Greetings, all...

I'm in the very early stages of planning a 2-story home that I'm trying to design from the combined perspective of efficiency, cost, simplicity and "green"-ness.

Because this is my first home design project, and I'm on the bottom end of a steep learning curve since most of my initial design choices were outside of the conventional stick-or-brick residential construction mold.

As a preface to my questions, I've linked a PDF with the basic design idea for the home. (I apologize for the file size, but it includes all the basic design sketches.)

From the purpose of cost-efficiency, I've tried to design the house to be as straightforward as I could:

- Rectangular slab foundation of 75'x30'
- Home footprint being a basic rectangle of 45'x30', the balance used to allow for patio and carport usage.
- Flat roof
- Both floors have 10' ceiling height
- Patio on roof, and a light frame glass greenhouse of 20'x20'
- 45'x10' area of roof reserved for solar panels (not part of initial construction, except for pre-wiring)

The construction and finish material choices I wanted are:

- Bamboo hardwood flooring for all first and second floor areas
- Bath and kitchen areas floored with glass tiles
- Steel-faced SIPs
- Metal siding
- Glass block for larger, non-vista windows

Electrical/HVAC choices:

- Radiant floor heating for first floor
- Pre-wiring for Solar panels

So, all of those things being established, here are my string of "new to the game" quesitons I will take anyone's advice on.

1. Before I learned about SIPs, I was very taken by steel-frame construction. Given a choice, I would prefer steel framing over stick for myriad reasons (insects, structural strength (I live in the PNW, so it's earthquake country), moisture resistence).  The more I see of SIP construction photos, I see many or most are framed exclusively with SIPs and don't appear to be using beams -- either stick or steel. Am I incorrect in thinking this? Or am I looking to marry SIP with steel-frame to accomplish what I'm attempting.

2. HVAC concerns with SIP. I am intially supposing that I would be using SIPs for the wall framing, the 2nd floor and the roof. Given I'm thinking both ceilings to be 10', and I'm hoping to use radiant heat on the first floor. I'm not sure what my choices are for 2nd floor heating and cooling. Do I need to be creative with the ducting and run it along the ceiling and try to make it a design element? Or is there a way to radiant heat the 2nd floor? What about cooling then? I'm not against exposed ductwork, since it can give a modern look if it's not overwhelming, but I'm just not sure what the options are.

3. Mechanical ventilation. Most of the sites I'm reading state that due to the tight fit of SIPs that mechanical ventilation would be required. Is this a unit that co-exists with the HVAC unit? Or does the HVAC work as double duty? 

4. SIP flat roofing. I am very decidedly positive about having a flat roof that can be used as patio space. I know that flat roofing is rare-ish in residential construction. I realize most people's aversion to flat roofing is the water drainage/leaks issue. Are there any advantages to using SIP for flat roofs I need to know about? Disadvantages? If I'm using SIPs for the rest of the house, is there any reason _not_ to use it for the roof? Does using the roof as a patio space (additional weight bearing issues) create any implications I need to worry about?

5. Foundation choices. I initially chose a large rectangular slab becuase it presented itself as the cheapest initial design chioce. But with choosing SIPs, and radiant heating, does the choice of slab foundation create issues that can be solved by another foundation chioce?

6. Stove heating. One element that is missing entirely from my current plan is the choice to have a wood burning stove. Other than choosing a location, are there any other considerations when dealing with a tightly-fit construction method like SIP?

7. Clean-air environment. I'm trying to head off any glaring air quality missteps from the beginning. That's why the steel-faced SIPs seemed appealing over the OSB variety. I am going with all hardwood and tile vs. carpet to keep the air cleaner. I also intend to choose air-quality friendly paint. Are there other things I need to consider in SIP construction that can have an impact on indoor air quality?

8. Moisture issues. Being in the PNW, there is a high precentage of the year spent in rain or wet conditions. Are thre any additional steps when using Steel-faced SIPs on a Slab foundation that are important to keep in mind?

9. Lastly, and in the more trivial category. Does anyone have experience with the impact of steel SIP and/or steel-framing as it pertains to things like WiFi, cellular and radio reception? Does all that metal enhance signal transmission, or hinder it?

Thanks in advance for any advice or pointers to websites, or references to PNW home builders or contractors with steel SIP and steel framing experience.

Jelly;

I had addressed many of

moibiusmuse's questions in a direct email to him/her. regarding flat roofs our steel sips can be done flat providing the roof membrane can handle water penetration in the flat. They can also be used as the finished roof in as little as 1/2" per foot slope

Panels on this job used at 1/2" / 12 pitch with Astec roof coating directly over panel skin has 10 year warranty

http://www.flickr.com/photos/21330431@N06/