sqt house. He said it wouldn't be over $100/month to heat or cool. He was right. I've heard this from 2 different sources that don't even know each other. one use to work for him, the other is a contractor Supplier who knows all the builders and architects in the area. this guy was Energy Star before there was Energy Star.

It won't be cheap up front, but pays back in savings.
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He must throw in a temp number you have to keep it at then.
 
I did some calcs comparing my current 1200sf house to my proposed 2700sf house (actually, wiggled it around some, current revision comes in at 2685sf). Calced square footage of windows compared to total wall footage, square footage, and total heated cubic footage. Proposed house comes out about 25-30% less in window/door area as a percentage of those areas, compared to the current house. So, at least I am ahead there.

Worse comes to worse, I'm just gonna put in a woodstove. Got lots of firewood out there.
 
I am with shawn on this one, with a few caveats.

1. I like the looks of a 2x6 wall, so my house will be built from 2x6, atleast on the exterior.

2. Your extra cost associated for doing this is NOT just going to be in the lumber and insulation. IE windows, doors, and trim will all increase in cost. Just remember that up front.

3. Cont. outboard insulation is THE future. Even commericial building code is adopting it. If you want to be on the cutting edge then this is the way to do. Like shawn stated, you need to have a single vapor barrier though. You do not want to trap moisture in the wall.


One solution i like is to do a "flash and bat" type system where you spray all of the cracks and where studs meet your plywood sheathing with spray foam (open cell) and then come back and use standard batt for the wall cavity. This eliminates most of your air infiltration while saving you alot of money. Open cell phone is expensive and if you fill the wall cavity very hard to relocate utilities later. This gives you the benefits with less cost and headache.

The company i work for just picked up a new product line (XCI Ply) that is poly iso laminated to sheathing (of your choice). Pretty much any thickness you want and rougly $2.5 a sqft. You can even get sheathing on both sides if need be.

awww.hunterxci.com_images_Xci_Product_Art_Archives_Product_Overvew_sm_XCI_Ply.jpg


Again though, windows and jamb details might become an issue.

If you want to spend money to save money....spend it on your windows.
 
@farmboy, that's an interesting product. We were having issues with the CI requirements in wood frame - partly due to how the windows install (face nails in the flange) and NFPA 285 issues with the exposed insulation in the cavity becoming a hazard. Looks like that addresses both.

People keep recommending spray in the attic, so I'll keep stating that it's not recommended in our climate due to dew point issues.
 
@shawn it seems to be the answers for alot of problems...but Vinyle windows are still lagging behind. NFPA 285 is turning alot of worlds upside down. We sell a ton of rain screen products and are dealing with it everywhere.

Another system we sell for commercial use is green girt. I will get some details on that if your interested, but it is basically a fiberglass Z that hold to insulation and eliminates any issues with thermal coupling.
 
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