Building the foundation walls

Although these steps may seem easy at first, they're in fact complex and require a lot of attention. In the end, these simple walls are the very foundation of your house and nothing in their construction should be left to chance.

We recommend you call on a formwork specialist for this task if you want to be sure your walls are solid and straight. A good contractor will use panels designed to withstand the pressure of the concrete. That alone makes his/her services worthwhile. Normally, the thickness of foundation walls varies between 6 and 12" (15.4 cm and 30.48 cm), depending on the number of storeys they have to support. Framework should be even, watertight and clean if foundation walls are to be at their best.
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1. Install the stud bolts and ribbon strips
2. Frame for the windows and doors
3. Plan the cold room, if one
4. Plan reinforcing bars for concrete balconies
5. Pour the concrete
6. Avoid future damage
7. Ensure a uniform pouring

1. Install the stud bolts and ribbon strips

Install the stud bolts and ribbon strips. To be sure the wood frame will be well attached to the foundation, you'll need to secure ribbon strips to the foundation using stud bolts spaced every 4 in. centre to centre. And here's a tip to make that easy: take pieces of two by four (5.080 cm × 10.16 mm), drill holes into them every 4" (1.22 m) and use them as ribbon strip. Nail them to the sides of the formwork, then insert the stud bolts through the holes making sure they're at the right height and level.

2. Frame for the windows and doors

Before pouring the concrete into the framework, insert the windows and doors frames. Cover them with temporary protective panels sealed with silicone applied to the edge of the panel, which you can then secure with nails or staples.

Secure the doors and window openings with nails, making sure they're at the right height and level. When that phase is completed, add two 1/2" diameter (1.27 cm) reinforcing bars over the openings. The bars should be longer than the openings by at least 6" (15.24 cm). Their role is to reinforce the top of the openings by means of a solid and resistant lintel.

3. Plan the cold room, if one

If you're planning a cold room, you'll need ventilation holes which you can make using sections of 4" (10.16 cm) PVC pipes cut in lengths that match the thickness of the foundation walls and inserted between the formwork panels in the appropriate places. Hold them in place with a nail on either side of the formwork.

4. Plan reinforcing bars for concrete balconies

Don't forget to plan for reinforcing bars for concrete balconies. Use 1/2" diameter (1,270 cm) bars, spaced every 8" (20,32 cm) centre to centre, installed in a right-angle criss-cross pattern to provide sufficient reinforcement for the concrete structure to bear adequate loads and resist shifting.

5. Pour the concrete

You are now ready to pour the concrete in the formwork. We strongly recommend you use a concrete pumpter and a competent operator for this task. And you should choose the type of concrete you'll use based on the width of the footing. Its resistance rating should generally be in the 20-25 mpa range. Many contractors opt for 25 mpa-rated concrete. Some even recommend the addition of air micro bubbles that help the concrete better cope with the effects of frost.

To be sure you've chosen the right concrete, call on the expertise of a laboratory that specializes in soil analysis.

6. Avoid future damage

When you are actually ready to pour, be sure the distance between the spout of the concrete chute and the footing does not exceed 5' (1.525 m). Otherwise, the impact of concrete falling from a greater height could damage the formwork and, eventually, your foundation walls due to the separation of aggregates (metal particles in the concrete mix), which form potholes, cracks or other irregularities in the concrete.

7. Ensure a uniform pouring

Also ensure pouring is carried out in a uniform manner to avoid the formation of cold joints, which occur when concrete is poured into the same formwork in two or more sessions. Such joints or lines in the concrete are to be avoided. When pouring has been completed, provide for a curing period of two days to a week to allow the concrete to dry properly before proceeding with the removal of the formwork.
You have just completed a crucial operation in the building of your house.
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