How to connect two buildings. How to attach a foundation to an existing one
The time spent inside the bustle of the city can not be compared with the rest in a country house. Many people prefer fresh air to urban smog. Therefore, the demand in private homes is maintained at a high level. But what if Vacation home is, but its area is not sufficient.
In this case, you can attach an additional room. At the beginning of such a construction process, it is necessary to connect the foundations. This action is associated with some features, which will be discussed.
Ways to connect two homogeneous foundations
Foundations are connected by rigid ties or tied to each other.
There are two main ways. One connection method is made using rigid connections, the other without directly binding one foundation to another.
A rigid connection method is called, in which additional reinforcing elements are fixed to the old base, and the frame of the new foundation is connected to them. Thus, two foundations, new and old, form a single whole.
In the second method, the so-called expansion joint is used. This method is used when connecting strip foundations. A tarred board or other material provided for by the project is laid between the old new strip foundations over the entire area of contact. Thus, two foundations are located side by side and are independent of each other, and the expansion joint compensates for the impact of one foundation on the other.
It is important to know that shrinkage of the new structure occurs in the first year. Therefore, the designer must provide for this process. In this matter, a lot depends on the soil and the choice of base, but one way or another, the shrinkage level must be established. This is done so that the foundation, brick walls and roof of the new building cannot sink to an unintended distance and form a crack between the old and new buildings.
Brick foundation and its features
Solid ceramic bricks are drilled for the foundation
Making a brick base is the most durable way to build a foundation for a building. This method is well used in the manufacture of bases for lightweight structures, such as gazebos, verandas, baths, summer kitchens and houses. When building a brick foundation, the use of expensive special equipment is not required. Its manufacture is quite simply carried out by one builder.
When choosing a brick, you should know that only full-bodied ceramic material should be used. silicate brick not suitable for foundation, its performance when used in wet ground is not good enough. Hollow ceramic brick does not have the necessary strength. Therefore, the choice must be made in favor of a full-bodied ceramic product.
Before laying bricks, the base for the foundation is prepared. The soil is compacted, a sand and gravel base is made or concrete preparation is poured with a height of 100 mm. Then the brick foundation walls are laid. It can be done in several ways, depending on the chosen thickness of the base. A reinforcing mesh is laid between the rows of bricks to increase strength.
After the construction of the foundation walls, they are waterproofed from the outside. The foundation is backfilled. It is better to use fine-grained sands to quickly remove moisture that will collect near the foundation. If significant loads are provided, then for their uniform distribution it is necessary to make a reinforced concrete armored belt on top brickwork.
A feature of this foundation is that it is quite simple to repair it. To do this, it is necessary to replace the cracked brick with a new one. You can also do it by connecting two bases. Alternately dismantling the old masonry at the docking points and shifting it again, they connect it with the new one.
It must be understood that the foundations are calculated for a certain weight of the building and they cannot be loaded just like that. For such actions, a procedure for examining the current state of the structure is carried out. Therefore, it is better when the foundations are independent.
Features of connecting foundations
In order to understand how to connect the foundation, you need to know the parameters of the existing foundation. First of all, you need to find out the type of existing foundation: strip or columnar. Next, the overall dimensions are measured. It is advisable to attach a foundation similar in type and dimensions to the existing one. For more information about the types of foundation, see this video:
This understanding is necessary in order to tie next to the existing foundation similar in parameters, since the same foundations will behave identically in the same soil.
Particular care must be taken to build in the spring. During this period, the soil is unstable due to the increased moisture content, which means that as it dries, the earth may shrink further. How to connect the foundations, see this video:
Sometimes it is advisable to postpone the construction of walls for one season, if possible. Or arrange a foundation in the fall before frosts, and build in the summer. The main thing is not to load the foundation with brick walls, reinforced concrete floors and roofs in unstable ground.
It is important to monitor not only the condition of the soil, but also the total weight of the future structure. It is necessary to calculate the weight of bricks, wood, metal, concrete and other materials used to build walls, ceilings and roofs of an existing building. Since the first foundation was calculated for this weight, the load on a nearby foundation under construction should be comparable.
Types of extensions
The level of the terrace must match the level of the floor
Each building has its own purpose, the method of constructing the base and the structure as a whole will largely depend on it. The main options are:
Depending on the extension, it can be determined whether the buildings will have to be tied in a rigid way or an expansion joint should be installed. It is quite possible that you don’t have to tie anything at all, since the foundation is not required or it will be columnar and shallow.
If a decision is made to expand country house, then it is worth performing the extension process as efficiently as possible so that it is one with the house.
After increasing the space, you can not only relax with your family, but also invite guests to enjoy together fresh air away from the bustle of the city.
The foundation for the extension must be securely docked with the existing foundation of the house. There are only two main options - either to connect the old and new foundation for the extension rigidly, using steel reinforcement as connections, or to use a simpler and less expensive connection of the foundation for the extension and the main foundation - by arranging an expansion joint between them.
A hard way to dock the foundation for an extension
The first rigid docking method gives a foundation that will work as a whole, and therefore it is possible to use it only in cases where the existing foundation has passed the settlement stage, and the new foundation will not cause additional settlements greater than the allowable value. The second condition - a rigid docking of the old and new foundations will be reliable only in cases where the soil at the base of the house is not heaving.
The technology of the device of the rigid connection of the foundation for the extension
Before designing a new foundation, you need to decide on the old one - determine its type, size and depth. If these parameters are not known, they must be determined by careful excavation. The depth of the foundation is determined by pitting.
One of the main conditions is that the depth of the new foundation should be greater than the depth of the existing one. It is clear that different types foundations perceive the movement of soils during heaving in different ways, so the foundation for the extension must be of the same type as the main one, regardless of the material and type of extension structures. The extension, as a rule, is made of materials that are lighter than those that make up the supporting structures of the main building - foam blocks, gas blocks, wood or wood concrete. But regardless of the type of extension material, the new foundation must have a greater depth than the existing one.
Rigid docking of the old and new foundations is done with steel reinforcement anchors. The existing foundation is drilled, the diameter of the holes should be slightly larger than the diameter of the docking reinforcing anchors. The depth of the joint must be at least 35 diameters of the reinforcement entering the body of the old foundation, plus double the length of the rod to enter the new foundation, this length is considered working. If the width of the existing foundation is not enough to comply with this rule for the working length of the joint, then the joint rods are installed in the body of the old foundation like anchors with wedging inserts, which ensures reliable fastening of the reinforcement inside the concrete.
The number of reinforcing anchors must be at least five per ¼ m2 of the vertical area of the junction of the old and new foundations. reinforcing bars are cut to the specified size and installed in the drilled holes. Washers are welded at the ends of the rods. When concreting a new foundation, all additional reinforcement must be located in the body of the new foundation, in compliance with the protective layer.
Connection of the foundation for an extension with the main expansion joint
This method is much easier and less expensive. The new foundation is arranged next to the existing one, but does not fit into it and works independently, as a separate element. The attached foundation is usually less powerful than the existing one, but nevertheless requires calculation. The technological gap between the foundations is arranged by laying boards wrapped in hydro insulating material- roofing material or polyethylene with a thickness of at least 250 microns. The minimum clearance is 50 mm.
In cases where the base soils are prone to severe heaving, the floor level of the extension is performed below the floor level of the main building, based on the amount of heaving. When the height of the extension is up to the second floor, the minimum distance between the main wall and the extension must be at least 20 mm. The resulting seam is filled with insulating material, most often mineral wool or polystyrene foam. The second option is somewhat worse for fire safety reasons, if the materials of the main building and extension are wood.
The outer sections of the junction of the main building and the extension are filled with mounting foam and a layer of weather-resistant elastic sealant, and then covered with a decorative overlay, fixing it to only one wall, most often to the main one. Thus, both the extension and its foundation do not depend on the main building and its movement as a result of the action of frost heaving forces, and do not affect it.
Types of foundations for an extension
For the installation of an extension foundation, rigidly fixed to the main one, there is no choice, both foundations must be of the same type.
The second way to build a foundation for an extension is simpler, and does not limit the choice of the type of foundation, the main criterion is the manufacturability of the device, safety for the existing foundation and, of course, economy. Most often, bases such as tape, columnar and their combinations are used, as well as screw piles. The latter option is somewhat more technologically complicated, but does not require earthworks and the ongoing work does not have a dynamic impact on the existing foundation.
Prior to the start of work on the foundation for the extension, preparatory measures are necessary - planning and marking the contours of the planned foundation. The marking of the inner and outer perimeters of a rectangular new foundation is done using the diagonal method, using a rope and pegs. A more complex configuration of the new foundation requires a division into sectors, while marking is performed by separate rectangles, calculating them independently of each other. After the markup is completed, earthworks begin.
The main issue, as well as the complexity of the device of an additional extension, is the choice of design for the extension and its correct pairing with the existing one. From a financial point of view, the installation of rigidly joined foundations is much more expensive than the installation of a separate adjacent foundation with an expansion joint. The older the main building, the greater the complexity and responsibility of both choosing the type of foundation and carrying out the work. And if the second type of docking is quite possible for independent work, then the installation of a rigid joint with the old foundation requires consultation with specialists and accurate knowledge of the ability of the foundation soils to heave and move.
The need to connect the old and new foundation arises during the construction of extensions or other structures in order to increase the size of the useful area of the building.
In the immediate vicinity of the operated building, a concrete slab, tape is poured or supports (pillars, screw piles) are installed.
Some of these types of foundations need to be "linked" to the foundation of the building. This task can be accomplished in several ways.
Before you begin work to increase the area of \u200b\u200byour home with the help of extensions, you need to obtain the appropriate permits. All distances from nearby buildings and neighboring areas must be taken into account and maintained.
The extension can be erected as an independent building or integrated into an existing one. It is important to consider that the building already in operation must be older than 1 year. During this period of time, it will give the necessary shrinkage and will not carry along a new foundation built nearby.
The old and newly erected base must be the same in type. If a residential building is installed on a strip foundation, the extension must be done on the same one. This will significantly reduce the risks of deformation of the combined, docked base.
Tools and materials for work
For the construction of the foundation, it will be necessary to perform a significant amount of earthwork, as well as reinforcement and concreting.
You will need tools:
- Shovels bayonet and shovel;
- Stretcher or garden wheelbarrow for moving soil;
- Hook for knitting wire;
- Roulette, marker, pegs, rope for marking the site;
- Bubble or water level, but the best choice there will be a level.
From the materials you will need:
- Reinforcement bars with a cross section of 8-10 mm;
- knitting wire;
- Cement brand not lower than M400;
- Sand and crushed stone of the middle fraction for the preparation and formation of a shock-absorbing "cushion";
- Metal studs (you can use reinforcement with a cross section of 12 mm or more) to tie the new foundation to the old one.
Connection steps
To properly combine the two foundations, you need to think through all the nuances of each stage of work in advance. It is necessary to choose the method of "ligation" of the bases. Several options are possible.
Method number 1: "tape-tape". Used to build a foundation similar in width and depth. It is carried out in several stages.
Marking the site for the construction of an extension.
They dig a ditch around the perimeter of such a width that it can fit the formwork for pouring the tape of the required parameters. The bottom and walls of the excavated trench are leveled with shovels.
Sand and gravel dumping is made, consisting of 5-7 cm of compacted sand and 10-15 cm of crushed stone, which is also compacted.
Tamping is done with a vibrating plate and improvised materials. For example, a barrel half-filled with stones, a piece of timber.
Formwork is assembled in a trench from any suitable lumber.
A reinforcing belt is made, consisting of two tiers of mesh with a mesh of 15×15 or 20×20 cm, interconnected by vertical metal rods.
A gap of 1.5-2.5 cm wide is left between the foundations, which is filled with mineral wool. The formwork is limited at the junction of the bases with a wooden or metal shield.
Using a concrete mixer, a cement-sand mortar is prepared in a ratio of 1: 3 (1 part of cement and 3 parts of sand, water and filler in the form of crushed stone or gravel).
Concrete is poured layer by layer into the formwork. Pierce it repeatedly with a bar of reinforcement so that all the air comes out of the solution.
After the concrete has set, the formwork is removed.
The damper seam of the foundations is closed with a rubber band or waterproofed in another way.
This way of tying the bases allows you to be sure that the new will shrink and drag the old with it. After shrinkage strip foundation it is increased in height so that it is in the same plane with the base of the residential building.
Method number 2: "plate-tape". It is carried out similarly to the previous one with the only difference that the damper seam is made longer: over the entire slab.
This docking method is optimal only for stable soils, when there is confidence in the absence of significant subsidence of the extension after its construction.
Hard connection
To rigidly tie two foundations, you will need to connect them using rebars. It will take at least 20 bars per 1 m2.
To install metal rods in the old foundation, they lay reinforcement in them and perform concreting.
From the side of the new foundation, bars are also laid and the joints are poured with concrete.
Construction of a column foundation
The best choice for building an extension would be to install it on poles. The soles of the supports should be located 15-20 cm below the TPG (soil freezing point), which will prevent their displacement during soil movements during periods of freezing and thawing.
If they build, the house with the extension is connected at the level of the lower floors.
Possible difficulties
If there is a high GWL (groundwater level) at the construction site, it is first necessary to make wall or ring drainage.
See the video for more tips:
On moving soils (sand or sandy loam), when building a new foundation, the corners of the old one are strengthened with piles buried in the soil by at least 100 cm.
One of the advantages of private households is the ability, if necessary, to increase the usable area by adding an additional one to the main structure. Thus, residential or utility rooms are obtained, for whom what functionality was not enough. In order for the extension to improve the living conditions of the owners, and not organize problems for them, it must be built according to existing technologies, and not according to the principle "somehow, if only it would be cheaper." Therefore, we will figure out how to properly settle down to the house, based on generally accepted methods and experience of FORUMHOUSE users.
- Foundation for extensions
- Wall materials
- Wall bonding methods
- How to make a roof
- Outbuilding functionality
- Registration of outbuildings
Foundation for extensions
There are two types of foundation for an extension - a rigid hitch and an expansion joint.
rigid hitch
Such a connection is designed for non-rocky soil and is justified when erecting a heavy structure of two or more floors, but only if the main building has already settled and the village. The new foundation must be of the same type as the main one (tape, slab) and match in depth, taking into account possible shrinkage. A bunch of tapes is made by means of reinforcement, for which the foundation of the house is dug out to the full depth, in the working area, too much exposure is fraught with deformation.
Holes for reinforcement are drilled in a checkerboard pattern in the foundation web, on the basis that their length is 35 times the diameter of the rod, and the length of the reinforcement itself is twice as large as the depth of the holes. The reinforcement is driven into the holes, in the future the protruding part will be filled with concrete, a common monolith will be obtained. A bunch of plates is possible with a thickness of more than 40 cm and the presence of a protrusion of the main plate of 30 cm; for coupling, the reinforcement is beaten off and welded with reinforcing cage new plate.
To perform a rigid hitch, it must be borne in mind that the flooded one, connected to the main one, must settle, ideally within a year. If it is not possible to withstand such a period, it is better to use another method.
Expansion joint
The most common type of bond is when a completely independent one is poured near the old foundation. Optimal for heaving soils for lightweight structures, the thickness of the seam is from 2 to 5 cm. In order to aesthetically connect the foundations, and
the seam at the junction remained the same along the entire length; boards pre-wrapped with polyethylene or roofing felt are used. Since the load on the base will be less, the drawdown will also be less, and the seam will allow the extension to play as planned without affecting the integrity of the house.
During the construction process, the joint between the walls is filled with insulation, and the seam itself is subsequently sealed with elastic means or closed with special flashings. One of the users found an interesting solution - stainless steel overlays, between which there is a layer of corrugated rubber.
zhp FORUMHOUSE User
In principle, you can buy such a “closing” for an expansion joint, immediately insulate the distance between the walls normally, close it from the street with a “closing”, and if over time there is shrinkage, compression or stretching, the “closing” compensates for this moment. And in order to return the rubber to its previous shape, it will be possible to unscrew the screws from the left side and drill again, in new places in the bricks.
Since the foundations are not interconnected, any type can be chosen for the extension, based on the characteristics of the soil and the expected load. It can be slab (monolith or UWB), tape (MZF or to the freezing depth) or columnar (pile).
Portal users prefer joining foundations through expansion joints, as the most justified and safe way.
mfcn Member FORUMHOUSE
Whatever good (non-rocky) soil, if it is not a rock, then you should expect shrinkage of the foundation of the extension in relation to the main house. Accordingly, measures must be taken to ensure that these shrinkages are non-destructive to the structure and provide acceptable functional properties of the structure. Hence: annex - in fact new house next to the old or light structure, the walking of which is permissible, and violations of the horizontal floor and jamming of the doors are permissible.
materials
Modern market building materials offers a wide selection for every taste and budget. Extensions made of foam concrete, aerated concrete, cinder block and similar large-format masonry varieties and frame structures. Frames are in the lead due to the speed of construction, relative accessibility and simplicity; in terms of energy efficiency, they are not inferior to stone buildings due to the use of heaters.
However, if possible, it is recommended to choose a material similar to the main one: wooden outbuilding to a wooden house, etc. This is especially true for houses that are not supposed to be sewn up with the same facade as the extension. If you plan to use siding or similar cladding, the choice is not limited.
Wall tie options
An extension to the house can have four walls or three, then the role of the fourth is played by the outer wall of the house. Four walls are relevant in extensions made of masonry materials, a bunch of walls is not required, and compliance with the masonry level gives an even seam. The presence of a layer of insulation between the walls allows the use of thinner blocks for the adjoining wall. At frame construction sliding ligaments are used: two vertical beams are stuffed onto the wall, between which a vertical extension beam is inserted.
Connecting beams in the annex
When the extension is assembled from profiled or glued beams or logs, the walls are connected to the house either with metal brackets or with special galvanized corners with a shelf of 63 mm or more.
The corners are planted on self-tapping screws, leaving a small gap for shrinkage. The seam in both cases is closed with a flashing or platband. Also, the docking of the beams in the extension is carried out by means of a tenon-groove system, the grooves are selected in the load-bearing wall, the tenon is cut on the built-in segments.
Roof device methods
The extension is brought under a common roof, when a rigid connection is made, if an expansion joint is selected, it is easier to cover the building separately, sealing the junction. Depending on the roofing material, the seam is closed with a stainless steel apron, from 30 cm wide, or with a special decorative element.
Rigid connection to the house from a bar.
mfcn
The shrinkage of the extension in relation to the main house imposes certain restrictions on the arrangement of the roof. Therefore, in practice, making an extension with a roof such as continuation of the existing one should be deliberate and reasonable.
Functional
As with the construction of a house, before erecting an extension, it is necessary to determine in advance the functionality, since different purposes require appropriate construction manipulations. If it is supposed to make living rooms, enhanced insulation is necessary. For the boiler room, bathroom or kitchen, communications are immediately laid. It's easier to change your mind and plug a couple of plastic pipes into the wall than to decide that another bathroom is needed and hammer a freshly built one.
Legalization of the extension
Before building a major extension, a permit must be obtained. In the city, this is done by the department of architecture and urban planning, in rural settlements - by the administration. You can build without papers, but then when you try to sell, bequeath or donate a house with an extension, you still have to draw up documents, but it’s more difficult, through the courts. In the event of a confrontation with the neighbors, they can sue the self-builder and insist on the demolition.
For anyone planning an extension, it is useful to study the topic on the forum. The user experience of our portal in the topic is also interesting. The article will help determine the type of foundation for the future design. And our video will teach you how to work with aerated concrete.