Carpentry Skilled Trades 1201 Footings and Foundations

The Foundation and Related Components Footings After the building lot has been excavated the actual building process begins with the laying down on the Footings. The footings function to provide the foundation wall, which will be added later, with a greater area to distribute the weight of the house.

The Foundation and Related Components Here in Newfoundland most footings are made by pouring concrete into a wooden form at least 300 mm wide and 200 mm thick. Footings must also be placed below the Frost Line (approximately 1 meter) to prevent frost heaving during the winter months.

The Foundation and Related Components Foundation Wall Forming Once the footings have set up the foundation wall form or cribbing is then constructed on top. Due to extreme pressure exerted by wet cement these forms must be well constructed.

The Foundation and Related Components Many home builders contract a company which specializes in foundation wall forming, this practice saves time and insures a measure of accuracy and safety. Foundations vary in size depending on the type of building being built but most foundation range from four to eight feet in height and are 8 inches or 200 mm thick.

The Foundation and Related Components Pouring the Foundation Walls With the form in place the concrete must now be mixed and poured. Concrete is a mixture of Portland Cement, Fine Aggregate, Course Aggregate, and Water. These ingredients must be mixed in proper amounts or the foundation may be weakened.

The Foundation and Related Components A common mixing ratio of the ingredients is or 1:5. In this formula One unit of cement is added to Two units of fine sand and Three units of course sand.

The Foundation and Related Components A common mixing ratio of the ingredients is or 1:5. In this formula One unit of cement is added to Two units of fine sand and Three units of course sand. The amount of water will vary depending on how wet the aggregates are to begin. To determine how much water to add it is best to complete a Slump Test.

The Foundation and Related Components Properly mixed concrete will slump by 20%, too much water will create a “soupy mix” that will slump too much, this condition will weaken the concrete.

The Foundation and Related Components Properly mixed concrete will slump by 20%, too much water will create a “soupy mix” that will slump too much, this condition will weaken the concrete. Well mixed concrete can be Stripped (process of removing the form or cribbing) after two-three days and will harden to maximum strength in 28 days.

The Foundation and Related Components Foundation Waterproofing (Damp Proofing) Once the concrete has been stripped the foundation must now be Damp Proofed before being Backfilled. Backfilling is the process of pushing earth back against the wall.

The Foundation and Related Components A common method of damp proofing is to coat the exterior of the wall with tar or asphalt. In addition many home builders today apply a layer of Styrofoam to prevent penetration of frost into the basement.

The Foundation and Related Components

To prevent water from collecting around the footings perforated pipe called Weeping Tile is placed at the lowest point to provide drainage. The weeping tile is then covered in course stone to prevent the holes form being clogged once the foundation is backfilled.

The Foundation and Related Components

With the foundation wall damp proofed and the weeping tile installed loose earth material is pushed back into the ditch surrounding the foundation wall (backfilled).

The Foundation and Related Components