How to make timber strapping. Tying screw piles with wooden beams: important points. Method of bundling with a profiled pipe

In individual construction, the owner strives to save every ruble, and columnar, pile or combined foundations are increasingly in demand: the construction of such a foundation for a house or other outbuilding requires much less financial and labor costs, time, and does not require the use of special equipment. But, as in any other issue, there are difficult moments in the construction of columnar foundations, and this is the tying of a pile foundation, that is, a kind of grillage if we are talking about concrete, and a powerful lower chord if the tying is made of wooden beams.

Why is foundation tying necessary?

The foundation itself is much easier and faster than doing the subsequent tying with timber, metal or concrete. However, it needs to be built, and why to do this, let’s look at it in more detail. To comply with the technology, you must correctly understand the operating principle of a pile or columnar foundation. Typically, such foundations are erected for objects with a low total weight, since the load capacity of any screw pile or pillar made of any material is quite enough to support the weight of the structure. In addition, tying screw piles with timber is much more profitable financially than constructing a strip or slab foundation, and construction time takes several times less. The photo below shows a double timber frame:

A pile foundation includes several piles - depending on the total area of ​​a private construction project, there can be from several units to several dozen. Piles can be steel pillars or reinforced concrete pipes immersed in the ground to a calculated depth, but not higher than the freezing point of the soil, that is, at least 1-1.5 meters. These pile supports hold the building above the ground surface so that the lower part of the house does not come into contact with the soil, absorb moisture or freeze from the ground.

But the columnar supports unevenly distribute the load from the weight of the building over the ground, and to prevent the house from warping, the piles are tied with a structure made of a suitable material. Such tying of a house made of timber reduces the pressure per m 2 from the mass of the object and evenly distributes the weight along the perimeter and along the internal and load-bearing walls of the house under construction.

The term “timber beam” refers to horizontal parts (wooden beam, steel angle, channel or I-beam, concrete grillage) connecting all piles or pillars to each other into a single monolithic structure. Any frame can be called a grillage, as it serves to enhance the strength and extend the life of the building.

Types and stages of strapping

The tying of the pile foundation with timber is done sequentially:

1. Prepare the foundation - level it and waterproof it;
2. Prepare the building material for the grillage;
3. Install the harness.

The screw piles are tied with timber or other building materials if the piles rise ≥ 0.5 m above the ground surface. The house can be not only wooden, but also built of foam, aerated concrete, hollow brick or SIP panels.

Types of strapping depending on the material of construction:

1. The grillage is assembled with beams for a wooden structure. A strong beam around the pile foundation is made with a cross-section of ≥ 150 mm and a square shape. Hardware for connections in the structure - steel pins M14-M16 or clamps made of soft thick wire. The timber must first be waterproofed and also impregnated with fire retardant and antiseptic compounds. Metal parts are protected with anti-corrosion agents;

2. A channel, angle or I-beam is attached to the piles by welding or appropriate hardware - the method of fastening depends on the material of the piles or pillars. The entire open surface of the metal grillage is coated with anti-corrosion compounds in 2-3 layers;

3. Reinforced concrete tying of piles is made prefabricated or cast in one piece. Structurally, such a frame resembles a strip foundation laid on piles or pillars. It is made for brick or block houses, but with appropriate calculations it can also be used for wooden buildings. Prefabricated framing uses beams that are laid on piles and connected to each other. To construct a solid grillage, formwork is made, into which a reinforcing frame is installed and concrete mortar is poured. The formwork is made removable (sheet materials, boards, etc.) or permanent (extruded polystyrene foam);

How to attach the harness

Before you begin tying the pile foundation, you should choose the method of assembling and fastening the grillage, as well as select the appropriate building materials.

The standard foundation piping with timber is connected to each other in two ways: a straight joint or an oblique cut. The joints are protected with an overlay of boards or a Gerber hinge. The external piping of the pile foundation is made double.

A wooden, metal and reinforced concrete grillage is attached to the piles as follows:

1. For threaded hardware – bolts, screws, studs;
2. For welding;
3. On clamps or staples.

Tape base

Strapping is needed not only for pile-screw and columnar foundations, but also for strip foundations, since it is difficult to attach wall beams, panels or logs to concrete. The strapping acts as an intermediate link between the material of the house and the foundation. The lumber itself is attached to the concrete using embedded reinforcement, which is installed when the foundation is poured.

Installing a wooden frame on a strip base:

1. The surface of the foundation must be strictly horizontal and level. The difference in height between the surface of the tape should be + / – 1 cm, so unevenness is filled with a thin screed, and smaller differences are adjusted with wooden pads;
2. The surface of the reinforced concrete strip must be waterproofed. To do this, use bitumen, roofing felt or thick polyethylene film. The material is laid or applied in 2-3 layers;
3. Holes are drilled in the timber with a diameter 1-2 mm larger than the diameter of the anchors poured into the body of the concrete strip. Each anchor is fitted with a rubber gasket and a wide steel washer, which protects the wood from deformation when the thread is tightened;
4. The strapping beam is laid on the waterproofing layer so that the anchors fall into the holes. The timber is connected to each other “into a bowl” or “into a paw”;
5. Nuts are screwed on top of the washers, and studs are not required at the connection points of the timber;
6. After installing the strapping belt, the assembly of the walls of the house begins.

Pile foundation

The most common methods for attaching timber frames to poles or screw piles when building a house are threaded connections and fastening with clamps. Double fastening makes the connection strong and durable, prevents the piles from loosening and distributes the load evenly across all piles. Preliminary preparation of wood before assembling the strapping consists only of impregnating the timber with antiseptic and fire-retardant compounds, and the preparation of metal parts is reduced to protecting surfaces with anti-corrosion compounds.

Sequence of tying a pile-screw base:

1. First, the timber frame is attached to a threaded connection to the piles. A beam of calculated length is placed between two piles, and where it contacts the metal, roofing material is laid. It is advisable to additionally impregnate the waterproofing with drying oil;
2. The beam is attached to the side posts with self-tapping screws, and to the bottom surface with studs or anchors;
3. To enhance the strength of the structure, spikes are cut into the outer corners of the beam, or the connection is strengthened by installing metal corners, which must be galvanized or coated with an anti-corrosion coating. The corner is attached to stainless steel self-tapping screws or galvanized screws;

In this way, the entire strapping structure is assembled - both on the outer sides and inside the perimeter.

If the piles are driven or screwed in the form of a flange, and it is not possible to attach beams to them on the sides, then instead of threaded connections, they are fastened with clamps: the timber is laid on the upper ends of the piles, and connected to each other with self-tapping screws. The metal grillage is held together by welding.

When connecting timber into a strapping structure, it is necessary to constantly check the horizontality of its surfaces so that during the further construction of walls they do not warp, resting on the uneven surface of the strapping. Control is carried out at the usual building level.

After connecting the timber along the perimeter of the object, it is necessary to place a structure made of timber of a smaller cross-section, connected by the letter “P”, with the ends down, between the piles on the beams located horizontally. This design is called a clamp - such a clamp can be made smaller in size than the strapping beam. With the help of these clamps, the entire harness is strengthened. During the assembly of the main frame, these wooden clamps are fastened to adjacent piles with threads or a metal angle. After assembling the harness, all connections must be checked for strength by loosening: if the structure does not move with maximum effort, the assembly is considered satisfactory.

The need to build on problematic soils dictates our own approaches and solutions.

One of them is, which provides support on deep, dense layers of soil.

Weak, waterlogged or loose surface layers do not participate in the operation of the support system, being, in fact, only an intermediate link between the upper above-ground structural elements and dense soils.

Individual piles, being vertical elements, take on a certain part of the load from the weight of the house, evenly distributed along all the trunks.

The grillage or strapping belt is responsible for taking the weight of the building and transferring it to the pile system, which should be discussed in more detail.

The pile system is a complex of vertical shafts immersed in the ground.

For further construction, a horizontal element is required that connects the supports to each other and serves as a reference line for the walls of the house.

This element is called a trim or grillage. It performs the most important function - it unites a group of individual trunks into a complex, making the pile field a single support system.

After immersion in the ground, the outer parts of the piles are cut, controlling their height to obtain an even horizontal plane at all reference points. Then special caps are installed on the upper parts - heads, equipped with horizontal platforms and shelves for mounting the harness.

The grillage usually follows the plan of the first floor of the house, i.e. load-bearing wall configuration.

However, for greater uniformity of load distribution and pile stability, additional transverse or diagonal beams are installed, increasing the rigidity of the bundle of individual supports and providing additional reinforcement to the load-bearing lines.

As a result, a design is achieved in which there are no separate supports; all of them are included in the integrated complex of the pile field.

Types of strapping

The piping belt for a pile foundation can be implemented in different design options. They have their own capabilities and are designed to work with different loads and conditions.

There are the following types:

Wooden

Use timber with a cross section of 200: 200 mm, or a pack of edged boards 50: 200. The beams are installed around the perimeter of the house (under the external load-bearing walls), along the lines of the internal load-bearing walls, and also connect the remaining supports in order to equalize the loads and tie all the trunks to the common system.

Corner joints are made into the wood floor, fastening to the ends is done through a double layer of roofing material for waterproofing.

The advantages of this solution are:

• Ease of processing, availability of material.
• The wood has sufficient strength and relatively low weight, which does not load the foundation.
• Installation is possible in the field, without the use of construction equipment or even without power tools.

The disadvantages of wooden types of strapping can be considered:

• Features of wood, tendency to warp or crack, need for high-quality waterproofing, etc.
• Fire hazard of wood.
• Possibility of material damage by insects or rodents.

Despite the obvious disadvantages of wood, a grillage made of timber is a common and popular option.

Metal grillage

Metal binding requires the use of welding.

From an installation point of view, it has noticeable advantages:

• High connection speed.
• Durability, resistance to all possible loads.
• A wide selection of types of rolled metal, allowing you to obtain various strapping options.

Along with advantages, metal strapping has disadvantages:

• The metal's tendency to corrode.
• The need for periodic maintenance of the structure (painting with waterproof polymer materials).
• Welded joints require the participation of a professional welder who is able to correctly select the operating mode and amperage. Otherwise, the seams will be brittle and brittle, which will create a significant danger to the building.

The main argument in favor of creating a metal frame is the high maintainability and speed of assembly of the grillage.

The cost of rolled metal and welding work is noticeably higher than that of wooden beams.

However, there are approximately the same number of supporters of this type of binding as there are fans of wooden parts.

The strength and stability of the metal are highly valued by users and increase the competitiveness of the material.

To increase the strength of the metal frame, it is recommended to use additional bolted connections.

Concrete

Concrete lining is almost a full-fledged analogue of a pile-strip foundation.

The fundamental difference is the distribution of loads - on pile-strip foundations, both elements share the loads equally, and the concrete grillage of the pile foundation only transfers the load to the supports, without performing load-bearing functions as such.

At the same time, being only an intermediate element, concrete piping allows you to get the maximum effect.

It has high strength, durability, load resistance.

In addition, the concrete grillage is able to compensate for changes in loads or load-bearing capacities of individual supports, redistributing or partially assuming new working conditions.

The advantages of this design are:

• Ensuring maximum load-bearing capacity of the system.
• Independence from climatic or weather conditions.
• Relatively low need for periodic maintenance.
• Durability, reliability of the material.

The disadvantages of concrete elements are:

• The complexity of creation, the need to perform various successive stages of work.
• Large volumes of materials (concrete, reinforcement, wood for formwork, waterproofing materials, etc.).
• It takes a long period of time for the lining to harden (28 days from the moment of pouring), during which further construction is impossible.

The construction of concrete piping is usually chosen when constructing large and massive buildings, where it is especially important to ensure the strength and reliability of the belt despite the high consumption of materials and labor costs.

NOTE!

For some types of piles, a combined version of the piping is often used, in which the grillage itself performs the main load-bearing functions, and the shafts are additionally connected by metal jumpers. This type of dressing is used, in particular, for screw piles. It strengthens the system and reduces the possibility of loosening or loss of traction.

Timber strapping technology

Most cases of using timber frames relate to the construction of frame houses on bored or screw piles.

Procedure:

• Cutting beams to length 200x200. Since a half-timber connection is usually used, the length of each span is measured in full, without taking into account the thickness of the adjacent beams.
• Laying the perimeter, connecting at the corners. A double layer of roofing material is laid on each head. Connections are sealed with jute strands.
• The beam is fixed on the heads using “wood grouse” - special wood screws with hexagonal heads.
• After laying the external beams, they begin to install the internal spans located under the load-bearing walls. Above the corresponding piles, recesses are made to the width of the beam (200 mm) and to half the depth (100 mm). Suitably prepared connecting elements of the internal spans are placed in these recesses.
• All parallel spans are connected with additional beams or boards installed on the edge. Self-tapping screws and galvanized corners with stiffeners are used for connections.
• The surface of all wooden parts is coated with an antiseptic and fire retardant composition.. After drying, apply a layer of waterproofing (hot bitumen or bitumen mastic).

Method of bundling with a profiled pipe

A profiled pipe has a structure similar to a channel, but in terms of strength it is much inferior to it.

This is due to the less durable metal used to make the profile pipe, thinner walls and other features of the material. To achieve maximum strength, corner joints are made overlapping or overlaying.

As an option, the ends are trimmed at 45°, welded, followed by strengthening the joint with an oblique angle for bolted connections.

Procedure:

• Trimming piles, installing caps.
• Laying beams along the outer perimeter, connecting corners.
• Laying internal beams, welding with external elements.
• Tying the remaining supports to obtain maximum rigidity.
• Applying a layer of protective anti-corrosion coating.

If possible, all connections are reinforced with metal gussets installed on bolted connections.

Channel bandage method

The difference between the channel piping technology and the method of installing a profiled pipe is the absence of standard ends.

The channel is installed with the wide side up, forming a horizontal platform along all the beams.

Otherwise, the procedure is similar to the technique for installing a profile pipe.

Usual channel dimensions m for piles with a diameter of up to 108 mm(a 160 mm channel is used for them).

Welded joints are additionally secured with bolted joints using gussets.

Welding must be carried out by a professional qualified specialist who has permission to work with critical structures. Waterproofing of the trim is carried out using traditional coating materials or protective polymer coatings.

Using reinforced concrete

The creation of reinforced concrete piping is carried out in stages.

Procedure:

• Formwork assembly. Horizontal panels (bottom) are laid on the surface of the heads, the side walls are attached to them and are firmly connected at the top by crossbars. The internal dimensions must correspond to the parameters of the grillage.
• Laying waterproofing. The bottom and inner walls of the formwork are tightly covered with a film or layer of roofing felt. The joints of the material are overlapped by 10 cm and the joint is sealed with tape.. The canvas must completely cover the entire surface of the bottom and walls of the formwork and fit tightly to the surface, keeping pace with it.
• Assembly of the reinforcing belt. Reinforcement with a diameter of 10 mm and smooth rods of 6 mm for vertical elements are used. The armored belt is knitted using soft wire, after which it is installed inside the formwork in the desired position. It is necessary to ensure that the horizontal rods are buried 2-5 cm inside the concrete.
• Pouring concrete. It is performed in one step, without long breaks (more than a day). Concrete should be poured from several points so as not to wait for the material to spread throughout the formwork.. After pouring, the surface is covered with polyethylene or burlap and left for 28 days to gain structural strength.
• The formwork is removed 10 days after pouring.
• After the end of the exposure time, waterproof the surface and proceed to further work..

NOTE!

To pour concrete lining, it is necessary to use dense grades of concrete from M200 and higher.

Using a board

Tying with a 50x200 board is done when high-quality timber is unavailable.

The technology is somewhat more labor-intensive, since each beam has to be assembled separately, but there are also advantages:

• No warping or screw turning.
• Possibility of more precise corner joints.
• Each board can be pre-treated with an antiseptic and fire retardant, which can significantly increase the resistance of the beams to biological manifestations or fire.

The work consists of making a kind of prefabricated timber from a pack of boards.

The boards are cut to length, trimmed in the right places for corner joints and collected in a tight package.

Pins are used for fixation which are passed through through holes and pulled tightly.

The formed beams are assembled using a technology similar to the method of installing timber frames.

The beams must be positioned so that the boards are installed on edge and not horizontally.

Useful video

In this section you can clearly see how tying, welding and finishing of a pile (pile-screw) foundation occurs (to the freezing depth):

Conclusion

The binding of the pile foundation is the connecting element between the individual supports and the walls of the house.

Taking the load, the grillage distributes it along the entire length and over all supports.

This allows you to reduce the load on each individual pile and form a sufficiently powerful load-bearing system capable of working in difficult conditions.

A large number of options for making trim allows you to choose the most suitable type for the selected wall material and construction conditions.

The efficiency of the foundation and the stability of the entire building largely depend on the quality and manufacturing technology of the grillage.

In contact with

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 speed up the work even more, 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 Source fucbgik.kal.ru.net

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 Source clubwell.ru

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. Source kursremonta.ru

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 Source pobudova.in.ua

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 Source postroifundament.ru

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 Source svaybur.ru

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 the penetration of condensed moisture onto the trim. 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” Source stroy-dom-pravilno.ru

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 hex 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 Source stroyfora.ru

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 Source zen.yandex.ru

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 Source vse-pro-stroyku.sqicolombia.net

Bottom line

A pile foundation makes it possible not to depend on the characteristics of the soil and climatic conditions of the region. If we are talking about the construction of a light frame house, tying the piles is usually done using timber.

The reliability and quality of any foundation depends primarily on strict adherence to technology at every stage of its implementation. And tying a columnar foundation with timber is no exception.

General information

Screw pile

A screw pile is a type of pile that is driven into the ground by screwing. As a rule, it is a metal pipe with blades welded to the base. These blades serve not only to immerse the structure into the ground, but also to evenly distribute the mass over a larger area of ​​the ground.

What is a harness

After installing the screw supports, they are fastened with beams, resulting in one rigid structure called a frame or grillage.

The framing of a house is essentially the overlap between the building itself and the foundation. This design evenly distributes the weight of the house from. In addition, the grillage is the first to take on the negative effects of the environment. Therefore, it must be strong, reliable and protected from moisture.

Timber is a material made by cutting a tree trunk from four sides. It has the same cross-section along its entire length. Currently, timber is the most popular material for lining the foundation. It is especially often used in the construction of log houses, bathhouses and other wooden houses.

The bottom frame made from softwood timber is most often used, as they have some advantages over hardwood:

• Higher service life and durability;
• High strength;
• Reduced moisture permeability;
• The price is usually lower than for hardwood.

Note!
The beam for strapping must have a cross-section of at least 150x150 mm.
When purchasing material, you must ensure that there are not even the slightest cracks on it, otherwise the build quality will suffer.

Before making a grillage, it is necessary to process the material:

• Antiseptic – to prevent decay and fungal development; (see article for more details)
• Fire retardant, which will increase fire resistance and prevent fire. This treatment is especially relevant for pine material, since this wood contains a large amount of flammable resins.

Advice!
When calculating the amount of material, it is advisable to add 10-15 percent, since during the work it may not be enough.

Glued beams are much stronger than regular beams, and they also have more accurate dimensions. As a rule, such material has protrusions and grooves. As a result, the structure made from this is very durable.

The main advantage of laminated veneer lumber is thermal and moisture protection. The design will be tight and without gaps in the corner joints. Of course, such material costs more than regular material, but it does not need to be dried and treated with an antiseptic.

Another advantage of glued material is that it does not rot and is very light in itself. Thus, a grillage made of laminated veneer lumber is an excellent solution.

To calculate the required amount of timber, you can use a simple calculator:

Wall length

m

Wall width

m

Wall height

m

Beam section

150x150 mm.

180x180 mm.

200x200 mm.

5 m. 6 m. 7 m. 8 m. 9 m. 10 m. 11 m. 12 m.

ru

• Strapping technology
• Tying a pile foundation with timber is carried out in several stages:
• Foundation preparation;

Preparation of building materials;

Direct installation.

• Tool
• If you will be tying the foundation with timber yourself, then you will need the following tool:
• Hacksaw or chainsaw;
• Electric planer;
• Screwdriver;

Drill;

Roulette.

1. Foundation preparation
2. Preparation is carried out in two stages:

First of all, you need to make sure the foundation is horizontal. Piles that are located above the required level must either be immersed deeper or cut off. If the supports are located below the required level, then a gasket should be placed on the head.

Then you need to perform waterproofing. To do this, a roofing material gasket is placed on the ends of the supports. You can also use bitumen or roofing felt.

Most often, the connection is made into the floor of the tree, when the cut is made “into the floor of the tree”, to the middle of the section of the beam at a right angle, the width of the cut corresponds to the width of the beam. Also sometimes they make a “half-paw” connection, when the cut is made at an arbitrary angle. This connection is more reliable.

Advice!
The easiest way to make cuts is with an electric planer.

Laying and connecting the strapping

After the piles are leveled, waterproofing is laid on them and the material is prepared, you can begin tying.

The instructions for performing the work are as follows:

1. First of all, you need to outline the corners. To do this, define the point as the first external corner; it can be marked with a nail. Then I mark the remaining corners in exactly the same way, and check their straightness using a triangle.
2. Next, you need to make one of the corners of the future object and lay all the prepared beams. It is necessary to lay jute tape between the joints. On straight sections of the grillage, it is best to connect the elements with a half-tree or “half-foot” head stop.
3. When all the elements are laid, it is necessary to once again check the straightness of the corners and the horizontality of the entire resulting structure.

Advice!
The beams can also be connected to each other using metal corners and brackets.

After the strapping beam on the screw piles is laid, it must be secured. Most often, the grillage is attached to the supports using bolts. To do this, holes must be made in advance on the pile heads, and after installation, holes must also be drilled in the beams; the beams must thus be attached to each pillar.

It’s even easier to use self-tapping screws instead of bolts, in which case you won’t have to make holes in the beams. After attaching the structure, cuts are made in the grillage for logs and partition beams.

Note!
After installing the trim, it is also necessary to lay a waterproofing layer on it, and treat open areas with mastic.

In some cases, the lining of a house made of timber is not done, since its role is played by the crown of the log house itself, installed on the foundation. This option is only possible if the floor joists are cut several crowns higher.

We looked at how to frame a house from timber with one crown. Quite popular is the double harness, which we will discuss below.

Double strapping made of timber is a more reliable design than the one described above.

It has the following advantages:

• The house turns out to be warmer.
• In double strapping, there are no cuts for beams and joists, so it is more durable than regular strapping.
• With double strapping, it is easier to remove and replace the logs during repairs, since they do not cut into the base.

When making such a design, the first crown is made of material with a cross-section of 200x200 mm. It is installed using the technology described above. In this case, it is also necessary to make cuts under the beams for the partitions.

When the first crown is completed, the second one is installed. Usually, for the second crown, beams with a cross-section of 150 x 100 mm are used, and they are installed end-to-end (the cross-section should not be square). All joints of the first row must be covered, while the corners are also connected - in a straight cut.

The partition beam is installed with its end in the middle of the beam of the first row so that there is a protrusion on both sides. Floor joists are laid perpendicular to the partition beam every 70-80 cm. They can be secured to the protruding beam using nails.

Advice!
The geometry of the harness is checked by measuring the diagonals.

This completes the work. You can learn more about double foundation piping from the video in this article.

Possible difficulties

When making a grillage you may have to face some difficulties.

• The piles are not screwed level. If it is not possible to bury the pile deeper, then you can not cut the pipe, but make a recess in the beam.
• The foundation turned out to be not square. In this case, the corners are leveled with a grillage.
  
• A crack appeared on the beam. In this case, the beam should be replaced.

Conclusion

Strapping is an extremely important stage of construction, since the strength and durability of the entire house depends on it. Therefore, it should be performed especially carefully, without deviating from the technology described above.

Developers quite often resort to using pile-screw foundations. It is most widespread in the construction of houses made of timber or light frame buildings. This type of base is supported by its low price and speed of installation. In some situations, a screw foundation is the only solution due to the special characteristics of the soil of complex terrain.

This type of foundation has a more complex structure. Its creation requires more time from builders. The width and height of the formwork are selected based on design calculations, which take into account parameters such as the weight of the roofing and rafter system, as well as the height, width and material of the load-bearing walls.

Reinforced concrete piping is performed in several stages:

1. Installation of wooden formwork along the perimeter of the external walls of internal load-bearing partitions. The strength of its bottom must be such as to withstand the weight of the poured concrete. During the installation of the formwork, the upper parts of the support pillars are passed inside the formwork box. In this case, the box will not be mounted on the ends. However, this approach requires the creation of temporary supports, which will need to be dismantled after the solution has hardened. To arrange the formwork, board or plywood with a thickness of 15-20 mm is used.
2. Covering the formwork box with waterproofing material. For these purposes, inexpensive roofing felt or polyethylene film is most often used. The waterproofing is attached to the edge of the formwork in several places. This is done so that during the process of pouring the concrete solution, the film remains in place and does not slide under the influence of the weight of the concrete to the bottom of the box. Adjacent waterproofing sheets are laid with an overlap of 20-25 cm. Also, waterproofing the formwork helps the concrete gain strength and does not allow it to lose water.
3. Reinforcement of the future grillage. First of all, this process is carried out in relation to piles. Reinforcing rods are inserted inside the supports. They must first be tied into the frame structure with special jumpers. After installing the reinforcement, the cavity of the supports is filled with concrete.
4. Reinforcement of the remaining grillage structure. This is done only after the concrete has hardened in the piles. The grillage frame is attached to the parts of the rods protruding from the supports.

Creation of a reinforced concrete grillage

• If the depth of immersion of piles in the ground exceeds 2.5 m, then sand must first be poured into them and compacted thoroughly. To make the base for the reinforcement rigid, crushed stone of a not very coarse fraction (no more than 20 mm) is poured there. Only after these procedures have been completed, a tied or welded structure consisting of several reinforcing rods 120-150 cm long is inserted into the support. It is necessary that these rods protrude upward to a distance that allows them to be linked to the upper belt of the reinforcing frame of the tape.
• In certain situations, it is possible to weld reinforcing bars to the outer surface of the pile. This is done in cases where the supports rise above the ground to a height of up to 35 cm. However, internal reinforcement is always a better option.
• After completing the installation of the reinforcement structure, the opposite walls of the box should be fastened together using jumpers. This is done to give it rigidity.
• To fill the formwork, concrete of at least grade 300 is used. To remove air cavities and obtain maximum density of the solution, it is necessary to vibrate it. After this, the surface must be leveled.
• A prerequisite for a high-quality grillage is that all planes must be filled with concrete within several hours. Otherwise, it will not be possible to achieve the required monolithic structure. You should think about this before ordering ready-made concrete or if you prepare it yourself.
• After pouring is completed, the grillage must stand until the concrete gains strength and completely hardens. It is worth removing the formwork after 10-14 days. It is not recommended to begin subsequent work related to the manufactured belt earlier than after 30 days. At low air temperatures this period will be extended.
• Gently cover the finished reinforced concrete grillage with an insulating layer and only then proceed with the following procedures. This is done by hot or cold laying strips of roofing felt on the horizontal planes of the grillage.

After completing all these operations, you can begin building the walls.

Ventilation in the reinforced concrete grillage

Another very important nuance should also be mentioned. Particular attention should be paid to foundation ventilation. If the concrete frame is located at a height of 30-40 cm from the ground, then it is not necessary to make ventilation holes in it. The air will circulate thanks to the vents in the intake, which is a structure that forms the base of the building. If the grillage is installed near the ground or on its surface, the above-mentioned holes should be provided in advance. This is done at the stage of formwork installation. Cut pieces of plastic sewer pipes are installed in the places provided for by the project. Thus, when pouring the solution, through holes appear in the grillage. The total cross-sectional area of ​​such vents should be about 0.25% of the base area.

Even with the availability of such a wide variety of technologies and materials that make it possible to equip pile foundation grillages, wood has still not lost its popularity. This is due to ease of processing, low price and relatively low weight. Also, the advantages of wood include the ability to independently install the strapping without involving additional forces.

Tying screw piles with timber is done using softwood lumber, for example, spruce, pine or larch.

Installation of timber is carried out on the heads. The presence of a waterproofing “misfire” between wood and metal is a prerequisite. To do this, a waterproofing material, for example, roofing felt, is placed on the heads.

Before installing the wooden frame, it is necessary to treat the wooden elements with an antiseptic composition. In this case, preference should be given to a composition that has a maximum service life, since the foundation has been in use for several decades. You can continue working only after the protective antiseptic has been completely absorbed and the timber has completely dried.

It is best to use timber that has undergone an atmospheric drying procedure to a “carpenter’s” moisture content, which is equal to 12% . Such timber is less prone to deformation during operation.

In any case, changes in the size of lumber are allowed. In this regard, regardless of the connection method and type of material, you should not immediately mark and cut it. Experienced craftsmen advise first placing the material on the heads and marking and sawing in this position. The ends of the beams formed after cutting must also be treated with an antiseptic before installation.

Most often, timber measuring 200x150 mm is used for grillage. If you plan to build a large house with two floors on the foundation, then it is better to choose a beam measuring 200x200 mm.

A beam with a cross-section of 200x150 mm is mounted on heads with a side of 150 mm. Thus, the height of the strapping beam will be 200 mm.

The process of tying a pile foundation with timber

Let's assume that, according to the project, the house being built will have a large area, and the pile supports are 70-75 cm above ground level.

Therefore, after screwing in the piles, a lower frame will be required. For this, profile pipes will be used. To fix the lower trim, a welding method is used.

The heads have a square shape due to its convenience for installing “packages” of boards or timber. The top plate, which serves as the “sole” of this element, has dimensions of 250x250 mm or 200x200 mm.

You need to drill several holes (3-4) on the “sole”. They are needed for fastening the frame beams and the head. A plumbing screw with a length of 120 mm and a diameter of 10 mm is usually used as a fixing element.

Next stage– laying waterproofing roll material on the heads. For this, roofing felt or one of the modern materials based on bitumen can be used.

The cut pieces of waterproofing should be slightly larger in size than the head area by approximately 20 mm in each direction.

The presence of waterproofing linings helps protect the wood from moisture penetration. The main problem is that the thermal conductivity and heat capacity of metal and wood differ greatly in their values. In the event of a strong temperature difference, condensation accumulates on the metal surface. This is why the site becomes wet. And everyone knows that wood must be dry throughout its entire service life. The waterproofing layer is designed to separate these materials and prevent condensed moisture from penetrating into the wood, thereby preventing its biological decomposition and premature “aging,” which has a positive effect on the durability of the entire foundation.

With a head size of 200x200 mm, a square-shaped fragment of waterproofing should have a size of 220x220 mm.

To prevent the waterproofing from moving from the head to the site, bitumen mastic is first applied.

So, the place for tying is ready. It's time to start installing the timber.

• As previously mentioned, proper installation involves spreading the timber around the perimeter of the structure. After this, it is necessary to check the perpendicularity of the beams. This is done by measuring the diagonal of rectangular sections of the foundation. If they match, then everything is done correctly.
• The installation process must begin with the fastening points of the timber at the intersection of the beams.
• The connection of the timber is carried out “in half a tree”. This method is the simplest and far from the most perfect. Experienced craftsmen resort to more reliable connecting nodes, one of which is “in the paw”.
• The ends of the timber after cutting should be smooth and neat. Otherwise, when joining them, it will not be possible to achieve a tight fit.
• It is recommended to additionally lubricate the joints with wood glue.
• Self-tapping screws with a hexagonal head, which are used to secure the timber to the heads, are screwed in from below.
• To make it easier to screw screws into wood, you must first mark the holes. This is done by creating a hole of a smaller diameter. This must be done after the timber has been laid on the heads. A socket wrench is used to tighten the screws.
• The insertion of the timber located inside the perimeter of the foundation is carried out “half a tree”. Cuts are made at the joints and excess wood is removed. Then you need to remove part of the edge of the beam, which is supposed to be cut into the main frame. The fragment to be removed is 150 mm long and half the thickness of the beam.

a) Corner connection; b) inner join

• The embedded part of the beam should fit tightly in the groove. In this case, the jumper becomes flush with the surface of the main external trim.
• For additional fastening of the connecting nodes, steel staples 25 cm long, made of rod with a diameter of 8 mm, are used.
• These fasteners are considered optional. In some cases, the length of the plumbing screws may not be enough to ensure reliable fixation of thick beams to each other.
• The bracket is driven into the beam at the beam connection points from above. The legs of the brackets are driven into intact parts of the beam, and not those that were weakened due to the selection of half-wood grooves.
• Sometimes driving the bracket to the required depth (flush with the surface of the beam) can be extremely difficult due to its large thickness. In this regard, this operation is carried out according to the following algorithm:
• Lay the bracket to the place of its installation and mark it.
• Make a cut along the marked line. Cut width – 78 mm, depth – 10 mm.
• In the places where the legs are driven in, drill holes with a diameter of 56 mm. This will prevent cracks from forming.
• Treat drilled holes and cuts with an antiseptic compound.
• Place the staples in the places intended for them and drive them flush with the surface of the beam.
• In connections at the crossroads of two beams, the joining is performed “half-tree”. Self-tapping screws are screwed from below, and staples are driven in from above, forming a square.
• In places where staples are driven in, the surface of the beam must remain flat. Otherwise, protruding parts of the brackets can significantly complicate the process of building walls.
• After completing the fastening of the beams to the heads, it is necessary to check the resulting structure for horizontalness.
• To do this you will need a construction or water level. The building level is used when the sides of the foundation are not too long.
• The installation of timber may have a difference in the line from one corner of the building to another within 5 mm. The linear parameters of the structure and its horizontality must correspond to the data presented in the design documentation.
• If there are errors, they will need to be taken into account in further calculations carried out for the construction of walls.

Conclusion

Thanks to the technical characteristics of some materials, it is possible to install the strapping yourself without involving a team of professionals or using complex equipment. But when constructing a massive structure and the owner of the site lacks experience, it is still recommended to seek help to specialists. When arranging the foundation, mistakes should not be made. This is not the kind of job to learn construction from.