Structural Foundation Roles In Custom Homes
The purpose of a foundation in every building structure goes beyond bearing load for the building. It offers the following benefits:
- Provides Support for Your Home
- Withstand Movement
- Offers Home Insulation
- Keep The Moisture Out of Your Home
- Prevents Insect Infiltration
Provides Support for Your Home
The foundation is your home’s anchor. If you’re building on a hill, you must make it to hold the house up no matter which way the ground leans. Without it, some parts of your home would sink into the ground more than others, causing cracks and settling damage to the house alone. But building a good foundation needs more than digging the ground and pouring concrete. You must tailor the foundation to the site. It involves considering the geology, soil conditions, water table, and air flows around your home. You must also set it and compact it to meet the construction code. The goal is to provide enough strength to hold all that weight even when the ground shifts underneath it, which often happens over time.
Natural forces, like soil moisture levels, are always changing. So are the temperature, tectonic plates, and water tables beneath your home. This could cause cracks in your foundation, breakage, or damage to your home. A foundation can help you resist these forces. It transfers the structure’s weight to the underlying soil or rock to prevent excess settlement or movement.
Offers Home Insulation
Foundations are the unsung heroes of your home. They provide support and stability for the foundation. They keep your family warm and comfortable by insulating the heat from escaping. Talk to a masonry expert to learn more about foundation types, styles, and materials that fit your home.
Keep The Moisture Out of Your Home
Keeping water out of your basement is one of the most critical parts of protecting your home, as it can cause loads of damage and lead to toxic mold. The best way to ensure it stays dry and safe from structural issues is by installing a foundation drainage system. A foundation drainage system will keep all water away from your house’s foundation. An internal drainage system works by collecting drops from the floor, ceiling, pipes, and drains within a wall. It lowers the moisture level so they can channel it away from your house’s foundation. The exterior drainage system channels smaller amounts of water through the outer home wall. It keeps water off the ground and away from wood, dirt, and plant roots which can cause cracks in concrete walls over time. If you notice any cracks or large holes in your basement wall, talk to us. We can get your interior or exterior foundation waterproofed. Let us perform these services soon before any further damage occurs.
Prevents Insect Infiltration
When it pertains to the protection of your home, you can never be too careful. A proper foundation will keep all the bad bugs out of your home that lives under the earth. It will also build a barrier between the wood framing from termites on the ground, which can cause severe damage. Without the proper foundation, your home will be vulnerable to insects that cause severe damage. It won’t last very long without a proper foundation for your home. Even with a suitable foundation, small cracks or signs of separation can show more significant problems. These issues could threaten your home’s safety. Many people neglect and forget to inspect their foundations. Let alone even repair them after a masonry expert performs an inspection.
Every house has a foundation, but not every home has the same type of foundation. The kind of foundation for a building structure depends on factors. These include house design, geographical location, and climate. Soil and moisture condition, project, and budget are also critical.
Every foundation plays a structural role in custom homes. Our discussion will focus on the structural foundation examination. Engineers consider this process for custom homes. We will also be having an in-depth look at when they are most suitable for use, among other vital things. Want to know more? Read on.
What is a Foundation Design?
When building a housing foundation, you must create a construction plan. The process of creating this construction plan is what constructors call foundation design. It is a vital function that structural engineers perform.
The foundation is the structural base of a building. It stands on the ground and supports the rest of the building. As a result, foundation design is a careful process that every custom housing foundation must undergo. There must be an extensive study of the ground below the foundation. It includes the design and materials the builders will incorporate into the foundation.
The primary purpose of every foundation is to hold a house up. Without it, the house will sink into the ground with many cracks and damage the structure. A good foundation will support the house and keep it even, whether there’s an earthquake or flood.
Foundation also supports a building by transferring the loads to the soil. It does this with enough bearing capacity and good characteristics for settlement.
There are several types of housing foundations. Most foundations have their installations at different depths. Builders lay slab-on-grade foundations on ground level. The depth that a housing foundation requires can depend on various factors. These factors Include:
Soil Bearing Capacity
Soil bearing capacity determines the load or weight the existing soil can carry.
There are several soil types, and every soil type has its property. The property of a soil type can affect the ability of that soil to support a housing foundation.
Without the interference of other factors, the smallest depth of a foundation should not be less than 18 inches. It allows effective removal of topsoil and different variations present at ground level.
Also called the frost line. It is the depth to which the soil can freeze during the coldest time of the year. Frost depth helps to determine the least depth for many types of Foundations.
The groundwater table is also vital. Understanding the height of the groundwater is necessary during soil study. It is because it can limit the depth of the foundation that builders use. It also affects the type of foundation that builders should use for the custom housing foundation.
Builders often build foundations with masonry materials. They use brick, concrete blocks, or poured concrete. It is because masonry provides a high level of compressive strength. It can also resist damage from soil and moisture better than wood and other materials.
A masonry foundation will usually extend above the ground. It is so that it can protect other construction materials from moisture. It includes other damages due to direct contact with the land.
Builders often reinforce internal masonry foundations as cost-effective and desirable building construction.
The reinforced masonry system relies on cementitious grout and rebar encapsulating reinforcement. It is for a bond to transfer stresses as a composite system.
Contractors sometimes use hydraulic cement to seal around raceways. They also seal pipes that penetrate concrete or masonry foundations.
Contractors sometimes build foundations with piers or wood posts. In cases like this, the builders drive the support of the foundations deep into the earth. They then allow it to rest on a rock or concrete pad. Posts and piers are often necessary when building on lands near water, on water, or in areas prone to flooding.
One of the most critical materials for housing foundations is the base or subbase of inorganic materials. Builders lay these materials under the foundation. Generally, clay and pressed soil have a minor bearing capacity and cannot carry much weight. It means the earth will not be able to hold the loads a building imposes. As a result, the contractors dig away the soil and replace it with a dry, dense, and uniform material. They can crush the stone or, in some cases, use gravel.
The soil can get its bearing capacity and shear resistance level. Another merit of the base material is that it promotes subsurface water drainage. It also does not expand with high levels of moisture like soil does.
Foundation Load Transfer
When contractors are designing a foundation, they must design it in such a way that it can transfer the load from the building to the ground. Engineers must also ensure that the foundation carries the sum of the dead load, live load, and wind load to the ground. The net load capacity that the foundation transmits to the soil must not be more than the bearing capacity of the earth.
The design of a foundation must also consider the settling of the building. It helps to ensure total control and uniformity of movement, which prevents damage to the housing structure.
Furthermore, the contractor must take time to understand the whole design of the foundation. It includes the superstructure and the characteristics of the ground itself. It helps the contractor identify any potential strategies. They will prove beneficial to the total construction.
What are Structural Foundations?
Structural foundations are the parts of a building that fixates the building into the earth. These foundations offer support for the main structure that we can see above the soil level. A structural foundation is analogous to the tree’s roots and the building as the tree’s stem.
One of the functions of a structural foundation is that it helps to transfer load from the structure to the ground. For instance, the slabs transfer their rights to the rafters. The rafters then share the load the joists apply to the beams. The beams then transfer their weight to the column, which moves the weight to the foundations.
One primary duty of civil engineers is to determine the bearing capacity of the soil. Then they will design the structural foundation to resist unnecessary stress. It will also resist overturning and sliding.
Different kinds of structural foundations depend on soil type and custom housing. Structural foundation is also vital for every house except the house doesn’t want to stand long.
Materials Used In Structural Foundation
There are several materials that building engineers use for structural foundations. They include:
Wood may look unsuitable for foundation material. It is often times a possible option. It is because concrete can be an expensive option in many areas.
The wood that builders use as foundation material undergoes pressure treatment. Engineers also ensure that the wood has a chemical coating. It helps to prevent rotting and to prevent termites from eating the wood.
Why do engineers consider wood foundations?
Engineers consider wood foundations for several reasons. These include:
- Wood foundations are more basic, quick, and easy to construct than other foundation types.
- If engineers treat the wood, it will make the wood durable and can withstand the elements.
- The design of wood foundations requires the maintenance of dry soil around the foundation.
- It means the engineers must maintain and construct the foundation’s wood. In return, the wood will be dry and free of mildew.
- Basement mildew, dampness, and leakage are common problems of other foundations. They do not always affect wood foundations.
- It is easier to finish a basement when builders make a foundation from wood. Builders place insulation between the wall studs to which they can attach drywalls.
- The basement will be warmer because wood is one of the best insulators. The wall studs of the foundation also provide large cavities for insulation.
- The only issue with wood foundations is that they’re usually thinner than other types of foundations. Engineers can work their way around this by using thicker wood.
Stones are suitable materials for structural foundations. They are strong, durable, and frugal when available near the construction site. Builders also use stones for low piers. They also lay them up without mortar if the economy is complex in that area. It is challenging to make stone airtight even when builders lay it with mortar.
Stone foundations are the best choice to protect the house from termite infestation. It is because they provide an impenetrable barrier to the house.
Why consider stone foundations?
When engineers use stones for structural foundation, the building will be more robust. Stone has a high compressive strength making it a better option than most other materials. The compressive strength is the most load a material can bear without breaking or cracking. Stone strength also depends on the type of stone.
Buildings experience all kinds of weather in different seasons. It is a vital factor to consider for foundations. Stone can resist any effect that weather elements can cause. Stone does not absorb water when it rains. As a result, there will be no future problems that come as a result of dampness.
Stone has a better advantage over other foundation materials. It is because the stone can withstand damage, pressure, and tear making it more durable.
Some instances that can cause wear and tear on structural foundations may not affect stone. Stone can also resist bending, wrapping, and denting, contributing to its durability. Part of this factor is its weather resistance also.
The estates that builders construct through stone need very little maintenance, and it is due to its durability. These buildings don’t need other methods that brick requires, such as color washing or plastering.
Concrete is the best and most durable material for structural foundation. It is hard, long-lasting, and strong in compression. Moisture does not affect concrete, and builders can make it very airtight for basement walls. Constructors can also cast it into any shape that the structural foundation requires. The materials builders use for concrete foundations are always best for durable structures.
For instance, builders can construct curtain walls with little concrete. It only needs a narrow trench and less formwork. The only demerit of concrete for structural foundations is the high cost of cement builders need.
Reasons to use concrete for structural foundations include:
Easy to Maintain
Engineers like to select poured concrete for structural foundations. It is because it does not need maintenance. Concrete foundations can resist insects, rots, mold, fire, and mildew. The changes in humidity and temperature effects have only minimal impact on concrete foundations. Engineers can also paint it, drill it, or seal it. All these hinges on the need for signage and building systems.
Concrete allows for design flexibility in structural foundations. Since it starts as a liquid that can form into any shape, architects and contractors can make any flexible design. Ogees, gentle or tight radii, and serpentines are obtainable with attention to detail. Other foundation materials may not be able to make these designs.
The concrete structural foundation also offers a quick construction technique. The result is that it allows for rapid progress. Cost efficiencies start with design and continue through labor also.
A custom homeowner can also save costs with this type of foundation. It is because the material has natural energy efficiency. It also promotes airtight construction and noise suppression.
Resistance to Damage
When it comes to water damage, concrete structural foundations have no joints. As a result, seepage is not possible. Also, with concrete walls, buildings face fewer service issues because there is little chance for mold or mildew to grow.
A concrete foundation offers twice as resistance to fire as other foundation types. Concrete also has the highest fire rating of all foundation materials.
Poured concrete can withstand loads of compressive strength. It can also withstand the weight of building structures.
Also, concrete structural foundations can resist flexural strength deformation under load. The building structure can bulge inward from forces that engineers apply to the perimeter of the foundation.
Concrete blocks are also suitable for constructing attractive and long-lasting structural foundations. Concrete blocks erase the need for unnecessary formwork. Their large size makes it easier and faster to lay up than bricks. The major demerit of concrete blocks is that builders find it more troublesome to make them airtight. It is especially in comparison to the standard concrete barrier. They also do not resist lateral forces the way a solid poured-concrete wall will.
Merits of Concrete Block Foundations Include:
- Concrete blocks are light and easy to install. Any builder who has experience installing masonry can establish a concrete block foundation.
- Engineers do not need wooden forms. They have to piece the block forms together. Then they will secure them, interlocking them at different lengths.
- Concrete blocks suit construction in seismic areas as they are versatile building materials
- The blocks are strong and have adequate insulation. When engineers use the rebar, it adds strength to the structure. The filled blocks also insulate the building.
One of the most popular materials among contractors is steel. They use it for structural foundation construction. It is because of the strength and durability that it offers. Builders use it in the form of steel rods and varying thicknesses. They can arrange the steel either parallel or perpendicular to each other. Structural engineers generally treat foundation steel as stainless and rust-free.
Advantages of Steel
Quality and Speed
Manufacturers make most steel structures at plants using prefabrication methods. It ensures the quality of the structural foundation and allows for a high speed of other installation.
Strength and safety
Steel has a strength that is as high as concrete. Engineers can control the assembly procedure for steel structures. Steel may not be able to resist flame because it loses its strength to high temperatures. It is not an issue as foundations hardly see exposure to flame.
Manufacturers also cover steel structures with refractory materials. It helps protect against corrosion, mol, and parasites.
Steel construction needs fewer working hours to complete. The rapid work rate means engineers can finish the structural foundation faster. Also, steel foundations are lighter in comparison to concrete. As a result, loads that the foundation footing transfers to the ground are lower.
An engineer also needs fewer materials to construct a steel foundation. It is the case, especially in comparison to concrete foundations.
By nature, steel is a flexible material that can withstand heavy loads. Today, engineers can create steel elements of various shapes and sizes to ensure high structural strength. The versatility of steel allows builders to bring any foundation structure to life. They can also integrate with the utilities.
Aggregate is not only one material. It is a combination of cementitious material, mixtures, and water. It also includes:
- Crushed Stone
- Recycled Concrete
- Other Geosynthetic Aggregates
Recycle and manufacture a combination of materials.
About sixty to eighty percent of the concrete mix comes with aggregates. Aggregates provide bulk and comprehensive strength to concrete. Constructors like to use them for their strength, workability, and ability to receive fine finishes.
If you need concrete to be strong and durable, you must use clean and solid aggregates. The aggregates need strong particles with no form of chemical absorption. It must also not have a clay coating or a combination of fine materials that can cause the concrete to deteriorate.
Why choose aggregates?
- Aggregates help in the production and reinforcement of concrete. It has many applications, especially in areas where engineers desire dead loads.
- Aggregates also provide insulation and internal curing for structural foundations. It may release absorbed water for hydration during curing. The collection for foundations helps in support and footing compatibility.
- Finally, aggregates increase the fire resistance and the insulating value of concrete.
Builders often use fly ash as supplementary material for cement when producing concrete. When they use it with concrete, fly ash hardens concrete more. Usually, this is by contributing to the properties of concrete through pozzolanic activity. It can also be through hydraulic action or both.
Why choose fly ash?
Fly Ash is a super-strong mineral powder used for decades in construction materials. It’s incredible strength and durability. With fly ash, builders use this new eco-natural material as an additive to concrete or cement in place of sand. It improves its strength while reducing the amount of binding material used by as much as 50%.
Fly ash is a cost-effective option for cement in many economies. Fly ash also requires less water and is easier to use in cold weather.
Other benefits include:
- Resistance to cold weather
- Produces various set times
- Has high strength gains, depending on the construction use
- Engineers consider fly ash as a non-shrink material
- It makes dense concrete with a smooth surface and sharp details
- Builders find it easy to work with
- Fly ash reduces permeability, bleeding, and crack problems
- Reduces heat of hydration
- Reduces emissions of CO2
- It provides a lower water-to-cement ratio, especially when compared to no-fly-ash mixes
Builders and homeowners use brick masonry foundations because it is cost-effective. Its unattractive appearance is also not visible once they use it.
The structural foundation that builders make from brick should be able to support the weight of the housing structure. It should also support the lateral loads that the soil next to the foundations imposes. Brick foundations should also be durable to withstand groundwater fluctuations and soil aggressions.
Builders can only construct brick foundations as masonry units. They can also reinforce it with steel bars to increase the load-bearing capacity of the structural foundation.
Merits of Bricks
Bricks are better at insulating the foundation from heat and cold than most materials. You tend to spend less on protecting the floor of your custom home when you use brick for the foundations.
As a result, brick structural foundations need fewer utilities. It also decreases the direct impact that the foundation has on the soil.
A brick foundation can last for years if the engineers design them per code. Some of the oldest buildings have brick foundations. When engineers install quality brick for the foundation, they can be sure that it will withstand the test of time. They are strong, load-bearing, and can support the structure of a building.
Bricks are strong and long-lasting, and they also age slowly. It results in low maintenance, so the custom homeowner doesn’t have to worry.
Many structural foundation materials cause a great deal of pollution that can harm the environment in several ways. Bricks are excellent sustainable materials. So, contractors and builders do not have to worry about polluting the environment in the construction process.
Types of Structural Foundations
There are several types of structural foundations. Let’s take an in-depth look at them:
A shallow foundation does not go beyond the safe bearing capacity of the soil. Engineers sometimes refer to this type of foundation as an open footing foundation. When constructing a shallow foundation, the builders must first excavate the earth. They’ll do this until the bottom of the footing, then build the base.
In this type of foundation, the entire footing is visible. Builders use this foundation type for lightweight buildings and meet conditions where the soil is perfect.
Freezing can damage shallow foundations. As a result, it is crucial to protect the foundation in cold climates. They should also construct the foundation below the frost line for insulation purposes.
These Shallow Foundations Types are:
Individual Footings or Pad Foundation
The footings of these foundation types are usually circular, rectangular, or square concrete. Builders often recommend them when a single column carries the load of the building.
When constructing a pad foundation:
- The building engineer divides the total weight on the column by the soil’s safe bearing capacity.
- Then the builders determine the type of shape that fits the construction according to the pressure.
The most accessible footing type is the individual footing, which does not need much-skilled labor. It is also cost-saving and time-saving compared with other shallow foundations. The different foothold is best when the column spacing is not close, and the load of the building is less.
The strip footing foundation acts as a support for the weight of a wall. The footing has a broader base, so builders sometimes refer to it as spread footing. It has more extensive groundwork that helps it to offer higher stability as it spreads across a range.
Builders use strip footings for walls and bridge piers where the latter is not more than 10 feet. The size and thickness of the strip footings depend on the type of soil present on the construction site. It is also crucial for the ground to be enough to support the structure’s weight.
Strip footing foundations are more suitable for building structures that have:
- Higher load bearing
- Boundary wall construction
A Raft or Mat Footing / Raft Slab
Raft foundation is one of the most efficient and effective ways to underpin a building to support it and reduce settlement risk. A raft foundation is a very thick concrete slab, up to two meters deep, resting on a large area of reinforced steel mesh lying on poor-quality soil. A raft foundation spreads the total load from the structure over its entire area. It results in lower stresses and settlement than other foundations, such as spread footings or columns.
Builders use raft or mat footings in cases where they plan to construct a basement. Here, they use the whole basement floor slab as the foundation. Raft footings are best for construction sites where the soil is weak. These footings spread the building’s weight on the earth, reducing the stress on the ground per space in the process.
A construction engineer will sometimes consider raft footings on sites with compressed soil. One clear example is soft clay, where a strip, pile, or pad is impossible without excess excavation.
When to Choose Raft Foundation
Builders Choose Raft Foundation When:
- The bearing capacity of the earth is low
- The builders need to distribute the load of the structure over a large area
- An individual or any other area of the foundation will cover about 50% of the whole ground area beneath the structure
- Stress on the construction site needs reduction
- Builders place the walls or columns so close to the extent that the individual footings will overlap
- The soil strata are unpredictable and contain layers of compressible soil
- Differential settlement is possible if engineers use exclusive footing
- There needs to be a basement construction
- Other types of footholds are not suitable enough
Types of Raft Foundation
An engineer can use several Raft foundation types. It depends on the condition of the soil and the load that the structure imposes on the foundation. The following are the different types of Raft foundations that builders use during construction.
- Flat Plate Mat
The flat plate is the most elementary form of a mat foundation. It is a choice for engineers when the walls and columns have uniform spacing at small intervals with small loads.
In this type of foundation, an engineer places reinforcement in both directions. They also place support at the column locations and load-bearing walls. The thickness of the flat plate mat has general restrictions of 10 mm for cost-effectiveness. A thicker slab is too costly.
- Two-Way Beam and Slab
In this type of raft, engineers cast monolithic beams within the raft slab. It then connects the columns and walls. The two-way beam and slab foundation is suitable when the builders place the columns at a longer distance, and the loads on the columns are variable.
- Plate Thickened Under Columns
When engineers subject the columns and load-bearing walls to heavier loads, they thicken the slab under the columns and walls. They also provide extra reinforcement to resist negative reinforcement and diagonal shear.
- Piled Raft
An engineer uses piles to support the raft in this foundation type. Piled raft is suitable for use when the soil at a shallow depth is compressible and the water table is high.
Raft piles under the raft help to reduce the settlement, providing resistance against buoyancy.
- Plates with Pedestals
In this type of raft, engineers provide a pedestal at the base of the columns. The purpose of this type of foundation is the same as a flat plate thickened under columns.
- Cellular Raft Foundation
Engineers also refer to this type of foundation as a rigid frame mat. This type of raft requires the walls to act as a deep beam. Engineers use stiff frame mats when columns carry heavy loads and the connecting beams exceed 90 cm in depth.
In this situation, the engineer places two concrete slabs, one on top of another. They then connect with foundation walls in both directions, forming a cellular raft. The rigid frame mat is very stiff and is an inexpensive option when builders use a slab with a very high thickness.
Another name for the strap footing is the cantilever or neighbor footing. It has a makeup of two different footholds, eccentric and concentric, both connecting with the help of a strap beam.
The strap footing foundation is best-suitable when a column is close to a property line. It requires an eccentric footing due to space limitations.
The engineer attaches the soil-bearing pressure distribution to the adjacent closed column. They achieve this with a strap beam via a concentric footing. The strap design should have a rectangular beam that spans between the columns.
The typical width of the strap beam should be equal to the width plus 100 mm of the largest column. The determination of the depth should be by the most significant bending moment.
The primary reinforcement’s location is on the top of the strap beam, with stirrups or links near the support. The strap may need bottom reinforcement to prevent settlement stress.
This foundation type is best for columns with space closings on soil with low bearing capacity. In situations like this, isolated footings may start to overlap.
Building engineers also use combined footing when constructing buildings or structures near a:
- Sewer line
- Property line
- Areas with restrictions on dimensions
When designing the combined footing, the centroid for the bedrock support must coincide with the centroid for the mixed loads. It will help ensure that the bearing pressure of the soil beneath the foothold has an even distribution. All these prevent uneven settlements of soil.
Deep foundations can go deep into the earth so that the structure starts to rest on top of the soil. They are often reliable in deep waters and target hard stratum.
There are two types of deep foundations. Let’s take a look at them:
Pile foundation is suitable for hard soil that extends very deep into the earth, far from reach. It is also good in cases where a raft or mat foundation is too expensive for builders to consider. Engineers sometimes use pile foundations when the building load is massive and has a high concentration.
Pile foundations are best for construction sites with compressible or marshy soil. Engineers recommend them when constructing bridges over canals and areas with ample water. If there is a chance of having irrigation in a place, a foundation is also a suitable choice.
Constructors drive the pile into the ground. Classification of piles is also in two working modes. The first mode is the bearing mode, while the second mode is the friction mode.
Bearing piles are best for places where the hard stratum is not too deep. In such situations, the pile transfers the load to the hard layer.
Frictional piles are more suitable in areas where the soil is too soft. Some builders leave the pile rough to increase a lot of friction. The abrasions can wear off in a natural and gradual way at some point leading to the failure of the structure. Professionals classify pile foundations into:
- Wooden Piles
Wooden piles have wood as their primary raw material. Some examples of these woods are:
These timber piles have a circular shape and a sharpened bottom. The diameters fall between 20 cm and 50 cm and are usually twenty times longer than their width.
The sharpened bottom can be blunt. Sometimes, builders support it with a metal point, setting an iron cap on the top. If the construction site has soft ground, builders use a round bottom. Otherwise, it is best to use a metal point if the earth is a boulder.
In cases like this, constructors must dig the ground below the water level to prevent decay. This type of pile is cost-effective and does not need heavy machinery to drive it.
- Driven Piles
Engineers used to drive piles into the ground with a Vibro-hammer or other similar machines. Concrete piles and steel (H beam) or tubular piles of steel that have capacities between 3000kN – 800kN
A driven pile is cheap and straightforward to install. It is necessary to consider the potential for pile head injuries and shaft bending when forcing the piles into the earth.
The pile is susceptible to noise and vibration. As a result, engineers do not recommend using this pile on soils with rocks or boulders.
The piles are long and slender so that they can transfer loads from a building. They achieve this by friction between the sides of the pile and surrounding soil. They also involve the bearing between the base piling and strata of the ground below.
Engineers can construct piles from wood, concrete, or steel. Steel piles often consist of helical hot-rolled, I-shaped sections or screw piles. Wood piles are huge timber sections that builders treat with pressure.
- Mini or Micropiles
Mini piles or micro piles are smaller bore piles with a diameter of 0.3m. Engineers can use them to support loads up to 1000kN in places with restrictions and difficult access.
They usually have a diameter of 0.3m and need smaller rigs below 2 meters high.
- Continuous Flight Auger (C.F.A.) Piles
There is no need for support or casings as the pile construction moves at a quick pace. The builders must drill, do the concreting, and fill the dug soil almost at the same time.
Once the builder pours the concrete, they should install the prefabricated reinforcement cage. Then, they should lower it down to the concrete.
- Concrete Piles
In a concrete pile, the builders drive a shell into the ground to make a hole the size of a specific diameter. After that, engineers fill the gap with concrete. Builders also refer to concrete pile foundations as cast-in drilled hole piles.
Building engineers leave the shell in the hole and sometimes fill it with concrete. This process aims to ensure that the cover protects the cement from eroding by the acidic water it may encounter in the sub-stratum.
Concrete piles are best when engineers want to build foundations from plastic to hard stratum. They prevent wastage and are best for construction in swampy areas.
- Reinforced Cement Concrete Piles (R.C.C.)
Reinforced cement concrete piles are often square, circular, or octagonal with a steel helmet on top. These piles are often between 15 cm and 60 cm in diameter, with lengths that fall between 3 m and 30 m. Reinforced cement concrete piles do not contain more than four percent steel. The engineers precast and sharpen them like they prepare wooden piles before use. After curing and seasoning the piles, the engineers drive them into the ground.
The execution of reinforced cement concrete piles is quicker than wooden piles. Engineers can also erect piles above the groundwater table. The disadvantage of these piles is that they are difficult to transport due to their heavy weight. Also, no damage must occur during transportation. Minor damage can cause transpiration difficulty. It is a significant reason for hiring professionals.
One class of piles is suitable as a part of the structural foundation. Structural engineers call them “sheet piles.” They use them to enclose certain areas and confine loose soils on construction sites. The sheets can be wooden, concrete, or reinforced cement concrete.
- Bored Piles
Engineers use these most popular types of deep foundations for construction. They can pre-drill the piles depending on the location of the pile holes.
Borehole stabilization needs a bentonite and casing system. The two types of bored pile foundations are end-bearing and friction piles. Both have a makeup of large solid columns that constructors bore deep into the earth.
Pile Foundation Construction
Generally, when designing a pile foundation, the engineer:
- Positions the location of the pile using wooden pegs or white paint.
- After positioning, the engineers make the case of the pile using a steel cage. They then pour concrete into the cage.
- The engineer also ensures that reinforcement is in place before pouring the concrete. Then they allow the concrete to set.
- After that, they can now drill the piles into the ground. They can use a driller named auger for this purpose.
- Once the builder drives the pile into the soil, they install a column cap. Then they join the caps of several piles together or leave them separate.
Caisson or Drilled Shaft Foundation
Structural engineers often recommend a caisson foundation in water overload sites. One open application is a dam. Caisson foundations are watertight boxes or cylindrical structures. Builders sink them into the water and fill them with concrete to form a foundation.
After filling the drum, they scoop the soil around it with daggers so that the drum can sink very well into the ground. The engineers will attach another caisson length if the drum is too short. They will then use daggers to scoop the sand so the drum can sink deeper.
Caissons have shaft or toe resistance to resist load from structures. They can carry columns better than pile foundations. They are also suitable when the depth of the hard stratum is between 25 feet and 300 feet.
Caisson foundations are the strongest for construction areas with lots of water. But it is also suitable for areas where deep deposits of soft clays and loose granular soil exist.
The structural designer must distinguish between each type of foundation. It will help them determine which one is best for the design. It is easy for a structural engineer to select the correct type of foundation for the design, but beginners can find it difficult.
Differences Between Footing and Foundation
A footing is a part of the foundation that supports it and transfers the load from the foundation to the larger soil area. In this way, the foundation becomes safe from the settlement. Engineers generally provide footing with reinforcement and cast it with concrete.
Construction engineers use footings in conjunction with shallow foundations. The depth and the width of any foothold also depends on the soil type and foundation size.
Footings vs. Foundation
Footing and foundation are not two different entities in building construction. Both together form a single component of a building structure, and the footing is the lowest part of a foundation.
The lowest part of a foundation is the footing. Engineers reinforce it with rebar to make it stronger. They select the type of foundation depending on the footing components. These include the basis of depth, soil type, and soil structure. Generally, there are more types of footing in shallow depth foundations when you compete with the dit foundation.
Finally, footing and foundation form one component of any building structure. The major difference is that the footing is the lowest part of the foundation.
You can differentiate both as:
- The part of the foundation that comes in contact with the ground is the footing. But the component of the building that transfers its structural load to the soil is the foundation.
- The function of the footing is to provide support to the building, while the foundation functions to support the columns.
- All footings are foundations, but not all foundations are footings.
Engineers sometimes embed footings and foundations to form a complete substructure. In such situations, they lay the foothold on the soil first. Then the foundation is next because it bears the load of columns.
Generally, most foundations have footings. Engineers don’t need to install the foothold beneath the foundation. Often, this is when soils are weak or losing in carrying the load of a structure. Footings perform better in good soil conditions. They are not suitable for poor soils with low bearing capacity.
Major Differences between a Footing and a Foundation
- The footing is the foundation part that stays in contact with the ground. A foundation is a component of a building that transfers its structural load from the superstructure to the earth.
- A footing transfers the load to the ground from the superstructure. The foundation remains on the earth and serves as a contact.
- A footing provides support to the entire structure. The foundation offers support for individual columns.
- Engineers must analogize a footing with the feet of the leg. Engineers may or may not compare a footing with the leg’s feet.
- Foundation has two main categories: shallow and deep foundation. Footing is a type of shallow foundation.
- Footing is the basement of the wall. Foundation lies under the foundation wall.
- Footings include slab and rebar. These are brickwork, masonry, or concrete fabrications. The most common foundation types include:
- It also contains:
- Lateral Supports
- Footing adds support to individual columns. A foundation is extensive support because it reinforces a group of bases in an entire structure.
- The number of footings depends on the foundation. The foundation serves as support and bears all kinds of loadings.
- Footing transmits the load to the soil. Foundation transmits the load to the ground.
- Types of footing include Spread or isolated footing. Combined footing strap.
The Types of foundations are shallow foundations and deep foundations.
Differences Between Raft and Mat Foundation
Raft and mat are the same foundation type. You can use the terms interchangeably. Usually, this type of foundation is best when the soil’s load-bearing capacity is low.
Engineers also consider it when a very narrow gap exists between successive columns. In these types of conditions, a mat foundation is helpful. It is because of its ability to distribute the load in a uniform fashion across the entire building. Something that other types of foundations find challenging to achieve.
The raft foundation remains one of the most common types of foundations. Engineers often consider raft foundations for building structures.
Frequently Asked Questions
What Are the Major Functions of a Structural Foundation?
The primary functions of a structural foundation for a custom home include:
- Send and distribute the total structure load to the bigger area of underlying support
- To provide structural stability
- To prevent differential settlement of the structure
What are the Main Types of Foundations?
Here, the total load of the structure that the foundation transmits to the base spreads over a large area. Builders construct the wall’s width to be thicker at the bottom in a stepped fashion.
A pile is a long vertical load. It transfers members with the makeup of either steel, concrete, or timber. In pile foundations, engineers drive several columns into the structure’s base. The primary piles are of two types:
- The Friction Pile
The friction pile supports the structure load. It is due to the friction between the surrounding soil and the pile.
- End Bearing Pile
Builders refer to the pile with lower ends resting on hard rock as an end-bearing pile.
In this foundation type, engineers sink hollow vertical shafts up to the hard bed. Then they fill the hollow junctions with inert material such as lean concrete or sand.
What is the Major Function of Structural Foundation?
The major function of a structural foundation is that it helps to transfer load from the structure to the ground. Structural foundations are the building parts that fixate the building into the soil. They offer support for the main building we can see above the earth level. We can view a structural foundation as the tree’s roots and the building as the tree’s stem.
Different kinds of structural foundations depend on soil type and custom housing.
We have had an in-depth look into the structural foundation for custom homes in the above article. It is worth noting that building and designing a stable and dry foundation is a straightforward process. It is crucial to get all the right details to call the foundation right. The best way to do this is to hire a professional contractor with a long-standing reputation for quality work.
As an extra precaution, you can hire an independent inspector. They’ll help inspect the foundation before framing begins. Giving your custom home the best original and quality structural foundation is worthwhile.
There are several types of structural foundations and footings for custom homes. We have discussed all these in the article above. The best one for your home will depend on your choice and the contractor’s expertise. Ensure you follow up on the process to know what is best for you and your custom home.