Insulation of basement walls from the outside with polystyrene foam, polystyrene foam

Thermal insulation of the basement from the outside External insulation of the basement allows you to reduce heat loss, protect it from dampness and the formation of cracks, which can lead to swelling of the soil. Even without heating in winter, in the insulated basement of the house, the temperature will not drop below +10 degrees.

The price for insulation materials is not high, so all costs will not be too high. You can learn how to insulate basement walls from the outside in this article.

Good reasons why it is necessary to insulate a used basement:

• vegetables freeze at sub-zero temperatures;
• storing garden equipment in an uninsulated basement is no different from storing it outside;
• installing a boiler room in such a basement will entail large heat losses and, consequently, additional fuel costs.

The simplest and most inexpensive way to solve this problem is to insulate the basement from the inside with polystyrene foam.

A private house

In private properties, some issues regarding floor insulation, and in general construction and installation work, are resolved much easier than in apartment buildings. Firstly, you can literally do anything you want: strengthen structures, apply a layer of thermal insulation, set up a workshop in the basement - there is no need to coordinate all this with different authorities. Secondly, you don’t have to worry about violating your neighbors’ sacred right to rest due to repairs, noise and dust. Thirdly, there is much more room for maneuver to make some changes to the progress of work that has already begun, without rushing to thoroughly choose the insulating material and method of its fastening.

You need to know this: insulating the walls and floor of the basement of a private house.

All options are suitable for use in a private home: polymer boards or mineral wool. The installation of a “warm ceiling” begins by thoroughly cleaning the surface of the ceiling from whitewash, any foreign inclusions, as well as moisture. Polystyrene foam will not stick to a damp, poorly dried ceiling, so you will first have to get rid of excess moisture using a heat gun, hair dryer, or basic ventilation. Next, you need to carefully inspect the ceiling for cracks, gaps and depressions: all of them will have to be sealed with cement-sand mortar. When this stage has been completed, you can begin installing the insulating layer.

Foam plastics are glued to concrete, wood and metal surfaces with polymer compounds. If the floor is standard, reinforced concrete, then special composite mixtures (Ceresit) can be used. The solution is applied along the contour and pointwise in the center of the slab. Sometimes it is recommended to duplicate the fastening with special mounting dowels with an umbrella head, but this is more necessary for slabs of large thickness (up to 100 mm).

To protect the main structure from the effects of condensation, a waterproofing device will not interfere. For this purpose, a special impregnation is applied to a clean and dry surface, penetrating deeply into the body of the slab, and insulation is glued on top of it. It is possible to use ordinary polyethylene film, but it will have to be secured (with clamps, staples or quick-installation dowels).

The installed insulation layer will have to be monitored to ensure that rodents do not live in it, the room must be ventilated and the condition of the material must be periodically checked. All joints between the slabs will need to be puttied, and on top of them you can install a false ceiling made of plasterboard, lay plastic lining or plaster with a gypsum mixture for interior work.

There are special “jointless” varieties of extruded polystyrene foam with interlocking fastening. But they will need to be rigidly fixed to the main structure using mechanical fasteners. Recently, construction companies have been offering a new service - blowing surfaces with polymer foam, which quickly hardens in air. There is an advantage from the absence of joints (a continuous monolithic layer is formed), but such an operation cannot be performed independently; you need to hire a contractor, and it is not cheap.

Basalt or glass wool blocks are laid on cleaned, puttied surfaces. There are 2 mounting options:

• frame (additional structures are required);
• directly onto the ceiling tiles.

In the first case, you will have to “spoil” the appearance of the ceiling by arranging on it a grid of crossed metal or wooden profiles. The cells formed after installation of the frame will contain elements for insulating the basement ceiling from the inside, so their dimensions must clearly correspond to the parameters of the slabs and the width of the rolled material.

The tape layer is fixed to the frame with wire, dowels, staples - any available solution. The tile is fixed in the grooves of the profiles; it can also be additionally pressed against them mechanically. It is convenient to cover such an internal layer of ceiling in the cellar with plasterboard or clapboard, using the same frame as guides.

The second method is not fundamentally different from installing polystyrene foam: apply glue, press, and so on until complete completion. Polyethylene must be laid on top of the thermal insulation to protect subsequent layers from condensation.

There are 2 methods of ceiling insulation

Stages and rules of external insulation

It is important to know these points, as they directly affect the quality and durability of the basement finish. This:

1. Work should only be carried out in dry weather. Since the work on insulating and waterproofing a cellar can take several days (everything will depend on the number of workers and the pace of work), it is best to carry out such activities in the summer or early autumn.
2. You will need to insulate the entire wall - from the foundation to the ceiling (floor). If you only insulate part of the base, it will do nothing.

Preparation for the process:

1. Remove the blind area.
2. Dig a trench around the entire perimeter of the house. Its depth should be at the level of the basement floor. The width is such that it will allow you to carry out work easily.
3. Clean the walls from remnants of building materials and old finishing. It is also important to remove dirt from it.
4. Inspect the wall surface for cracks and chips. If such are found, they should be sealed with a solution of cement and sand. After the solution has hardened, you can continue further work.
5. If the surface of the basement walls is finished with foam plastic, then you will also need to level the base so that the sheets lie flat.
6. After preparation, the surface should be finished with a primer. There should be several layers. Only after it has been completely absorbed into the base can work continue.
7. The waterproofing material can be fused to the walls after applying a primer.
8. Next, you can work with the insulation.

Polystyrene foam or extruded polystyrene foam

Work on insulating an external wall using these materials can be carried out on your own. This type of work does not require any special skills or knowledge. These materials are the most common today, which are used as insulation.

The basement walls are insulated with extruded polystyrene foam slabs

Process:

• Calculate the area of ​​the wall and determine how many insulation boards will be required for the job.
• It is important to add about 10% to the result obtained for the battle.
• Prepare the solution.
• Apply glue evenly to the foam board and glue it to the base. Such work must begin from below. Each row is attached to the base with an offset relative to the previous one.
• After finishing, you need to coat the seams between the sheets. This should be done using cement mortar. Also, if necessary, you can cover the entire surface of the slabs with this solution.

Expanded clay

This material is free-flowing, and therefore installation work can also be carried out on your own. The disadvantage of such insulation is that it is necessary to make too large a layer, since its thermal conductivity is lower than that of foam plastic. The recommended layer is 10-20 centimeters.

Scheme for insulating basement walls with expanded clay

Work order:

• Another wall is erected at a distance of 20-30 cm from the basement wall. It can be made from brick.
• Gravel spills along the bottom.
• Drainage is laid and diverted away from the building.
• Expanded clay is poured into the gap between the walls.
• The second additional wall from the outside must also be waterproofed.

After this, the expanded clay is compacted and a concrete screed is placed on top of it. It is also important to put waterproofing underneath. You can refuse to install insulation.

Important! For the interior decoration of the basement walls, you can use the same material as for the exterior. Only the use of expanded clay in this case will not be effective, since it will take up the usable area of ​​the room. Typically, insulation from the inside is carried out using polyurethane foam.

Floor and its insulation

Not only the basement walls should be waterproofed and insulated. Such work should also be carried out on the floor. They are made using the same material that was used for the walls. Expanded clay should be poured or polystyrene foam should be placed between the joists, first covering the floor with waterproofing material. You can also put a film on top under the main floor to prevent moisture from entering the room.

Scheme of floor insulation in the basement on the ground

If there is no log system on the floor, then you can make it yourself using timber. It is also recommended to first waterproof them with a solution that will prevent the appearance of mold and mildew. The beams must be placed at a distance of 50 centimeters from each other, connecting them together with planks. If necessary, insulation can be placed on top of the first layer of waterproofing. After such work, the main floor is installed and finished.

Thermal insulation of the basement floor

Scheme of floor insulation in the basement.

The floor and ceilings above a basement that does not have heating should not be left without thermal insulation. The insulating material for the floor must be resistant to compression, since it will be subject to a large load; in addition, this material must minimally absorb moisture and be durable. Foam plastic or extruded polystyrene foam is most often used as such insulation. Sometimes mineral wool insulation is used, which strongly absorbs moisture or various bulk materials for thermal insulation.

The floor in the basement can be arranged in different ways. First of all, you should prepare the foundation for it. To do this, broken bricks or crushed stone are compacted into dry soil. If the soil is wet, you should put a waterproofing layer of crushed stone impregnated with bitumen or fatty clay on it. Peat, charcoal, expanded clay and even straw can also be used as insulation material. The base of the floor is covered with reinforced concrete or monolithic concrete. Any flooring can be used.

The simplest algorithm for organizing the floor in the basement looks like this:

• deepen the entire floor surface by 30 cm and level it;
• pour a 10-centimeter layer of crushed stone;
• cover the crushed stone with a sand cushion 5 cm thick;
• compact;
• pour hot bitumen;
• reinforce with concrete screed and iron mesh.

Preparing for basement insulation work

Before insulating the basement, it is necessary to find out the characteristics of the soil at the building site. If its water saturation is higher than normal, it is recommended to carry out drainage work in order to drain groundwater from the underground part of the house. The drainage system consists of drainage pipes with holes. They need to be laid alternately on a gravel bed made with a slope of 3-5% below the base of the foundation. After installation, the pipes must be covered with washed crushed stone. When the drainage system operates, groundwater, seeping through the crushed stone, penetrates the laid pipeline, through which it is then discharged to the sewer or to a separate well. To prevent pipes from silting, the crushed stone bedding must be protected with geotextile - a filter material. It allows water to pass through perfectly, retaining small soil particles. Thanks to this filtration, the drainage system will not become clogged for a long time. In addition to draining groundwater from the basement, before insulating it, it is necessary to examine the condition of the buried part of the walls. First, they need to be cleaned of dirt or old insulation. If after this, cracks and chips are found on the basement walls, they should be sealed with sealing mastic. All identified surface irregularities must be smoothed using a cement mixture. Otherwise, the fit of the insulation boards to the basement walls will not be tight.

Ventilation and drainage device

Proper basement ventilation.

After insulation work, the humidity in the basement may increase significantly, so it is necessary to take care in advance about the drainage, ventilation and drainage system of its walls.

For ventilation in the basement, it is recommended to provide special openings in the base, located 5 m from each other. These holes close only in severe frosts. To create drainage systems, special membranes are installed, expanded clay fillers are installed, or drainage pipes are laid.

After this, it is necessary to cover the underground part of the foundation with a glass wool mesh or cover it with hollow bricks. Sometimes drainage backfill is additionally made along the base. If the material remains visible after backfilling the soil, it is covered with tiles or brickwork.

To protect the cellar from precipitation, you can build a blind area of ​​asphalt or concrete around the entire perimeter of the building. Such a blind area will remove melt and rain water from the foundation. When creating a blind area, it is necessary to pay special attention to its joints with the basement walls. To protect against groundwater, you can equip a clay castle.

Advantages of basement insulation with polystyrene foam and its disadvantages

The experience of thermal insulation of basements with polystyrene foam indicates that even at a foundation depth of more than 7 m, it is reliable, regardless of the brand of this material and the duration of exposure to groundwater under pressure. When deciding to insulate a basement with extruded polystyrene foam, you need to know about its advantages and disadvantages in order to use this insulation as efficiently as possible. The advantages include the following:

• Basement insulation with polystyrene foam creates an excellent coating with low thermal conductivity.
• The weight of the insulation is so small that it does not exert any serious load on the basement walls.
• Compared to other methods of thermal insulation, protecting the basement from dampness and cold with polystyrene foam will cost much less, especially since a lot of material will be required to insulate its walls.
• Thermal insulation 100 mm thick is comparable in thermal conductivity to brickwork one meter thick.
• After installation, the finished coating is slightly susceptible to aging and is stable in shape and size.

The disadvantages of expanded polystyrene include, as mentioned above, its flammability and the release of toxic fumes when the material is heated.

Material and its choice

Since the main problem in the basement is dampness, you need to choose materials that can withstand it. Therefore, you should not use mineral wool insulation, which can absorb moisture into its structure and lose its properties over a short period of time.

For thermal insulation or thermal insulation of the cellar, you should use:

1. Extruded polystyrene foam. Thermal conductivity is (0.035−0.04 W/m2)
2. Penoplex (0.03−0.035 W/m2)
3. Expanded clay (0.12 W/m2)

These types of insulation are the most suitable for exterior decoration of the cellar, and therefore they are used most often.

In addition to thermal insulation, waterproofing must also be used. To create a layer that will not allow moisture to pass through, you need to use the following materials:

• Additives that are added to concrete during construction and prevent moisture from penetrating into the solution from the soil.
• Directional isolation.
• Coating type insulation.

Insulation of basement walls from the outside with extruded polystyrene foam

When it is possible to perform external insulation, they are often limited to it. In this case, labor costs are higher, because excavation work is added: the base from the outside must first be dug out.

In addition to EPS, to treat the outer part of the foundation you will need bitumen mastic or other bitumen adhesive, as well as asbestos cement slabs.

During the preparation process you need:

• level the wall;
• waterproof the wall with bitumen mastic. Wait until it hardens;
• treat with an antifungal compound (slaked lime, copper sulfate).

Approximately 5 days after waterproofing, you can begin insulation:

1. Glue the EPS onto the waterproofed surface with bitumen mastic. Only cold mastics that do not contain a solvent are suitable for this purpose. The mastic is evenly distributed over the entire slab, the slab is pressed against the wall and fixed for half a minute.

2. The slabs are installed from bottom to top, end-to-end, tightly fitting each other. Their thickness should be the same. The height of the masonry above the ground is about half a meter.

3. Foam the seams.

4. Cover the outside of the masonry with asbestos-cement slabs.

5. Fill the ditch with soil.

Insulate inside or outside?

The basement can be insulated from the outside and from the inside, but external thermal insulation will have a much stronger effect than internal insulation. Insulating cellar walls from the inside is appropriate in cases where it is not possible to do it from the outside. The outer layer of insulation will protect the wall and moisture-proof coating from temperature and mechanical influences. In turn, internal thermal insulation can contribute to the appearance of water at the point of contact of the insulation with the basement wall.

External thermal insulation has many advantages over internal insulation.

External insulation of a cellar or basement has many advantages:

• The overall microclimate in the basement will be improved.
• The surface of the walls of the basement or cellar will become warmer.
• Condensation will stop forming on the walls.
• The dimensions of the basement will remain the same after all work has been completed.
• A more profitable solution from an economic point of view.
• In a properly made thermal insulation layer, cold bridges will not form.
• External waterproofing will be protected from mechanical stress.

Relevance of the work: is it necessary to insulate?

PPU is not afraid of mechanical influences, because After application to the surface, it gradually hardens and becomes very durable.

Heat and lack of moisture are the main criteria that every room of every building must meet, regardless of its purpose. And if it’s a residential building, even more so. After all, you will agree - it is unlikely that you will enjoy living in a cottage, suffering from cold and damp for almost half the year?

It is the basement that is one of the reasons for this phenomenon. The lack of a high-quality hydro- and heat-insulating layer leads to the fact that moisture and cold penetrate inside the basement (by the way, even thick concrete walls do not stop the water). Naturally, the poor microclimate under the house will immediately become noticeable in the living quarters: the floor will be cold, and mold and mildew will gradually appear on its surface and on the surface of the walls. This:

• spoils the completed repairs;
• accelerates the destruction of the structure;
• negatively affects the health of people living in the house.

Preliminary waterproofing of the room

Before insulation, horizontal waterproofing of the room is performed (if it has not already been done). You can choose any insulating materials (the market offers a wide range). Only after the waterproofing is done can you begin to insulate the walls of the basement or cellar from the outside.

It is recommended to additionally treat the surface of the heat-insulating material, which will be located below ground level, with waterproof mastic. In addition, before insulating the basement walls from the outside, these walls need to be leveled. It will not be superfluous to apply antifungal agents.

It is recommended to begin work on external thermal insulation of the basement 5-7 days after you have completed all measures to protect against moisture.

How and what to insulate a basement with

This operation can be performed in different ways, but the most effective is considered to be insulating the basement walls from the outside. Using this technology, the walls are finished with thermal insulation material at the construction stage. As a result, they do not freeze and condensation does not form on them.

The whole process comes down to finishing the walls, floors and ceilings with thermal insulation material.

Moreover, the overlap should be touched only in two cases:

• If the temperature in the basement is lower than the rest of the house;
• When the room is warm and there is a cold floor above it.

As for the choice of the heat-insulating material itself, there is one condition - it should not absorb moisture. An excellent option is to insulate the basement walls with polystyrene foam. At the same time, waterproofing is also carried out.

Note! To get a dry and warm room, it is also necessary to install a drainage system around the perimeter of the building.

The procedure for insulation work

To insulate outside walls, special slab insulation materials are usually used, which are easy to install. The slabs are fixed to the waterproofing layer using adhesive mixtures or mastics. Treating the entire surface of the insulation board with mastic reduces the risk of the insulation shifting when the ground moves.

Related article: How to stick photo wallpaper on a wall with wallpaper

It is recommended to carry out insulation immediately during the construction of the house.

Cold mastic must be applied to the surface of the slab, then pressed against the wall and held until the adhesive hardens (usually 30-40 seconds).

The laying of thermal insulation slabs should begin from the bottom (strictly along the perimeter); the slabs can protrude 30-40 cm above the ground.

It is important that the insulation boards are of the same thickness. In addition, it is necessary to ensure that they are tightly adjacent to each other. It is recommended to immediately seal all resulting voids with construction foam. In the future, the slabs will be securely supported by a layer of soil. The main thing is that they do not move apart or move.

Insulation of basement walls, as noted above, should be carried out during the construction phase of the building. If for some reason this was not done, then it is better to insulate the basement yourself only from the inside. External insulation in a built house can only be done efficiently by professionals. It is not recommended to do such work yourself without the appropriate skills due to the high risk of weakening the foundation and walls of the building.

Insulating the cellar lid

The cellar lid is the part of the building through which air passes most intensely. If it is not insulated correctly or not at all, this will lead to large heat losses in winter. It is important not only to insulate the cover from the outside, but also to ensure that the joints and door jamb are also protected. Rubber and polyurethane gaskets that can be attached around the perimeter of the lid are suitable for this. When installing insulation, you need to create a single layer between the wall and the door so that air does not penetrate from the outside. It is better to insulate the lid with rigid insulation. Suitable polyurethane foam, which hardens within a few seconds after spraying, polystyrene foam or polystyrene foam. After fixing the material, it must be covered with a sheet of plywood, wood or plastic. It is important to ensure that the cellar lid does not open arbitrarily or from the wind, but is firmly attached to the surface.

DIY basement insulation technology

Let's look at how complex basement insulation is carried out using penoplex (the technology will be similar for polystyrene foam and expanded polystyrene). Note that comprehensive thermal insulation includes external and internal insulation (in particular walls, floors, ceilings).

In addition to insulation for work you will need:

• material for interior decoration;
• polyurethane foam;
• reinforced polymer mesh;
• waterproofing material (bitumen mastic);
• adhesive solution;
• concrete or external plaster;
• tool.

Internal insulation

Any type of expanded polystyrene is most often used precisely to insulate the basement from the inside. Here there are some features for each of the available surfaces: ceiling, floor and walls.

Wall insulation

Insulating the basement walls from the inside helps maintain the temperature in the room. In addition, to avoid condensation accumulation in the basement, it is very important to use high-quality waterproofing materials. This will ensure long service life of the thermal insulation and prevent the destruction of the structure as a whole.

Next, polystyrene foam boards are attached on top of the material chosen for waterproofing. Glue is usually used for fastening. After all the walls are covered with slabs and the glue has dried, additional work is carried out on the surface of the basement walls.

A concrete screed is used to strengthen the structure. To create it, it is recommended to purchase M100 cement and use additional reinforcement. Do not be too zealous; the screed layer should not be too thick.

Since any basement has high humidity, an additional layer of waterproofing material will not be superfluous, but this item is optional. After insulation with polystyrene foam materials, the surface can be covered. For this, you can use various materials, it all depends on the budget and wishes of the owner.

Important! Not a single joint of the thermal insulation material should protrude, since these are the places that are most vulnerable to the formation of condensation.

wall insulation

Floor thermal insulation

In practice, bulk elements are used as thermal insulation components for the floor in basements and cellars. Peat or sawdust are great for this. To prevent moisture from penetrating from below, you first need to lay everything with an insulating film, then make uniform mounds, and also, if necessary, apply a coating so that the material does not spread, but remains in place.

Thermal insulation of the floor with sand

To insulate a bulk or traditional cellar, it is recommended to choose sand as insulation for the floor. It has a relatively low cost, but at the same time it has excellent heat retention qualities. To achieve the best performance, the composition is distributed evenly and covered with finishing or film on top.

Thermal insulation of the basement entrance

Previously, we looked at how you can insulate the ceiling in the cellar, as well as other structural elements. However, the job will not be completed unless the input is properly insulated. Here you have to face the following nuances:

1. Structures cannot be insulated with polystyrene, as the exit may subsequently be blocked.
2. It is recommended to cover the entrance with insulating protection both from the inside and outside of the basement structure.
3. Immediately before starting thermal insulation work, it is necessary to free the input element from all unnecessary things.
4. It is recommended to insulate the door or hatch from the cold with mineral wool, which is attached from the inside of the cellar.
5. On the outside, a more compact heat-resistant element (insulating film) needs to be glued to the entrance.
6. It is recommended to use a material that is larger than the input.
7. A film must be sewn on top of the thermal insulation material, followed by finishing elements.
8. The door frame should be secured with foam to cover the gaps.

Advantages and disadvantages of the material

What can be distinguished from the advantages and disadvantages of foam plastic boards for insulation?

The material is afraid of high temperatures, which, however, is practically not relevant for the cellar.

The advantages of the material include:

• Good thermal insulation properties.
• Polystyrene foam weighs little, so it does not put stress on the walls and foundation.
• When compared with traditional and modern analogues, polystyrene foam is a very affordable thermal insulation material.
• The material has a high level of moisture resistance.

As for the disadvantages:

• If we consider the option with external insulation, then polystyrene foam is unlikely to be suitable here, because when heated (for example, from sunlight) it begins to release vapors.
• When exposed to fire, polystyrene foam will begin to melt and burn, releasing toxic substances. However, in the case of a cellar, this problem, as a rule, is practically irrelevant.
• Foam plastic is subject to mechanical stress, so before installing the insulation, it is necessary to check the integrity of the installed slabs, because some of them may be cracked.

Experts recommend purchasing foam plastic with a density of 25 for insulating cellar walls.

All work on insulating the basement can be done with your own hands, so there is no need to involve specialists in this process. If the cellar needs to be insulated in an already built house, then it is recommended to insulate the room from the inside, because in the process of carrying out external insulation work, certain problems with the foundation may arise.

Useful tips

If you decide on external thermal insulation of the basement, a few tips will be useful for you that will help increase the efficiency of the measures taken:

1. It is better to carry out insulation in dry and clear weather. Especially if instead of EPS you use regular foam, which is less resistant to moisture.
2. Never neglect waterproofing. This operation not only prevents damage to the insulating material, but also protects the foundation and walls of the basement from destruction.
3. When choosing a mastic with which you are going to glue foam or EPS, pay special attention to its hydrophobic properties. And do not apply it pointwise (as I described for interior work), but in a continuous layer. Then it will play the role of another waterproofing agent.
4. The edge of the glued insulation material must rise above the ground level (after backfilling) by at least 50 cm.

A basement like this is everyone’s dream.