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What is Grillage Foundation? Types, Advantages and Disadvantages of Grillage Foundation

In construction, grillage foundations are shallow foundations that are typically installed at the base of columns to distribute the weight of columns, piers, or scaffolds across a more expansive area. A joist ceiling is constructed by layering or tiering them at right angles, each one supporting the next one. Foundations made from grillage are most suitable for soils that have minimal bearing capacity.

It ensures that transmission loads are distributed over an appropriate base area, thereby preventing extensive excavations. In addition to being used in commercial structures such as office buildings and retail businesses, it can also be incorporated into house construction.

An important component of a grillage foundation is the grillage beam, as well as the spacing beams and foundation bolts. The grillage beam is composed of steel or wood bars that are connected together to provide a sturdy foundation.

Spacing beams are perpendicular to grillage beams on either side and provide additional support for lateral stresses. Grillage beams are attached to the concrete or steel-reinforced concrete footing underneath them with foundation bolts.

Various characteristics of Grillage Foundation

Here are the few characteristics of Grillage Foundations you need to know:-

• Creating an even distribution of weight for the house and the piles is made possible by the grill connecting the foundation to the single structure.
• In most cases, these foundations consist of monolithic reinforced concrete structures. Usually, steel foundations for grilling provide resistance.
• There must be a minimum clearance between the grillage beams of around 8cm so that the concrete can be poured and compacted properly.
• Despite not carrying any weight, the concrete filling keeps the beams in position and prevents corrosion.
• It is recommended that the concrete depth below the lower tier be kept at a minimum of fifteen cm.

A few types of Grillage Foundation

There are three types of grillage foundations: wooden structures, steel structures, and concrete structures. A substance's choice is determined by a variety of factors, including the type of construction, height, and weight of the structure.

A grillage foundation can be one of the following types:-

Timber Grillage Foundation

The basis of a timber grillage is built of wood planks. It is supported by a succession of huge timbers known as grillages. The grillages are bolted together and piled parallel. Concrete has been used to cover the whole system of grillages and bolts.

Further, each layer of grillage is perpendicular to the layer above it, making this foundation beneficial on soils with limited bearing capacity.

Grillage length is related to building load and inversely proportional to soil safe bearing capability. The grillages are bolted together once they have been placed in the grid. Concrete is used to fill the gaps between the grillages in each tier, which, in addition to keeping the grillages in place, prevents relative movement.

Steel Grillage Foundation

Steel grillages foundations are similar to timber grillages in that they are made of steel shafts. The structure is supported by a series of shafts of different types, grillages are piled similar to each other and are bolted or welded together.

Depending on the weight of the structure, the steel joists should be sized appropriately. In the case of a need for the joists to be one, they can be joined together, if needed. As with a timber grillage foundation, the steel joists are arranged parallel to each other in each subcaste. In addition, each subcaste is vertically related to the contiguous subcaste.

To get more clear ideas, go through the following exclusive construction video tutorial.

Lecturer: Amazing Civil Engineering Study

The individual footing area of a grillage foundation is equal to the weight on the column divided by the safe bearing capacity of the soil. The whole joist structure is concreted over. On both sides of the joists, a concrete cover of at least over a hundred mm is maintained. It prevents corrosion of the steel beams.

Reinforced Concrete Grillage Foundations

Neither timber nor steel grillage foundations differ in thickness from the thick concrete foundation. Concrete grillage foundations differ only in their material; reinforced concrete grillage foundations are built from reinforced concrete.

The grillage foundations were constructed from timber and steel for a long time. As a more recent concept, reinforced concrete grillage is a newer concept that has been made possible by advances in concrete technology. Precast concrete grillages, cast-in-place concrete grillages, and pre-tensioned concrete grillages are all available.

Basic Benefits of installing a Grillage Foundation

• It takes less time and materials to construct.
• As a result of not being sprayed on frozen ground, it reduces heat evaporation from the foundation of the home.
• It lowers the house's vibration level.
• Grillage Beam installation takes less time and fewer resources.
• This foundation may be utilized for large buildings such as column piers and scaffolds.
• It has the ability to distribute weight across a broader region.

Basic drawbacks of installing a Grillage Foundation

• In this case, piles need to be constructed at a depth that is suitable for the project.
• Under the network, airspace must be filled and heated.
• Excavation of a bigger area is required, raising the excavation cost.
• It is influenced by a greater lifting power.
• This type of foundation may have slightly different column alignments.