Two-story 950 SF off-grid building plans on existing concrete slab
Hello. I’m brainstorming. I would appreciate any guidance or leads as I’ve never built a building before, done my own contracting, or utilized much green building techniques. I need to build this place in the next 6 months. I live in Western Colorado outside of Rifle, CO 81650. I think it’s building Zone 5/6/7 (they’re all around… can’t tell which exactly).
1. Existing slab is 20×32 feet that I want to utilize. I do not want to cut into the slab… it’s perfect. I do not want a crawl space. I plan on putting the minimalist utilities into thickened (11-1/2″) double insulated walls. Each floor will have an open floor plan but bottom floor will have a small bathroom and storage room.
2. It’s to be an off grid agricultural building used for greenhouse and horticultural activities. It’s going to have a kitchen and bathroom for lab and convenience.
Each floor will have about 475 SF. I have to keep it under 1,000 SF total.
3. I’m leaning toward a metal building with either wood post/beam or metal framing and a 1:12 skillion metal roof. I have about 40 double pane aluminum windows and a large 7′ tall x 13′ long commercial tempered glass wall and door to install also… I’m making it for greenhouse and lab work so I want lots of light.
4. It will have two small wood stoves centralized on each floor for heat and some cooking. A medium 11 CF 8amp fridge. It will use a 400 gallon wall tank cistern for water supply. I will have a 100 gallon LPG tank for cookstove and perhaps hot water backup. I have a single 20amp circuit about 120′ away that I could connect from my house for a few small needs (like HVAC control, oven, fridge, a few emergency LED lights) but that will be next year when I have budget. I want to make it all 12/24/48 volt and use solar panels to charge a few batteries and do most of the hot water heating and lights through it.
5. Single toilet, bathtub, two sinks will use a new septic system that I install. I am considering a compost toilet and running the sink/shower waters to a large hole as I have no neighbors. Otherwise a septic will be installed.
Any suggestions as to how I could build this 20×32′ two story building and make it user and upkeep friendly?
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Replies
Andy,
Garfield County is Zone 5. Since the footprint is so small, I would suggest using (R-5 minimum) exterior foam on a standard 2X4 wall. The double wall will eat up quite a bit of square footage. Also on the plus side, you probably can find reclaimed foam for a fraction of the cost of new material. (More on this topic at https://www.greenbuildingadvisor.com/article/calculating-the-minimum-thickness-of-rigid-foam-sheathing.)
To expedite the construction, you might be able to have the walls framed off-site and then truck to your location.