Thanks everyone for your posts. Big thanks for dreamhome for his detailed post. Our lot is in old, mixed neighborhood. We have a 400k property adjacent to ours, we also have 150-200k properties next to us. Overall, we think of our neighborhood as "nice", not upscale by any means, but not ghetto either. However I don't really understand what does neighborhood has to do with cost of construction. The construction process and cost of materials should be the same for any neighborhood, right? (we do own the land already) Our first house was fully custom - everything in it was custom, floor to ceiling windows,open staircase, heated floors etc... Unfortunately, in my town everybody was just scratching their heads when I showed them elements of the house I wanted to build, and they said "uhhhhhmmm, never done this before, don't know how much it will cost, need one month to research". I forgot I don't live in major metrolpolitan area where people are used to something more than Walmart. I looked over at least 50 000 stock house plans, every single house plan site on the first 100 pages of google, exclusive plans and so on... I checked local construction firms plans, we found one plan that was very pretty outside, while offering all the space we need in a small square footage package, and we fell in love with it (we're very picky) and we want to stick with it. It's a pretty stock plan that doesn't require anything fancy, and we don't want hardwood floors, carpet is fine with us. Two-three years ago my cousin built their own house (2300sq ft) for 120k. Now they were fighting for every dollar of course, getting competitive quotes for everything, really getting the best deal for every single service and material... and in the end they built their house (pretty decent house dare I say) dirt cheap. Which makes us wonder if we should just forgo hiring greedy contractors altogether and just... do it ourselves. I have the winter coming, good time to read construction books and educate myself... I will of course have my select contractors bid against each other, but if they don't go down in their quotes much...

You have definitely done your homework, hopefully I can offer a few suggestions... As I think that you already know, using coated laminated glass will give you the same SHGC performance as you would get from an IG, but at the loss of the IG U-factor improvement. Keep in mind that laminated glass will generally have a shorter warranty period than will an IG (depending on manufacturer - but shorter warranty for lami versus IG is fairly consistent in the industry). Depending on the IG manufacturer (and materials), IG seal failure is not likely to be a problem. The better systems in use today have seal failures significantly less than 1%. There is significantly less reason to anticipate "down the road when the seals blow" than you might think. There is at least one other consideration when dealing with internal softcoat coated laminated glass. There are several different laminated glass interlayers in use today. It is likely that you will be looking at a PVB interlayer since a significant majority of laminated glass windows use PVB interlayers. Without going into all the technical details, not all laminated glass manufacturers who deal with coatings are comfortable with the compatibility or longevity of laminating softcoat coatings with PVB interlayers. Cardinal, for example, doesn't even offer an internally coated PVB laminate. Okay, all that said, I am really not trying to talk you out of using a coated laminate, I am offering a few other considerations...hopefully not making your call more difficult. In the case of an IG I would agree completely that getting a coated LowE coating or getting the LowE coating on a tinted lite is superior to an IG with separate coated lite and tinted lite. "I guess I could order the SolarBan 70XL in Atlantica tint to get even better SHGC, if PPG makes the 70XL in tint (on one piece of glass.)" I believe that PPG does offer the 70XL tinted as well, if so I think that it would be worth your while to check it out. "Also no one I've talked to even mentions the 70XL even though I am aware of it. I am surprised about how few Low-E options are presented by window/glass companies. Either they don't know about them, don't understand them, or believe their customers are incapable of understanding the differencea." --- All of the above? I am curious why you want to temper the glass in the laminate? While I understand (and agree with) your desire to temper the lites in the IG (I would do both lites at your sizes - I would also consider thinner glass since tempering would allow you to safely go thinner), but since laminated glass is a safety product that meets all the same safety codes as tempered (actually exceeds tempered in some respects), from a strictly safety standpoint there is no reason to temper the glass as well as laminate it. Although some folks advertise "self-clean" glass, other folks call it "easy-clean" glass just to avoid the controversy of the glass "cleaning" itself. It is a photo-catalytic titanium dioxide coating that does work really well. A few window companies offer it as a standard, others as an option, and others don't offer it at all. And while I don't deal directly with glass or window pricing, based on what you are asking for, and since you are in SoCal, I don't see that your glass quote is really out of line, which doesn't make it less painful. You are considering some potentially expensive options.

In the end, there are largely two types of people who comment on these threads. Those who are building houses and those who have built houses. While I admit certain people who have built houses in the past are a bit jaded, I think you need to realize that experience does count for something. I advise those who are starting the process to not so quickly discount the advice of those who have been through the process. I have built two houses in the past and was solidly into building the third when I decided not to do it. I had firm pricing to get it done and was pretty confident that I had an initial cost laid out, and my house came back more significantly higher than the OP's. Construction labor in my area is only 8% higher than Texas, but my house came back at almost 30% higher, and this price didn't include flooring, bathroom fixtures or cabinets. I do realize that it is possible for this to happen but become concerned that the OP is focusing on the wrong items. I feel my concern was validated when he posted the specs of his custom build. A 14 SEER AC in Texas is a bit silly. In fact, it doesn't even meet the currently enacted future minimums. The marginal cost of 16 or 17 SEER is reasonable in North Texas, which has something like 3,000 cooling degree days. My experience tells me that this isn't the only questionable thing going on here. Someone who is willing to cut that corner is probably going to cut others. The question isn't whether or not you can build a house in North Texas for $120 per square - the question is should you build a house in North Texas for $120 per square. In the end, labor and overhead are only so much of the build. Please don't feel the need to answer that question for me. I don't need, or even care, to know. However, you might consider listening to some of the people who have completed their build, because it is tends to be a bit of a humbling experience.

The bigger question is whether the addition you have in mind can be built within your budget. Design is one line item of the overall project budget, but it's not the most significant one.