The use of metal piles under the foundation

Varieties according to the burial technique

The main way to classify piles is by the way they are buried. There are the following types.

• Reinforced concrete drilling - installed in a pre-drilled well. Despite the presence of preliminary earthworks (drilling of wells), with this method of installation, there is no shock effect on the pile. This minimizes the likelihood of damage to the concrete post during its installation ..
• The screw piles at the working end have a cutting edge in the form of a screw winding. Screw supports of small diameter and length are screwed into the ground manually using a gate, and large ones - using special mechanisms. One of the advantages of screw supports is that, if necessary, they can be removed (unscrewed) from the ground and installed in a new place. To increase the bearing capacity of the screw support, after screwing it in, the resulting funnel is poured with concrete, which makes it non-removable.
• Driven piles have a pointed end and are immersed in the ground without preliminary excavation using special equipment: vibrators or hammers. To protect the upper part from damage during diving, a steel ring is put on it. The disadvantage of this method of mounting supports is the possibility of damage to both the pile itself and the waterproofing, if any.
• Bored ones refer to supports that are placed directly in the ground. The essence of this method is preliminary drilling of wells and their subsequent filling with concrete mixture.

Step-by-step instruction

To independently create a strip foundation for a future home, bathroom or other building, you must follow the accepted work procedure.

Site preparation

The construction site needs to be cleaned. Remove all deposits, plants and ideally topsoil, 10 centimeters.

Next, we can start labeling. The boundaries of the house are determined according to the plan.

If a trench is to be dug, the boundaries of the trench are marked with pegs and ropes. The trench must be wider than the actual thickness of the foundation for timber formwork to be installed.

Calculation of the number and production of piles

To determine how many piles are needed to determine their properties, it is necessary to calculate the load that they must withstand.

It is necessary to analyze the soil and determine how much load it can withstand. It is better if this analysis is carried out by a specialist.

The accuracy of the calculations determines how reliable and durable the house will be. You can hire specialists to perform this calculation, or you can do it yourself using one of the computers on the network.

After you have determined all the values, you can start building. The locations of the foundation columns have been determined. For drill piles, holes are dug and screwed into the ground.

Formwork

If it is made of a monolith of concrete, then part of the tape requires formwork. It can consist of panels, plywood, metal or plastic signs.

Once the formwork is ready, the next step is to knit the reinforcement for the foundation.

Why do you need reinforcement of a strip foundation with piles

Concrete is a tough material that cannot withstand bending stresses. The use of reinforcing bars can successfully resist these forces.

If reinforced concrete bored piles are used in the foundation, then the strip part must be reinforced with reinforcement connecting it to the piles in the frame.

The result is a solid spatial reinforcement structure made of concrete, which gives it mechanical strength and protects it from cracking.

Fill

After the installation of the reinforcing cage, the concrete is poured into the formwork. It is recommended to do this immediately and form the entire strip. If there is no such amount of solution, it is allowed to lay the layers, but before the previous solution dries, it is necessary to fill in one more layer.

To eliminate possible voids and air inclusions during pouring, it is best to use vibrators or at least a piece of reinforcement to break through the grout, removing air from the concrete.

Final tweaking

Depending on the condition of the concrete, the formwork can be removed at least 3 days after it has hardened. Healed completely in 3 weeks.

The surface must then be carefully sealed, for example with bitumen mastic. A layer of insulating material, such as roofing felt, is laid on the surface, and the wall has already been laid.

Watch the video below for more information on how to make a true strip base stack for your home:

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After developing the concept of building a country house, taking into account the options for equipping the foundations, there is a natural desire to use all the advantages of the founder of the tape, but at the same time to reduce labor costs for earthworks and the use of materials. This should also mean long-term cost savings.

The foundation of the pillar and the strip foundation will come to the rescue, the possibility of its independent construction and will be discussed further

This should also mean long term cost savings. The foundation of the pillar and the strip foundation will come to the rescue, the possibility of its independent construction and will be discussed further.

Screw pile resource

To increase the operational life of the SHS, anticorrosive treatment of each product is required in accordance with GOST R 9.905, 9.908, 5272. Manufacturers use the following anticorrosive technologies:

• cold galvanizing - it peels off almost completely even when the pile is immersed due to the abrasives contained in the ground;
• hot-dip galvanized - lasts a little longer, does not provide the declared 75-year resource;
• powder painting - lasts 30 - 50 years after installation, is destroyed by walking currents in the ground;
• painting with bituminous compounds - protects from ground water, regardless of the height of the groundwater level, provides a 50 - 70 year service life

To increase the resource at home, experts recommend the following paintwork materials:

• VL 05 soil + cold galvanizing (IR 02 enamel) + fiberglass - a resource of 300 - 400 years in extreme conditions, there is no electrochemical corrosion;
• IR02 or Zinga Metall enamel + polyurethane or epoxy two-component enamel - created to protect oil pipelines (air, underground), have a 50 - 100 year life;
• ground VL 05 + polyurethane enamel Hempel, Masco - standard level of protection for the bottoms of icebreakers, submarines, fuel and lubricants tanks, 30 - 70 years service life.

Even with the purchase of SHS with a factory anti-corrosion layer, it is necessary to cover the piles with the specified compositions for reliability.

Varieties of foundations on metal supports

When the installation of the supports is completed, then they begin to connect the heads. This is done in the following ways:

• connected with wooden beams;
• perform strapping with a channel;
• reinforced concrete tape-type grillage is poured;
• create a monolithic concrete slab.

The characteristics of screw piles and the process of their installation are shown in the video below.

Self-production of metal supports is shown in the video below.

The use of metal piles allows you to quickly erect a lightweight structure with significant uneven terrain, unstable soils. Their independent production and installation significantly reduce construction costs. All work should be performed in pairs, observing the installation technology. Then the created structure will stand without problems for more than one decade.

Screw-in bearings: advantages and disadvantages

All types of metal screw piles have their own advantages and disadvantages. First, about the shortcomings - there are few of them, but the most significant of them is the metal's susceptibility to corrosive processes. It is especially difficult to use metal piles in wet soils, unprotected supports, when in contact with moisture, are easily covered with rust, which is aggravated by aggressive or chemical subsoil waters.

Industrial pile supports have a protective coating that is often damaged when screwed into the subgrade, especially in soils with a certain percentage of rock inclusions. To protect the surface of metal screw supports, it is worthwhile to carry out additional protection of the piles before sinking into the ground.

When erecting annexed premises to existing buildings, screw piles are an excellent way out when building foundations in cramped conditions. The piles are screwed into the ground without damaging the existing foundations, providing reliable support for an extension to the house, veranda, terrace, gazebo and other structures.

Almost any soil is suitable for screwing in screw piles, even the weakest, deep-freezing and water-filled, these supports are not used only in hard rocky soils. The load-bearing capacity of soft and wet soils is greatly increased when screwed metal support structures are immersed in the soil.

Screw-in support elements for foundations are used when constructing foundations for buildings near any engineering communications, highways. Foundations made of screw supports can be erected at any time of the year; these works do not require significant interruptions when concreting pile cavities.

Features and scope of use

This type of foundation is erected on problem soils (eg peat bogs) and sloping reliefs (hills, slopes). When erecting it, the type of soil must be taken into account for the correct choice of the type of piles.

The pile foundation in appearance and design resembles a strip base. The main difference is that for a pile with a grillage, the grillage itself is much smaller and lies on piles, and not in the ground. This feature perfectly protects the "tape" from moisture and heaving. At the same time, areas of seasonal compression or expansion of the soil "pass" by the supports.

Application area:

• when constructing structures on weakened, boggy and peaty soils;
• on sloping terrain;
• in the coastal zones of lakes, rivers and reservoirs;
• to reduce the cost of work;
• if necessary, quickly complete construction work.

Peculiarities:

• allows you to start building a house immediately after driving the piles;
• suitable for installation in any climatic conditions;
• has an increased margin of safety and a high degree of reliability.

Support structure

The base of the pile is a metal pipe, the diameter of which varies from 57 to 133 mm, and the wall thickness is 2.5-5 mm. The standard length is in the range of 50-1170 cm. If necessary, it is increased by welding on special couplings.

Such a pillar is designed to transfer and further distribute the load from the structure to the soil. If necessary, the inner cavity is filled with concrete, which significantly increases the strength.

During construction, supports of the diameter required for the loads are used.

Screw piles are obtained by welding the blades to the pipes, or using the factory casting technology. One support is capable of withstanding a load from 1 ton to 11. This is determined by its diameter, wall thickness, the quality of the metal used for the manufacture, the number and shape of the blades.

Metal supports end on the surface with a head. It is designed to be fixed to the base grillage.

The head design is a metal plate (or a fragment of a profile) welded onto the upper end of the pipe.There are the following types:

• perforated, designed for bolted (screw) connections of foundation elements;
• solid: metal parts of the base are welded to them.

The head is reinforced from below with additional plates to increase its strength.

The outer surface of pile pipes is often coated with anti-corrosion compounds to protect it from moisture. These purposes are served by:

• bituminous or polymer mastics;
• moisture resistant paints.

Installation of metal piles

Twisting screw piles

Screw piles are installed in the ground either mechanically or manually. They are screwed mechanically in particularly hard soils or when the length of the pile pipe is more than 3.5 m.

Pile pipes up to 2.5m long are screwed in by hand. In this way, you can deepen the pipe by more than 2.5 m, but at the same time, a second pipe should be welded onto the twisted part and the deepening should be carried out further by hand. This will require 3-4 people.

First, you need to make a small depression and install a screw pile strictly vertically into it. As a lever for twisting, a long metal pipe is used, which is attached either directly to the head of the pile with a cable, or a special device is put on the head.

When twisting, 1-2 people hold the pipe strictly in an upright position, and two people rotate it with a special lever until it reaches the design depth.

After the piles are rolled in, the tops of the pipes are cut to zero. In order to increase the strength, the pipe is poured with cement mortar or reinforcement is made and poured with concrete.

Mechanical installation of screw piles

According to the method of installation, they belong to the driven ones. It is a long rod with a pointed lower end. Due to the laboriousness of immersion in the ground, such piles are most often used in the construction of industrial buildings.

They can be installed by pressing into the ground, as well as by shock-mechanical method. In soft soils, metal piles can be immersed to a great depth, lengthening by welding as they are immersed to the lower design mark. After the installation of metal piles, head caps with holes or anchors are welded onto their upper parts. Pile strapping is performed using a channel or other strong metal structure.

Often, to give the pile additional strength, it is poured with cement mortar or concrete. With a small diameter of pipes, several pieces of ribbed reinforcement are used, which are inserted into a buried pipe and poured with concrete.

When using large-diameter metal pipes as piles, a reinforcing frame is prepared separately and placed inside the entire pipe. After pouring with concrete, such piles will become more durable and will significantly increase the service life of the structure placed on such a foundation.

Do you need insulation?

Warming will be required in the following cases:

1. The reinforced concrete grillage was poured. The base in this case becomes the main source of cold. The house is leaking heat, which will affect the increase in heating bills.
2. The walls were installed on a wooden or metal grillage. Here, under the house, there will be a space that will be blown by the wind. In winter, this will damage the floor of the first floor and the lower part of the walls.
3. Engineering communications pass through the underground space. If the base is not insulated, the pipes will quickly freeze and be damaged.

Conclusion: insulation is an important part in creating a pile foundation. The base must be supplemented with a gravel-sand cushion, a layer of insulation material. It is better to perform work before pouring the grillage.

Strengthening the pile foundation

This term means a whole range of measures aimed at strengthening one or more pile elements grounds:

• To strengthen the supports at the stage of their installation, reinforced concrete soles are used, which are arranged under the lower part of the pile. To strengthen the already operated support and to repair it in the event of cracks or partial destruction, so-called reinforced concrete clips are used. To do this, the wellbore is expanded and a concrete mixture is poured, which, after solidification, reliably fixes and supports the product.
• To strengthen the grillage at the construction stage, metal linings from corners or channels installed at the corners of the foundation are used. Strengthening of the concrete grillage is made by the gunning method: applying a mortar mixture under high pressure. The repair compound is applied in layers, with each layer being reinforced with a mesh of thin galvanized wire.
• Strengthening the entire pile foundation in cases of insufficient bearing capacity, subsidence or partial destruction is a complex technological task that only specialists can do. The reinforcement of an incorrectly calculated or erected pile foundation depends on the type of soil. One of the methods of soil compaction around the piles is used: cementation, silicatization, resinization, firing.

The same technologies are used to strengthen the soil around the ground part of the pile foundation. If a simple subsidence or erosion of the soil is observed around the grillage, they are poured with denser materials (fine gravel or gravel).

What is a strip foundation on piles?

The strip pile foundation combines the advantages of two types - column and flat strip foundations. The first one performs the main work on interaction with the ground, and the second one ensures the distribution of the load of the walls of the structure.

At the same time, the material requirement for materials for the construction of the foundation is significantly reduced and labor costs are reduced.

Application area

Piles and strip foundations are suitable for the construction of a wide variety of buildings, from fences to brick houses, wooden beams and more modern materials such as aerated concrete, foam blocks, etc.

When using logs, they themselves can act as a pile-based grinder. If the structure consists of small elements, a rover is necessary.

There are several options for pile and strip foundations. The differences lie in the design of the lattice and the manufacture of the piles. In the simplest case, protocols can be used as such.

It's a short-lived material, but it's cheap. Usually coniferous wood is used and impregnation with mixtures is mandatory to protect against mold, fungi, etc.

Piles are not installed without the use of special equipment, so there is no need to talk about their use in independent work. And delivering them is not easy. ...

Monolithic

The monolithic foundation includes the manufacture of a monolithic reinforced concrete tap of the coupler, regardless of the type of pile.

This allows you to build almost any building from any modern material.

The load from such a foundation can be very high, although the load is slightly higher than with simpler options.

Screw

Another possibility is the use of prefabricated auger piles.

These are iron structures with threaded blades at the end. They will remind someone of a screw, a drill, but they are really screwed into the ground.

This type of pile is produced with a diameter of 57 mm and a length of 1650 mm. Given the corrosion resistance of the material from which the piles are made, it is not recommended to use them on soils with a high acid content (pH less than 5.5).

It turns out that attention to the acid-base balance is also important when building a pile foundation. For building a house, the optimal stack size is 108 or 133 mm in diameter and 2500 mm in length.After all, it is easier to cut off the surplus than to weld the missing one, especially since this length in most cases allows you to go below the soil freezing line

After all, it is easier to cut off the surplus than to weld the missing one, especially since this length in most cases allows you to go below the soil freezing line

For building a house, the optimal stack size is 108 or 133 mm in diameter and 2500 mm in length. After all, it is easier to cut off the surplus than to weld the missing one, especially since this length in most cases allows it to fall below the soil freezing line.

The benefits of this type of pile include, but are not limited to, the following benefits

1. A minimum amount of excavation is required.
2. This is a little time consuming.
3. High speed when performing work.
4. High "stability" in the ground due to the narrow entrance to the ground.

The disadvantage of piles is that the piles require a place for screwing in, which makes them difficult to install near other buildings, as well as low corrosion resistance.

With bored piles

These piles are manufactured locally. A hole is drilled in the pile, formwork is installed, reinforcement is installed, if necessary, and concrete is poured.

This option applies to almost all soil types. The main thing is that the depth of the piles should be greater than the depth of soil freezing in the area.

The benefits of this type of fund include, but are not limited to, the following benefits

• Low cost.
• Simplicity and speed of installation.
• You can do without special construction equipment.

Among the disadvantages, it is especially difficult to maintain the required accuracy when drilling and aligning the upper pile belt.

Regardless of the pile depth, approximately 10 cm of sand should be poured into the ground as a cushion.

Pouring the ground part of the pile foundation

If the ground allows, and the building site is relatively flat, the grillage is often made directly on the ground. To perform such an operation, the head should not rise more than 100 mm above the ground level. After all the supports are installed, proceed to the preparation and pouring of the strip foundation along the piles. This is done using the following technology:

• The upper part of the soil is removed along the perimeter of the foundation to make a small trench.
• The next step is the construction of removable or non-removable formwork. The most suitable material is planed boards, which are knocked down with crossbars to the desired height.
• The trench is filled with sand and gravel mixture to the level of the pile head. The pillow is moistened and tamped down to avoid sagging.
• A reinforcing cage is installed in the formwork.
• The concrete mixture is poured to the level so that the reinforcement frame is completely immersed in concrete.

Advice! If concreting work is carried out in hot weather, the concrete-filled formwork is covered with plastic wrap, and it is recommended to moisten the concrete itself every 12 hours.

Product characteristics

Metal piles have a number of advantages and disadvantages, which are shown in the table below.

Building on a slope with a pile foundation

Pile foundation - advantages and disadvantages

The advantages of such grounds include the following aspects:

• The possibility of erecting a building in difficult areas when it is not possible to apply other types of foundations.
• Relatively low labor intensity and high installation speed.
• Minimization of construction costs, since a pile foundation is considered one of the cheapest options.
• The absence of earthworks allows preserving the natural landscape on the construction site.

Of the disadvantages of this type of foundation, the following factors are noted:

• The need for calculations, since the piles have a bearing capacity limitation.
• Lack of basement.
• This type of foundation is suitable for the construction of relatively light structures.
• The need to perform the strapping of piles, as well as their high-quality waterproofing.
• The complexity of the arrangement of the floors of the first floor: the use of effective materials for thermal insulation is required in order to exclude freezing.

Metal support elements

Steel support

For the construction of foundation foundations, structures from a metal rolling profile are used; the project may provide for the construction of supports from an I-beam, channel or pipes.

In some cases, open-section pile elements are used, which are easy to manufacture by welding, obtaining supports from metal of any length. Typically, metal profile pile elements are driven into the soil by driving using a conventional hammer.

The industry produces special pile elements for the construction of metal foundations, they are immersed in the ground by the screwing method. Screw metal piles are used for the construction of foundations on soft soils with low bearing capacity, in areas with difficult terrain and high groundwater levels.

The installation of supports is carried out manually; 2-3 people with some construction skills can easily cope with the work. Simultaneously with the immersion of the supporting elements in the soil, it is compacted, which makes it possible to increase the bearing capacity of the base.

Purpose of screw piles

The first pile structures with screw tips in the Russian Federation began to be used exclusively for the needs of the army in the middle of the 19th century. They could be used for temporary structures or in difficult operating conditions. The declared resource was 100 - 180 years, which modern manufacturers cannot boast of. Currently, SHS and other modifications of piles are used for:

• building a house in a swamp, a slope, in a dense building, a forest zone, on soils with a high ground level, low bearing capacity;
• budget construction of fences, MAF, gazebos, outbuildings;
• strengthening tape, slab bases;
• manufacturing of engineering systems, for example, grounding a house, water intake wells.

The height of the SHS is practically unlimited - when the lower element with the auger blades is immersed to the ground level, the next piece or several can be welded to the pipe to ensure the achievement of layers with bearing properties. For installation, three people are enough or one foreman with a powerful electric drive with a gearbox.

This manual is suitable for the installation of screw piles under a building erected using any technology from different wall materials. Recommendations will help to avoid mistakes, to increase the operational resource of the dwelling.

Good publicity

Supports strapping

By themselves, piles are not yet considered a full-fledged foundation.In order to evenly distribute the total load from the structure over all the supports, they must be strapped - combined in a horizontal plane. Such a strapping is called an upper or grillage, and the following materials are used for its implementation:

1. For wooden houses, the practice of tying with a wooden coniferous beam is practiced. For additional protection of the wooden grillage, the timber is treated with antiseptics and impregnated with water-repellent compounds. Waterproofing, for example, several layers of roofing material, is mandatory under the headings.
2. Tying with rolled metal: channel, I-beam or corner is suitable if reinforced concrete or metal piles are used. Metal products are pre-treated with anti-corrosion protection.
3. Reinforced concrete grillage is equipped in the case of the construction of external walls from piece material: brick or wall blocks. It can be made by laying ready-made reinforced concrete pillars or by pouring concrete, having previously erected the formwork and laid the reinforcement.

Technology

Each specific solution of the pile foundation has its own installation technology. In general, the device of the pile foundation is carried out in the following sequence.

1. Preparatory work. The horizontal leveling of the site, the leader in the nature of the axes, the marking of the location of the piles.
2. Immersion of piles into the ground. Produced according to the technology for a specific type of pile.
3. Cutting off the ends of unfinished piles, setting up a pile grillage.

The technology for constructing a pile foundation for each type of pile is described above. It should be noted that when choosing a method of installation, one should be guided not only by economic feasibility, but also by design experience in each region of construction. Local design institutes have developed standard flow charts, which contain complete information on the production technology of work, work schedules have been drawn up, as well as specifications of the required machines, mechanisms, equipment and materials.

A pile foundation may be the only acceptable solution for weak-bearing soils and difficult geological conditions. In other cases, one should be guided by the principles of economic and technological expediency. A pile foundation device may be required for high-rise buildings, critical or unique facilities. This solution makes it possible to increase the reliability of the base of the building, to prevent unwanted deformations and movements.

Despite the technological complexity, in some cases, the construction of a pile foundation can be economically justified. The device of the pile foundation does not require large volumes of earth and concrete work; the construction can be carried out in the winter without additional measures. The use of piles can shorten the turnaround time. A striking example of this is the construction of foundations for cottages using metal screw piles.

The advantages of a pile foundation include:

• the possibility of the device in special geological and climatic conditions;
• high reliability and stability of the foundation;
• a small amount of earth and concrete work;
• a large number of various design and technological solutions.

However, the pile foundation has a number of disadvantages, mainly related to the complexity of the construction technology. Among them:

• the need for special machines and mechanisms;
• qualified personnel is required;
• there is a significant likelihood of unforeseen difficulties during the construction stage.

It should also be noted that in most cases the cost of a pile foundation will be higher than that of similar shallow foundations.

Making piles with your own hands

The simplest options for screw metal piles up to 6 m long for light buildings can be made independently at home.They can be used as a base for baths, sheds, fences, wooden houses. To work, you will need the following tools and materials:

• Bulgarian;
• sledgehammer;
• mount;
• welding machine, electrodes;
• tape measure, chalk or marker;
• building level;
• pipes with a diameter of 60, 80 mm (they are selected according to the approximate value of the load);
• steel sheet 4 mm thick.

The creation of a homemade product occurs in the following sequence:

• a blade with a diameter of 122 mm is cut out of sheet steel;
• put it on the pipe;
• the end of the last grinder is cut into triangular scallops in number from 3 to 6, which is determined by the pipe diameter;
• they will be connected with a sledgehammer into a cone, welding the joints by welding;
• a workpiece is welded to the tip from the inner edge;
• then the blade is stretched with a pry bar so that it lies completely in a spiral on the pipe;
• weld the place of contact by welding.

The cutting edge of the blade is sharpened in the form of a wedge.

Foundation options

Scope of application

The main provisions and requirements for the design and conditions for the use of pile foundations are regulated by SP 24.13330.2011 and SP 50-102-2003. In accordance with these regulatory documents, the foundations are designed on the basis of the conducted engineering surveys. The main areas of application (the basis for the arrangement) are considered to be the presence of soils with a weak bearing capacity on the building site. Such soils include:

• Loams.
• Peat bogs.
• Sandstone.
• Quicksands.
• Abundant, vegetative, loess-like soils.
• Other soil types with unstable or weak structural bonds.

Also, the following factors are considered the basis for the use of pile foundations:

• High GW level.
• Swampy area.
• Seasonal flooding of the site during floods.
• Seismic activity in the development region.
• A significant difference in the surface of the site in height.

In addition, the foundation for a building on piles is organized in cases where the construction of other types of foundations is not rational from an economic point of view. For example, a large amount of excavation work for the arrangement of a monolithic or slab foundation.

Another area of ​​application of pile foundations is the construction of pre-fabricated buildings, since the speed of their arrangement allows maintaining high rates of construction.

Differences between the pile-strip foundation scheme

The disadvantages of this system include the following:

1. Many jobs have to be done manually. The drilled holes do not allow the use of construction equipment for digging trenches.
2. When tying reinforcement to supports, some skills in building a horizontal frame are required. The reliability of the building depends on the output of the height of the piles and the correctness of the strapping.
3. It is preliminarily recommended that you familiarize yourself with the bearing capacity of the soil. Based on these data, the surface load is calculated.

Most often, the laying depth is 35-42 cm below the zero mark. Preliminary work on the creation of the pit provides for the removal of the upper layer of soil to the bearing level. After that, a recess is made to the height of the dumping cushion. The perimeter is filled with adhesive (the minimum height is 20 cm above the ground surface).

The total height is determined taking into account the severity of the building and the bearing capacity of the soil. The structure is partially recessed. This model is a grillage connected to the ground.

In conditions of highly heaving soil, there is a possibility of squeezing out the base with the outer layer of the earth. In the worst case scenario, the concrete supports pop out of the wells (or break off at the heads).

Such cases occur when construction rules are not followed. In order to avoid such situations, a blind area is installed, more stable supports are used, or the foundation is redone (for a grillage).