Laying a foundation on an area with an uneven surface is associated with certain difficulties. First of all, for the correct calculation and design of the foundation of a house, a geodetic survey of the construction site will be required, which will reveal the degree of slope of the site, and geotechnical surveys, which will determine the composition of the soil being developed. There is no point in saving on such work, although it does lead to considerable additional financial costs.
Construction of foundations on medium slopes
Columnar-type foundation for uneven areas
Here it’s worth thinking about what type of foundation is best to use. For example, for a strip base you will have to use a lot of bedding, and you need to do this first at the lowest point and then evenly level the bottom horizontally. Such construction will be financially expensive, but it can be used in the construction of small buildings.
As an option, you can use a column-and-strip foundation here. It has a number of advantages over conventional tape, namely:
- there is no need to carry out detailed geodetic calculations and select the optimal installation depth of the tape;
- a minimum of sand cushion is used here, and the pillars can even be installed in several tiers;
- You can immediately install a concrete strip on the finished pillars.
It is clear that such a foundation on an average slope costs a little more, but in some cases it justifies itself. The construction of a strip structure has a number of nuances, namely:
- Incorrectly placed and compacted bedding will spread over time, followed by the tape.
- Before creating a sand cushion, you must first equip a foundation pit with smooth walls, and only then lay the cushion.
- There is no need to strictly adhere to the same thickness of the pillow; it can be different, but not less than 30 cm.
After erecting the structure, you need to make vertical soil dumping. For this, non-heaving soil, such as sand, is used. The blind area needs to be made away from the base at a slight angle, but always with a slope towards the larger side.
Foundation formwork: how to install it yourself
Placing formwork under the foundation is a mandatory work required during the construction of buildings. It consists of creating a frame, filled with concrete to create the foundation of the future house. Strict requirements are imposed on formwork: strength, reliability, ease of assembly and disassembly. Its installation should not take much time and effort. And the first thing you need to do is decide on the type of formwork. It can be removable or non-removable. The first type is dismantled after pouring the foundation, the second becomes part of the house.
Building a house on the relief
By terrain we mean the structure of the surface - mountains, lowlands, hills, valleys, ravines, bulges and depressions, plateaus. The relief is determined by the slope - the fall of the surface, which is calculated by the ratio of the difference in height between two points on the ground to the distance between these points projected onto the horizontal (see figure) or the tangent of the angle of inclination of the terrain line to the horizontal plane at a given point. Slope is measured as a percentage. For example, a rise of 15 m per 100 m of horizontal movement corresponds to a slope of 0.15 (15%).
Relief slope diagram
Flat terrain is considered if its slope is no more than 3%, a low slope is from 3 to 8%, an average slope is up to 20%, and a steep surface has a slope of more than 20%. The best from the point of view of construction are areas that are flat or with a minimal (up to 3%) slope towards the south, as well as those that have a minimum slope from the central part down on both sides (Fig.)
Schemes of the most successful sites for construction with a minimum slope
Here, construction is made as easy as possible: with such a topography on the site, various options for the location of the house and other buildings can be implemented.
Sites with a slope of up to 3%
can be used in the construction of standard houses. Only small slopes are required to drain water from buildings - they are created by adding soil, when using stones, gravel, cement, a small slope is created from the house to the surface with a height of approximately 50 cm. The width of the fill is on average 1-1.5 m wider than foundation.
If the slope is small - up to 7%,
then it is suitable for the construction of buildings without basements. However, it is possible that at a slope of 5-7%, soil will need to be added from the foothills (see figure).
A site with a slight slope of 5-7% with soil added to the foothills of the slope
If the slope exceeds 8%,
the unevenness of the surface can be used to construct a basement floor. In such cases, they do not make a flat platform, but create a lower floor by cutting out part of the slope mass. This option is good for building an underground garage, if access is possible from the side of the slope (see figure).
A site with a cut-out part of the slope for the construction of an underground part (garage, etc.) with a slope above 8%
When the slope is steep and exceeds 15-20%,
It is worth considering developing a special house design that takes full advantage of the steep slope. The inconveniences of a slope can be turned into undeniable advantages if you use it to build a multi-tiered dwelling, which will make it possible to create separate blocks in the building: for example, guest rooms with their own entrance, a workshop, a summer kitchen, a garage, a storage room. If you have to build on difficult terrain, you need to turn the site into several leveled, flat surfaces. All buildings are placed on horizontal platforms, and their width determines the size of the buildings.
To do this, terraces are created, which are secured with retaining walls and connected by steps. Even with a slope of 12%, buildings are best erected on terraces (see figure).
A site with a steep slope (more than 15%) equipped with terraces with retaining walls
A house built on terraces can be multi-level, have verandas on different tiers, balconies, and patios. The terraces also have platforms, paths, recreation areas, gazebos, and so on.
In the case of a significant difference in relief, more than 15%, it is recommended to install retaining walls so that the vertical seams in adjacent rows of stones do not coincide. Retaining walls are made of concrete slabs, boulders, bricks, timber, stones (see figure).
Terrace made with retaining walls made of boulders with a slope of more than 15%
If the wall height is high, the stones are held together with mortar. The largest stones are located in the bottom row. To increase the strength of the retaining wall, all rows of stones are laid with an inward slope. The slope along the boundaries of the site is also secured with stones, and the best material for this will be granite, sandstone, and limestone.
How to use a laser level
This tool is useful when performing most marking, installation and finishing work.
The principle of operation of the level is simple: it shows a perfectly straight horizontal line due to the self-leveling mechanism located inside the device.
Watch additional video:
Correct use of the level consists of following several simple recommendations:
- Preliminarily remove all obstacles along the path of the laser line;
- It is not recommended to exceed the optimal distance from the level to the object specified in the instructions for the device;
- The device must be installed on a flat surface or tripod;
- If there is no self-leveling function, before starting work, adjust the level using the built-in bubble level.
By following the above recommendations for leveling the formwork, you can flawlessly complete the entire range of marking and installation work.
What to choose
We have looked at several options that you can use for areas with a large slope. They all have their pros and cons. Let us immediately determine that a slab foundation is not suitable. You can make a kind of hit parade by analyzing the pros and cons of each reason. So, in last place is the slab base. It is chosen very rarely. What should we put in third place? Of course, a strip foundation, due to the fact that its construction will require a lot of effort, land work and investment.
The columnar foundation took second place. It is good, but not as good as our winner, namely the pile foundation. Only he deserves the highest praise when it comes to problematic soil with a slope. It's all about ease of installation, minimal work and investment.
DIY wire fencing
Designing a barbed wire fence begins with choosing the type of structure; the installation of the product itself will depend on this. Next, you need to determine whether it will be an independent structure or an additional one to an already finished structure.
For self-fencing, you must have support posts, between which the wire will be attached. Racks are chosen from wood, metal or concrete. Installation occurs by implanting posts into the ground at a certain distance. The gap between the pillars should not exceed 2.5-3 meters.
If you are planning to construct a fence yourself, you need a list of special tools, as well as protective gloves and thick clothing to protect yourself from injury.
Installation algorithm:
- Territory marking
- Installation of support posts
- Installing brackets using bolts or welding
- Installing a barbed spiral on the brackets on top, using special brackets
- Pulling a double string through the entire length of the helix
- Alignment of the spiral and its fastening using special twists
- Installing barbed wire between posts at a distance of 15-20 cm
- Connecting the wires together with mounting brackets.
To strengthen the structure, the wire is connected to an electric current source. But for this you need to hang a warning sign.
Barbed wire fencing is perhaps the best way to protect private property. The design does not require high costs and does not cause great difficulties in installation and operation. An excellent solution to protect your property from unwanted attacks.
How to make shields
When pouring the foundation, you may encounter a problem such as expansion of the formwork. This problem occurs for two reasons:
- Incorrect material chosen;
- Frame panels for concreting were assembled and installed incorrectly.
In order to make durable formwork from edged boards, lumber with a cross section of 100×25 mm and 150×30 mm is used. The shields will need to be supported with bars with a cross section of 100x50 mm. It is also used for installing vertical formwork posts located in increments of 80-100 cm. Installation of panels consists of several stages.
Install vertical posts made of 100×50 mm timber.
Sew up the inner walls with boards 2.5 cm thick using wood screws.
The mounted panels are supported by bars installed on the outside of the formwork. The step between the supports is 60-70 cm. This design will withstand the pressure of concrete. After the foundation is poured and acquires brand strength, the wooden frame is dismantled and the lumber is used for other purposes. For example, for lathing a rafter system or installing a ventilated façade.
With a shield height of 90 cm and concrete being poured mechanically (from a concrete pump), the pressure per 1 linear meter of the frame will be at least 2300 kgf/p. m. The formwork may not withstand and become deformed. Therefore, its walls must be tightened with metal pins secured on the outer sides of the frame with nuts.
Construction of a strip foundation on a slope
The base in the form of a concrete strip is very popular among private developers, due to its ease of construction and low costs. However, the construction of a strip foundation on a site with a slope should be approached with special responsibility.
Like any construction process, the construction of a foundation takes place in several stages.
Site planning
At the first stage, it is necessary to draw up a detailed plan of the construction site, located on the slope of a hill, and indicate the location of the future foundation. The main task is to determine the lowest point of the soil, since it will determine the depth of the strip foundation. The estimated height of the foundation is measured down from this point and about half a meter is added to the bed of sand and crushed stone. When planning, it should be taken into account that along the entire length the base tape should lie at the same level, and its upper part should rise slightly above the ground level.
Ways to reduce the slope of a site
In most cases, a site on a slope requires some reduction in the height difference, and the degree of complexity of the work depends on the magnitude of the slope.
A slight slope, not exceeding 3%, does not require complex work; to do this, it is enough to add soil in the right places and strengthen it with silicates.
A slope of up to 8% can be leveled by backfilling the strip base with soil that rises from the foothills.
Differences of up to 10% are considered problematic, but in this case you can build a basement floor by placing it directly on the slope.
If the steepness of the slope exceeds 10%, then the construction of structures to protect against landslides is required in such an area.
Excavation
Digging a trench is one of the main stages of building a foundation on a slope, but it is where the whole process begins. At this stage, it is necessary to accurately follow the calculations performed, especially those relating to the depth of the foundation. This is explained by the fact that this parameter will be different on different segments.
Construction of formwork
The presence of height differences on the site somewhat complicates the construction of formwork, since regardless of the degree of slope, the upper part of the base must be strictly horizontal. For this reason, the formwork at the lowest point of the slope will be significantly higher than at the highest point. Another important point is choosing the right board for formwork.
Making formwork
At the bottom of the prepared trench, be sure to make a cushion of sand and crushed stone, and each layer is well compacted. The height of the pillow should be about 0.2 meters.
Foundation reinforcement
A strip base on a slope requires a reinforced reinforcing belt, for the manufacture of which steel rods are used. Neglect of this stage causes deformation of the foundation and, as a consequence, destruction of the entire structure.
Creation of a drainage system
To ensure effective drainage of moisture away from your foundation and home, you need an excellent drainage system. However, it is not recommended to carry out this step on your own, as special research is required. Therefore, the creation of a drainage system should be carried out by an experienced specialist.
Pouring concrete
The foundation on a slope must be poured in one go to prevent delamination of the concrete mass during the drying process, which can lead to rapid destruction of the base.
The poured concrete solution is carefully compacted using a special device, which allows air bubbles to be removed. The finished foundation is left for about a month with proper care, so that the solution completely dries and hardens.
How to level the formwork
There are several ways to level the formwork. The rules for carrying out work are reflected in specialized documentation: SNiP 3.01.03-84 “Geodetic work in construction” and SNiP 2.03.01-84 “Concrete and reinforced concrete structures”.
In most cases, individual developers do not have time to study the rules and regulations. Therefore, the most useful are the recommendations of builders, based on the requirements of SNiP and optimized for different conditions of concrete pouring work.
Strip stepped foundation
Before you start work, you need to make a choice between different construction technologies:
- monolithic reinforced concrete;
- prefabricated reinforced concrete.
For the same reason as in the previous version, the monolithic method of constructing a strip foundation is the most optimal. In addition, the foundation built using this technology is a solid product. When constructing this type of foundation, they are guided by the joint venture “Design and construction of foundations and foundations of buildings and structures.”
You can make a support for a house with a slope of 10% in the following order:
- The slope on which the tape will rest is cut so that a stepped descent is formed. The height and width of the ledges are calculated so that the angle between the horizon line and the visual line drawn from the surface of the ledge to the base of the slope does not exceed 30 degrees.
- The steps of a kind of terrace are compacted and reinforced with reinforcing mesh.
- A layer of soil is poured over the mesh.
- They dig trenches for retaining walls located across the slope, install formwork, and pour the foundation. Walls located along the slope are placed in such a way that their edges are at the same level, while the mark of the sole may differ.
- After the concrete has hardened, soil is added in order to equalize the difference between the lower and upper elevations of the slope.
If the slope percentage of the site is less than 8%, a stepped slope is not necessary. The strip foundation is installed as for a flat area
It is important to note that tape is one of the most disadvantageous types when working with height differences. Construction at different levels will be very labor-intensive and expensive
It should be used only if a basement is needed.
Common types of foundations
Most often, four types of underground structures are built on slopes:
- straight tape;
- stepped foundation;
- columnar;
- pile
Strip foundations
They can be done with your own hands. A straight tape is justified in conditions of a slight slope of the site and if it is necessary to use a basement under the entire area of the house. The inconvenience and disadvantage of constructing a straight strip foundation is that during its construction it is necessary to maintain certain proportions of the height and width of the strip. This entails excessive consumption of concrete, reinforcement and formwork. In addition, the developer will have to face:
- with a huge volume of earthworks;
- with the requirement to install a reliable retaining wall;
- with the need to install a support embankment upon completion of work.
A stepped foundation is more economical, since its base is located not at one, but at different levels. It is buried gradually in the form of ledges, repeating the direction of the slope of the site. If we start from average values, then the concrete base is located almost at the same distance from the surface of the earth along the entire perimeter of the house. The complexity of implementing a stepped structure lies in the arrangement of formwork for pouring concrete and the need to install vertical reinforcing bars at the junction of adjacent strips.
Columnar foundations
It is advisable to make such a foundation on finished terraces, between slopes or in rock. To install the pillars, holes are dug to a dense soil layer. The supports have different heights, depending on their location relative to the slope of the terrain. Retaining walls in the form of a monolithic trapezoidal strip are installed in the upper and lower parts of the site. The installed supports are combined with a grillage that levels the upper edge of the foundation.
Backfilling of soil at the level is carried out either before the installation of the pillars, or after the installation of vertical structural elements.
Pile foundations
The advantage of installing piles is the absence of large volumes of excavation work and the ability to quickly erect objects on almost any slope. To install a pile foundation, products of different lengths can be used. Their tip rests on dense soil, and the shedding of the upper layers does not affect the structural deformation of the structure.
When installed correctly, the piles are not afraid of the forces of frost heaving and the effects of groundwater. They have many positive properties, but they also have disadvantages. One of them is the impossibility of constructing a full-fledged basement under the house.
Pile foundations on slopes require not only a grillage, but also piping between adjacent supports. This element gives the structure greater stability.
Factors to consider when pouring
When constructing foundations on uneven areas with a surface slope, it is imperative to follow building codes and adhere to technology. But a better solution would be to involve professionals. The construction of such foundations has some distinctive features, mainly related to preparatory measures and additional work.
The following important factors that you should pay special attention to will help you get rid of unpredictable consequences in the future. 1
A competent foundation design is a necessary condition for the construction of a facility on uneven sites. It includes calculation:
1. A competent foundation design is a necessary condition for the construction of a facility on uneven sites. It includes calculation:
- base dimensions;
- weight load of the building on the foundation;
- exerted specific pressure on the ground at various points;
- temporary loads.
The hydrogeological assessment of the site allocated for construction and soil analysis are of great importance. To do this, in most cases they resort to drilling exploration wells.
2. Creating an effective drainage system requires careful preliminary calculations. Accumulating moisture is the main source of many troubles, which can lead to slipping and even collapse of the soil in the mountainous part.
3. Mechanical soil consolidation is an important addition to the drainage system when terrain slopes are more than 10 degrees. The most affordable and simplest option is the so-called weight - a bulk layer of denser soil rocks. The additional mass will prevent possible soil movement. In addition, such work makes it possible to form and partially level the construction site, preparing it for digging a trench or foundation pit.
4. The construction of appropriate formwork consists of the complexity of its preparation in the conditions of existing elevation differences on the site. To maintain the horizontal level of the foundation being poured, the formwork at the lowest point of the site is made higher than at the top.
5. Reinforced foundation reinforcement increases the strength of the foundation. For the frame, metal reinforcing bars of large diameter are used or their number is increased
In this case, special attention is paid to the corners of the assembled frame structure, and the lattice elements are placed at a distance of no more than 15 cm from each other
6. In order to properly fill the foundation with concrete mixture, it is necessary to ensure its continuous supply. When constructing a base on an uneven surface, this factor is of particular importance. Increased loads during the further operation of the building categorically do not allow the underground part of the structure to be poured in several stages, since it is guaranteed to lead to ruptures at the boundaries between the set layers. In addition, careful compaction of the concrete mixture is required during the filling of the formwork in order to prevent the formation of cavities.
The above measures, which must be taken into account when constructing the foundation of a house on areas with an uneven surface, entail increased financial costs. However, the additional work carried out significantly prevents the threat of soil sliding or washout, being a reliable guarantee for the construction of a high-quality foundation and long-term operation of the entire structure.
Alignment
An important point in the construction of formwork is its leveling. Recommendation from builders: there is no need to try to level the upper planes of the frame “to zero.” On the contrary, it is better to make the walls of the formwork several centimeters higher than the planned height of the foundation. And on the inside of the boards, apply marks with a marker, drawing horizontal lines corresponding to the required plane of the foundation to be poured.
The main difficulty is to draw these lines correctly. It is not difficult to pour and level concrete over them. To complete the task, you can use a water level.
First, find the required height of the foundation at the lowest marking point. Apply a water level flask to it, remember or mark the water level. Then, using the second flask, the corresponding marks are placed on the remaining pegs. Draw lines and, if necessary, duplicate them with thin wire.
There is another point of view on alignment: the walls of the frame should be aligned “to zero”. For these purposes, at the marking stage, the height of the foundation is determined in the manner indicated above and ropes or fishing line are pulled at this level. Shields are mounted based on these devices.
The second way to level the formwork walls is to cut the panels along the lines drawn along the fishing line or rope. When pouring concrete, it is compacted with a reinforcement bar and leveled with a rule, which in this case should rest on the walls of the formwork.
What to base the choice of foundation for houses on a site with a slope?
The main advice is to take into account not so much personal predisposition as objective factors. The types of foundations described above perfectly withstand various types of loads and their combinations:
- the pressure of the house structure directed directly downward;
- influence of longitudinal and transverse shears;
- uneven application of force from the soil and atmospheric factors.
A properly calculated foundation can last for several decades and maintain its strength under any influence. Professional architects and designers of InnovaStroy will help you choose the best option specifically for your site.
It is worth noting that all foundations in areas with a slope must be made with reinforced reinforcement. The use of high-quality concrete allows you to create a monolithic foundation, the prices of which differ little from those built on flat areas.
This is interesting: How to make a spiral staircase to the second floor, attic: let’s look at it step by step
Settlement actions
To make the appropriate calculations for building a foundation on a slope, you can use special programs with the introduction of data obtained during the study. To obtain a more correct calculation, many factors must be taken into account:
- Results of soil research.
- Weight of the structure, including frame, floors and roofing system.
- Payload, which includes the weight of the furniture and the total mass of the occupants.
In addition, calculation work involves determining the corresponding costs:
- Cost of research work.
- Material for foundation construction.
- Rental of heavy construction equipment.
- Cost of earthworks.
- Costs associated with strengthening the soil and installing a drainage system.
Fence on a site with a slope: options
Before making a fence on a slope, you need to evaluate your own strengths and the tasks of the fence, determine the drop and slope of the surface. If this is protection from destruction, then it is advisable to build it from stone or brick on a strip foundation. If you install a fence on an uneven area for decorative purposes, then you can choose wood, corrugated sheet or picket fence as a building material.
Sloping fence at the dacha
The type of terrain slope may vary. In this regard, it is worth noting the following:
- A low slope will allow you to build a fence that follows the correct curves of the landscape. In this case, the fence fabric can be level. The foundation for the fence is either completely absent, or a strip foundation is used.
- On a steep slope, these fencing construction options look unattractive. At the same time, the need for strengthening will require a thorough construction of the foundation. The fence can be made level by installing a leveling or stepped base. That is, the individual elements are in the form of steps and have different levels.
Wooden picket fence on uneven ground
If there is no need to strengthen the soil on the slope and the construction of a reliable foundation is not in the construction plans, then you can build a fence from Euro picket fence, boards, chain-link mesh, or corrugated sheets. You can build a fence with steps, mounted on poles, gradually rising.
The downside of this fence is that large voids appear at the bottom in the form of a triangle. They give open access to various animals. Intruders can also get in.
Thus, the fence protection function can be combined with a decorative one. You can get rid of voids under a wooden fence by cutting out the lower part in the shape of a triangle.
Fencing a private house
If you install a fence on a slope, the choice of building material will also depend on the personal capabilities of the home owner:
- A fence made of wood or corrugated board is the most suitable way to build it yourself.
- Fencing made of beams or picket fences can be used for a fence that follows the slight elevation of the site.
- The most durable, but also the most expensive, is a concrete, brick and stone inclined fence. The construction of such fences will require a lot of preparation, experience, and a significant investment of time and money.
Metal picket fence with stone pillars
Types of formwork
Foundation formwork is divided into two main types:
- Removable, removed after the concrete mixture has completely hardened. For the manufacture of such a structure, wooden boards, shields, or metal elements are used.
- Fixed ones remain with the mortar for the entire existence of the future building.
But designs also differ in the type of material used to construct them. There are metal and wooden structures. That is why, before placing the formwork under the foundation, it is necessary to finally decide on its type and the material used for this. To make the task easier, it is worth familiarizing yourself with each option in detail.
Wood formwork
This option is the oldest and, nevertheless, still widespread. To construct this element, wooden boards and various shields are used. In order to connect the individual elements, beams are used. For the same purposes, a variety of ties, staples and wire may be required.
Metal formwork
Formwork made of metal is a more reliable and durable option. The most suitable options here are aluminum alloys and galvanized steel. Each of the proposed options has its own characteristics. You can purchase a ready-made design or make it yourself.
Permanent formwork
This type can be made of metal. But the most commonly used is polystyrene foam, which at the same time also serves as a thermal insulation layer. This type of construction is produced in the form of separate blocks, which are connected at the site of construction before pouring the solution.
Special reinforcement is used for the connection, which also serves to enhance strength.
Strengthening the slope under the foundation
Laying a foundation on a slope requires preliminary work to strengthen the slope. They are needed in order to avoid soil heaving in winter, its shifts and other phenomena that can destroy or make the foundation less durable.
All options for strengthening slopes are based on the principle of reinforcing soil layers in order to increase their stability and strength. If the angle of inclination does not exceed 7-10%, it will be quite enough to plant shrubs and trees, which will reduce the likelihood of landslides and keep the soil surface intact thanks to their branched roots.
You can create a rock garden by building ledges at the base of the slope and providing regular watering to the rocky garden.
If the angle of inclination is greater, you can install metal spacers that are dug in over the entire area of the slope, use logs, stones, geogrids, biomats secured with anchor bolts. Terracing is also a good option - creating retaining walls that are easy to construct and durable. Before constructing a retaining wall, a layer of soil is removed, drainage is made, and flat stones are laid over the hill.
When choosing a specific method of strengthening a slope for a strip, pile, slab or column foundation, take into account the features of the structure itself, the orientation to the cardinal points (slope and the site as a whole), the magnitude of the angle of inclination, the proposed waterproofing layer, soil composition, the depth of groundwater and freezing of the ground , specific features of the relief.
How to avoid surface leveling work
Leveling can be minimized or completely eliminated by following a number of practical recommendations for constructing a concrete base strip:
- Before installing the formwork, you should thoroughly clean the bottom of the trench under the foundation and perform sand preparation. The layer of sand under the foundation must be at least 10 cm. Next, it is leveled, moistened with water and compacted. After that, control alignment is carried out. A smooth sand cushion allows you to place the concrete mixture into the formwork more efficiently, without dips and drops.
- If the top of the formwork panels corresponds to the level of the desired horizon, then this greatly facilitates leveling the surface during the process of laying the concrete mixture. Smoothing of concrete is carried out by simply moving the board/rule resting on the upper edges of the side formwork panels.
- The correct selection of crushed stone fraction plays a significant role in compacting concrete and creating the most even horizon. This recommendation is important for developers who independently construct a monolithic strip: to save concrete, they often supplement the mixture with rubble stones. The best crushed stone parameter, from the point of view of creating a flat surface, is 5 – 20 mm.
- When pouring the foundation, the concrete mixture should be sufficiently plastic, but without excess water, so it will be easy to level even with a trowel, similar to self-leveling floors, creating a flat surface.
- If possible, a screed with cement-sand mortar is performed on the top of the concrete as soon as possible after pouring (in the initial stage of setting). In this case, the connection of the leveling and base layers is of the highest quality.
Recommendations for constructing different types of foundations on a slope with your own hands
If you have construction skills and a budget deficit for construction, then you can do the work of installing the foundation yourself. With correct calculations and an accurate understanding of the characteristics of the soil and slope, a foundation made with one’s own hands will last for decades.
Modern construction is carried out using new technologies and materials. Before you begin installing the foundation of the house, you should read the literature and find out about them. Now, along with metal, fiberglass reinforcement is used for the foundation. It is not subject to destruction from contact with water and has a number of other advantages.
Also in the construction literature you should read topics about whether insulation is needed for the foundation and whether reinforcement for the foundation can be welded. This information will be very useful for those new to construction and more experienced craftsmen.
To increase the strength of the pile foundation, it is necessary to make a frame for the foundation from reinforcement. The piles themselves are also reinforced. You need to understand how to properly knit reinforcement for the foundation. In many ways, the strength of the structure depends precisely on the rigidity of the reinforcing mesh used.
Installation of formwork: technology, instructions
The content of the article
- Installation of formwork: technology, instructions
- How to install formwork
- How to make formwork for a foundation
Despite the fact that formwork is a simple and often temporary structure, its installation should not be treated with disdain. If you decide to make it yourself, you should study in detail the technology and instructions for its creation, and select the right materials for its formation.
What is formwork
Formwork is an auxiliary structure. It serves as the basis for creating foundations for residential and industrial buildings, fences, garages and other structures. Formworks have been used in construction since ancient times. The development of technology for their installation is inextricably linked with the development of architecture, and these structures should not be treated with disdain.
Formwork is a box-shaped structure, a frame into which concrete is poured. The shields of the structure do not allow the solution to spread until it “sets.” After the hardening process is completed, the formwork is usually dismantled.
For each type of structure and the types of their bases (foundations), a certain type of formwork and its construction technology are used. In construction, there are two main types of such structures - temporary and permanent. In addition, they are classified according to purpose, design features, and materials used.
Columnar structure for a residential building on a slope - this is possible!
If you need to quickly build a frame house with your own hands on a slope, then a columnar foundation design will be the most suitable. This foundation is designed for a small building mass, and most importantly, its advantage is low material costs for installation.
When constructing such foundations, it is necessary to erect a number of load-bearing pillars using one or another building material
When installing a columnar base, various materials are used: wood, brick, concrete. Wood is the most economical material and also requires the least amount of time. At the same time, when using wood, it is necessary to work out the waterproofing system, then the service life of the structure will be more than one decade.
Brick for columnar foundations is most often used. It is durable, reliable, but requires a lot of time and skills for installation.
The reinforced concrete columnar base is reliable and strong. Its installation requires additional formwork. In addition, it takes time to install and dry the foundation before starting the main construction.
Choosing material for construction
To install removable formwork, boards made of inexpensive wood are used. There are no special requirements for the material; the structure must be dismantled after the concrete has hardened.
Another option is possible - installing a frame made of expensive wood. After dismantling the structure, the boards are used for finishing work (for arranging the floor or ceiling, interior decoration, and so on).
Fixed formwork is mounted from durable materials:
- Steel. Metal sheets are suitable for monolithic and strip foundations. The advantages include the ability to bend the sheets at the desired angle, excellent waterproofing of the foundation. The downside is the high cost of the material.
- Reinforced concrete. Reduces concrete consumption without losing structural strength. But the slabs are heavy, so working with them is quite difficult and requires the use of special equipment.
- Expanded polystyrene. The formwork is made up of separate blocks that are firmly fastened together. Among the advantages are ease of assembly and the ability to give a certain shape. The structure has thermal insulation and waterproofing properties. Disadvantages - difficulty in selecting individual parts (for example, round sides), high cost of material.
- You can build a structure for pouring the foundation from available materials: slate, corrugated sheets, unnecessary pipes and other items that can be shaped. If you make the calculation correctly, the benefits of using scrap materials are obvious.
What difficulties might you encounter?
Building on a slope can present some problems, especially if the height difference is significant or if it is located near the shore of a reservoir. The main reasons may be deep ravines and the possibility of landslides.
In such cases, the first priority is to increase the degree of structural rigidity. For this purpose, metal structures are most often used, which are connected to each other with durable strapping.
To obtain a design that will have all the relevant characteristics, it is necessary to take into account a number of factors when performing calculations and selecting materials. For example, the greater the angle of inclination, the greater the likelihood of collapse or landslides. Quite stable slopes are areas with a slope not exceeding 10%.
The most common problems
We will provide a list of violations that can be found in areas with elevation differences:
- during rains or during a thaw, the soil liquefies;
- the occurrence of landslides on the ground under its own weight;
- soil disturbance and sliding partially in weak areas;
- the occurrence of cracks when pressure is applied to the soil of the slope.
What types are suitable for the slope
Optimal types of foundation for a slope:
- Strip foundation is the most common option, reliable and durable, simple and fast. Requires backfilling, at least minimal leveling of the terrain; it is more suitable for slopes with a slight slope or where another choice is not relevant (then choose a stepped belt type, which demonstrates greater load resistance and strength).
- Columnar foundation - when arranging a structure on a slope, be sure to back up each column with a supporting wall, which increases the resistance of the foundation to lateral deformations. Suitable for the construction of frame and wooden buildings.
- Slab foundation - involves the implementation of special reinforcement, which retains the soil during the movement. Rarely used for slopes, as it requires large-scale work, leveling the site, and is expensive.
- Pile foundation - suitable for all types of buildings, for the steepest slopes. A practical and effective option, but requiring the use of special heavy equipment. The design is reliable, durable, and economical. Piles are made of metal, wood, reinforced concrete, of any size and shape.
- Combined foundation - when several elements of a pile and strip foundation are built, for example.
When considering a columnar or strip foundation, the latter is usually chosen due to the simplicity and low cost of construction and the good quality of the foundation.
According to their design, strip foundations are divided into: prefabricated and monolithic strip. According to the depth of immersion, the structure can be of a recessed or shallow type.
Monolithic structures demonstrate better resistance to axial tensile loads and load-bearing capacity. Typically, a buried type is chosen that can withstand ground shifts and heaving when the soil around the house is affected by temperature changes. The greater the angle of inclination, the greater the depth of immersion.
Principles for the construction of strip foundations on sloped areas
When starting to design the foundation of a future building, it is worth considering that the higher the level of difference in surface heights, the more complex and labor-intensive the required set of work will be. Modern technologies for constructing a foundation on a surface with complex terrain provide several options for its construction, of which the most applicable are recessed and shallowly recessed strip-type foundations. Their mutual use for buildings on slopes does not create problems during the further operation of the building and ensures high reliability of the structure.
The construction site is protected from the upland side of the slope in order to prevent it from being flooded by rainwater. To do this, a temporary earthen rampart is erected or a drainage ditch is dug, which, after pouring the foundation and making the blind area, are replaced with permanent storm drainage trays. The further volume of work performed depends on the degree of slope of the earthen surface.
Areas with a slight slope
With small unevenness or a small height difference of no more than 10-20 cm, the area can be taken as horizontal. Excavation of soil for a pit or trench should begin from the most elevated part of the site. The deepening is carried out at the same level and does not change along the entire perimeter of the foundation. In this case, it is necessary to take into account the depth of the fertile layer. If its lower boundary in some part of the developed area exceeds the calculated depth of the foundation, then it is necessary to increase the depth of the trench at the highest point, which is calculated by the formula:
Ht – calculated depth of the trench or pit;
Hpv – height difference at the construction site;
Hps is the value of the fertile soil layer.
In some cases, you can get by by cutting off part of the surface of a slight natural slope or adding soil in the lowlands of the construction site. In this case, the fertile layer is first removed and it is strengthened by careful compaction using silicates.
Areas with a medium slope
If the height difference is more than 20 cm, it would be wrong to start developing a trench for the foundation from the highest part of the site, since in this case the base of the foundation at the lowest point may end up on the ground surface or even higher. The lowest part of the site is taken as the base level from which to start.
Digging a trench in the lower part is carried out to the calculated depth, taking into account the possible impact of frost heaving forces, but not less than the thickness of the fertile layer. The entire remaining perimeter of the excavation for the foundation is made at this level. In situations where the difference in heights on the site is greater than the depth of the foundation, the size of the trench to be torn off is taken to be equal to the difference. But in this case, the consumption of concrete when pouring the base of the building will increase significantly. In order to save money, the width of the foundation base can be slightly reduced, but to reasonable limits.
At the end of the work, the finished foundation is backfilled with non-heaving soil, which is carefully compacted layer by layer. Around the building, the soil surface is planned towards the natural slope and a blind area is made.
Areas with a high slope
Before starting work, the construction site is divided into parts to allow the construction of horizontal terraces at different levels, while the height of the ledges should not exceed half a meter. A landslide wall is constructed for each zone. They begin digging a trench from the lowland part, having previously removed the plant layer of soil. Further deepening at each level is carried out according to design calculations.
The stepped construction of a strip foundation requires the mandatory installation of high-quality drainage, since the natural movement of groundwater from the side of the mountain slope after the construction of the structure will become difficult. The possible accumulation of excess moisture will have extremely negative consequences. In this regard, the drainage system is designed in advance. It is installed around the entire perimeter of the house with deepening to the lower level of the trench, taking into account the sand cushion.
It is advisable to carry out this option for constructing foundations only in areas with a large slope, since the cost of such work is extremely high. They can only be entrusted to highly qualified specialists.
Briefly about the main thing
Before you start building walls, you need to make sure that the first crown or first row of masonry will lie on a flat horizontal surface. If a significant deviation from the level is detected, mistakes made at the initial stage of construction will have to be corrected and the base leveled. Knowing how to lay out a zero on a brick foundation, by pouring an additional layer of concrete or installing an armored belt, you will select the optimal leveling option. The choice will depend on the degree of distortion: if it is small, you can get by with grinding or plastering the upper surface, but serious differences will require leveling with brickwork or pouring concrete into formwork with reinforcement.
