Preface. Many owners of private houses are interested in the question of how to properly insulate the basement of a house from the outside with polystyrene foam (penoplex, polystyrene foam or polyurethane foam). We will tell you how to make thermal insulation for this structure with your own hands, using extruded polystyrene foam and foam boards. At the end of the material we have posted detailed video instructions on this topic.
The basement of the house should be waterproofed and insulated for the winter, then you will save money on heating the room. In this article, we will consider the technology of thermal insulation of the base of a building with polystyrene foam with our own hands in order to reliably protect this structure for the winter. Let us remind you that for better protection of this structure, you should additionally insulate the strip foundation and blind area around the house.
Is it necessary to insulate the basement of a house with polystyrene foam?
The main task of the base of a bathhouse, a house and any building is to protect the walls of the house from the negative effects of moisture coming from the soil and foundation. But the base also needs protection. To waterproof concrete surfaces, penetrating waterproofing Penetron or liquid bitumen waterproofing should be used. The use of extruded polystyrene foam will add thermal and waterproofing qualities to the structure.
Is it worth it to insulate the basement for the winter with your own hands? Thermal insulation of the basement of a private house is carried out to reduce heat loss in the house, as well as to protect structures from moisture. Thermal insulation will have a positive effect on the microclimate of the basement of a residential building. More often, to insulate the facade and base, mineral wool of increased rigidity or polystyrene foam boards are used, which will reliably protect the structure from bad weather.
How to insulate the basement of a house from the outside with polystyrene foam
There are two options for thermal insulation of the basement of a house - internal and external. The difference is where the insulation is attached. External insulation is more popular because it allows you to protect the structure from freezing and achieve better heat retention. External thermal insulation minimizes seasonal heating and cooling of the base, which can lead to its gradual cracking due to temperature changes.
How to insulate the basement of a house with penoplex
Penoplex, like technoplex, is nothing more than extruded polystyrene foam. This thermal insulation material consists of tiny polystyrene foam granules with air enclosed in them. Penoplex has excellent thermal insulation and does not absorb moisture, due to the fact that the granules are closed. In addition, extruded polystyrene foam is more durable than polystyrene foam.
When using penoplex, the base will be well protected from freezing. It is better to choose high-density foam or extruded polystyrene foam for finishing. By doing the work correctly, you will reduce heating costs and protect the structure from freezing. Watch the video at the end of the article on how to insulate the base yourself, from which you will learn even more information on this topic.
How to insulate the basement of a house with polystyrene foam
Polystyrene foam is cheaper than extruded polystyrene foam and, thanks to this, is very popular among private developers. But it is better to use the material outside residential premises, for example, for thermal insulation of a brick wall or the facade of a house. Polystyrene foam, like penoplex, is highly flammable and, when burned, releases toxic substances that are hazardous to human health.
After insulating this structure, special attention is paid to the decoration. The cladding allows you to give the base an aesthetic appearance and protect the insulation from negative environmental factors - moisture, ultraviolet radiation and frost. Various materials can be used for cladding. Decorative plaster, siding and PVC panels are the most common option.
How to insulate the basement of a house with polyurethane foam
Polyurethane foam is an expensive technology for thermal insulation of structures, therefore it is more often used in the construction of industrial buildings. To insulate the base with polyurethane foam, you will need professional equipment or enough money to order services. At the same time, polyurethane foam fits perfectly on any surface and creates a continuous waterproof layer of thermal insulation from the street.
The base, insulated from the outside, can be finished with PVC panels to imitate wild stone and it will look much more impressive, plastered with ordinary mortar. Whatever insulation and finishing option you choose, remember that insulating the basement of the house from the outside with polystyrene foam will help keep the house warm in winter, and the floor on the first floor of a private house will not require thermal insulation and will be comfortable to walk on.
Many novice builders, among those who are lucky enough to own their own country plot, and who want to carry out most of the work on their own, make many serious mistakes at first. And one of the quite common ones is ignoring the issues of reliable and insulated foundations.
The resulting “picture” is interesting - as a rule, everyone remembers the external design of the basement part of the wall. Without in any way belittling the importance of neat finishing, we agree that it will not subsequently determine the level of comfort of living in the house and the durability of the building’s structural elements, but the quality of hydro- and thermal insulation directly affects this. Therefore, let's look at a very important topic - complete insulation of the foundation base from the outside. By the way, some technologies for thermal insulation of this part of the foundation also require its finishing.
Why is it generally necessary to insulate the foundation, and the basement in particular?
From a layman's point of view, the very formulation of the problem may not seem entirely clear - what is the point of insulating the foundation? After all, for the most part it is not directly adjacent to residential premises, and, it would seem, cannot in any way influence the microclimate in them. And if basements are not created, or they do not require maintaining a certain level of temperature, then why even start one?
This is an extremely common misconception! The foundation, like other structural elements of a building, needs reliable insulation, and this need is caused by a number of reasons of various properties. And, probably, first of all, thermal insulation of the foundation is a task aimed at maximizing its strength and durability, on which, of course, the operational life of the building itself directly depends. Let's look point by point and start with the most common - strip foundation.
First of all, it must be said that truly high-quality thermal insulation should include comprehensive insulation of both the vertical walls of the foundation (basement) and the blind area around the perimeter of the building. Otherwise, talking about the effectiveness of such measures will be naive.
- A massive reinforced concrete foundation without thermal insulation on the outside will always be a powerful cold accumulator in winter, from which it will spread to adjacent building structures. It is clear that the floor level of the premises on the first floor, as a rule, is located above the plinth line, and the walls and ceilings have their own insulation. But such proximity always leads to excess heat loss and, accordingly, to completely unnecessary, extra costs for energy resources used for heating purposes. Practice shows that even just competent insulation of the foundation gives a significant, up to 20–25%, saving effect, all other conditions being equal.
1 – ground level;
2 – foundation base;
3 – basement part of the foundation;
4 – building wall;
5 – ceiling (floor) of the first floor;
6 – insulation of the external wall;
Of course, the scheme is not a dogma, and some variations are possible. So, in particular, the layer of horizontal insulation (under the blind area) can be located buried, right down to the level of the sole. But even in this case, it must be laid so that there is no gap between it and the vertical thermal insulation of the foundation wall.
We understand the required thickness of insulation
It is probably clear that the thickness of the foundation insulation must obey certain rules. The same Penoplex boards are available in a wide range of thicknesses, and it will not be difficult to purchase the necessary material for single-layer or, if necessary, even two-layer thermal insulation. But how to find the right thickness?
To do this, you can carry out certain thermal calculations using formulas or even just tabular data.
Vertical thermal insulation of the foundation
Let's start with the vertical layer of insulation. The calculation will be based on the following formula:
Rsum = hф/λф + hу/λу
Rsum– total heat transfer resistance (measured in m²×°K/W) that a building structure, in this case a strip foundation, must have. This is a standardized tabular value established by Construction Norms and Rules (SNiP) for all regions of Russia, depending on the characteristics of their climate. If you wish, you can find tables on the Internet for various areas; this parameter is probably known in all local construction or design organizations, but it will be even easier to take the value from the diagram map below.
Please note that for each region three values of this thermal resistance are indicated: for walls and enclosing structures, for coatings and for floors. In this case, we are interested in “for walls” - in the columns these are the top values, highlighted in purple.
hf And λf– parameters characterizing the thermal characteristics of the foundation tape itself: this is the thickness of the tape in meters ( hf) and the thermal conductivity coefficient of reinforced concrete is a tabular value.
hу And λу– similar parameters of the insulating layer.
This means that if the thermal conductivity coefficient of the selected insulation material is known, then it is easy to calculate its required thickness using simple arithmetic operations.
And in order not to force the reader to dive into independent calculations, we suggest using a special online calculator, which already contains all the thermal dependences and the necessary tabular values.
The thermal insulation properties of a building material are highly dependent on humidity. Complete water saturation can significantly increase thermal conductivity. This problem is especially relevant for the basement of the building.
In this article, we will show readers of the site one of the ways to insulate the basement of a house and possible options for subsequent external finishing.
In the autumn-spring period, the combination of high humidity with low temperature with insufficient waterproofing of the basement and in the absence of insulation can cause destruction of the basement and freezing of the walls at the floor level of the first floor. To avoid this, not only waterproofing is carried out, but also the basement is insulated with subsequent finishing.
Selection and installation of insulation
Since the basement of the building is operated under conditions of regular direct exposure to water (rain, snow), it is highly undesirable to use hygroscopic materials. Expanded polystyrene is best suited - it is hydrophobic (it repels water, not absorbs it), does not rot, and has low cost with high thermal insulation properties. However, the thermal conductivity of polystyrene foam decreases at high humidity.
For insulating the base, it is better to take extruded polystyrene foam, it is stiffer. This is especially true in cases where heavy tiles (for example, “wild stone”) will be used as a final finish.
At the initial stage of the work on insulating the base, it is necessary to prepare the surface. To do this, the wall is cleaned of mortar drips, local protrusions (with a pick), etc. This is followed by priming with a deep penetration primer. After it dries, the base is waterproofed. Compositions based on epoxy resins are suitable.
Installation of insulation sheets occurs using a special adhesive composition (sold as a dry mixture in bags, mixed with water). The use of specialized foam adhesives is allowed (for example, Tytan Styro 753).
When installing insulation boards, it is necessary to achieve a common plane of the external surfaces.
After the glue has dried, the insulation sheets are additionally secured with special fasteners - dowel umbrellas. To do this, holes with a diameter of 10 mm are drilled through the insulation in the wall. The depth of the holes must correspond to the length of the dowel part of the fastener. The most common standard size is 140mm. The holes, as a rule, are positioned so that each sheet is secured near the corners and in the middle - 5 fasteners.
Installed umbrella dowel.
When installing dowel umbrellas, you should pay attention to sufficient wedging of the dowel in the body of the wall using a plastic or metal nail included in the fastener kit. Poor-quality fasteners are often difficult to install into the hole; in this case, you have to trim the layer on the dowel part.
Formation of a protective layer
After installing the insulation boards on the base, we begin finishing it. To do this, we need a façade mesh and an adhesive (also called reinforcing) composition. Usually this is the same glue - many manufacturers produce universal mixtures suitable for both gluing insulation and “plastering” it.
The mesh is usually taken with a density of at least 145 g/m2. It is necessary to cover the entire area of the wall. The joint of individual pieces of mesh should be done with an overlap of 5-10 cm. Apply a layer of adhesive to a section of the wall with a spatula, then apply a mesh and again pass the spatula along the plane of the section, embedding the mesh into the adhesive composition.
A section of a wall with a formed protective layer.
For ease of work, it is better to divide the wall into separate sections. If they are made too large, the composition will have time to dry out, which will make it very difficult to level it with a spatula.
Finishing the insulated basement part of the wall
Almost any type of finishing can be done on top of the protective layer - decorative plaster compositions (for example, bark beetle), facing with various tiles, siding, decorative stone, etc. Possible options for finishing the base are presented in the following photos.
In the event that the insulation of the base has formed a protrusion from the plane of the wall, its upper edge must be protected from precipitation by ebb for a base made of a sheet of roofing steel or other materials.
To preserve the foundation of the house, as well as save on heating the entire building, the owners insulate the basement with various materials. After all, the ground floor is also above ground. Therefore, it is susceptible not only to soil heaving, but also to external climate influences.
Many owners think that after insulating the basement of the house above the ground, all problems with cold floors will be solved. This is a common misconception among novice builders.
After all, the base is not just a separate element of the structure. It is part of the foundation. Therefore, every owner of his home should know how to insulate the basement of a building from the very bottom. This action will save heat in the house.
Before thermal insulation of the underground and above-ground parts of the foundation is created, it is worth deciding how to insulate the base of the building. After all, a wide selection of thermal insulation materials allows you to perform insulation in different ways.
There are several types of materials used to insulate the basement, basements and foundation:
- expanded clay – it’s cheap, but it’s better to use it to insulate houses that are lived in during warmer months;
- mineral wool - the cost is average, the protection is also average, but is unsafe for the health of people performing insulation;
- polystyrene foam - prices are low, the thickness of the layers varies widely, but is difficult to cut and very fragile;
- expanded polystyrene - average cost, non-toxic, easy to cut into required parts, long durability;
- polyurethane foam - the price is high, the quality is excellent, but spraying must be done with special equipment, observing safety precautions.
Professional developers recommend choosing modern materials that are easy to use, have sufficient durability and are not susceptible to chemical influences. That's why the best option would be to insulate the basement floor with extruded polystyrene foam. True, compliance with the technology of polystyrene foam insulation and further operations, such as finishing or cladding, is mandatory.
How to insulate a base with polystyrene
In order for the insulation of the base to give maximum effect, it is worth knowing the order of priority of the actions performed. To work with extruded polystyrene foam it will look like this:
- Digging a trench along the foundation around the entire perimeter.
- Cleaning the basement floor of debris and old cladding.
- Prime the cleaned surface with waterproofing mastics.
- Insulation of the base, starting from the corners of the building.
- Complete covering of the basement floor with polystyrene slabs.
- Additional strengthening of slabs on the plinth.
- Further finishing with cladding materials.
The first step is to remove the soil from the very foundation of the building. To do this, a trench is dug if the foundation of the house is of a strip or monolithic type.
The depth of the trench should be the same as the foundation of the building itself. But the width can be adjusted, but make it so that it is convenient to work with insulation boards.
It is worth remembering that for columnar or pile foundations of houses, insulation can only be done externally.
It is imperative to clean the entire surface of the foundation before further work. This will not only remove the old worn-out layer, but will also help the insulation lie flat without large seams.
Before insulating the base of any building, it is worth thoroughly priming it. To do this, you can use liquid mastics, which are evenly applied to the surface and dry quickly, creating an excellent protective film.
After this, you can begin to insulate the base from the outside. You need to start such actions from the corners of the building, since they take the most load from the external influences of the atmosphere.
Thermal insulation of the basement floor with polystyrene foam
To properly insulate the base from the corners, you should simply cover the corner part with polystyrene foam of greater thickness than the rest of the surface of the base.
For regions with a temperate climate, where winters are not very long and precipitation is average, polystyrene 5-6 mm thick can be used to insulate the surface. And for corners, 10 mm material is optimal.
Thermal insulation of the basement part of the foundation is carried out according to the following scheme:
- dilute the adhesive mass in the proportions indicated on the container;
- let the mixture brew for a certain time;
- prepare slabs of material by cutting them into pieces convenient for work;
- Apply the adhesive composition to the slab and let it spread a little over the surface;
- attach the slab to the surface of the foundation and press firmly;
- strengthen the remaining slabs on the foundation wall, joining them using grooves;
- treat the resulting seams with foam;
- apply a protective fiberglass mesh to the finished insulation;
- cover the mesh with adhesive solution.
After the insulated foundation has dried, the underground part of the foundation is backfilled with soil. And on the above-ground part of the foundation, finishing is done with plaster or facing with brick, stone or ventilation material.
Cladding work after insulating the basement
After the insulation of the base from the outside is finished, it is worth covering it. This will not only give the above-ground part of the foundation additional beauty and well-groomed appearance, but will also protect the insulation from external influences of the sun and precipitation. And it will maintain a stable temperature in the basement and eliminate dampness.
Before you start covering the basement floor, it is worth protecting the polystyrene slabs from physical influences. And at the same time, further strengthen them on the surface.
Special plastic dowels with wide heads must be driven into the joints between polystyrene foam. To do this, use a drill to drill holes 1-1.5 cm longer than the dowel itself. After this, a dowel is inserted into the holes, and a nail is driven into it. This structure is carefully driven into the wall with insulation.
It is important to remember that fastenings with dowels should be made 4 pieces for each sheet of insulation. This will protect the material from premature deterioration.
Now you can begin leveling the surface of the basement. To do this, you can plaster with mortar or putty the base wall with plaster.
Upon completion of the work, any finishing will be placed on such a surface without any problems. This can be laying with facing bricks or decorative stone, painting, spraying with finishing materials.
In order for the work on thermal insulation of the foundation to bring the desired result, it is worth listening to the advice of professional builders. And they recommend adhering to the following rules:
- Insulation should be carried out only in dry weather - the material will lose many of its qualities if damp.
- The thickness of the slabs must be chosen taking into account the materials from which the building is constructed - the colder the base, the thicker the thermal insulation should be.
- It is worth storing polystyrene in a place where it will not be exposed to direct rays of the sun - it is destroyed by ultraviolet radiation.
- The adhesive compositions that will be applied to the boards must be water-based - the solvent will destroy the structure of the polystyrene.
By following these recommendations, you can make high-quality insulation yourself, no worse than specialists.
Today on the construction market you can find a wide variety of thermal insulation materials that are, to one degree or another, suitable for. Both traditional and new technological materials do their job well. Insulating the base with polystyrene foam or penoplex is a modern trend, which is due to the many positive characteristics of the materials used.
In addition, these insulation materials are very affordable in all respects. Of course, you can use the usual polystyrene foam, but builders recommend paying attention to modern insulation materials.
Expanded polystyrene boards have good thermal insulation properties and are easy to install.
Insulating the basement of a house with extruded polystyrene foam or penoplex is a labor-intensive and difficult process. In addition, the importance of this work lies in the fact that the durability of the house will depend on the correct implementation of insulation. If, for example, the basement is insulated with polystyrene foam efficiently and in accordance with all the rules, then the cost of heating the house in winter will be noticeably reduced, because the entry of cold air flows into the room will be limited.
The construction market now offers polystyrene foam boards with a thickness of 30 to 120 mm. The required thickness of the thermal insulation layer should be determined taking into account the following parameters:
- The thickness of the walls erected and the material from which they are made.
- Climatic conditions of the area in which construction is taking place. For example, in central Russia it is recommended to choose slabs with a thickness of 50 mm or more. In the corners, by the way, the material will freeze faster, so for these areas you can take slabs of greater thickness.
- If the house is still under construction, it is recommended to build a sinking base, which will hide the layers of thermal insulation and waterproofing.
In addition, if you use polystyrene, expanded polystyrene or even ordinary polystyrene for insulation, it will be easier for you to carry out decorative work in the future. The materials are easy to process after installation. In addition, you can put brick, tiles and other decor on top.
Preparing for insulation of the base
Insulation of the base with penoplex or expanded polystyrene can be carried out only in the autumn or summer, because at a positively high temperature there will be the highest quality adhesion between the insulation and the adhesive composition.
Installation of insulation is carried out on a previously prepared surface.
It is necessary to prepare in advance the surface of the base that is supposed to be insulated. All defects that exist on the surface (pits, crevices, cracks, smudges, etc.) must be completely eliminated and coated with plaster. After this work, the plaster should be given a little time to dry, then it should be cleaned and the surface covered with an additional layer of primer.
Tools and materials
First of all, you need to choose insulation: polystyrene foam, polystyrene, expanded polystyrene. It must be taken into account that the density of the material must be high.
The base can be insulated with extruded polystyrene foam or penoplex of any width, but it is best to take a thicker one.
You will also need plastic dowels, which are used to fasten the insulation, and reinforced mesh, which is necessary at the puttying stage. Insulation of the base in this case will be of the highest quality.
What else do you need:
- Putty, paint, primer.
- Sloping corner.
- Hammer, construction knife, meter strip, notched trowel, brush and roller.
To make truly high-quality insulation, you should not skimp on building materials.
Work order
With the proper approach, insulating the base is not as difficult as it might seem at first glance. As soon as the surface is thoroughly cleaned of contaminants, you can begin priming. It is recommended to select a deep penetration primer that will provide the required surface characteristics.
Scheme of proper insulation of the base.
By the way, the insulation of the base with foam plastic is carried out in the same sequence, so you can take this article as a basis when using this heat insulator.
- Upon completion of all preparatory work, you can begin installing the insulation. Regardless of what you choose: foam plastic, polystyrene or expanded polystyrene, it is best to start insulating the base from the corner. This approach will allow you to make high-quality markings, as well as cut the thermal insulation material in advance.
- Using a notched trowel, thoroughly coat the entire surface with glue, then apply polystyrene foam or polystyrene foam to the wall, hold for a while until the adhesive sets, and release.
- All joints that are formed when working with expanded polystyrene or penoplex must be carefully glued, for which traditional mounting tape is used. Once you have glued several sheets, you need to secure them with plastic dowels. Polystyrene, in principle, is easy to process, so making several holes can be done without difficulty. Using dowels, we carefully and securely fix the polystyrene. Thanks to this, it will not fall off or sag throughout its entire service life.
- As soon as the process of gluing and fastening the heat insulator to the surface of the base is completed, it is necessary to attach the slope corner to the same glue. Then the reinforced mesh is installed using cement mortar. It is best to cut the mesh to the size of the insulation material. Next, we wait until the solution dries, after which we begin finishing work.
The adhesion of the thermal insulation material will be of the highest quality if all stages of work are carried out at a positive temperature. When frost occurs, cracks will not appear in this case. In principle, any insulation of a room must, as already mentioned, be carried out in summer or autumn, when there is no precipitation or sudden temperature changes.
Features of slab installation and subsequent finishing
If, after purchasing polystyrene foam boards, you find that their thickness is not enough to provide normal thermal insulation, then the insulation can be fixed in two layers so that the required thickness is achieved. Many experts say that with good adhesion, the double layer of polystyrene foam boards will actually be one whole. To prevent the formation of cold bridges, it is necessary to ensure that the installation of two layers of slabs overlaps at the seams. However, with vertical displacements of the soil, the insulation layers delaminate, causing serious heat loss.
Options for fastening dowels.
The question of whether to install insulation in two layers is very controversial, therefore, if there is such an opportunity, it is worth returning the unused material back to the store, and purchasing slabs of the required thickness to replace it. As a rule, stores now accept goods back without problems for some time.
The insulation of the basement is carried out on the outside of the house. Expanded polystyrene boards are glued to the surface of the base using any suitable adhesive composition that does not contain solvents that can potentially destroy the material.
The bottom row of polystyrene foam boards must be laid with emphasis on the base. It's great if you have a small foundation overhang that was made during construction. Despite this, very often polystyrene is laid on a gravel backfill where the foundation was built. Polystyrene foam can also be installed over gravel backfill, although many experts caution against such steps. If there is no protrusion, it is convenient to insulate with penoplex.
As a decorative finish, tiles, bricks, natural stone, facade paint, and plaster are laid on top of the insulation. It is recommended not to use decorative tiles or sand-lime bricks, which at sub-zero temperatures lose many of their characteristics and chips begin to form at the edges of the material.
Advantages of modern insulation materials
The cost of modern thermal insulation materials is not as high as it was 10-20 years ago, so almost everyone can afford to buy polystyrene or use another equally high-quality material to insulate the base.
Using penoplex for insulation.
It should be noted that polystyrene and polystyrene foam, as well as, in fact, penoplex and expanded polystyrene, have fairly similar characteristics:
- Minimum thermal conductivity coefficient.
- Excellent sound insulation characteristics.
- High moisture resistance.
Due to these basic qualities, you can use modern polystyrene, penoplex or other material to make high-quality insulation.
Expanded polystyrene from many respected manufacturers is an excellent alternative to the separate use of insulation, soundproofing and waterproofing materials.
The cost of expanded polystyrene is slightly higher than many traditional insulation materials, but in the end the total cost of installing high-quality thermal insulation will be significantly lower. If the high prices for polystyrene foam are scary, then you can use foam plastic for insulation, which is a little more affordable.
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