How to tie a pile-screw foundation. Tying the foundation on screw piles: recommendations for tying with a channel and step-by-step instructions for tying with timber The main dimensions of grillages - how their dimensions differ

Protecting the foundation from water

Shallow foundations require particularly careful protection of structures and soil at the base of the foundation from moisture from surface water. Saturation of the soil with water reduces its load-bearing properties and increases the magnitude of frost heaving forces.

To drain surface water (melt, rain) from the house, I recommend:

Be sure to raise the ground level under the house and around the building.
Correctly arrange the blind area around the house.
Install a drainage system for organized drainage of water from the roof and blind area away from the house.

Construction of an embankment under and around the house

On construction sites, both with and without a slope, it is always necessary to provide and carry out an artificial increase in the ground level by adding third-party soil.

The installation under the house and around the embankment has the following advantages:

The thickness of the freezing layer of natural heaving soil decreases, which will lead to a decrease in the forces of frost heaving of the soil under the base of the foundation.
The bearing capacity of the soil under the base of the foundation increases.
Conditions are created or improved for draining rain and melt water from the house.
It becomes possible to increase the general surface level of the area around the house during landscaping and the delivery of fertile soil to the area. The soil level on the site, as a result of various economic activities, increases over the years. A house without an embankment will eventually end up in a hole.

Blind area

To drain water from the house and the site, it is necessary to properly perform the blind area, as well as organize the collection and removal of water through a surface drainage system.

The purpose of the blind area is to protect the foundation and the soil at the base of the foundation from moisture from surface water. Before installing a blind area, the soil level around the base of the house must be raised above the surrounding area. To do this, add soil to a height of at least 100 mm.

When constructing a blind area, a dividing tape is laid between the backing and the concrete of the blind area or an air gap is left. The blind area should be able to move slightly vertically relative to the fence.

This is not how a blind area is made! Errors: a – the blind area is not raised above the ground level on the site; b - in addition, the blind area does not cover the filling of the sinuses of the foundation trenches.

Drainage from the roof and blind area

Near-surface trays for removing water from the roof and from the blind area away from the house.

Which foundation is better? Pros and cons of foundations

Bored foundation for a wooden, frame house or bathhouse

Timber for home, bathhouse in your city

Beam. Profiled. Glued. Natural humidity. Log. Log house. board. edged unedged

For a wooden, frame or panel house with a basement on wooden beamsa columnar foundation with a grillage high above the ground will be the most economical option.

For the above light buildings, it is recommended to install a shallow or non-buried strip foundation in the following cases:

For frame and panel houses on medium and highly heaving soils.

Previous article:

The growing popularity of frame construction is explained by the fact that this method allows you to build houses in a very short time. To further speed up the work, pile-screw foundations are used as the foundation. The fact is that in the process of their arrangement there are no wet processes. To provide the foundation with proper stability, you will need proper tying of the pile foundation.

For the stability of a wooden house, it is not enough to drive the piles into the ground - they also need to be fastened together from above

Features of a pile foundation

Pile-screw foundations are very common in low-rise construction. This is especially true for the construction of frame and timber houses, which are lightweight.

This is explained by the following advantages of pile structures:

Possibility of use on difficult soils. This refers to weak, heaving and frozen soil. The same applies to uneven areas, when, due to the characteristics of the topography, this type of foundation is the only possible solution.

Long service life. Compliance with construction technology, the use of high-quality materials and proper operation ensures a long service life of the pile foundation (at least 100 years).

Cheapness. Other types of foundations are much more expensive.

Simple and fast construction. Special equipment is usually used to immerse screw supports, which allows this procedure to be completed in a few hours. There is also a manual screw option that can be handled by 3-4 people.

Screwing in screw piles using special devices will significantly save time

When laying a foundation using screw piles, labor-intensive excavation work will not be required. The main thing is to correctly calculate the depth of screwing and the distance between the supports.

The determining factors in the calculations are the massiveness of the future building and the characteristics of the soil - its composition, the depth of groundwater and the degree of freezing.

When considering the possibility of using a pile foundation, it is important to take into account the fact that the structure does not have a continuous supporting surface. This causes known difficulties when using materials for small format walls. The current problem is solved by tying screw piles, for which several technologies can be used. The correctness of this procedure directly affects the strength qualities of the finished building.

The reliability of the entire building will depend on the strength of the pile foundation

Why do you need a harness?

The function of the strapping is performed by the upper element of the base - the grillage, for the arrangement of which you can use several methods (the choice depends on what the house is being built from). The grillage cannot be considered a mandatory structural element of a pile foundation. Despite this, it is recommended to use it in every case, which guarantees the reliability and stability of the structure.

The grillage performs the following functions:

Evenly distributes the load on the piles. This is especially true for situations where, due to the characteristics of the soil, the supports have different immersion depths. This state of affairs can cause distortions and shrinkage of the building. Thanks to the grillage, the risk of such situations is minimized.

Creates an overall structure from individual piles. After this, the supports stop “living their own lives”, forming a reliable frame for the house. As a result, the spatial rigidity of the structure and its service life increase by 2 times.

Ties the foundation around the perimeter. A shallow and recessed grillage helps to increase the area of support on the ground and creates protection for the underground area from influences from the street.

Scheme of a pile foundation with a shallow grillage

On our website you can find contacts of construction companies that offer foundation repair services. You can communicate directly with representatives by visiting the “Low-Rise Country” exhibition of houses.

Foundation piping is classified according to the type of material used:

Wooden from timber. It is used in the construction of wooden frame houses and timber buildings. The arrangement procedure is inexpensive and can be carried out alone or with one assistant.

Boardwalk. Small wooden and frame buildings are equipped in this way. To construct a grillage, the so-called a composite beam made from several wooden planks.

Metal. A channel grillage can provide stability for a two- or three-story wooden house.

Reinforced concrete. This design demonstrates the greatest reliability and durability, and can be used in capital construction. During the construction process, the concrete solution is poured into pre-assembled formwork equipped with reinforcing mesh.

Tying a pile foundation with timber is most popular in the construction of country houses and cottages. This is especially true in regions with harsh climates and permafrost.

Wooden strapping is used only for frame buildings and houses made of timber

Material selection

The pile foundation grillage is most often constructed from 200×150 mm timber. If the house being built has impressive dimensions, then it is better to use timber 200×200 mm. Using material 200x150 mm, it must be laid on the heads in a narrow part. Thus, the strapping beam will have a height of 200 mm.

Preparing the base of the heads

For the convenience of subsequent construction procedures, the tops of the piles are equipped with special square plates (heads) measuring 250x250 cm.

They must be prepared accordingly:

Drill several holes (usually 3-4 pieces). They facilitate the procedure of attaching wooden frames with plumbing screws. The size of the screws is 10x120 mm.

To attach the harness to the heads, holes are made for self-tapping screws.

Waterproof the caps with roofing felt or innovative bitumen material. When cutting pieces for each head, make a margin of 20 mm per side: this makes fixing easier.

Thanks to waterproofing gaskets, protection is provided for wooden framing elements from the damaging effects of moisture. Its source is condensation that forms on a cold metal surface during temperature fluctuations. Every effort should be made to keep the wood dry at all times.

The waterproofing layer between the sole of the head and the beam prevents condensed moisture from penetrating the frame. This significantly increases its service life and prevents rotting. To prevent the waterproofing sheets from moving, the base of the cap is coated with bitumen mastic.

Waterproofing between the head and the timber is mandatory, otherwise, due to exposure to moisture, the strapping can quickly “wear out”

Fastening the bars

To facilitate installation, preliminary laying of timber around the perimeter of the entire structure is used. This makes it possible to comply with all design parameters for tying the foundation with timber. The laid beams must have a right angle to each other. To check perpendicularity, measure the diagonals of the corner sections - they must be identical.

The procedure for installing the timber:

The starting point for installation is chosen to be fastening units in areas where the beams intersect with each other.

The joining of timber is usually done “in half a body”. Less commonly, a more reliable “claw” connection can be used. To ensure a tight fit of the timber, its ends must be cut as evenly as possible. The connecting areas are additionally coated with wood glue.

The timber is fastened to the base of the heads using self-tapping screws with a hexagonal head, which makes it possible to screw them in from below. The screwing procedure is facilitated by pre-drilling small diameter holes at the attachment points. A socket wrench is used to tighten the screws.

The beam inside the perimeter of the grillage is also cut into half a body. Before this, the timber in the connecting areas is equipped with grooves.

Connection of grillage beams at the corners of the foundation perimeter

After this, it is cut to a part of the end, which is immersed inside the main harness. It is necessary to ensure that the embedded fragment fits inside the equipped seat as tightly as possible.

Additional fastening

For reliability, the elements of the connecting nodes are additionally fastened with steel brackets made of a metal rod with a diameter of 8 mm. This must be done when the length of the screws is not enough to firmly fasten thick beams. The location for installing the brackets is chosen to be the top part of the beam, opposite the connecting nodes. The sharp ends of the fasteners must be driven into solid sections of the timber that are not equipped with half-tree recesses.

It is not always easy to completely hammer an 8 mm thick staple into wood, so this procedure is implemented as follows:

Markings are applied. To do this, simply attach the fastener to the surface of the beam and trace it with a marker.

A groove 10 mm deep and 8 mm wide is cut along the marking line.

The points on the surface where the legs will be immersed are equipped with holes with a diameter of 5-6 mm. This will protect the timber from cracking while driving the staple.

Holes and grooves must be treated with antiseptic impregnation.

Hammered staples should not rise above the surface of the beam

The staples are being driven in. They must be immersed flush into the surface of the timber

At the intersections of two beams, a “half-tree” joint is used. The self-tapping screws are screwed in from below. The staples (4 pieces) hammered in from above should form a square shape.

The installed brackets should not protrude above the general surface, otherwise this will create difficulties for subsequent construction work.

Video description

About the features of tying a pile foundation in detail in the following video:

Checking the horizontal structure

When the beam tying of the screw piles is completed, the finished structure is checked for horizontalness. To do this, use a water or building level. The permissible diagonal difference between opposite corners is no more than 5 mm. All parameters of the finished harness must correspond exactly to the instructions in the design documentation. The observed errors must be taken into account during the construction of wall structures.

Checking horizontality is a mandatory step; if you bypass it, you can get many problems with your house in the future

Bottom line

A pile foundation makes it possible not to depend on the characteristics of the soil and climatic conditions of the region. When it comes to building a light frame house, the piles are usually tied using timber.

Frame construction is very light. Therefore, why build a complex foundation for it? I understand if you are planning to build a brick house on three floors with an attic or want to build a panel colossus on your site. Then yes, the flag is in your hands, go ahead and arrange the foundation according to all the rules of military siege art - drive columns of mixers with concrete onto the site and transport trains of reinforcement. And don’t forget the small army of Uzbeks to build all this splendor.

Okay, jokes aside, someone is building and needs a light foundation. The man decided to place his frame on a pile foundation - his soils are such that the ground level is high and in winter frost heaving does not give rest.

Of course, the nicest thing to do is to install an insulated Swedish slab (USP) under a light frame house, but now we are not talking about it, but about the pile foundation.

To combine individual piles into a single structure and evenly redistribute the weight of the entire house across all piles, a grillage is used.

A grillage is a horizontal power structure that connects together all the elements of a pile foundation and serves to evenly distribute the weight of the house onto each pile. Oh yes, I already wrote almost the same thing just above!

Well, in order not to spend too much money on the foundation, a lightweight pile foundation and an equally lightweight grillage, which is part of this pile foundation, are used.

What do we have in the end, what are the grillage options for a frame house?

A steel grillage on steel screw piles is the most versatile option. Suitable for almost any soil and can be installed at any time of the year, including.

What is good about this grillage? The fact that it is cooked from ready-made shaped steel products, angles and channels, right on the site at the time of installation of the pile screw foundation. The design turns out to be durable and light, if, of course, you took the time to find one, and not one that either has holes or the electrodes stick.

A steel grillage on screw piles is the lightest and most durable.

You can place the lower frame on such a grillage and then mount the entire frame of the house on it. To attach the lower framing of the frame to the grillage, eyelets for bolts are welded onto the top of the steel structure.

The grillage itself is attached to screw piles either with fasteners or welded. The second option is preferable, since the entire structure will be more rigid. Although a frame house actually doesn’t care what kind of foundation is underneath it, because the frame, like a box of matches, is rigid in itself.

Concrete grillage on reinforced concrete and screw piles

A more budget-friendly, but no less rigid, design will be achieved if you make a concrete grillage in a frame from a corner.
This grillage can be mounted on both steel and reinforced concrete piles. Moreover, on reinforced concrete piles you can do without using a corner, but then you will have to increase the height of the grillage by 1.6 times.

For example, if in a frame from a corner a concrete grillage can be made 30 centimeters high, then without a frame you will need to make a grillage even 45-50 centimeters high.

Naturally, the grillage is reinforced with reinforcement, as it should be - this is not even discussed.

The concrete grillage is attached to the piles as follows:

In the case of using an angle, the angle itself is attached to the screw piles, usually welded. So the steel frame containing the concrete becomes one with the steel screw piles.
In the case of using a simple reinforced grillage, it is attached to concrete piles using reinforcement that is tied or welded. After pouring the grillage with concrete, it forms with the piles, in fact, a single concrete structure.

Naturally, when using a concrete grillage on bored piles, the consumption of concrete will be significant - 1.5 - 2 times more than when using a reinforced concrete grillage in a frame made of a load-bearing angle.

Wooden grillage for a frame house

You can also lay a wooden closed frame on screw piles or on a columnar foundation, which will simultaneously act as a lower frame and serve as a kind of grillage, only.

This wooden grillage is the lightest and cheapest.

Wooden grillage on a pile foundation - bottom view.

If you connect this closed frame with piles, you get a relatively rigid and very light structure. At the same time, this frame will not serve as a lower frame. The lower frame frame cannot be used as a grillage, since it does not have enough strength to hold all the foundation piles together.

Therefore, a wooden grillage is assembled either from timber of at least 100x100 mm, or from boxes made from boards 50x100 mm.

A wooden grillage is attached to the screw piles through bolts, and either the lower framing of the frame is already attached to it, or the vertical posts of the frame are placed directly on the grillage.

Comparison of grillages: pros and cons

Just below you see the pros and cons of various types of grillages, which are collected in a table. Using it, you can compare the positive and negative aspects of a particular design:

Grillage type
Steel grillage on screw piles	Easy installation Lightweight design In any season	Requires skilled labor
Concrete grillage in a frame on screw piles	Tough enough Less expensive Also suitable for log houses	Less durable Heavier than steel
Concrete grillage on concrete piles	Even less expensive Suitable for houses made of light blocks	Increased concrete consumption Heavier than steel
Wooden grillage on screw or concrete piles	The most budget You can do it yourself without a crew Can be done even in winter	The most fragile of all Prone to rotting Absorbs moisture Mobile

As a result, it’s worth thinking about which grillage to choose for a frame house. If the house is small and light, then you can install a wooden grillage. If the frame is made of timber or filled with heavy insulation, then, without options, you will need a steel or concrete grillage on screw or concrete piles.

Any foundation on piles is made of two parts - these are the piles themselves, which are used to transfer pressure to the load-bearing layer, and the grillage.

Not many novice builders know what a grillage is and what it is intended for, but, nevertheless, it is of great importance in the design of the base.

This article will discuss the types of grillages, their purpose and main differences.

The concept of grillage and its varieties

A grillage is a horizontally placed section of a pile base, which is used to receive and transmit loads from the walls of a building to the piles. In addition, the grillage allows you to combine all the piles into a single product, so it is extremely important to create rigid connection points when working.

Depending on the type of base and geological parameters of the soil, the grillage may have differences:

By location. It can be located on the ground, be deepened, or not touch the surface at all.
According to the components used in production. Reinforced concrete, metal, wood or ordinary concrete can be used for production.
By design. Monolithic, prefabricated-monolithic and prefabricated grillages are manufactured.

The design diagram of the pile foundation can be seen below.

Types by placement

Depending on the location of the tape relative to the surface of the earth, the following varieties exist:

high grillage, also called hanging;
increased;
recessed

You can see the location of the different types relative to the ground in the diagram below.

High

This type is located above the soil level, and its lower structure rises 10 cm relative to the planning level of the ground. This variety has good stability and integrity and allows you to avoid possible damage to the foundation. If there are no necessary gaps, the grillage or connection nodes may be deformed, which will lead to the pulling out of the piles.

As a result of choosing a high grillage, a ventilated space is created under the floor, which will ensure a high level of moisture in the house and coolness in the hot season.

The disadvantage of this solution is the lack of sealing of the space between the soil and the lower plane of the ceiling. Cold air flows and the absence of a stationary air layer increase the heat loss of the building. Because of this, when building a house in a harsh climate, the floor will need to be insulated. Another disadvantage is the inability to build a full-fledged basement or basement.

Elevated

This type is more common and involves placing its sole at ground level.

As a base for the tape, a cushion based on sand or gravel with a thickness of 10-15 cm is used, for installation of which the required amount of soil is removed and replaced with gravel.

As a result, an anti-heaving cushion is formed that prevents frost heaving of the soil.

The gravel bed reduces soil moisture levels and prevents water accumulation. The undoubted advantage of such a grillage is the absence of a ventilated space between the ceiling and the soil.

Recessed

How is a recessed grillage installed and what is it? This type is distinguished by placing the tape below the ground surface.

A shallow pit is dug along the line of the installed piles, at the bottom of which a crushed stone cushion is mounted. After this, formwork is installed in the trench, and reinforcement and concreting are carried out.

Fastening between the elements is carried out by monolithing the tops of the piles in the grillage.

Varieties by type of material

Depending on the design of the building and the pressure on the foundation, the grillage can be made of the following materials:

reinforced concrete;
metal;
wood;
concrete.

Reinforced concrete product

This type has a high load-bearing capacity and is characterized by stability, strength and long service life. It was these qualities that guaranteed it widespread use. The reinforced concrete grillage contains reinforcement, which increases strength, and concrete, which allows it to withstand high pressure. Reinforcement can be performed either by individual rods fastened into a single frame, or by pre-assembled frames. To learn how not to make mistakes when installing a grillage, watch this video:

When creating the base of the grillage, it is extremely important to provide a good protective layer for the reinforcement.

Metal structure

The metal grillage is made from rolled profiles: I-beams or channels. It has good strength and rigidity.

Often used when creating foundations based on piles and screws and in the construction of one-story buildings.

The channel is laid on the heads of metal piles and secured by welding. The main disadvantage of this material is its low corrosion resistance, which leads to the need for additional protective treatment of products.

Wooden grillage

This variety is used exclusively for wooden buildings. Installation of wooden boards is carried out through a waterproofing gasket designed for this purpose. For this, roofing felt or roofing felt is used. For information on installing a wooden structure in a frame house, watch this video:

To avoid wood rotting, the grillage is treated with special antiseptics. The timber is fastened to the pile using bolts or brackets.

Concrete structures

A device of this type is identical to the reinforced concrete product discussed above. However, there are a number of features. The design does not provide reinforcement. All pressure is absorbed and distributed by concrete.

When using this type, it is necessary that the pile heads extend into the concrete to a level of 10 cm. A concrete grillage can only be used when constructing one-story buildings.

Types by type of construction

Depending on the design parameters, grillages are of the following types:

prefabricated;
monolithic;
prefabricated monolithic.

Prefabricated structure

Often this structure is made of steel beams held together by welding. The main disadvantage of this type is the difficult installation of heavy beams and the low strength of welding fasteners.

Such types are laid on the pile heads and secured; there is no need for embedding. This solution is perfect for non-permanent houses with a service life of up to 20 years.

Monolithic grillage

This product is manufactured as a one-piece structure, which is poured directly on the construction site. This category includes concrete or reinforced concrete materials of strip or slab type.

The tape variety is more widely used, but the tiled variety is indispensable for poor geological soil conditions.

The work of installing a monolithic grillage is not highly labor-intensive and will not require large financial costs.

Prefabricated monolithic

It consists of factory-produced prefabricated parts, assembled like a construction set. After assembly, all seams are sealed, creating a single product. Used in industrial construction for multi-storey buildings. For more information about installing a monolithic grillage, watch this video:

This type is expensive and requires special equipment and precision during installation.

As can be seen from the article, the grillage is an important part of the foundation. There are many types of such products. The choice is made based on the type of foundation and soil parameters.

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Classmates

With the growing popularity of frame houses, they have become widespread.

Screw piles installed according to the markings on the construction site, alone, do not have sufficient stability.

To combine them into a single supporting structure, it is necessary to make a grillage. A foundation on screw piles with a grillage is enough solid foundation for any construction project.

A pile screw foundation with a grillage differs from other types of foundations in the following ways: advantages:

Possibility of use on weak, heaving soils, as well as in areas with permafrost or tundra.
Possibility of installation regardless of surface topography, characteristic of all species.
Durability. If installation and operation rules are followed, the service life can reach 100 years thanks to steel manufacturing technology.
Low cost compared to supports made from other materials.
High speed and simplicity. Typically, screw supports are immersed in the ground using special equipment. If this is not possible, it is quite possible to do this manually with 3–4 people.

Important! Buy foundation piles only from trusted suppliers, ask for quality certificates to avoid purchasing low-quality products made from low-grade materials.
Otherwise it will be required.

Useful video

Check out the tying of screw piles visually in the video below:

conclusions

The grillage is a necessary part of a pile-screw foundation. Correct installation of this structure will greatly increase strength and reliability structure, will give it stability. In difficult seismological and climatic conditions, a grillage is the only correct solution for the construction of frame houses.

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