Do-it-yourself layout of the foundation of the extension from gas blocks. Work with fittings. Pouring the foundation for the extension

Some features
Extension base: tape with rigid connection
The foundation for a bath or garage
Foundation type "chairs"

It so happens that the owners who have their own wooden house are no longer satisfied with the size of the occupied area. The reasons why a finished wooden house does not meet the requirements in terms of usable space are different - a banal lack of finance in the main construction, an increase in the family, etc.

Ideally, if an additional room is planned at the stage of the main construction. Then it will be possible to immediately determine where the foundation will be for an extension to the house, make it and leave it until better times. If this did not work out at the construction stage, then the preliminary construction of an extension to wooden house must be coordinated with all land services and the general plan of the building.

Some features

So, if all the paper questions are in order, you should tackle the foundation itself. Craftsmen do not recommend deviating from the basic construction of the foundation, that is, if the type of foundation near the house is the same, then it is impossible to build using a different technology. This is due to the quality of the soil on the site and its ability to sink.

The foundation for an extension to a wooden house can be different in technology - tape, columnar, slab, pile.

The systems also differ in their features, if a garage or a bathhouse acts as an extension. However, there can be only two connections with the main house - a rigid and an expansion joint.

What are the differences between the two compounds?

A rigid connection is possible only with a large thickness of the main foundation of the house.

Or when the slabs protrude from the common base of the house at least 40 cm. good conditions for soil - no heaving or slight shrinkage - it is used. After all construction works a single facing of the foundation gives an overall picture of a wooden house.

What is an expansion joint? This is the most cost effective connection to the base. It is good in that, in the event of shrinkage of the extension, it does not deform the foundation related to the main wooden house. Even a simple tow can act as a waterproofing, depending on the purpose of the extension.

Back to the table of contents

Extension base: tape with rigid connection

If the main house has already shrunk, the ground ditch is dug to a depth of 2 m. It is worth knowing that the foundation of the annex in any case should be higher than the main one - subsidence of the soil is inevitable - and below freezing of the soil.

To build a foundation above ground level, formwork is used - flat boards protruding from the trench by 20 cm.

Then a sand cushion is made in the ditches around the perimeter. To make it more reliable, the sand is watered several times for better compaction. To strengthen the structure, welded pieces of reinforcement are used, also laid along the entire perimeter. To avoid corrosion, the reinforcement is placed on the bars until the pillow is completely dry.

Further, in the base of the common foundation, holes are drilled for reinforcement. This method is called anchor. The reinforcement should be ¾ of the thickness of the main tape and protrude from it by 50 cm. You need to take 5-6 pieces of reinforcement. for a meter length.

After the reinforcement is driven in, its ends are welded together, in transverse pieces. After that, the ditch is poured with concrete mortar. For greater strength, they are butted, that is, they use construction waste when pouring to increase stability. In the heat, the concrete should be poured several times with water. This is done to prevent cracking.

The foundation slab is suitable for subsiding soils. Expensive due to the large amount of concrete and reinforcing elements.

Reinforcement is exposed from the common protrusions of the base of the house, so that later it can be welded with the reinforcement of the annex slab. The reinforcement of the general base should not be exposed less than 30 cm. The construction of the foundation is carried out in the same way as the foundation of the house.

Column foundation with expansion joint. Suitable for frame buildings timber, log.

Aligns land plot for construction. Individual pillars are made of concrete using reinforcement. Also, from each pillar, anchors should protrude to tie the first crown. The pillars are deepened along the perimeter of the ditch by at least 2 m.After the final hardening of the concrete, waterproofing is performed using roofing material or other cloth.

Pile-screw foundation. The installation principle differs little from the columnar one. The piles are screwed along the perimeter of the ditch. Concrete pouring is performed on request.

If not, the plus will be that when dismantled, they are easily transferred to another place. To fasten the first crown, heads are used, they are welded onto piles.

The construction of an extension to an already finished dwelling is the same responsible and complex process as the construction of a separate house. The only positive difference is the lower costs for Construction Materials... An additional building can move relative to the main house and vice versa, so the most important part of the structure is the foundation for the extension. If you want to do the work yourself, then you should consult with a specialist who will select designs and tell you what materials are suitable for your site. In order to understand what the master is talking about, we recommend that you study this material, which tells about the types of foundation for an extension, the process of pouring and the features of this difficult procedure.

The photo shows a finished base, as well as a partially laid floor. A columnar foundation was chosen here.

You may find yourself in two situations, which will determine the amount of time spent on work and financial costs:

You erected a house with your own hands, and also participated or independently engaged in the design. You know what type of soil you have on your site and the parameters of the foundations of the house.
The dwelling was bought, and it was built several years ago. In this case, you do not know the properties of the soil, characteristics and design features.

Base scheme for the extension. The number "1" is old foundation, under the number "2" - a new base, under "3" - jumpers, and under the number "4" - air vents.

The foundation for the extension is selected according to the same criteria as the foundation for the house itself. Usually the best solution is the type of foundation that was taken for the dwelling. It can be a strip, pile or columnar base. It goes without saying that monolithic foundation used for an extension is extremely rare.

The main point is the way of attaching the attachment foundation to the main one or the absence of this action. For an extension, two types of construction are used:

Rigid connection. By the name you can understand that the foundations are interconnected. Experienced builders recommend choosing this type with a strip base, when the basement of the building enters, along with the foundation, into monolithic structure... Also, a rigid connection is used on slightly heaving soils and in the case when the shrinkage of the future structure is known even during design.
Separate base for the extension. It is worth choosing this type if the weight of the main house greatly exceeds the weight of the extension. It is important here to separate the bases - for this, it is necessary to lay out a heat-insulating layer between them, and then provide reliable waterproofing. It can be a layer of foam, roofing felt or simple foam.

Rigid connection - construction process

Rigid connection diagram. Under the number "1" are the fastening brackets, under "2" - the house, under "3" - the extension.

The base joining process is as follows:

The first step is to determine the size of the foundation of a private house.
A hole is dug close to this base, then a sand cushion is placed in it. The depth of the pit for the extension should not be deeper than the base of the dwelling.
Drilling is performed in the main foundation. As a result, holes should appear along the thickness of the reinforcement rods, their depth is 0.5 meters for the corners and ¾ of the width of the foundation in other places.
When the drilling is complete, you can drive in the reinforcement, the size of which should be calculated in advance. The protruding rods are the frame. So that the structure does not move in the future, it is necessary to weld washers to the ends of the reinforcement.
Next, the standard operations are carried out: pouring and laying the formwork.

Building a separate base

This is a suitable option for lightweight construction. For example, you can take a veranda or a large closed gazebo. The foundation for an extension to a house of this type is carried out according to the standard scheme: a hole is dug, a small layer of sand pillow is placed there, then the filling stage begins.

How, you can find out after studying the instructions. It is worth saying that it is up to professionals to determine what type of base is suitable for your site. Sometimes the peculiarities of the soil do not allow making a separate foundation, despite the light weight of the structure. To be sure that you are doing everything right, take a consultation. You can do the work yourself.

We carry out the markup

Filling, formwork installation - all this is physical labor. It takes a lot of time, but it is easier to make it than the theory - the markup. You will need stakes and twine.

Advice! The best solution would be a shallow tape-type base. This is especially true for novice builders, because the strip foundation is easier to disassemble into equal rectangles.

The stakes are driven into the ground along the perimeter, the string helps to get a perfectly even rectangle - for this it needs to be laid diagonally. Armed with a level, you can find out if the sides are even at the future foundation. This also applies to the inner sides around the perimeter.

Foundation pouring process

Extensions rarely have large dimensions, so work can be done without renting special equipment. You can make a small pit with your own hands. In the example, we will analyze a standard strip foundation, because it is he who is most often chosen for an extension. After completing the digging of the hole, it is necessary to perform primary insulation: for this purpose, coarse gravel and sand are used. Such a pillow must be carefully tamped. Before going under the extension, it is necessary to supply all the necessary communications.

The photo shows a dug moat for an extension. As you can see, a rigid connection has been selected here.

You can correctly fill by following these instructions:

Components are placed in a container for a concrete mixer or mixing on their own. It is recommended to choose the proportions indicated by the manufacturer. The sequence is as follows: first comes water with gravel, then sand is poured, the last ingredient is cement.
It is recommended to erect the formwork even when the moat is 80-90% full and the base is level with the ground. It is worth starting to get the formwork only after drying.
When the foundation for the extension gains strength, it will need to be covered with waterproofing material. Done, it remains to build the building itself.

How to make a foundation for an extension to a house updated: October 1, 2017 by the author: zoomfund

Read on

Quite often, suburban real estate owners think about increasing the living space. Buying a house and building anew in another place does not always have the strength, desire and financial ability. The way out is to increase the area of the existing house. But, as with any construction, the most important step will be to make a high-quality foundation for an extension with your own hands.

Experts recommend building a foundation for an extension of the same structure as for the main structure. This is due to the fact that foundations of different types will interact with the soil in different ways, which means that their shrinkage will differ. Therefore, it is not worth saving and making the same foundations for reliability.

Today there are three main ways to connect foundations:

creation of a monolithic foundation connected by thick metal reinforcement;

construction of two independent foundations with an expansion joint between them;

pile-screw foundation.

In what situations will one of these methods be optimal? Before pouring the foundation for an extension, you should take into account its severity and the characteristics of the soil. A solid foundation is suitable for a house that has stood for several years, and, thanks to the uniform soil, practically did not shrink. Otherwise, it is rational to make a separate foundation and connect it to the house using an expansion joint. But regardless of the chosen method, the foundation for the extension should be deepened to the same depth as the foundation of the house or a little higher, taking into account future shrinkage.

Before starting work, you need to know exactly all the dimensions of the existing foundation. For the columnar, the depth and dimensions of the pillars, for the tape, the width and level of deepening. To do this, a hole is dug near the wall of the house and the structure of the base is measured.

Finding out the depth is not difficult, and the width can be measured using a metal rod with a hook at the end. It is bent at an angle of 90 ° and, holding the bent part horizontally, is threaded under the foundation. Then the rod is turned until the hook rests against back side... Having made a mark on the bar, they take it out and find out the width of the foundation.

How to make a foundation for an extension to a house with rigid reinforcement

As already mentioned, this method is rational for an established house, the shrinkage of which is over. In addition, it is only suitable for non-porous soils.

Device technology:

the size and depth of the old foundation is determined;
a trench is dug, the depth of which should not exceed the depth of the laid foundation;

then holes are drilled in the old foundation, the diameter of which will be slightly larger than the diameter of the reinforcement;
the depth of this hole is calculated using the following formula: reinforcement diameter multiplied by 35;
if the width of the foundation is not enough for such a hole, then the reinforcement is simply clogged. For this, a longitudinal slot is made at its end and a wedging insert is inserted. This method of fastening the reinforcement is very reliable;

calculation of the required number of reinforcement rods. On average, for a closed loop of a new foundation, 20 rods are required per 1 m2 of foundation. They are cut using a grinder or an emery machine. For an open circuit, the number of reinforcement is calculated individually and depends on the width of the future base;
rods are hammered into the drilled holes, but before that small washers are welded to their ends;
after which the formwork is made, all the reinforcement is laid into it and poured with concrete.

Everything, it remains only to wait for the complete hardening of the solution and you can start construction work.

In what cases is rigid docking used?:

in the event that the extension will have a common roof with the house;
when the foundation of the house is tape;
with a shallow strip foundation, when the basement forms a monolithic system with it;
if the building stands on a columnar foundation, then the fastening is carried out on a plinth, which means that it must have the required width and height;

Separate foundation for an extension to the house

This is an easier and more popular way to build a foundation for an extension to a house. It is a separate base, which is located in the immediate vicinity of the main structure, and an expansion joint is installed between them. The function of this layer is to protect the structure from deformation and cracks during shrinkage. For the manufacture of the seam, a heat-insulating moisture-resistant material, roofing felt or ordinary tow is used.

When calculating such a foundation, it is also necessary to take into account the characteristics of the soil and the final weight of the extension. Taking into account the future shrinkage, initially the foundation is laid slightly higher than the finished one.

Key points to consider:

the gap between the old and the new foundation should be 5 cm. For this, before starting concreting the foundation for the extension, boards covered with waterproofing are applied to the already finished base. In the future, they will perform the function of an expansion joint;
for a small one-story extension, a 2 cm expansion joint is sufficient;
the seam itself can also be filled thermal insulation material(best of all with polystyrene or polystyrene foam) and closed with a weather-resistant sealant. Outside, it is masked by a decorative overlay;

How to make a columnar foundation for an extension

If the extension is made of lightweight materials (OSB or wood), then it is optimal to make an inexpensive columnar foundation. With its size of 7x3 m, it is enough to install 6 support pillars.

Stages of work:

wells are drilled to a depth below the freezing level;
a sand cushion is poured onto the bottom and fiberglass reinforcement is installed (it does not need to be treated with waterproofing compounds, and is not inferior in strength to metal);
formwork of the required size is installed on the overhead part;

the whole structure is poured with concrete.

If it is necessary to increase the height of the pillars, red brick masonry is made.

Foundation on screw piles

This is the simplest and cheapest option for creating a foundation for lightweight extensions. Their only drawback is their susceptibility to corrosion, but this can be avoided by high-quality anti-corrosion treatment.

It is distinguished by a high speed of installation, and after the completion of the work, it is permissible to immediately proceed to further construction. In addition, for a small object, the piles are screwed in on their own, which further reduces the cost of work.

If the extension is made to create a separate zone, and not to expand the room, then the foundation must be made separately and have an expansion joint;
it is recommended to fill the strip foundation in the fall, and start construction in the spring;
for a small extension, a pile-screw or shallow strip foundation is suitable. All other types are irrational due to the high cost relative to the entire building.

Summing up, we can say with confidence that making the foundation for an extension with their own hands is within the power of the majority. The main thing is to choose one way or another correctly. So, for a small and light veranda, a columnar or pile-

If you own a suburban real estate, then for sure at least once thought about how to increase the living space. There is not always the financial ability and strength to acquire new house or rebuild it, the solution may be to increase the area of an existing building. In any such construction, the most important stage is the creation of a high-quality base for the extension.

Design features

If you are thinking about the question of how to make a foundation for an extension to a house, then you should listen to the opinion of experts who advise to form the foundation of the same structure as the foundation of the main building. This is due to the fact that different foundations can interact with the soil in their own way, which can cause different shrinkage. Therefore, do not economize and build reliable identical foundations. Before adding to the house, you must choose one of the three existing ways of connecting the bases. The first provides for the formation of which will be connected by thick metal reinforcement. The second method involves the construction of independent foundations, between which will be located. The third technology is a pile-screw foundation. Before pouring the base, it is necessary to take into account what the severity of the extension will be and what characteristics the soil has.

A solid foundation is excellent for a building that has been in use for several years and has not shrunk due to the uniform soil. Otherwise, it is recommended to make a separate foundation by connecting it to the main one using an expansion joint. Regardless of which method of creating the foundation was chosen, it should be buried just as much as the base of the main house was buried. Sometimes the foundation is placed slightly higher, taking into account the shrinkage.

Foundation on rigid reinforcement

If you are faced with the task of how to make a foundation for an extension to a house, then you can create a foundation on rigid reinforcement that is suitable for an established house. The shrinkage of the latter at the start of construction work must be completed. This design is not suitable for heaving soils.

Methods of work

Initially, it is necessary to measure the depth and dimensions of the old base, only after that you can start preparing the trench. Its depth should not be greater than the depth of the foundation. In the old base, holes are made with a diameter slightly larger than the diameter of the reinforcement. The depth of the holes should be determined by the following formula: for this, the diameter of the reinforcement should be multiplied by 35. If the width of the base is not enough for the hole, then the reinforcement must be hammered, for this a longitudinal cut is made at the end, and then the wedging inserts are installed. This technique of fixing the reinforcement is quite reliable.

Working with fittings

If you are thinking about how to make a foundation for an extension to a brick house, then the above method is perfect. To do this, calculate the number of rods. For a closed loop of a new structure, about 20 elements are most often required for each square meter of the foundation. The components are cut with an angle grinder or using an emery machine. If we are talking about an open circuit, then the number of reinforcing rods can be determined individually, depending on the width of the future foundation. The rods should be installed in the drilled holes, but before that, washers are welded to their ends.

Quite often, home craftsmen are interested in how to make the foundation for an extension to a house. Increasing the room will allow this to be done. Speaking of the above, it should be noted that further actions provide for the creation of formwork, into which the reinforcement is laid. The resulting space is poured with concrete. Then the solution is left until it hardens completely, after which the master can begin construction work.

Cases of using rigid foundation joints

Rigid docking is used when the extension is combined with a common roof with the main building, as well as if there is strip foundation... This method of connecting the bases is also used when the building is installed on a columnar foundation, and the fastening is carried out on a plinth. This indicates that the given element must have the required height and width. Hard docking of the two structural elements can be used with tape type, when it is included in one monolithic type system.

Formation of a separate foundation

Before making the foundation for it is necessary to take into account that the most popular and in a simple way is the construction of a separate foundation. In this case, the foundation will be located quite close to the main building, and an expansion joint should be installed between the structures. The function of the layer is to protect the structure from deformation and cracking during shrinkage. To form a seam, it is necessary to use a moisture-resistant heat-insulating material, tow or roofing material. Considering that the structure will still shrink, the foundation should be laid higher than the finished one.

Work technology

If you are thinking about how to make the foundation for an extension to the house, it is recommended to consider the photo in advance. They will allow you to understand which technology is the best to carry out the work. The gap between the new and the old base when forming a separate foundation should be 5 centimeters. Before the start of concreting, boards covered with a layer of waterproofing are applied to the finished base. In the future, these elements will play the role of an expansion joint. In the presence of a small extension on one floor, a seam with a thickness of 2 centimeters will suffice. The filling of the resulting space can be carried out with a heat-insulating material, which is quite often penoplex or foam. And you can close the gap with a sealant that is resistant to weathering. Outside, everything can be masked with a decorative overlay.

The foundation for an extension to a house from blocks can be created using this technology, since it is the most acceptable.

Creating a columnar foundation

If the extension is supposed to be formed from light materials like wood, then the best option will become an inexpensive foundation on pillars. If the dimensions are limited to 7x3 meters, then it is enough to prepare 6 support pillars. It will be necessary to drill a well in the soil, going deeper below the level of soil freezing. A sand cushion is laid on the bottom, fiberglass reinforcement is installed, and then the formwork of the required size is placed. The resulting hollow space should be poured with concrete, and if it is necessary to increase the height of the supports, red brick masonry should be made.

Base on piles

When professional builders are thinking about how to make a foundation for an extension to a house, they most often resort to the method of forming a foundation on screw piles. This is due to the fact that this design is the cheapest and easiest for lightweight buildings. One disadvantage is susceptibility to corrosion, but this can be excluded by the method of anti-corrosion treatment. Installation work it will be possible to carry out in the shortest possible time, after the completion of the work it is permissible to proceed with further construction. For a small object, the supports can be screwed in on their own, which will reduce the cost of work.

Concrete preparation

Before making the foundation for an extension to the house with your own hands, you should ask how the concrete is correctly mixed. The success of further work will depend on its quality. The darker the color of the cement, the more reliable and stronger the mixture will be. If you have not yet encountered the mixing process, then you must remember the correct sequence for placing the components in the concrete mixer. Initially, there is water, then crushed stone, sand and cement are laid. Consistency must be observed in order to achieve uniformity in the composition. While all the components are being mixed, the concrete mixer should be turned on, but during the rest of the equipment motor, you can measure the ingredients and bring them up for subsequent mixing.

Conclusion

If you are faced with the question of how to make a foundation for an extension to a house from blocks, then you can use the above recommendations. They require the use of appropriate mechanical equipment for mixing the mortar. This will exclude the formation of a seam between the poured layers.

Everyone who buys a plot plans to expand over time. If you have purchased a plot already with finished house, then when the time comes to expand, you will first of all face the question of building a foundation. If you just bought a plot, without a house, then when the construction of a house begins, building a foundation, it is better to immediately think over the construction of an additional foundation for a future extension. In the future, when additional space is added to the house, it will stand stronger and you will not have to worry.

You need to carefully study the properties of the soil under the main foundation and at the place where you are going to make additional area;
you need to know the depth and width of the base under the main house;
know the exact load exerted by the house on the foundation;
you need to know the type of foundation erected under the main house.

Having learned all these details, we can conclude - what kind of foundation to build for an extension to the house.

There are two types of extension to the house:

with rigid reinforcement - closed loop;
creating an expansion joint - an open contour.

The first option is suitable for a multi-storey building that has been in existence for several years and has hardly shrunk. Also, if in place of the house there is a uniform, not heaving soil. The second option for an extension to the house is suitable for almost all other cases. It must be remembered: a properly erected foundation is half the success of the construction.

Rigid reinforcement for monolithic and tape types of base

This method is definitely suitable for an extension to a house with a monolithic or strip base... The essence of this method is that holes are made in the foundation under the main house for reinforcement, which will be driven into the main foundation. It will also serve as the basis for the foundation for the extension.

Let's take a closer look:

first, we dig a pit for the extension, it should be leveled to the depth of the foundation under the main house;
when we see a strip or monolithic foundation, then we drill holes for reinforcement in it;
to find out the width of the foundation under the main house, you need to take a metal rod with a hook at the end and thread it under the base. Then it is constantly turned and threaded inside, after the hook catches on the edge on the other side, a mark is made on the rod and pulled out. This will be the width of the base under the main house;
reinforcement with a longitudinal cut is driven into the drilled holes, and a wedging insert is inserted into this cut. The holes should be half a meter deep, and the diameter of the reinforcement is 14 mm;
these protruding pieces of reinforcement will serve as the basis for a new foundation for an extension to the house.

Expansion joint for tape and monolithic base types

It must be remembered that it is correct to make the foundation for the extension the same as for the main house. Those. tape - tape, monolithic - monolithic. If, however, make a foundation of a different type, then it can shrink and then there will be problems with joining. It is better not to save money and do everything right.

Let's take a closer look:

first, a trench is dug, the same depth as under the main house;
leveled with a pillow of soil and rubble;
formwork is under construction. You need to mark everything up correctly;
reinforcement is laid out and you need to fill everything in stages with concrete, constantly piercing with a shovel or vibrator (so that there is no air in the solution);
when, after a week everything is dry, you can make the basement of the extension;
the distance between the two foundations should be at least 5 cm if the house is 2-3 storey. If the house is one-story and not oversized, then the distance between the two bases is correct to leave 2 cm;
this gap between the two bases is covered with thermal insulation or waterproofing (polystyrene, roofing material - they will do). The creation of this layer (seam) is necessary so that over time, when the extension shrinks, the walls and the house as a whole do not suffer.

If the extension is needed not for the room, then it can be made of light material, and the foundation for it can be made of columnar or pile. You can make such a foundation with your own hands. You can also build this kind of foundation to a wooden house. A wooden house is lighter than a brick or concrete one and is cheaper and less laborious to build.

Foundation on screw piles

Screw piles are pipes with helical blades. They are screwed into the ground and fixed with concrete mortar. The screw-in depth should be below the freezing of the soil. If you screw the piles with your own hands, then you need to use a special device in the form of a lever. First, the places where the piles will be inserted are outlined on the territory. Then indentations are made. After installing the piles, the remaining space between the ground and the pile is poured with concrete. And the top of the pile is also cut and filled with concrete.

Piles are a very resistant material, they can withstand heavy loads and last a century.

The only negative is that they corrode. But if it is well processed, covered with a special agent, then this is not scary for him either. Since wood is a relatively light material, such a base is suitable for a wooden house.

Columnar base

Of course, if you purchased a house, and it has a monolithic foundation or strip, then it is better to make the same foundation. However, if the extension will not carry any load-bearing or important function (it will not be intended for living, for example, a barn), then a columnar base can be chosen for such an extension. It is the least time consuming and least costly. Today, asbestos pipes are often used for the construction of a columnar base. They are stuffed inside with concrete mortar for stronger stability. It is quite easy and simple to build from these pipes.

first level the terrain for construction. Then they outline the places - where the pipes will be inserted. Dig grooves for them. The depth should not be lower than the depth, the main foundation of the house. When erecting a columnar foundation, you need to know exactly the depth and dimensions of the foundation pillars under the main house if there is the same foundation;
a cushion of gravel and crushed stone is placed in these recesses, everything is tamped well;
then they put pipes and fill them inside with rubble and broken bricks, pour concrete mortar;
the space left between the pipe and the ground is covered with crushed stone at the bottom, and filled with concrete mortar - for greater stability.

In case a decision is made to install a columnar foundation of a different type:

digging depressions below the freezing of the soil or on a par with the foundation under the main house;
a pillow in the form of gravel and crushed stone is placed in these recesses, tamped;
then the formwork is built. Reinforcement bars are placed inside and everything is poured with concrete;
in a week, when the concrete is dry, you can build on the extension;
if such a foundation is being built for an extension, for example, to a wooden house, then you can install 3 pillars on each side.

Usually, when you need to add additional space to wooden frame at home, they use just such types of grounds, since this is a more profitable, but at the same time, high-quality method of construction.

Before making a base for an extension to any house (frame, brick, concrete, wooden), you need to remember the basic rules so that the structure will serve for many years:

the base of the extension must be the same as the base under the main house;
the depth, thickness of the foundation of the extension should be the same as that of the foundation under the main house. The foundation of the extension can be laid just above the foundation of the main house. When there is a shrinkage of the foundation under the extension, then the two foundations will rise on the same level.