Eco-Building on the Cheap: Foundation & Framing

We wanted to build a shop to do projects, plus we needed a place for our Balance of Systems (BOS) for our off-grid equipment. Other than our chicken coup, this was our first building attempt together. We wanted it to be functional but didn't have a huge amount of cash to spend on it. We also wanted to use local products as much as possible and started with a gravel bag foundation. The gravel came from our friend's gravel pit...the sandbags, unfortunately, had to be obtained through an online store.

Gravel Bag Foundation...

• Filled sandbags with gravel to about 3/4 full, tamped, then used pieces of wire sewn through the top of each bag to hold together.
• First tier of bags were laid flat on the leveled ground, butted up against each other (end to end) to form our 18 x 18 shop foundation.
• Two strips of barbed wire were afixed on top of the first level of bags around the entire perimeter. This is supposed to help hold the next level of bags in place.
• Second tier of bags were laid on top of the first tier, over the barbed wire and staggered from the first level so that the seams were offset between the two layers. 
• Covered the entire bag configuration with chicken wire and used fence staples to secure to the bags.
• Used cement in various places on top of the bags to help level the bag foundation in preparation for the sill.
• Foundation was cobbed (2 coats) and a thick cement coat was added to complete the gravel bag foundation after we finished framing the shop.

Now, normally with a bag foundation you would also have made a gravel trench that went below the frostline with your bag founation on top. This would prevent damage to your foundation and structure if the ground heaved during extreme temperature changes. We chose not to do this, only because much of our earth here already contains a fair amount of gravel and rock. Hopefully, it won't be an issue for us!

Framing the Shop...

• Obtained wood locally from a small family business.
• Created a sill with 2 x 8's and drove 3/8" rebar, 3 feet long through the sill into the bag foundation to secure the sill to the foundation.
• Used 6 x 6's for corners and doors & doubled up 2 x 6's for posts on about 4.5' centers. 
• Used 2 x 4's for horizontal support and tying the posts together.
• Researched high wind load roofs and, from recommendations, decided to build gabled roof ends which are supposed to be excellent in hurricane prone locations.
• Constructed an 11/12 roof pitch - about 42 degrees - ideal conditions for our latitude for winter sun conditions if we decide to add solar electric or solar hot water later.
• Built rafters on 2' centers and used hurricane straps as extra security. 
• Bought used metal for roofing, also obtained locally.  
• Designed the overhang on the south side to keep out summer sun and let the winter sun in. This allows us to take advantage of the low sun from mid-Oct to mid-April and helps heat the interior of the shop.
• Used Board and Batten system: 1 x 6s placed and secured vertically from top horizontal beam to bottom (sill); 1 x 3s placed and secured vertically over the gaps between the 2 x 6s. I love the look and feel of it!

Shop in it's "almost complete" form. Total spent: about $2000

Up Next: The Fun Part...

Straw Clay Infill (for insulation & thermal mass).