A house must have a strong base or foundation. The ground under the building has to bear the weight of a house. House Foundations are designed to support the building and to prevent it from moving during natural hazards.
If it is a weak soil, the foundations must be made stronger. If the house has more than one
floor the foundation must also be made stronger.
After your Architect have finished designing your building, before you start building your foundation. It is important to do structural analysis. You can also undertake an Unprofesional or DIY (Do it yourself) Survey
Before starting a foundation, it is important to investigate the conditions of the soil. To do a general survey, carry out an assessment of the soil, to avoid encountering problems later. Look out for the presence of large trees, boggy ground, wells or mine shafts and clay soils, all of which are observable without requiring trial holes.
After doing a DIY survey, it is important to ask for a professional ground survey before you start work. Trial holes can be dug around the site so that a view can be taken on the best means of placing the foundations.
An experienced engineer should be consulted in determining the appropriate level for the
foundation if there is uncertainty.
Make sure your structural designer have calculated the amount of weight the building will carry.
The engineer will determines the size of beams and pillars that will help carry that weight.
He/she also determines the number and sizes of rods that will be put into the beams and pillars to strengthen them for carrying the weight.
Identify all the load-bearing walls and the width of the trenches to be excavated.
The depth of excavation is very important. On tricky grounds, you might have to go down 2 metres deep.
Soil for a good foundation that can carry the weight of a house must be well drained so that it is dry and not
waterlogged. Building in waterlogged soil will eventually lead to the house sinking or collapsing in the future.
Digging out the trench
Concrete is laid to a depth of at least 150mm.
Laying the concrete
Blocks are laid up to finished floor level.
Laying the blocks
Install the footings
Seal the footings to protect them from moisture.
Be sure to purchase a high-quality sealer very important.
Once the concrete has cured, use concrete block to create the stem walls if you’re building a basement.
Start with your block wall in the corner of the foundation with “leads,”
Builders can string a line — allowing them to build a plumb and level wall between the two points.
The result is a straight and level wall that’s crucial to keeping all of the basement walls consistent.
Treat your foundation walls with another round of sealer to keep moisture out.
Acrylic-based sealers can be applied immediately after finishing the concrete.
FOUNDATION AND BUILDING FAILURES – QUALITY OF MATERIAL
The quality of material used is a factor in building failure. The choice of building materials, such as sand and
gravel, affect the strength of the building, and care must be taken to choose the best materials. Mixing
good clean ingredients with little water makes strong concrete.
Wrong ingredients seriously weaken concrete.
Strong columns provide strength to the structure.
Ensure to enforce hollow blocks.
Exposed metal should be painted with rust proof paint to prevent corrosion.
Cross bracing of walls and roof. The walls and roof need bracing against lateral movement.
In order to resist lateral forces, walls and roof structure need cross bracing all levels.
Use broken rock should be used in foundations, not unbroken rounded river stone or rounded seashore stone. River
stone can be used if broken.
Coral sand should never be used in any construction.
Coarse sand should be sieved to remove stones, fine particles and dust.
Mixing of concrete – Ensure adequate cement is added.
Limit water, and use only clean water.
Concrete should stand up when mixed, not flow away due to excessive water.
Do not use any water that is salty. This destroys concrete strength.
If the sand contains stones, reduce the amount of gravel added.
Strong columns provide strength to the building.
Column reinforcement should be 4 vertical bars with hoops holding them together, spaced at approximately the
same as the width of the column. Bars should be anchored in the foundation.
End of hoop steel should be bent 135º into the center of the column.
Column steel must be covered with a minimum of 2cm of concrete all round.
Do not put pipes down the centre of columns.
Hollow block walls should have a reinforcing bar every 80cm which is concreted into the blocks throughout the
height of the wall and is inserted into the floor or foundation when it is cast. It is good practice to fill all
holes in hollow blocks to provide further strengthening to the walls.
This is used when dealing with difficult soil. Engineers have to come up with a custom solution that will fixed the soil issues and this is referred to as being ‘engineered’
Piled foundations were the perfect solution for this waterside home on the Thames, as they allow the house to move slightly and water to travel underneath should any flooding occur. Piles are driven into the ground and then filled with concrete, and the whole foundation gets topped with a ground beam to build off.