I'm formulating a plan to build a home (as green as possible) in Roanoke, VA on a mountain (elev ~2,000 ft).

The goals are: - simplicity - cheap utilities (i don't think net 0 is feasible price wise) - functional

I've renovated homes previously on my own and understand the basics of renovations, but I've never built a house, let alone a green one. So I would love your critique if you have some spare time and would like to give it (please be as honest as you'd like, but kind if possible!)

It seems that a slab on the mostly flat lot would be the cheapest foundation option, so thats the idea currently. Then we're thinking of a basic rectangle/square shape, like a 35x35 box. The first floor would be very open, hardly any interior walls. At the moment SIPs look attractive, so lets say those for the example.

As for a roof, a single, 31 degree pitch, SIPs, covered by standard, light colored metal, topped with as big of an array as is affordable. I've seen 10,000kwh kits for $20k after rebates (don't know yet if these are crappy panels, etc).

The lot faces south perfectly (and also a great view) so I was thinking a large bank of argon filled windows along the back to bring in winter sun, and have the roof hang over enough to prevent too much summer sun (this means the larger side of the house wall will face away from the sun).

Would love to do 3 floors, two facing the sun/view, and 3 on the north side where the roof slopes up (basically just to fill that space, so more like a half floor).

From what I have done before, I can source materials to keep the kitchen costs to $15k, master bath to $6k, other full bath to $4k and a final half bath to $2k (so 2.1 baths). All the plumbing will be tied to the same stack and the kitchen, half bath, and two full baths will all be backed up to each other for minimal plumbing runs.

Mini split ductless systems seem to be a great way to go for efficiency, and i'm thinking probably 3 zones, one for each floor.

Flooring would be a mix of stained concrete (main floor only and radiant heated if possible) and bamboo elsewhere. Finish would be simple, moulding would be simple and minimal.

As for siding, I'm undecided here. Looking for something cheap that works, nothing more.

So what do you think? What am I missing from my thought process here? Am I looking at $350 a sqft? I was hoping for something reasonable but some of those pieces are totally foreign to me and thus pricing them seems impossible.

Thanks for any feedback!

andrew

You can spend $350/sf if you want, or $150/sf; it's all in the details. You'll have to design the house and price out all of the materials and whatever labor you're not doing yourself to get a better sense.

A square house may be the most efficient shape (actually, round is the most efficient). but it's hard to get good natural light in a house that shape. Consider your rooms, view, and light when laying out a plan. A rectangle usually works out better for the people that actually live there. You do have the right idea designing the house to fit the land. This is an important step that many people ignore when designing a house.

The cost could be just about anything. Our DIY ICF house was less than $100/ sq ft, but I did 95% of the work my self. It probably would have been double that or more if I hired a a turn-key contractor. We have a metal roof, and fiber cement siding. The house is just one floor at 1400 sq ft, but we have a full basement that could easily be turned into living space. It is a walk-out, so there are windows and a door, plus with ICF, it's already insulated. Although a basement costs a lot more than a slab, we could double the size of our house easily and cheaply. Without HVAC, it never gets below 60, or above 78 degrees, so it barely needs any HVAC.

We used quality windows (Marvin) and I did a lot of nice work inside and out. The floors are 120 year old reclaimed heart pine. I custom made all of the moldings. The kitchen came to $8K with all custom cabinets (DIY), a tin ceiling, and a mix of maple and laminate counters. We have two Mitsubishi mini-splits, and they are quiet and efficient. In our mild climate in upstate SC, we go for long stretches without using heat or air.

You haven't indicated whether you plan to do some or all of the work yourself. Either way, build a house with good bones, such as quality, long lasting structure, siding, roofing, and windows. SIP's were my runner-up technology, but ICF was easier for one old man, working alone. If I had the extra money, I would have used a SIP roof over a light metal frame, but I went conventional framing to save some $$$. I insulated the ceiling instead of the roof deck, so the attic is hot, but I don't have any mechanicals up there.

When you start talking about going over 2 floors, with the ground floor being mostly open concept, the structure plan gets a little more involved. Not sure how SIPS would effect this as I have never looked into designs using SIPS. A little bit larger footprint with say a main floor and a loft tucked up into and exploiting the single pitch roof area might be significantly easier from an engineering standpoint and still yield the same relative square footage. As a plus this would give you a little more roof area to play with. 35'X35' X 2.5 floors = 3062SQ/FT 58'X35' X1.5 floors = 3045 SQ/FT. The loft concept would make that portion of the main floor feel really large inside with a vaulted ceiling and would probably work well with a radiant main floor heating system... Also adds the option of a lookdown hallway or balcony, or internal openings down into the main living area...

Two questions that often get overlooked are 1. How long are you planning on living in this house? 2. How old are you now? If this is a "dream" house you are putting together for your own enjoyment, to live in for a very long time, those 2 questions often lead to a third question: 3. Are you really going to want to(or be able to) deal with 2 stories worth of stairs during the projected time you are planning on occupying this home? With the main floor being mostly open concept, it sounds like the bedrooms and master bath are up at least 1 flight of stairs? Age creeps up on us all. The house we are building now is VERY different from the one we started planning 15 years ago...

From a thermal standpoint, aboveground walls are usually the weakest link and will shed(or gain) the lions share of your thermal energy. In a 2 story rectangle, the wall area can easily double the ceiling area. The ceiling insulation however will probably fall in the R50+ish area, while the walls, unless you build something "non standard" are probably going to be in the R25ish area. They also have a nasty habit of collecting doors and windows resulting in a lower overall R value.? Because of the insulation differences reducing the wall surface area and increasing the floor and ceiling areas is probably better from an efficiency perspective.

Putting more of the wall area below ground puts it in an exposure area of typically 50-60F most of the year as opposed to the above ground temperature exposure and winds. It is usually advantageous to push the mechanicals down into the basement. Basements can also be a good place for garage and shop spaces if the terrain lends itself to a walkout basements. But they do cost more money. How extreme is your weather at the build site. Any hurricane after-effects or tornados? This could be an issue with a taller structure also... A basement shelter can be worth it's weight in gold if extreme weather is a possibility...

Good Luck.

Take a good look at a frost protected shallow foundation/slab along with some upsizing and additional insulation in the above ground space with the money saved by not having a basement.

Once you have a well insulated house, it doesn't take very large south facing windows to over-heat it. I'd only make a "large bank" if you want the view.

Sounds like you may have 100% of the roof covered with solar panels. I wonder if that somehow allows some reductions in roof cost (for example, why cover the whole roof with expensive metal and then cover that with solar panels?).