# Calculation of the safety factor of a garden path - 1

## Service life determines the basis

The paths that serve as access roads to the parking lot and garage, connecting the main buildings on the site, are used with the greatest intensity. The larger the size of the site, the more its transport lanes look like full-fledged roads. The load on their canvas is low, and the service life of the garden "highways" stretches for decades. But all this will be only on condition of preparation of a qualitative foundation.

### Foundation is necessary

Transport lanes are operated with the highest frequency and load, and their service life is equal to the life of the main building on the site, therefore they are made of the most durable materials. These are mainly solid concrete, preformed concrete tiles, clinker (burnt clay) bricks, cast blocks, gravel and asphalt. All these materials have a large specific weight, and if we remember that the width of the tracks for transport varies from 2 to 3 m, it becomes obvious that a massive base for them is needed. The gravel-sand pad evenly distributes the weight of the web over the surface, but also exerts significant pressure on the soil itself.

Modern builders, following the wishes of the customer, often neglect the elementary physics of loads and "close their eyes" to the fact that the pressure of the masses of the roadway and its base is directed not only vertically downwards, but also is distributed to the sides. Unfortunately, in today's homestead construction, there are frequent cases of striking "bungling" when a road for transport is built right next to the house. The result of such "saving the useful area of ​​the garden" manifests itself either immediately - in the form of cracks on the walls of the house caused by the displacement of the walls of the foundation, or a similar picture develops over time - a slight displacement due to a slight violation of the integrity of the foundation filling is gradually aggravated by moisture entering the cracks and cracks. To avoid costly and troublesome alterations of the foundation, and sometimes overhaul of the entire structure of the building, it is possible only for those who managed to "turn on their heads" in time and move the path away from the house. Another common "blooper" of landscapes is called - tree by the side of the road.

Usually, it never occurs to anyone to plant a sprout of a tree at the edge of the roadbed, which over time promises to grow into a multi-meter giant and plow the entire road with its roots. But for some reason, this only applies to plants from our places. And when an exotic sprout is chosen for planting, then for some reason it is believed that in our cold latitudes it cannot rise above a meter and a half. But there are still exceptions: when, after a few years of harsh adaptation, the trees suddenly receive a "gift" in the form of an unexpectedly mild winter with heavy rainfall or a heating pipe laid nearby. Or when a family often visits the house and even settles on the site, which means that sewage water begins to drain in large quantities, and septic tanks are always full and warm. In a word, the "ice age" ends abruptly for a tree, and it begins to grow rapidly, moreover, with the growth of the root system.

All of the above illustrates the good old rule, which is fraught with neglect even now: the path for transport should not be located closer than 2 m from large trees and the border of the building foundation.

### Earth to earth strife

In the process of organizing a full-fledged foundation, first, using pegs and a rope, the contours of the path are marked on the ground. A trench is being dug inside the borders. If the soil is very loose, it is recommended to reinforce the walls with plywood shields and wooden posts. The depth of the trench in most cases is equal to the thickness of the soft soil layer: depending on the area, on average, it is from 100 to 300 mm. The best ones are soils from large rock fragments. For them, the depth is provided for 100-300 mm. The quality of the soil decreases as the size of the fraction of debris decreases to crushed stone, with the thickness of the carrier layer playing a role. Sand is suitable as a base, but a supporting layer of crushed stone with a thickness of 150-200 mm is required on top. Sandy loam, loam and clay filter water much worse and are subject to the danger of frost heaving, in addition, in a state saturated with water, their bearing capacity sharply decreases, therefore, they need a trench up to 500 mm deep.

Lime soils - from a different classification. If it is a dusty fraction, the bearing capacity is low, if limestone crushed stone is good, although it is inferior to crushed stone from igneous rocks. The depth of the trench is chosen mainly for reasons of ensuring drainage of the base. In areas that are seasonally flooded and especially waterlogged, a drainage layer is strictly required. The degree of soil moisture is directly proportional to the thickness of the supporting layer. Naturally, in the construction of paths for cars, "safety margin" is welcomed, pedestrian paths - less.

### Ram and ram again

The very technology of laying base materials is standard. The bottom of the trench is wetted with water and filled with 200-350 mm thick material. But here it should be remembered that if a trench is dug deeper in a swampy area, then, accordingly, the thickness of the dense material increases. Experts advise using a "layer cake" as a dense material: 50-100 mm - a layer of coarse sand, the rest - crushed stone mixed with sand, or crushed stone covered with 20-40 mm sand. Because of savings in private construction, instead of rubble, recyclable materials are often used - broken bricks or concrete. Construction experts do not recommend this approach because chaotically broken pieces are difficult, and often impossible, to fit tightly to each other.

It is better to use rubble made from recycled concrete. The use of construction waste is completely unacceptable, because it may contain pieces of plastic or rotten wood, which, breaking down, form voids in the base over time. Any brick, except for clinker, is destroyed in the ground.

The dense material laid at the bottom of the trench is carefully tamped. This is a very important stage of work, the quality of which should be closely monitored. When the construction is carried out on its own, it is better to repeat the operation once again. After all, it is she who is the guarantee of the correct, and most importantly, the long service of the future track. The hackwork will show itself already in the next season: ground fluctuations caused by changes in humidity and temperature will affect the state of the base, and the outer coating will begin to crack, it can go in waves. Within five to six years, the owner of the site will be guaranteed to be provided with a new "hobby" - patching holes or completely remodeling garden paths. But even then he will have to face the problem of high-quality thrombosis. It is carried out in layers, and each layer is wetted with water in advance. The best results in this difficult matter can be achieved by using a vibrating plate, and for large fractions of crushed stone and a large thickness of the compacted layer - and a vibratory roller, but not a garden one. The high quality of the result can be guaranteed by the use of crushed stone of different fractions: the lower layer is laid out from a larger fraction, for example, 20-40 mm, the upper one - 5-20 mm. The finer fraction falls on the lower one in "wedging", which means that the upper layer wedges the lower one and fills the voids as tightly as possible.

### The main thing is dry

At the base of even a small road (except for sandy soils), drainage should be provided. The underground waters are powerful enough to erode the foundation of any fortress, therefore, a "highway" should be laid on the territory of even a small estate, armed with a map of their flow: each direction is duplicated by drainage pipes. However, experts say that the flow of underground streams is changeable (unless the site is located on a granite slab), therefore, it is easier to do - across the path, drain pipes of a small diameter are laid at its base. The frequency of their laying is directly proportional to the degree of wetland - from 0.5 to 1.5 m. The trench under the track can also cross already laid drainage pipes. This brings us back to the question of the timing of the arrangement of the main tracks. When a road is laid on an area with a fully formed drainage system, the process of excavating the soil from the trench becomes a kind of archaeological excavation - the risk of damaging the pipe is great, and extreme caution should be used when handling a shovel. To protect the pipes from damage, they are covered with gravel mixed with sand.

### And fill from above

The resulting dense "sandwich" of the base is completed with a layer of mortar: 1 part cement to 3 parts sand. It is recommended to be poured for hitching under thin finishing layer slabs with increased use load. In other cases, the finishing layer (paving stones, tiles) is laid on sand, or, when a rigid base is needed, on a sand-cement mixture.

Maria Novikova, designer

## Calculator for calculating concrete on a strip foundation

Foundation Calculators

With this online calculator, you can easily calculate concrete for a strip foundation.

Calculation formulas for typical types of tape bases have already been entered into the calculator. You just have to choose the appropriate type of tape, indicate its dimensions and parameters of the partitions (if any).

Please read the additional information on concreting in order to more correctly apply the results of the calculations:

1. You probably know that the base for the foundation is pre-filled with rubble and rammed. The resulting pillow has a porous structure due to the voids between the stones. Why are we talking about this? Because a small part of the concrete mix will go to fill these voids.
2. Another insignificant increase in consumption will occur due to the compaction (subsidence) of crushed stone under a huge weight, a poured monolith
3. The same must be said about the formwork. The higher the height of the base to be poured, the more internal pressure it experiences. The boards bend, the distance between the walls increases and, as a result, the required volume of concrete mix grows. To minimize this effect, lumber of sufficient thickness is used, the structure is securely fastened to the ground, and screeds are installed between the walls.
4. Despite all its weight, concrete is still a porous material. Yes, there are many air bubbles in the thickness of the mass poured into the pit. This air slightly increases the fill volume. It would seem - great! But not for the foundation, because the porosity dramatically reduces its strength. To release the air from the pouring, the concrete mass is vibrated. What is important for us here is that with the release of air, the final volume of concrete also decreases slightly.

Default Our calculator calculates the concrete volume for a strip foundation for an option when the following requirements are met:

• crushed stone bedding is sufficiently compacted using a vibrating plate
• the thickness of the boards and the methods of their fastening ensure the absence of deformations
• the concrete mass does not vibrate.

But if you think that in your case there is a possibility of small deviations of the required amount of concrete from the calculated one, then you can set the required safety factor up to 10% in the data entry form.

When you may need it:

• use thin boards with high pouring heights (this happens very often: they make a removable formwork from an inch, and then they let it on the crate)
• pour concrete directly into the pit from dense soil without formwork (in as a result, the walls are not even, the thickness of the tape "walks")
• did not compact crushed stone and (or) used large crushed stone for the pillow
• plan to use a deep vibrator.

Do not forget that for pouring standard foundations for residential buildings, it is recommended to use concrete grades of at least M250-M300. For small light houses on good soils and outbuildings, brands from M150-M200 can be used. Read more about how to get a concrete mix of the desired brand at home here.

The monolithic tape must also be reinforced - this will prevent the monolith from cracking and losing its integrity. For an ordinary strip foundation, the concrete calculator does not take into account the volume occupied by the reinforcement, since this value is minimal. But, if you will pour the canvas into a reinforced base with rods of large diameter, then it may make sense to take into account the space occupied by the metal, because it will reduce the required amount of concrete.

The main (working) reinforcement is laid in the lower and upper parts of the belt. It is these areas that are most susceptible to tensile stresses. Intermediate longitudinal and transverse reinforcement is also performed. When joining the rods, it is required to observe the required length of their overlap, which depends on the diameter of the rods and the grade of concrete.

Reinforcing rods are tied together with a knitting wire using a hook. Welding of rods is not permissible, since when heated, the metal loses most of its strength and is not able to withstand the design loads. The only exception is fittings of a special brand, but they are also more expensive.

If you have any suggestions on how to improve this concrete volume calculator on a strip foundation in order to increase the accuracy and convenience of calculations, be sure to write about it in the comments.

Respectfully yours and your home information portal ProfSovet.

## Completion of laying the garden path

The pavement is laid on top of the sand. Tiles or stones must be laid out in accordance with the intended pattern, and every detail must be carefully tamped. A medium sized rubber mallet can be used for this.

At the end, you need to carefully cut off the fragments of geotextile protruding above the ground. The seams between the slabs are covered with dry sand and rubbed with a stiff brush or broom. You can also use concrete or sand-cement mortars for grouting. The slots along the contour of the path must be covered with fresh earth and the surface must be leveled.

The garden path on the geotextile is finished and ready to become an integral part of the landscape of the garden plot.

## Supports and platform

Even at the stage of project development, it is necessary to link the type of coverage under the canopy and the method of mounting the pillars. Except for cantilever canopies and canopies, which do not have external supports. Compared to a house, it’s like choosing the foundation and flooring of the first floor - the floors can be on the ground, on concrete or wooden floors, and all have a different structure.

There are several options for this part of the canopy:

• A hole is dug for each pillar. The underground part of the column is fully or partially concreted. The covering is laid between the standing posts.
• A hole is being dug under each pillar. The formwork is installed, the armopoyas and the mortgage for the anchor or the heel of the post are mounted, concrete is poured. A metal pipe or a "glass" support for a wooden post is then attached to the mortgage. The covering is laid between the posts.
• A shallow strip foundation is laid along the perimeter with embedded pillars. The coating is laid inside the perimeter. The plinth of the foundation is covered with tiles, it can also serve as the basis for a protective or decorative wall (including when installing a grate for climbing plants).
• A monolithic slab is poured, with embedded pillars. The site is covered with a concrete base.
• Collect a platform from large-format paving slabs on a footing. Secure with anchors to the heel support tile.
• Attach the rack heel supports to the wooden deck deck.

For the last two options, we can talk about small shade canopies when wind and other loads on the supports are insignificant.

### How to choose supports for the canopy

There are standards for calculating the strength of foundations to useful, wind and snow loads. Moreover, wind loads are negotiated separately for different regions, taking into account the height of the structure. Including, for heights up to 5 m. But first you need to decide on the diameter and material of the support.

Calculating the fracture strength of a pillar is akin to the task of strength material for a beam with one clamped end. A person cannot overcome such a task without preparation, but it has long been solved by professionals. For canopy supports, it will be enough to choose a profile pipe 80x80x3 mm or a round pipe with a similar cross-sectional area and wall thickness.

Drawing of an arched polycarbonate canopy

And this is for the most difficult conditions. In reality, taking into account the location on the leeward side of the house, a solid fence or the wall of an outbuilding, you can take a smaller pipe.

With a support made of wood, it is even easier - you need to apply the analogy method (there is one for any field of activity). Suffice it to recall that in light frame houses for corner (bearing) racks, a beam with a section of 100x100 mm is used, and the canopy from the point of view of loads is not "heavier" at home.

### Foundation

For canopies standing on a foundation (strip or slab), the parameters of the foundation are calculated - the width and depth of the strip, the thickness of the slab.

For canopies with a solid fixed roof on separate pillars, the supports should be calculated by analogy with the pile foundation - taking into account the loads and characteristics of the soil. And this is the most common design option.

Useful video for choosing a foundation for supports:

### Depth of the underground part of the racks

With heaving soils, everything is simple - the pillars must be buried below the freezing depth 20-30 cm... In most regions of the European part of Russia, this will be approximately 50% of the aboveground part. Which is in line with most of the recommendations of this kind.

For dense soils, this size can be reduced to 1/3 of the aboveground part. Sandy soils, although they belong to loose ones, are no worse than dense ones in terms of bearing capacity. As a rule, they are classified as non-powdery (if the site is not located in the river floodplain). And for the underground part of the support, it is enough to dig a hole deep from 80 to 100 cm... But if in dense soils the support can be clogged with crushed stone, then in sandy soils the underground part of the column must be concreted.

### Distance between posts

If you look at articles on a similar topic, you can see a rather large spread of the recommended values ​​of the distance between the canopy posts - from 1 m to 5 m... The difference is very big to be guided by these recommendations. There are standardized methods for calculating the pile foundation, to which the underground part of the column can be attributed. And in this case, the calculation of the number of pillars and the distances between them has the following algorithm:

1. Approximately determine the number of supports sufficient for the convenience of using the canopy. Let's say that the front part allows you to drive the car, and the side racks are symmetrically distributed and do not visually "overload" the structure.
2. Choose the shape of the roof and the type of roofing. The quantity and quality of all materials are evaluated. Calculate the weight of the rafter system, lathing, roofing, ceiling filing.
3. The load from the rest of the structure is assessed: pillars, taking into account the concreting of the underground part, fencing, decorative elements, engineering equipment and communications (for example, the weight of cables and lamps).
4. The reference values ​​of wind and snow loads characteristic of this region are added to the weight of the entire structure.
5. Calculate the load on one support. If the canopy by either side rests on another structure, the calculated value is adjusted downward.
6. Multiply the resulting value by 1.2 (20% of the safety factor), divide the final design load by the total area of ​​the supports (taking into account concreting). If the obtained value is less than the standard design soil resistance by 10%, then the supports are sufficient. When significantly lower than 10% - the number of posts is excessive, higher - not enough. In the latter case, it is necessary either to reduce the distance between the supports, or to increase the concreting area of ​​the pillars. Alternatively, a metal plate can be welded onto the heel of the posts.

If the number of supports is increased, then the calculation is carried out anew, taking into account the load from additional pillars.

### Installation of poles for a canopy

Work on the installation of poles is of the following order:

1. Marking is carried out on the site.
2. They dig a hole or drill a hole of the required diameter to the calculated depth. Consider the size of the sand and gravel cushion at the bottom.
3. A sleeve made of roofing material is inserted into the hole. It acts as a formwork and does not allow moisture from the concrete to be absorbed into the ground. With its help, you can also make the heel widening, if during pouring the sleeve is raised by 5-10 cm.
4. A pipe or timber is inserted into the sleeve, the lower part of which is treated with bituminous mastic.
5. M300 concrete is poured, compacted by bayonetting with a piece of reinforcement.
6. The pillar is fixed with temporary spacers until the concrete stone gains strength (under normal conditions, concrete gains 70% of the brand strength in 7 days, and this is enough).

## Video

From this video, you can learn how to correctly make garden paths:

Concrete path

From the covers

Of stone and gravel

Stone mosaic

Original garden path

Of stone

Combined option

Classic stone path

From cuts

From saw cut and gravel

From the deck plank

From garden parquet

Pebble path

## Strip foundation: what it is

First of all, strip foundations differ in the degree of penetration into the ground.

Recessed strip foundation laid below the level of freezing of the soil, such a structure is intended for large heavy structures with a deep basement or basement. Strictly speaking, experts do not consider it economically feasible to organize a buried strip foundation with a height of more than 2.5 m, therefore, for a house with high basements or basements, it is better to consider other options.

For light country houses, a buried foundation is not recommended: the low weight of the structure will not be able to compensate for the effect of the forces of frost heaving of the soil on a large area of ​​its underground surface. This is fraught with uneven movements of the foundation and a change in its geometry, which will inevitably affect the state of the structures of the house.

Shallow strip foundation it is arranged above the freezing depth and is recommended for climatic zones where this depth is no more than 1.7 m. On non-porous soils, the final depth of the foundation does not matter much and is dictated only by the engineering characteristics of the building. On heaving soils, the foundation is laid at a minimum depth of 0.75 - 1 m, and measures must be taken to drain and warm the soil.

Also, the strip foundation can be monolithic or prefabricated.

Monolithic strip foundation is constructed by pouring concrete into the formwork. It is considered the most durable and reliable, but it takes time for concrete to harden and is quite expensive due to serious earthwork and the need to attract hired labor.

Precast strip foundation is constructed from separate structural elements. Most often, these are reinforced concrete FBS blocks (small-format concrete and expanded clay concrete blocks, and even bricks are often used). The advantages of a prefabricated foundation are simplicity and speed of assembly and the ability to erect walls immediately after its completion, since there is no need to wait for the concrete to harden. The disadvantage of specifically FBS blocks is their large weight and size - this is inconvenient when building a small house. In addition, all types of prefabricated foundations are suitable only for non-porous and slightly porous soils. With an average degree of heaving of soils, it is allowed to build a prefabricated foundation only from blocks containing outlets of reinforcement for their connection to each other.

Foundation blocks FBS

## Gravel-sand pillow

Lay geotextile at the bottom of the pit, which will protect the path from weed germination... Fill with a gravel pad, then a sand pad. All layers must be carefully leveled and compacted, for example, with a vibrating plate.

By the way, the following sequence of works is very convenient. They dig a trench across the entire width, taking into account the height of the curbs without deepening at the bottom of two grooves, cover geotextiles, cover and level gravel everywhere. Then, on the sides, a border is placed on the mortar on top of the gravel, and after it has set, a sand cushion is poured into the pit, and proceed to the next stage.

Already before laying the tiles, thoroughly moisten the sand and let it dry for a couple of hours.

Note: if you plan to move or park a car along the track, the "pie" scheme will be slightly different. First, sand is laid on the bottom, then gravel, and on top of the substrate another reinforced concrete layer of 12-15 cm with expansion joints and drainage holes is poured, and only then the dry mixture and the tile itself are poured.