Do-it-yourself blind area of ​​paving slabs around the house

Recommendation points

• Can paving stones function as a blind area
• Soft and hard types of blind area
• Period of work
• Excavation
• Filling device
• Concrete works
• Laying tiles

Although foundation protection is rarely paved with paving slabs, this option still deserves the right to life. We will talk about the features of this blind area, the feasibility of its device, as well as ways to make really high-quality protection, and not just a path around the house..

Can paving stones function as a blind area

At a first approximation, it may seem that there is really no difference between concrete and paved blind area. Well-laid paving slabs with the correct slope really take about 95% of the precipitation over their surface, but this only applies to rainwater. The situation changes dramatically during unstable winter weather.

The fact is that the cap of snow and ice that forms in the immediate vicinity of the plinth tends to thaw during the day. The percolation of moisture both into the soil and into the thickness of the bedding has sharply negative consequences and it does not matter at all that the volume of the incoming water is simply scanty. The worst that can happen is the saturation of the soil with water and a sharp increase in its heaving properties. But even if the water freezes immediately below the surface of the blind area, it is highly likely to lead to swelling and deterioration of the coating..

In order for the blind area to perform its function correctly, it must work as a one-piece hydro-barrier, while the upper layers of the bedding should be protected. This can be done either by ensuring their high hygroscopicity, or by organizing a water-repellent layer directly under the tile. Both options are good in their own way and therefore will be fully considered today..

Soft and hard types of blind area

The blind area of ​​tiles can be arranged both by the usual method of laying with a hydro-barrier device, and on a concrete base. These two types of device are called soft and hard respectively..

The soft method is good because it does not imply additional concrete work. However, in this case, the filling must be carried out strictly in layers, ramming each layer to the appropriate density. The main difficulty is to ensure the highest possible hygroscopicity of the material poured over the hydro-barrier. Also, a complex bedding device requires the use of special means that anticipate the erosion and punching of layers..

Soft blind area from paving slabs: 1 – compacted soil; 2 – the foundation of the house; 3 – gravel; 4 – sand; 5 – hydro-barrier; 6 – geomembrane; 7 – gravel; 8 – geotextile; 9 – sand; 10 – paving slabs; 11 – sand pillow; 12 – concrete base; 13 – drainage tray; 14 – border

The method of laying tiles on a concrete base is also quite viable. Usually, the device of a rigid blind area is divided into two stages: pouring the foundation and directly laying the tiles. The difficulty is that concrete work must be carried out around the entire perimeter of the building at one time at each of the two stages. However, the preparatory layer can be poured without formwork, using as the last dump of soil left after excavation.

Blind area of ​​paving slabs on a concrete base: 1 – compacted soil; 2 – the foundation of the house; 3 – gravel; 4 – a mixture of gravel and sand; 5 – foundation; 6 – reinforced concrete layer; 7 – a corrective screed; 8 – mortar for paving slabs; 9 – paving slabs; 10 – border; 11 – concrete base

Period of work

It is better to decide in advance at what stage of construction the blind area should be installed. The fact is that it will not be possible to give an unambiguous answer to this question, it all depends on the type of substrate. As a rule, after the foundation is laid, a mixture of clay soil forms around the building, which greatly complicates the movement of workers, the delivery of building materials, as well as the decoration of the walls and basement. On the other hand, arranging a blind area entirely and immediately is fraught with damage to the tiles, for example, from scraps of building mixtures falling from a height. If, however, to refine the adjacent strip at least to the level of the bedding, the work can be greatly facilitated. But, we repeat, you need to act depending on the type of blind area device.

If a rigid blind area is chosen as the preferred option, the only difficulty is in the correct determination of the zero mark. As a rule, they try to bring the blind area to the same level with the courtyard covering, which remains unknown until the completion of the roofing and glazing. At the same time, the earlier the protection of the foundation from the incoming moisture begins to act, the better. Therefore, in this case, the ideal solution would be to pour the concrete preparation almost immediately after removing the formwork from the foundation, and then raise the level to the desired level either with a layer of concrete or with gravel bedding and a screed..

When arranging a soft blind area, everything is somewhat simpler. The gravel embankment can be planned arbitrarily at any time, without worrying in advance about the accuracy of reaching the general level. However, gravel itself will not protect against water ingress into the ground, therefore, a device is required at least the simplest, but continuous waterproofing that can serve until the completion of finishing work. The best option would be a regular polyethylene film, laid under the gravel, protected from above and below with thin layers of sand of 20-30 mm.

Excavation

When all the work on the installation of the blind area is well planned, you can proceed to implementation. The first stage is the removal of the top layer of soil around the foundation to a sufficient depth. It is determined by the desired final coverage level and can vary from 150-200 mm..

The first step is to decide on the width of the strip on which the soil will be removed. It should be 15–20 cm more than the width of the blind area, which, in turn, is determined based on the depth of the foundation support. It is believed that the minimum width of the blind area is 80 cm, otherwise it will be extremely inconvenient to walk on it. This width corresponds to a foundation depth of about 100 cm.For every 20 cm increase in depth, the blind area must be expanded by at least 5 cm, that is, conventionally 1: 4. Of course, everything here depends on the so-called cone of soil wettability. On this question, an exhaustive answer will be given by compiling a hydrogeological profile.

Excavation should be carried out at a variable depth, deriving a common support plane (bottom). Thus, it is better to start work from the lowest point of the plan, despite the fact that the width of the blind area is calculated according to the depth of the foundation at the highest point. It is necessary to remove the soil in such a way that the bottom of the pit is on average 20–25 cm below the desired level of coverage when installing a soft blind area and 15–20 cm lower when installing a hard one. If the blind area is planned to be insulated, an additional 50–70 mm should be removed. It is better to dump the soil into the adjacent territory, in the future, part of it will be used for backfilling. When installing a soft blind area along the outer border of the pit, you need to dig a drainage trench about 15 cm deep.

Filling device

The main materials for creating an embankment for both types of blind area are coarse open pit sand of fraction 0.7-1.5 and gravel of fraction 20-25. It is desirable that the sand be thrown through a mesh to remove clay inclusions, while gravel is best used after being exposed to the open air for 2-3 months. In both cases, the gravel layer is poured first. They align the pit to a mark 15 cm below the final level of the blind area. Further, the paths of the embankment device diverge.

For a rigid concrete blind area, formwork from a waste board is installed in the pit, which is 10–12 cm less than the actual width of the preparation. The board is supported on the outer wall of the pit with inserts from a bar of suitable length. This formwork is needed to form the so-called “tooth” of the foundation, which increases the stability of the blind area and prevents moisture from leaking under the concrete. After that, I fill up the wide part of the pit with a mixture of gravel and sand to such a level that, in the end, the thickness of the concrete preparation is at least 70 mm.

Adding under a soft blind area is performed according to a different scheme. The preliminary gravel layer is raked towards the foundation, ensuring a slope of at least 15: 1. All subsequent layers should be poured and tamped with such a slope. Next, a 20 mm layer of sand is poured onto the gravel and thoroughly rammed until there are no more distinct footprints on the surface. A hydro-barrier is laid on the resulting layer. The latter can be glass insulation, membrane waterproofing and even a used banner fabric – the choice remains entirely with the developer. The width of the water barrier should be such that its edge is approximately in the middle of the drainage ditch. It is recommended to secure the opposite edge to the plinth or foundation with planks and dowels.

After installing the hydro-barrier, it is necessary to form a bedding under the tile itself. To exclude its silting and punching, needle-punched geotextiles are rolled out at the boundaries of the layers, and a geomembrane is laid directly on the hydro-barrier. Next, layer-by-layer backfilling is carried out: first, gravel with a layer of about 10 cm, then leveling the embankment of sand until it reaches a mark below the desired level by the thickness of the tile. The sand in the upper layer can be replaced by screening out blast-furnace slag of a coarse fraction.

Concrete works

Pouring with concrete is carried out along a complex profile. To ensure an even outer plane of the “tooth”, the wall of the trench should be reinforced with a board. For this purpose, the excavation is carried out along a wider strip, so that later it remains possible to easily remove the formwork. It is very important to separate the concrete preparation from the base with a polyethylene foam tape.

Concrete work, as already mentioned, can be carried out in one or two stages. At the first stage, the concrete is poured without reinforcement with a layer of at least 40 mm. The lowest grade concrete available can be used here. The surface can perceive the through load after a week of exposure, but it is better to install the scaffolding on the blind area only 28 days after pouring. Please note that the formwork board is not removed until the second stage is poured, but it can be half-sprinkled with earth.

At the second stage, pouring is carried out with concrete of a class not lower than B25, it is optimal if antifreeze modifiers are added to the mixture. Before pouring, the concrete surface must be thoroughly washed from dirt and a reinforcing mesh with a cell of about 100×100 mm and wire from 3.5 mm should be laid on top. Pour in the second stage to the approximate level of the coating minus the thickness of the tile and an additional 20-25 mm for the device of the corrective screed.

Laying tiles

When installing a soft blind area, tiles can be laid immediately after the completion of the top layer of backfill, usually this is done, sequentially bypassing the perimeter of the foundation. But for laying tiles on a concrete base, you first need to accurately determine the level of the yard covering, and even better – lay it first, and only then proceed to the completion of work with the blind area.

The technique for laying tiles on concrete is extremely simple. To do this, a corrective screed is first applied, due to which the surface is brought out below the finishing level by a tile thickness and an additional 5–7 mm. The material for the screed is high-quality cement with a high degree of hydrophobicity, usually for these purposes a set of chloride salts and surfactants are added to the mixture. The screed also provides a slope of at least 20: 1, so the mortar must be thick.

After the screed has dried, tiles can be laid. With a 10–12 mm comb, a layer of hydrophobic mortar is applied to the screed, then the stones are freely stacked and sunk using a rule. To facilitate alignment, it is recommended to first lay the starter row, which is aligned with the longitudinal mooring and pressed down no more than half the height of the comb, and then plow the remaining plane. It will be easier to do this if you pre-install curb stones or a flat rail from the outside. That is, at first, one transverse row is freely laid on the solution, which is completely pressed by the rule to the desired level, and the starting line and the curb act as restrictive beacons.