Related question:

With Zip-R, since the insulation makes it 2-3X thicker than standard sheathing, does that mean windows will require jamb extensions? If so, what sort of cost (time & $$$) does that incur?

I'm wondering if it's be easier/cheaper to use insulated siding instead. Our builder recently mentioned a high-end vinyl that's foam-backed.

oc- stay away from insulated siding. It is overpriced and the r value compared to full sheet insulating (zip, exterior foam boards such as xps) is not as good.

Around here zip board is about $35/ sheet. Standard ZIP is around $16/sheet. Can not forget about the tape however, as it adds around 25% to the price of the sheets.

your climate also depends it ZIP-I makes sense or if you are better off using standard ZIP and exterior insulation for additional r value. R 2.5 and R5 sheathings are quite low for a big part of the US. In many heating climates you should be targeting 7.5-10 r externally.

Northern VA in my case. R13 is code, which i what they are putting in the walls. 1.5" sheathing added to the sheathing and jamb extensions will run a couple grand if I am right. The additional sealing, lower utilities (by a small amount), comfort, and noise reduction are worth it to me.

straight sheathing price difference (2 level above ground, 2500sqft house) should be about 2k more for the insulated, 1.5" sheathing, (using a high fudge factor).

Figure 30 windows, a few doors and a sliding glass door at about 50 dollars extra for each to have thicker jamb extensions (which is way generously priced IMO). So about 3700 dollars in extra cost, builder will mark it up to around 5500 of course. A price I would be willing to incur for the stated benefits of sound abatement and raising the R value to around 19.6, with a true r value around 16-17 vs 11 or so due to thermal bridging.

Builder already uses the zip system and tape, so no additional cost there.

I was budgeting about 10-15k in systems upgrades from standard, insulated sheathing, laminated glass windows (sound abatement), laminated glass in the doors, instant hot water system and upgrading from 13seer with dumb hvac to multistage HVAC system since noise bothers me to distraction.

Think I am way off with the above? (house is 26'x45' + 24'x17' garage, two above ground levels with 9' ceilings)

a quick note on "code". that word is tossed around here all the time. It is often confused with "good". Remember, all "code" means is the minimum standard you can construct something too. "Code" would be equivalent to off the shelf particle board cabinets and laminate counter tops (technically worse I guess). When I throw that at clients, they typically think twice, especially if they are hoing and huming about a $2k upgrade to the shell of the home that will provide payback, but do not blink an eye at dropping $50k on their kitchen cabinets. Not necessary targeting you as you are at least knowledgeable of the benefits, however more so for other readers reading this thread. I read too many threads where responses are "that is code here, so that is all I NEED to do", then see their pictures of their $90,000 kitchen in the other forum.

one option is drywall returns. My walls are about 10" thick, so I have drywall returns and wood sills, so no jamb extensions are required. drywaller charged about $200 more for it total.
Also do more reading on the instant hot water heaters...they are not as good as they are lead to believe.

I have an rennai in my house now :) I am well aware of how they work.

The payoff is a bit questionable, but I needed a condensing unit or something with its own intake and exhaust vs using a chimney flue. Instant or tank and instant won for a slight upcharge. BTW, I "needed" it only because I was trying to limit the draft in my house. Terrible allergies...
In a brand new house though, it isn't a terribly large up charge. Just have to make sure to get the right one that is suited to your environment and your lifestyle.