Ceiling insulation with expanded clay

Expanded clay advantages and disadvantages

Like any material, expanded clay has its pros and cons. To make an informed choice, you need to get acquainted with the properties of the insulation. Among the goods of this type offered on the market, expanded clay is not a novelty: it has been used for several decades and has managed to establish itself in the best quality.

Bulk thermal insulation is a granule of 3 different fractions. Any type of expanded clay is suitable for roof insulation; material of different sizes can also be combined.

It is important to know that effective insulation of the ceiling from the cold can only be achieved by backfilling a layer of 30-40 cm thick.

Expanded clay granules are made of burnt shale clay. During the firing process, the surface of the lump is sintered, and the inner layer acquires a pronounced porosity, which is noticeable at the fracture. It is the cavities of the bubbles that give expanded clay insulating properties, since air has a relatively low thermal conductivity. According to the same principle, materials such as penoizol, EPPS, polystyrene, etc. are arranged. But, in comparison with them, expanded clay has its advantages.

Among the advantages of granular clay thermal insulation:

absolute fire safety, since expanded clay does not burn, does not melt and does not emit harmful substances when heated;
lightness, which is important when insulating the ceiling;
resistance to mold, decay or damage by rodents, as ceramics are biologically stable and hard enough;
ease of use of the material;
long service life - expanded clay withstands more than 25 cycles of thawing and freezing, does not decompose.

The price of 1 m³ is low and comparable to the cost of other heat insulators (mineral wool, expanded polystyrene).

Among the minuses, the most obvious drawback is the presence of dust generated during firing and transportation of pellets. Like other insulating materials, expanded clay is able to absorb moisture, which reduces its insulating properties. All heaters have an increased tendency to absorb moisture. It can be considered a disadvantage, but the easiest way is to take appropriate measures and protect the thermal insulation material from water.

Bulk material is inconvenient for insulating false ceilings. Despite the lightness, the granules are heavy and create an additional load on the coating.

Helpful Hints

When the ceiling goes to a residential attic, then expanded clay should be poured so that there is a gap between it and the attic floor covering. If this is not done, the grains will constantly creak under the feet of those who walk above. But when backfilling is done correctly, expanded clay will also perform the function of soundproofing material.

Sometimes you have to insulate sloping attic ceilings. For this purpose, it is better to choose other types of heaters. Bulk material cannot be laid on an inclined surface: round granules will roll down. Expanded clay backfill is used only on a horizontal plane.

Self-leveling mixtures should not be used for pouring screeds on expanded clay. The liquid mass will drain between the granules until it saturates the entire insulation, and when the layer thickness is large, the repair will result in a round sum. If you need to make flood floors in the attic, then you first need to lay a concrete screed, and then apply a thin layer of leveling mixture.

By pouring expanded clay to a thickness of only 10 cm, you can already save up to 70% of the heat that escapes into the atmosphere through the ceiling. The popularity of expanded clay for insulating ceilings in private wooden houses is due to its low thermal conductivity and low price.

The fire safety of pellets is also important.

Ceiling insulation with expanded clay began to be performed since the receipt of this material at the beginning of the last century.The popularity of the use of expanded clay has not faded to this day. Expanded clay floor insulation performs three protection functions: thermal insulation, sound insulation and moisture insulation.

Lightweight expanded clay used for floor insulation consists of porous, ceramic granules formed by the expansion of special clays at high temperatures.

Directions for the use of lightweight expanded clay:

base of isolation.
Filler for concrete blocks and panels.
Hydroponics.
Site drainage.

The isolation device is performed in three ways: dry filling, combined filling, wet screed using factory dry building mixtures.

The technology of ceiling insulation by the method of dry filling is performed with expanded clay of different fractions. If you backfill only with granules of one fraction, then the density of the layer will be inhomogeneous, which will adversely affect its thermal conductivity. If you mix granules of an average fraction of 5-10 mm and granules up to 5 mm, then the filling will be dense, non-shrinking: small granules will fill the spaces between the middle ones, a homogeneous layer will be obtained.

What is expanded clay

Expanded clay is a small-sized granule, due to small pores having a small weight. These granules are obtained by firing clay. We can safely assure you that expanded clay is also an environmentally friendly natural material, moreover, it is characterized by relatively good technical indicators, such as:

Noise and sound insulation - muffles blows;
Heat insulating properties - retains heat well;
Frost resistance - does not collapse even at low temperatures;
Fire resistance - the material is not affected by fire;
Strength - its structure does not change under the influence of water (hot and cold);
Durability - the properties of expanded clay do not change even when exposed to high or low temperatures, it lasts much longer than other heaters.

Ceiling insulation technology with expanded clay granules

Before insulating the ceiling, it is imperative to lay a layer of a dust- and vapor-tight membrane (polyethylene, for example). In cases where thermal insulation is installed in a bath, this is of particular importance due to the large amount of water vapor in the air. No other preparatory actions are required: loose insulation will perfectly fill all the irregularities, easily penetrate into niches and gaps between structural elements.

To work on the insulation of the ceiling, the following materials and tools will be required:

thick polyethylene film or isolon, foil, etc.;
Scotch;
expanded clay of any fraction;
bucket and shovel;
a tool for leveling the backfill (even a rake will do);
cement and sand for screed, sheet materials for coating - if necessary.

A screed or flooring is done if it is planned to use the attic as a residential or utility room. Their installation is optional and remains at the discretion of the owner.

How to insulate a concrete floor?

For concrete floors, expanded clay, as a ceiling insulation, is an ideal material. Impervious to dust and vapors, concrete does not require even minimal preparation. Therefore, backfilling can be done in just a few hours.

To make the expanded clay layer even, you need to install beacons from thin bars or boards to a height equal to the thickness of the layer. These elements are aligned horizontally using the building level.

When buying expanded clay, you need to take into account the shrinkage coefficient of the granules. It is approximately equal to 1.2, so it is better to buy a little more. Laying consists in pouring out the contents of the bags between the beacons and leveling the layer with a rule. If desired, you can do without beacons, performing level measurements directly on the backfill.

If it is not planned to walk in the attic, then it is enough to lay a layer of polyethylene on top, connecting the panels with adhesive tape. The film protects the backfill from moisture from the atmosphere. But expanded clay can be protected differently:

Pour the granules with cement milk (a liquid solution of cement in water) and dry the backfill for at least 7 days.
Lay a reinforcing mesh on top and make a screed from a cement-sand mortar.

A screed over expanded clay will protect the bulk material from moisture and will make it possible to move along the heat insulator without the risk of destroying its layer. The ability to retain heat with this method does not suffer at all.

Ceiling insulation in a wooden house

The technology of ceiling insulation in a wooden house involves the use of a moisture-proof barrier. To do this, you can take any material from those that are used for a similar purpose. The most affordable is plastic wrap.

It is advisable to lay a waterproofing layer across the ceiling lag in order to securely close them too. The width of the film is usually no more than 3 m, so the individual strips will have to be joined together. This is also done using a certain technology:

roll out a strip of polyethylene over the surface, covering the beams protruding above it;
lay the next panel with an overlap of at least 5 cm on the previous one;
glue the joint with a wide stationery tape.

When the polyethylene is laid, a protective material should be applied to it. To do this, you need ordinary clay. It needs to be crushed (a fraction of about 1 cm) and covered between the lags with a layer of 5 cm.

What layer of expanded clay is needed to insulate the ceiling in this case? According to building codes, expanded clay insulation begins to effectively perform its function at a thickness of 10 cm. This layer is enough to insulate a bathhouse or garage that do not need constant heating.

In a private house in central Russia, the entire space between the lags will have to be filled with insulation until a thickness of about 20 cm is reached. Only in this case will it be possible to perform high-quality thermal insulation of housing. Calculating the volume of pellets in cubic meters is simple: you need to calculate the area of \u200b\u200bthe ceiling and multiply it by the thickness of the layer, expressing the value in meters. Add another 20% to the resulting figure for shrinkage.

It is best to buy expanded clay of different sizes: by mixing a large fraction with a smaller one, you can achieve a dense layer that practically does not lose height. Backfilling is done in the same way as in the previous case. When using a rake to level the granules, turn them upside down so as not to tear the polyethylene. After the heat insulator is laid, polyethylene is again spread over it and the log, joining the overlapping strips and securing them with adhesive tape.

How is expanded clay made?

Expanded clay is produced in several stages:

Low-melting clay, which is the starting material, is loaded into a thermal chamber, in which it softens to a dough state.

Then the material is quickly heated under the influence of a temperature of 1000-1300 degrees Celsius - this leads to the fact that the raw material "boils". "Boiling" contributes to the formation of voids in the material, during cooling of which porous granules are formed - fractions of expanded clay.

Under the influence of high temperatures, the surface of the material will melt - thus, a good hermetic shell appears, which has high qualities of strength and wear resistance, and even resistance to mechanical stress and damage.

The quality of the future product directly depends on how accurately all the rules of technology were observed. Since information on the production of expanded clay contains information about its environmental friendliness, the question of whether expanded clay is harmful by itself disappears.

Expanded clay ceiling insulation pros and cons

Of the positive points stand out:

Ecological cleanliness, use in residential premises;
Availability of material, you can buy in any region with delivery;
Cheapness of the product;
Low coefficient of thermal conductivity, effective insulation;
non-combustible material;
Absorbs noise;

Shrinkage of the floor when exposed to high loads leads to cracking of the granules, compaction and increased thermal conductivity;
The thickness of the backfill layer significantly hides the height of the room;
High labor costs when performing wet claydite-concrete screed.

Nevertheless, this material is still used today. The production of expanded clay concrete slabs and blocks is in demand in low-rise construction. Lightweight floor slabs reduce the load on load-bearing walls, which can now be made from lightweight aerated concrete. Floor insulation using expanded clay is a multidisciplinary stage of work.

3 About expanded clay and its properties

Bulk materials began to be used to insulate houses more than one decade ago - much earlier than foam plastic and mineral wool appeared. Of course, initially it was not expanded clay, but sawdust, sand and clay.

This material, like the infrared warm floor under the tiles, began to be widely used as an insulator about a few decades ago. He gained popularity very quickly, and has not lost it to this day (whereas the once popular polystyrene and mineral wool are gradually losing demand, giving way to more convenient counterparts).

The raw material is rapidly rotated in a large red-hot oven, forming into small granules with different diameters and "baking".

Expanded clay insulation is most often used for the floor, as well as for the ceiling (from the side of the attic). Less commonly, the material is used for backfilling into voids between partitions - that is, for wall insulation.

4 About the pros and cons of material and technology

Let's consider why it is so valued and why it is so popular to insulate the floor (and other parts of the house) with expanded clay. The list of advantages of the material is as follows:

A layer of expanded clay poured onto the floor

low thermal conductivity (0.1-0.18 W / mK) like polyethylene pipes in underfloor heating systems;
improving the sound insulation of the room;
lightness (and therefore - the absence of a large load on the floors - which is important in a wooden house);
environmental cleanliness (unlike most modern materials, natural clay is used to create expanded clay);
absolute safety for humans, both under normal conditions and at elevated temperatures;
incombustibility;
cheapness;
durability;
biological neutrality (even when saturated with moisture, the material does not contribute to the appearance of mold);
lack of interest in insects and rodents (a great option for floor insulation in a private house!).

By the way, with regard to thermal conductivity: if we compare a layer of expanded clay with a thickness of about 10-12 cm, in terms of efficiency it is equal to about 25 centimeters of wood or almost 100 cm (!) Of brick. However, at the same time, it is several times inferior to the same foam or mineral wool, whose thermal conductivity is 0.04-0.05 W / mK.

Of the significant drawbacks, only poor moisture resistance can be distinguished - with prolonged contact with moisture (or when a large amount of water gets on the insulation at once), expanded clay absorbs it, and dries for a long time.

As a result, the weight of the layer increases and its characteristics deteriorate.

Thus, we can draw a simple conclusion: when working on insulation with expanded clay (it doesn’t matter what exactly - the floor or the ceiling) - it is very important to follow the correct technology (which we will consider below)

Floor insulation with expanded clay between the lags

Now let's figure out how good the method of such isolation is:

no need to install a complex multi-layer structure (as, say, when using mineral wool);
no need to adjust the material (whereas polystyrene or mineral wool - you need to cut it into pieces of the right size);
simplicity and speed of application;
the possibility of carrying out all stages of insulation with your own hands, without the use of special equipment and tools (both for the floor and for the ceiling);
Can be used on uneven surfaces.

Of the significant drawbacks, only one nuance can be distinguished: this is the need to use a large layer of backfill. Where you can get by with a sheet of foam plastic 5-10 cm thick, you will need a layer of expanded clay 15-30 cm.

It is difficult to call this a significant problem, since the heat-insulating "pie" when using foam plastic also comes out quite thick. The disadvantage is felt if it is required to perform floor insulation in a room of standard height (about 2.3 m). In this case, the loss of even 10 centimeters will be noticeable, and 20-30 will make the room uncomfortable and uncomfortable.

5 About the varieties of material

The material itself, like Isospan AM, can be different. The differences are primarily in the size of the granules. It could be:

Crushed stone - obtained by crushing large pieces. The granules can be of different sizes. It is used to backfill the base layer.
Gravel - obtained according to the technology described above (during firing and during rotation of the drum). The diameter of the granules is from 5 to 40 mm.
Sand - the smallest (up to 5 mm in diameter) granules. They are good because they allow you to tightly fill the existing cracks, cracks, recesses.

Dry floor screed on expanded clay

Another way to classify a material is its density. In this regard, expanded clay is divided into 10 categories - with a density of 250 to 800 kg / m³. It goes without saying that the greater the density, the more efficient, but also the more expensive the insulation.

Styling features

Beginners are often lost in the question of what layer of gravel expanded clay is required to reliably insulate walls and ceilings, and what additional elements are needed to create a heat-insulating "cushion".

It is recommended to pour a thick layer of large expanded clay for full insulation, but taking into account the total load on the ceiling ceiling. In cold regions, the height of the filled gravel reaches half a meter, and, despite the insignificant mass of the granules, the insulation makes the structure heavier.

Gravel sand is poured under the main layer, and in addition, two types of insulation are laid under the bulk material and on top of it: steam and hydro. To reduce the cost of the project, polyethylene or roofing material is used, but the vapor barrier is broken, since the film creates the effect of a greenhouse, and condensate accumulates if the room is poorly ventilated.

When planning to pour only one fraction, they spread the membrane fabric, choose which optimal layer is needed, and scatter expanded clay to the height required for insulation, evenly distributing it over the ceiling surface.

To enhance the insulation and sound insulation of a wooden or concrete ceiling, the material is rammed by mixing sand with expanded clay.

The same effect is achieved by combining gravel with smaller granules. It is possible to increase the heat saving indicator by filling the granular insulation with concrete. In this case, it is not necessary to lay a vapor barrier under the screed.

Professionals do not recommend insulating the last floor if it is a flat roof ceiling without an attic. This applies to baths and residential buildings. Expanded clay is highly hygroscopic, which negatively affects the thermal insulation properties of the granules.

Whatever fraction of clay expanded clay you take, during operation and operation as insulation, the material emits dust, and therefore for a plank ceiling an additional layer to contain dust is required.

The optimal thickness is 10 cm, a thinner layer of expanded clay is ineffective for insulation, and in regions with low temperatures, the height of the embankment starts from 20-40 cm, subject to an appropriate ceiling height or the possibility of its reconstruction.

The multi-caliber fraction and lightness of expanded clay allows you to create an effective heat-saving "pillow". All insulation work is simple and it is possible to equip the ceiling with your own hands, without special building experience. Also, consumers are attracted by the low cost of the material, the lack of special equipment for installation and performance.

Rules for working with expanded clay

Firstly, expanded clay should be poured only on the substrate. It is better to use a vapor barrier substrate. The side covered with a layer of foil should be laid in the direction of the room to be insulated. This is especially necessary when expanded clay as a ceiling insulation is used in a bath.

Thirdly, the thickness of expanded clay for insulation should be from ten to twenty centimeters.

There are several types of expanded clay. All of them differ in purpose. Three types of expanded clay are usually sold:

Expanded clay gravel. It measures 0.2 to 0.4 cm and has an angular shape. Only the foundations of buildings and structures are insulated with such expanded clay.
Expanded clay gravel is used to insulate the ceilings of buildings. Such expanded clay has a small fraction of about 0.1 to 0.2 cm and a rounded shape.
The smallest of expanded clay is the so-called expanded clay sand. Such sand is not used for insulation.

Advantages and disadvantages of expanded clay ceiling insulation

Expanded clay has more than enough advantages, so let's focus on the most important of them:

The insulator is highly durable among many other materials.

Expanded clay is fireproof, because it does not burn and does not emit substances hazardous to human health into the atmosphere.

Thanks to its special porous structure, this insulator weighs much less than other similar materials.

It is not edible and is not attractive to various bugs, rodents, bacteria, molds and fungi.

The low price of the material explains the fact why it has been successfully used to insulate the ceiling for more than a dozen years.

High thermal insulation qualities are complemented by excellent soundproofing properties, as it quickly absorbs acoustic vibrations.

The material easily absorbs moisture, while not increasing its own weight and without losing its basic qualities.

Expanded clay crumb or crushed stone does not cause allergic reactions in households or animals due to its natural origin.

Like other bulk type thermal insulation, expanded clay is very easy to use.

Thanks to the fractional shape of the outlet, the air between the individual stones further improves thermal insulation and creates natural convection.

Consider the possible negative aspects that may be associated with the use of expanded clay as a heat insulator:

Its effectiveness is directly related to the thickness of the insulation layer. In other words, it makes no sense to make the thickness of the bedding less than 20 or even 40 centimeters.

This material must be reliably protected from atmospheric moisture or precipitation.

It is optimal to use it for thermal insulation over reinforced concrete floors. Firstly, they are quite monolithic in themselves and are able to withstand the weight of expanded clay. Secondly, they reliably retain crumbs and dust from spilling down.

When insulating houses made of wood, expanded clay must be protected by a vapor barrier both from the top and from the bottom.

It is not recommended to pour this insulator on the ceiling, hemmed to the beams from below. Given the weight and volume of expanded clay, it is possible that he will be able to break through the entire structure, which will collapse into the room.

Features of thermal insulation of the ceiling with expanded clay

We can say that expanded clay on the ceiling is clay familiar to everyone. Raw materials are subjected to processing at high temperatures, as a result of which granules of small size are formed. Their porous structure creates the thermal insulation properties of expanded clay.

Based on the size of the insulation fraction, there are several main varieties of it. The smallest does not exceed 0.1-5.0 millimeters and is used where insulation is carried out by backfilling. But more often, a fraction with a size of 0.5-4.0 cm, which is called gravel, is still in demand.

The expanded clay layer for ceiling insulation must be thick enough to provide an effective heat-insulating cushion. Despite the fact that the granules are not very heavy, the load can be very significant due to the backfill thickness of 50 cm or more.

To improve the heat-saving characteristics, it is optimal to use an insulating material based on fractions of different sizes. The main layer is made of coarse gravel, and it is protected from above and below by small sand granules.

Carrying out thermal insulation with expanded clay raw materials allows you to solve several problems at once:

Since the material, among other things, acts as an excellent sound insulator, it can reliably maintain peace and quiet for the household during bad weather or isolate it from noisy neighbors.

In the coldest weather, heat will remain in the room, since the heated air cannot find cold bridges for itself (with proper insulation), and therefore is forced to go down again.

In hot periods of the year, expanded clay reliably prevents the ingress of cold from the outside of the building, so a cool microclimate will be maintained in the premises.