Any construction project must start with a strong foundation because it offers stability and support to the entire structure. For smaller structures and additions, a strip foundation is a popular option because it provides a stable base that distributes the weight uniformly over the ground. Knowing the fundamentals will enable you to confidently take on this crucial step on your own.
A continuous strip of concrete, usually reinforced with steel, serves as a strip foundation, supporting and transferring the weight of a building to the earth. It’s crucial to evaluate the soil before starting and to calculate the foundation’s dimensions based on the building’s weight and the soil’s carrying capacity.
First, use pegs and string to mark the outside perimeter of your foundation. By taking diagonal measurements from corner to corner, you can make sure the corners are square (the measurements should be equal). This is an essential step in keeping your foundation aligned and accurate.
Next, dig the trench to the necessary depth and width by following the marked lines. The type of soil and local building codes will determine the depth. This can typically be found at a depth of 1.0 to 1.5 meters. To create a stable foundation for the concrete, clear out any debris and make sure the trench’s bottom is level.
It’s time to lay the foundation formwork once the trench has been prepared. This defines the shape and size of the foundation by serving as a mold for the concrete. To make the formwork, use stake-secured wooden boards or metal panels. Before pouring the concrete, double-check for alignment and level and make any necessary adjustments.
To enhance drainage and stop water from building up beneath the foundation, cover the bottom of the trench with a layer of gravel or crushed stone before adding concrete. This procedure lowers the possibility of water pressure-induced cracking in the concrete, preserving its integrity over time.
It’s now time to combine and pour the concrete. To ensure the right proportion of cement, sand, gravel, and water, follow the manufacturer’s instructions when preparing the mix by hand in batches or with a concrete mixer. To ensure even distribution, pour the concrete into the formwork starting at one end and working your way towards the other.
After pouring, level the concrete with the top of the formwork using a screed board or straight edge. To eliminate air pockets and produce a dense, consistent consistency, consolidate the concrete by hammering the formwork’s sides or vibrating it with a mechanical vibrator.
Lastly, keep the concrete damp for at least seven days to allow it to cure slowly. By doing this, the concrete is strengthened and the likelihood of cracking during the hardening process is reduced. After the formwork has dried, carefully remove it to reveal your completed strip foundation, which is now prepared to safely and dependably support your building project.
- Basic requirements for LF for a private home
- Preparation and calculations
- Materials and tools
- Choosing concrete to pour
- Armature
- What to use for waterproofing?
- Installation and manufacturing technology with photos
- Surface marking
- Preparing the trench
- Drainage device
- Cushion and formwork
- How to make reinforcement?
- Fill
- Proper care of concrete after
- Hydro- and thermal insulation
- Laying tape: prefabricated and monolithic
- Basic mistakes and tips for construction
- Video on the topic
- 200,000 + LARGE DO-IT-DIY FOUNDATION / DO-IT FOUNDATION FOR A COUNTRY HOUSE
- DIY strip foundation for 180 thousand rubles., detailed instructions
- How to make a strip foundation with your own hands
Basic requirements for LF for a private home
Events featuring "ribbon" are executed while considering current SNIP standards. The primary guidelines for building a reinforced concrete slab foundation are found in SNiP 2.02.01-83, with supplementary guidelines found in GOST 13580-85. Important requirements also pertain to SNiP 3 foundation construction. 02.01-87 and SNiP 3.03.01-87, the document on load-bearing and enclosing buildings.
Fundamental specifications needed to build the ribbon:
- Following the technology (do not change anything in the order of work and the rules for their implementation).
- Composition of building materials (they must be of high quality).
- Reinforcement procedure (metal frame is an integral part of the base, giving it basic strength).
- Compliance with the proportions of materials from the design part (volumes cannot be used in larger or smaller quantities) of the foundation design.
Large safety margins are required in a strip foundation for a private home because the main loads will "go" to it.
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Preparation and calculations
The base’s dimensions are used to calculate the monolithic strip foundation’s dimensions, reinforcement, and concrete volume. The quantity of reinforcing and concrete is associated with:
- type of foundation (only the outline of the house is laid or is there a division inside into sectors);
- brand of concrete;
- width and length of the “tape”;
- base thickness and height.
The soil type and the future house’s wall thickness are key factors in establishing the foundation’s specifications. They are employed in the computation of whether the foundation should be built on the earth’s surface or at a significant depth. Another factor is the format of the building material used to create the "tape."
The load level dictates the kind of strip foundation:
- Recessed – for massive buildings built on soft soil.
- Shallow – used for light-weight buildings, as well as for fences and wooden houses.
A concrete belt is installed 20–50 cm into the ground in the shallow version of low-rise construction, depending on the depth of installation. It is buried less than 50 cm in the second instance.
The area of the foundation, the volume of concrete needed for filling, and the quantity of metal needed must all be determined in order to determine the quantity of materials needed. The amount of wood needed for the formwork must also be chosen.
Watch the video to calculate the reinforcement on your own:
The video illustrates how the foundation was calculated using the load-bearing load:
Go here to learn more about figuring out strip foundations.
Materials and tools
Prior to beginning construction of a strip foundation, the following materials must be ready:
- wooden boards and bars – for formwork;
- reinforcement – for a reinforcing effect;
- crushed stone and sand – for the “sole”;
- wire – for tying metal rods;
- waterproofing material – for formwork;
- concrete – for pouring mortar (prepared or ordered immediately before the pouring stage).
A board that is between 15 and 20 mm thick is sufficient. Selecting bars with a cross section of 30–40 mm is advised.
Prefabricated concrete is utilized more frequently, but in cases where the volume of concrete to be laid is substantial or transportation is challenging, rental
- mortar unit (mobile),
- concrete pump (capable of supplying up to 64 m),
- container for intermediate unloading and wheelbarrow for moving.
Additionally useful are a shovel and:
- wire cutters,
- nails and hammer for formwork,
- saw.
Additionally, having a vibrator for concrete and a tying gun for wire would be handy.
Choosing concrete to pour
Should you choose to mix your own concrete, you will need to purchase and combine crushed stone, cement, and sand. ratios of 3:1:3, correspondingly. Selecting cement brand M 400 is advised. A pre-made solution with the mark M 300 or higher is available for order.
It is preferable to purchase pre-made concrete because mixing it yourself will not allow you to fill the "tape" completely. The strength and integrity of the base will suffer as a result.
You can learn more about concrete grades for strip foundations from this article.
Armature
For the strip foundation, certified reinforcement must be used when construction is done in accordance with SNiP regulations. Steel with a diameter ranging from 10 to 32 cm is laid for longitudinal reinforcement. 12 cm when positioned vertically.
Terms of use of fittings | Minimum diameter of reinforcement bar | Regulatory document |
longitudinal working reinforcement along a side 3 m or less | 10 mm | Appendix No. 1 to the design manual “Reinforcement of elements of monolithic reinforced concrete buildings” (Moscow, 2007) |
longitudinal working reinforcement along a side more than 3 m | 12 mm | Appendix No. 1 to the design manual “Reinforcement of elements of monolithic reinforced concrete buildings” (Moscow, 2007) |
structural reinforcement | the cross-section is equal to 0.1% of the cross-sectional area along the height of the gap between the layers of reinforcement and half the width of the tape | point 3.104 Guide to the design of concrete and reinforced concrete structures made of heavy concrete (without prestressing). (Moscow, Stroyizdat, 1978) |
transverse reinforcement (clamps) of eccentrically compressed elements | not less than 1/4 of the largest diameter of the longitudinal reinforcement and not less than 6 mm | paragraph 8.3.10 SP 52-101-2003 Concrete and reinforced concrete structures without prestressing reinforcement |
transverse reinforcement (clamps) of knitted bendable frames | not less than 6 mm | paragraph 8.3.10 SP 52-101-2003 Concrete and reinforced concrete structures without prestressing reinforcement |
transverse reinforcement (clamps) of knitted frames with a section height of 80 cm or less | 6 mm | point 3.106 Guide to the design of concrete and reinforced concrete structures made of heavy concrete (without prestressing). (Moscow, Stroyizdat, 1978) |
transverse reinforcement (clamps) of knitted frames with a height of more than 80 cm | 8 mm | point 3.106 Guide to the design of concrete and reinforced concrete structures made of heavy concrete (without prestressing). (Moscow, Stroyizdat, 1978) |
Find out more about LF fitting diameters here.
What to use for waterproofing?
Buildings without basements need to have a layer of horizontal waterproofing to shield the interior and external walls from moisture seeping in from below.
There must be a minimum of two layers of horizontal waterproofing in the external walls of buildings with basements and brick or stone walls. The upper layer is optional for interior walls.
Bitumen roofing coatings, insulating coatings, roofing insulating coatings, or insulating coatings made of polymeric materials are used for horizontal wall waterproofing.
More protective pads or drainage must be installed for external wall vertical surfaces that come into contact with the ground.
Installation and manufacturing technology with photos
The following steps are part of the typical construction work algorithm:
- Surface marking.
- Preparation of a trench.
- Drainage device.
- Cushion.
- Installation of formwork.
- Reinforcement technology.
- Fill.
- Stripping.
- Waterproofing and insulation.
Surface marking
Based on the authorized plan found in the building permit, the planned house is marked on the property prior to the commencement of excavation work. Pegs are used on the site to indicate the boundaries of the trenches that are provided.
In order to create foundation formwork, the trench is made slightly wider than the house’s boundaries when the belt is erected on soft ground.
Preparing the trench
The base of the foundation needs to be on stable soil, no matter how deep you intend to dig. They could be:
- sandy loam layers,
- clay,
- loams,
- rocky layer.
Typically, they are buried beneath regular soil and grass. It is necessary to remove such a surface before starting foundation work. According to the project, the depth matches the size of the house’s base, plus an additional 10 to 30 centimeters for a sand cushion. A rope that has been stretched is used to indicate the trench’s boundaries.
Drainage device
To avoid the buildup of pressurized water close to the exterior walls, the drainage system is intended to remove soil through a drainage pipeline. The system is made up of drainage systems, control, and flushing components.
In well-permeable soil, moisture can form without the need for drainage. Drainage is required to remove the resultant water if the soils are viscous and poorly permeable.
Cushion and formwork
Fine gravel and river sand are poured into the trench’s bottom. Materials are dispersed and lead addition is added gradually while being carefully compacted. The "floor" is leveled in this manner. The pillow is this one. It can reach heights of 10 to 30 cm.
Don’t ignore the cushion; during seasonal soil swelling, it redistributes and lessens the load on the "belt." The next step is to apply a horizontal layer of roofing material waterproofing.
Formwork may be fixed or movable. Made of OSB or wooden boards, it is removable. They are going to be taken apart as soon as the concrete sets. Layers of expanded polystyrene or penoplex are used to create permanent formwork; these layers also act as insulation. This layer is regarded as a good heat insulator and shields the solution from moisture.
The width of the wooden boards used to construct the formwork is specified in the design documentation. Since they form the outer layer of the strip foundation, they are positioned along all of the walls of the excavated channels.
Boards that are 15-20 mm thick and bars with a cross-section of 30–40 mm, or laminated chipboard, are frequently utilized for "tape" formwork. Learn more about the cushion’s structure and formwork here and here.
How to make reinforcement?
Wire and steel rods are required. The last group to become "connected" to one another is the reinforcement. Elements that are vertical are positioned 5–10 cm above the "floor" and secured to horizontal surfaces using wire. The end product will be the foundation’s metal skeleton.
Diagram connecting methods:
Process of reinforcement in accordance with SNiP:
- the steel bond must be rigid, which will prevent it from moving when the concrete is poured;
- if welded parts are used, then the welding method is permitted only without changing the shape;
- the bend of the rods must have a radius identical to its fixed value in the construction project;
- the step when pouring is no more than 25 cm;
- between longitudinally embedded rods the distance should be no more than 40 cm;
- between the transverse rods a segment of no more than 30 cm is made;
- the device must have joints that must match the strength of the main material.
After the reinforcement is finished, the solution is poured into the formwork, creating a robust belt that is monolithic. Prior to beginning the concrete pour, communications (water supply, sewage, and ventilation) are installed.
Fill
If mortar is not applied to the reinforcement on all sides, the steel will eventually rust.
The entire surface needs to be covered at once with concrete mortar. There’s no reason to break the lines of height or length. Using a shovel and trowel, you can assist in the process of spreading the concrete evenly inside the formwork.
Filling the strip foundation in a circle will cause the perimeter to rise gradually. To make it easier to lay the first row of bricks or other building materials later on, the concrete is leveled (screwed) at the end of the process.
You will learn about pouring a strip foundation from this article.
Proper care of concrete after
It’s crucial to make sure the solution is completely filled after pouring. An specialized vibrating machine is used for this. It is traversed across the concrete’s surface. In the event that it is unavailable, some reinforcement will do. They have the ability to puncture the fill and release air.
It takes 28 days for the concrete to "stand up" after it has been poured. In order to prevent drying out and concrete cracking, it is crucial to cover the tape with polyethylene.
Hydro- and thermal insulation
Reliable waterproofing of reinforced concrete is necessary when groundwater levels are high around the edges of a building site. Usually, coating is used on top, at the basement level of the building.
The trench’s bottom and sides are covered with roofing material to protect the integrity of the ground-level strip foundation. During and after the base’s formation, the material will provide dependable protection from soil moisture.
It is feasible to place insulation on top of the pillow, preventing soil freezing-related foundation deformation. You must leave five centimeters between the insulation and the reinforcement.
After the concrete becomes more dense, you must also place three to four rows of bricks on top of it and lay a strip of roofing material that is the same width as the base. To drain rainwater from the building’s walls, it is preferable to create a blind area all the way around the house.
Everything there is to know about insulation and LF waterproofing can be found here.
Laying tape: prefabricated and monolithic
Strip monolithic, also known as block foundation, is mostly built on solid, dry soils and can be used beneath a variety of buildings. Specialized cushion slabs made of reinforced concrete can be used.
Because they don’t have to stand like a "lente" for a month, a prefabricated strip foundation made of blocks can greatly expedite the foundation’s construction.
By hiring a crew, you can expedite the "ribbon"’sconstruction. All phases of the work are finished more quickly when there are more workers.
Basic mistakes and tips for construction
Inaccuracies in evaluating the state of the groundwater table, the building soil’s quality, and the behavior of the chosen foundation during use can frequently result in irreversible financial and technical harm.
Perhaps the house’s foundation will extrude, collapse, or spread to the sides. You should carefully consider the area’s groundwater map and apply the waterproofing layer to prevent such issues.
By excavating and probing the soil, you must ascertain the allowable load on the building soil as well as its characteristics in order to calculate the size of the foundation (if such data is not available for the area).
The Russian Federation’s load table:
Because most soils swell at the end of winter, the base of a strip-type house is situated below the freezing level of the soil. The foundation will probably float in the spring if this rule is broken.
It is not possible to add water to the prepared solution. It will no longer be absorbed by the concrete, but it will still create voids that weaken the material and cause deformation.
As it provides a sturdy foundation for your construction, building a strip foundation yourself can be a satisfying project. It is essential to begin with meticulous planning and site preparation. After clearing the area of any debris, use stakes and strings to mark the foundation’s dimensions.
Next, level and compact the trench after excavating it to the necessary depth and width. For stability and drainage, place a layer of gravel or crushed stone at the bottom. As you pour the concrete, place formwork along the trench’s edges to hold it in place.
To achieve the proper consistency, make sure the concrete is thoroughly mixed and adheres to the recommended ratios. Using a screed board to level the concrete, evenly pour the mixture into the formwork. As directed by the manufacturer, let the concrete cure completely.
After the formwork has dried, carefully remove it to reveal the completed foundation. Examine it for flaws and make the required corrections. For the concrete to be strong and durable, it must be properly cured; therefore, make sure the concrete stays moist throughout this process.
After the foundation has completely dried, backfill the area around it to stop soil erosion and strengthen the structure. You can build a strip foundation that will serve as a solid base for your building project by paying close attention to detail and following these instructions.