How to Design a Basement Floor in an Apartment Building

To answer the question about the height of the plinth for a building made of aerated concrete, you first need to understand its essence and the tasks it must perform.

The basement is the above-ground part of the foundation from which the walls of the first floor begin. The base can be concrete, as a continuation of the foundation, or made of brick.

The main task of the plinth is to protect the walls from getting wet, for example, from a layer of snow in winter and from splashing rain. But what height of the base should you choose and is it always needed? More on this below in the text.

Let us immediately note that we do not recommend building a base out of brick, since this does not make the slightest sense, due to the fact that brick is capable of raising water very high from the foundation. In other words, brick does not work at all as a waterproofing material.

We wrote in more detail about this issue in our previous article - is aerated concrete necessary for a brick base?

Pros and cons of the plinth in different buildings

Let's look at the differences between a purchased and a self-built plinth.

In a separate house

The advantage of such premises in the private sector is obvious - it is an increase in the living or usable area of the house. You can place anything in it.

Boilers, gas equipment.
Pantry for storing food supplies and things.
Living room.
Gym.
Kitchen.
Cinema.
Sauna, swimming pool.
Workshop.
Library.
Garage. The disadvantage of this option is that the odors of oil and gasoline enter the residential area. You will need good ventilation, as is the case with a sauna and swimming pool.
Living room. If the house is located on a hill, the wall can be completely glazed and a beautiful winter garden can be equipped.

At the same time, you do not take away a single centimeter of space from the local area. An additional advantage is that there is no need to insulate the floors on the ground floor. The semi-basement will act as an air buffer between it and the ground.

The disadvantage can be considered an increase in construction costs. Equipping a semi-basement will require additional costs for design, waterproofing, heating, lighting, ventilation, and internal repairs. Also, when making calculations, you need to include an item for future maintenance costs. This is especially true for the arrangement of living rooms.

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What does the ground floor mean in multi-apartment housing?

As for urban development, the advantage is the reduced price of apartments with this location. The difference between ordinary and basement housing can be large or almost imperceptible, depending on the layout of the property and the year it was built.

Minuses

Since these are often older houses, they can feel damp and cold.
The street is very close, which means that most likely the noise will interfere with proper rest.
According to SNiP 31-01-2003, clause 5.5, the premises are not intended for housing, which means you cannot register in it. But if all the documents are in order and the developer was able to register the property as residential, there should be no problems with registration.
Increased risk of theft. It is reduced by bars on the windows and a good door.
Lack of daylight. Depends on the layout, some apartments are difficult to distinguish from ordinary ones.
Psychological discomfort. The windows of the room may be level with the ground, which is unusual for many people.
Possible problems with selling the premises. Most buyers are concerned about the location of the apartment. This means that you can only sell at a reduced price.

When purchasing, pay attention to the walls, floors, characteristics of the area and yard in which you plan to live. Check the documentation carefully. If you choose moisture-resistant finishing materials, as well as high-quality windows and doors, most of the disadvantages are reduced to zero. But in new buildings there may be no shortcomings.

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Ground floor and basement - what's the difference?

Both the basement and the ground floor are premises partially or completely buried in the ground. So what is the difference between one and the other? The difference between them is technological and lies in the depth to which they are immersed:

the ground floor is recessed below the planning level of the ground by less than half;
the basement is below this level by more than half or all.

It should be taken into account that both rooms can perform different functions - if the ceilings are below 180 cm, then this is a technical underground floor, regardless of the level of depth. With higher ceilings, they can be classified as residential premises.

Gym in the basement
In small areas, basements/basements allow you to create additional, necessary rooms without increasing the total building area of the house.

Tips for arranging and finishing the basement in a private and apartment building

At the stage of planning and construction of the base, two important factors must be taken into account that affect the durability and reliability of the building.

Construction works

One of the factors is waterproofing. To do this, drainage is required. If the groundwater level is high, a drainage system is created along the perimeter of the pit with water pumping out, or construction water reduction is performed. The video contains a detailed explanation of the basement waterproofing system.

The second thing that is important to consider is ventilation. For it, vents are created in the wall - holes 15*25 cm (approximately). They are covered with a mesh. In addition, climate systems are installed. You cannot skimp on these two technologies, since the durability and comfort of the base depend on them. During operation, you need to monitor the condition of drainage systems, roof gutters and blind areas.

Alternative options

Along with monolithic technologies, piece construction materials of small and large format can also be used to create strip foundations. In the first case, this is a revered brick - so we will pay a little attention to it.

Brick tape

When constructing a basement floor from brick, you only need to take for work a clay, well-fired version, which builders call “iron ore.” You can distinguish it by color: the longer it is fired, the more saturated red, or even red-brown, it turns out.

The rich color of the brick indicates a good degree of firing

So:

The aesthetics of the products are not particularly important here, so you can buy the most inexpensive backfill brick. But so that you don’t have to plaster or veneer the visible part of the base when it is brought to the surface, you can use a facing brick to lay the facing verst.
Unlike all other foundation options, which can be laid directly on the ground, there must always be a concrete foundation under the brickwork. This can be a reinforced concrete footing (10 cm thick), or a full slab foundation (30-40 cm thick).
In the first case, the brickwork must necessarily widen downward. If the walls are up to 3 m long, their thickness will be 380 mm (1.5 bricks). In this case, the width of the supporting part of the wall should be 640 mm (2.5 bricks). On longer walls, these figures increase to 510 and 770 mm respectively.
When the walls of the basement rest on a monolithic slab, there is no need to widen it, so the masonry is erected like a regular wall. However, brick walls have many mortar joints through which moisture can be absorbed - so it needs enhanced waterproofing.

Layout of a brick basement floor

Laying the plinth in the ground part

This plaster will create an impenetrable barrier to moisture on the outside of the brick wall.

Coating basement walls with bitumen mastic

Naturally, these are hydrophobic additives to the solution, but this is not enough. When it comes into contact with the ground, there is always a chance that the masonry will get wet - especially when the groundwater level is close. Therefore, the outside should be plastered with waterproofing plaster, and then floating waterproofing should be done (see Waterproofing basements from groundwater: options and execution of the work). In dry soil, it is enough to coat the masonry with bitumen mastic and cover it with roll material.

Note! When there is a monolithic slab at the base of the basement floor, instead of brick you can also use small-format concrete blocks - only not cellular ones, but ash concrete ones: cinder block or expanded clay concrete block. You can also use polystyrene concrete blocks. Just remember that such masonry cannot be used as an independent foundation!

Disadvantages of the design

Often, if there are advantages, then there must also be disadvantages. However, in this case, if there are any disadvantages, they are not objective, but depend on the specific situation. Here we can highlight only two main ones:

One of them is cost . Since the basement is a fairly large part of the structure, it requires a large amount of building materials. Accordingly, the higher it is, the more expensive its construction will be. Especially if it is planned to be covered with decorative materials.
The second disadvantage is related to its inappropriateness . This is possible when, for example, the walls of the building themselves are quite low. Then it will look ridiculous and visually shorten the house even more.

For some, the need to create a staircase . Because the higher the base, the higher the location of the door and the more steps to the entrance. For some, this climb may be uncomfortable or difficult.

Insulation of the basement of a private house

Developers usually always pay enough attention to insulating the external walls and floors of the first floor of the house, but often neglect to eliminate the cold bridges in the basement through which heat escapes from the house.

To eliminate the cold bridge in a house with floors on the ground, the base is insulated from the outside to a height of at least 1 m down from the floor level. The insulation layer is buried in the ground below the blind area.

When building a house, it is recommended to insulate the base and underground part of the foundation to a depth of at least 0.5 - 1 m from the outside with a layer of insulation. This insulation option for different wall structures is shown in the figures above.

Insulation of the base and foundation allows you to eliminate or reduce the depth of soil freezing in the basement space with wooden or concrete floors on the ground, as well as under the base of the foundation. This reduces the impact of frost heaving forces on the house structure.

If we supplement the vertical thermal insulation of the foundation with a horizontal thermal insulation skirt, we will get the design of a thermally insulated foundation - the best for a private house.

In addition, the thermal insulation of the base eliminates the cold bridge

through the base and load-bearing part of the wall, bypassing the thermal insulation of the floor and wall.
In a single-layer wall, the floor is raised to the level of the second or third row of masonry.
The vertical waterproofing of the base is raised to the same level. 2 - waterproofing; 4-5 - plaster on a grid; 8 - finishing; 9 - floor on the ground If the soil on the site is not heaving

or weakly heaving, then the task of combating the forces of frost heaving is not worth it. In this case, it is only necessary to get rid of the cold bridge through the base and load-bearing part of the wall.

To eliminate the cold bridge in a house with single-layer walls

without insulation of the base, it is necessary to raise the floor to the level of the second or third row of masonry blocks of the outer wall. This is sufficient, since the material of a single-layer wall has low thermal conductivity.

The load-bearing part of two- or three-layer walls is usually made of material with high thermal conductivity. To eliminate the cold bridge in two- or three-layer walls, you can cover only the upper part of the base with insulation, approximately 0.5 m below the floor level. This will increase the length of the heat flow path along the base.

If the basement space under the house is not heated, then the basement is covered with thermal insulation on both sides.

In multi-layer walls, to eliminate the cold bridge, cover one outer or both sides of the base with thermal insulation (for houses with an unheated basement or floors on the ground)

For multilayer walls, another way to combat the cold bridge is used. The lower rows of masonry of the load-bearing part of the wall are made of wall material with low thermal conductivity. The floor level is raised in the same way as for a single-layer wall.

For insulating the base and underground part of the foundation, extruded polystyrene foam slabs (penoplex, etc.) are best suited.

It is convenient to insulate strip foundations. The design of pile foundations with bored (including TISE) or screw piles is more suitable for a cold base. Insulation of such foundations is quite problematic and expensive.

The basement space of houses with pile foundations is usually not insulated.

The design of the basement and floor of the first floor of a house on a pile foundation is chosen taking this circumstance into account.

Next article:

How to make your home warm - breathability and ventilation

Previous article:

Leveling, wall covering with dry plaster and plasterboard

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Basement waterproofing

For any type of basement, a prerequisite is waterproofing to prevent the impact of precipitation on the material, and if there is a basement, also to protect it from groundwater rising into the room through concrete capillaries.

Various materials are used to perform insulation:

Impregnation based on bitumen. It is often used in the part protruding above the ground, applied with a brush or roller, and then covered with a finishing material.
Roll material based on bitumen or rubber. It is used along the entire height of the plinth, both from the inside and outside. The disadvantage of this material is that when installing the finishing, it is necessary to use spacer panels, since natural stone or tiles cannot be glued onto such waterproofing.
Liquid glass. Impregnates the source material to a depth of 1-2 mm and forms a reliable water-repellent layer.

Also, before the construction of load-bearing walls begins, the junction of the masonry and the plinth is covered with waterproofing material, most often bikrost or roofing felt is used.

It is glued to bitumen mastic by heating in one layer. You should not use roofing bicrost, as it contains crumbs, this will prevent good adhesion of the base to the masonry.