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Concrete Foundation

A concrete foundation, with metal reinforcement, is perhaps the strongest base to give your home.

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The foundation acts as the base for your home. You cannot go back and redo it once the house is built, so it pays to do it right the first time. Reinforced concrete is perhaps the strongest option available to you.

For the purpose of this guide, we will be describing a fabric-formed foundation. They are cheaper and easier to set up, as well as offering a vapor barrier. Solid forms are more expensive and not as flexible as fabric. However, if you wish to use them, the process is very similar.

Materials & Tools
Materials

Lumber

Wooden or metal stakes

Plastic

Metal reinforcement

Any metal needed to attach walls (depending on the material walls)

Fibers

Cement and sand

Tools

Hand saw

Hammer

Measuring tape

Scissors

Pliers

Concrete tools (for mixing and pouring)

Level

 

Step 1: Design

You will need to have an overall design of your house in your mind before you pour the foundation.

  1. Know what material you will be using for the walls, as the foundation will need to be wide and strong enough to be able to support them.
  2. Decide if you need any uprights connecting the foundation to either the walls, doors, windows, etc.
  3. Where will the utilities (water, gas, electricity, grey water) be coming in or out? Do any of these things need to be accommodated in the foundation?

 

Step 2: Preparation
  1. Level the area of your building site.
  2. Add a layer of sand and compact it well.
  3. Mark and lay out where you want your foundation to be. You can dig it partially into the ground if you wish. If you need to, you can consult our guide on squaring a building.

 

Step 3: Forms
  1. Hammer in wooden stakes periodically along both the inside and outside lines of your foundation.
  2. Attach lumber (1″x4″ works well) to these stakes at the height you wish your foundation to be. Make sure that each side is level  and even with the other side.
  3. Lay black plastic in between the lumber, so that it forms a U where the foundation will be. Leave some slack in the bottom, so that the concrete can fill it.
  4. Attach the plastic with staples to the outside of the lumber.
  5. Periodically put some chucks of wood, the width of your foundation, in between the lumber. These can be taken out as you fill with concrete, they are just there to ensure that your foundation stays the width it should be.
  6. Lay your reinforcement in the plastic, lifting it off the ground so that it will be in roughly the middle of the concrete.You must always put metal in the concrete, as it can crumble without it. When using several pieces of something like rebar, make sure that they overlap each over at least a foot on each join.

 

Step 4: Concrete
  1. We use a 3:1 mix of sand to cement. We also add fibers for extra strength. You want to add as little water as necessary, as concrete gets weaker the wetter it is. It needs to be uniformly mixed, so that you cannot see any trace of sand.
  2. Fill the forms with concrete, tamping it as you go. It helps to have a small crew, with someone mixing, someone moving the mud, and someone filling the form.
  3. Level off the top by troweling the concrete in between the two sides of lumber.
  4. Once the concrete has hardened, cut the top of the plastic away from the lumber and remove the lumber and stakes. The plastic will remain in place, under the concrete, as a vapor barrier.
  5. Cure the concrete (keeping it moist) for several days.