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Larry425
New Home Construction

First time posting to this site. I am in the process of making a five year plan that involves starting construction of a new home in approximately 5 years. I have some construction experience as I work for a Commercial Mechanical Contractor.

The home will be about 40 minutes outside of Louisville KY.
Will have a full walkout basement approx. 1500 SF
Main floor approx 1500 SF with a 2.5 Car garage
Upper floor Cape Cod Style approx 850 SF

I have a few questions that I want to see what people think. I will be self-contracting the work myself.

1) I plan on using ICF for the basement walls as I have priced it up and its roughly same cost as traditional standard concrete walls. Is it worth the money to go from 2x6 exterior walls on the main floor to ICF there too?

2) I am also thinking of using Radiant floor heating on the main floor will this provide enough heating for the whole house? Is this Cost effective because I would also still have to have a separate AC?

3) Is spray foam for insulation really that much better than Bat insulation or blown in?

I will have more questions as the time gets closer to getting a final budget together

keith3267
Re: New Home Construction

Have you looked at SIPs (structural insulated panels)? Here is an article comparing the cost of ICF walls vs.SIP walls.

http://architangent.com/2013/05/the-hidden-costs-of-icf-the-value-of-insulated-concrete-forms/

If you are building in an area with a history of tornado activity, then the value of safety enters the equation, but it looks like you will have a solid basement to escape to.

As for comparing walls for energy efficiency and energy economics, then consider the following. The walls themselves account for about 20% of your total heat loss (winter) and gain (summer). This is an overall average, it can vary a lot. The heating and cooling of your house accounts for about 60-65% of your total energy bill.

A typical 2x4 wall with no insulation has an R value of about R-4 to R-5. With some type of siding on the outside and sheetrock on the inside, you have cavities with walls about 3.5" apart and they are usually fairly well sealed up, but they will exchange air with both the outside and inside of the house, just not a lot.

The studs make up at least 10% of the wall and each stud has an R-4.4. The outside sheathing adds about an R-1 to R-2 and the sheetrock has about an R-0.2. So the R value at the studs is about an R-5.6 to 6.6. If you add R-13 to the cavities, your through wall insulation of the cavities is now an R-14 or 15, but that is a little less than 90% of the total wall, you still have a little over 10% at around R-6 or so. The simple math puts this wall at R-13.2, but it is actually a little less. It take calculus to accurately calculate the theoretical value because some heat travels laterally along the sheetrock to the studs where it finds less resistance to get to the cold side, then along the siding to radiate out into the great outdoors.

But here is the point so far, adding R-13 takes the wall from a 4 to the 13 range which is about a 70% reduction in heat loss/gain. If your building, adding the R-13 doesn't cost that much and it will have a quick payback. If you go to 6" studs and R-19, your stud areas will have an R-7 The simple math say the total R value of the wall will be about 18.7. That's about an 80% reduction over the uninsulated wall. This additional 10% comes at a higher price, but often not too bad, but payback will be longer. Same for a foam insulated 4" wall. A foam insulated 6" wall will probably save you an additional 8%, but the cost is much higher. SIPs and ICF would be about the same, around 12% of an uninsulated wall.

A typically insulated 1500 sf house in your area, R-13 walls, R-19 ceiling, contractor grade windows would probably run $1000 to 3000/year to heat and cool depending on the energy source. The walls would account for $200-600 of that. You will need to do the math yourself to determine what the point of diminishing returns is too great for you. If you are getting a loan for this house, you need to factor in the cost of the money (interest) to determine how long the payback, or if there will even be payback. Also consider the future cost of energy for the source you are going to use.

Clarence
Re: New Home Construction

Look into the use of Foam Core Concrete Panels.
Also Structural Foam Core Panels.
Both of the above may save cost due to the fact once the concrete is placed both sides will be complete or you can add a finish as selected.

Larry425
Re: New Home Construction
Clarence wrote:

Look into the use of Foam Core Concrete Panels.
Also Structural Foam Core Panels.
Both of the above may save cost due to the fact once the concrete is placed both sides will be complete or you can add a finish as selected.

I have a Price from a contractor to do the basement for 35,000 using Nudura ICF that is everything except excavation as I have that covered from friends. They also can do the main floor using it for an additional 22,000 that is doing 9 foot ceilings on both floors using the 6" concrete with approx 3 inches of foam on both sides. I am thinking by the time I pay for the 2x6's and insulation to do the Exterior walls of the main floor and sheating on the outside that this may actually be pretty reasonable.

Mastercarpentry
Re: New Home Construction

Call me old fashioned (because I am) but I prefer traditional time-proven building methods where future repairs might be problematic (such as a basement wall supporting a whole house above it). Yes, energy costs matter and should be considered, but the biggest consideration is whether a structure will last. Cast-in-place concrete has a proven history of durability; the newer methods haven't been in use long enough to match that. When they have been then I'll consider them as an alternative. I've seen too many engineering failures and product failures to not be skeptical. I'm not a "luddite" by any means but neither am I easily convinced. If it can be easily removed and repaired if it fails I'll use it. If not I want to see the empirical evidence of history to prove the claims being made that the product will do what it should. Cast-in-place concrete can be insulated with foam panels which while not as efficient, will absolutely not ever give problems and to me that peace of mind is worth more than some gains in energy savings. Build for strength, everything else matters not if the structure fails!

Phil

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