To elaborate on thermal bridging since it was brought up again... there are several ways to calculate it, but to keep it as simple as possible, here is how it affects your total wall's insulation. First thing, if you put in r20 rated insulation product, you are certainly not getting an r20 wall for cavity walls. Other products such as ICF and SIPs (some SIPs even have thermal bridges) are nearly thermal bridge free and have what is called continuous insulation. My home is an ICF house from the footings to the roof, and there are no thermal bridges anywhere until the roof line. This gives me an r28 continuous insulation. However with wood frame structures, you have a framing reduction to take into account. Most new homes, studs, heads and plates take up anywhere from 18-25% of the wall area. (lets keep the numbers whole and rounded for easy math) Say you select blown fiberglass in a 2x6 wall, gives you roughly r20. You have 1000sqft of wall surface. That r20 is only for the stud bays, and every 16" roughly you only have an r1 due to the stud (framing factor) So you have 800 sqft of wall at r20 and 200 sqft of wall at r1. . Your "r20" wall is performing at an r16 on average with the studs acting like heat sinks. Add just 1" of XPS foam to the exterior (r5). Your r20 turns into r25, and your r1 turns into r6. Now 200 sqft of your wall is an r6 vs an r1 and reduces the heat sink effect.The materials to add that 1" XPS would be roughly 500-600 for that 1000 sqft wall. The upgrade from blown fiberglass to open cell foam is typically more than that. For adding exterior foam, details are pretty simply up to about 1.5" thick. After that, the details change and become more costly. Luckily for you, in zone 4. 1.5 is about as thick as you need to go. 1" would be a good start, and your details really do not change. I have detailed 1" foam and windows 1 of 2 ways. Either install the sheathing and foam and then the window. Or with 1" foam, most window flanges are 1 1/8"+ wide, so you can install the window and then install the foam. This gives them about 1/8"+ lap for a caulk joint for trim to hide the foam. The trim stands proud of the window with this detail obviously. 1.5" adds another step. I like to detail a frame out around the windows and butt the foam into it. So frame the wall as normal, install sheathing, then rip a 2x4 in half to give them 1.5x1.75 furring to frame out around the window RO. Install the foam, butt into the furring around the window, and then set the window, nailing into the furring. Everything planes out, and quite simple. Obviously this can also be done with 1" foam too, its just not necessary. There are lots of details floating around out there. Check out green building advisor as well. You can also checkout my blog for more details and nerdy building information. Again, a very untechincal explaination, but you get the idea hopefully. Here is a link that might be useful: home building blog

IMO $13,500 is too much to pay for the task. What does LSU say (in an unvented attic) about 1. Humidity removal from the attic (or are you cooling the attic too?) and 2. Condensation forming. Breathable attics have been the rule for 40 years. I'm sceptical of otherwise. Guess I should check out the energystar website for what current thinking is. I don't have alot of respect for what universities say about some issues...here in Texas, Texas A&M still supports synthetic chemical fertilizers while the masses and pros have moved on the organic fertilizers. Monsanto and others provide research money....follow the money.

Proper attic ventilation would be more efficient. Grey shingles might have a little more reflectivity, but when asphalt shingles warm up in the summer, they get blistering hot no matter the color. A shingle will get too hot to handle even on a warm sunny day let alone the summer months, that is why getting the hot air circulating and out of the attic is key. If you want to take it a step further, you can install radiant barrier on the underside of the rafter/trusses coinciding with venting to keep the hot from the roof penetrating the attic. Here's a link to mr. ed sumpolec who is a retiered nasa engineer and gives out his phone # for a reason. It's best imo to talk to him in person about your particular project/install as it varies according to region. Here is a link that might be useful: radiant barrier

I used Owens Corning's custom design web site to pick a type of shingle and color. You can have your contractor give you a price for each grade. Once you get to the web site select your house type then at the next page select the "custom" tab and then pick which shingle grade you are interested in and then below you will see all the shingles in that line. Select one and you will be amazed. You can save the pictures to file to show your contractor. Also you can experiment with siding and veneer types by selecting the "Collections" tab. I used this site to pick my siding color, type and color of shingles. Here is a link that might be useful: Owens Corning