Unique properties of perlite-based insulation. Types of thermal insulation boards - what to choose for insulating the roof and the entire house Using perlite for insulating a water floor


The raw material for the production of perlite is volcanic rock, which, when heated, can increase in volume (swell). As a result of heat treatment of perlite aluminosilicate water-containing rock of volcanic origin, a non-toxic, non-flammable, lightweight and highly effective insulation material is obtained - expanded perlite.

Scope of application

Due to its high physical and technical properties, this material has found wide application V different industries industry:

  • metallurgy,
  • energy,
  • construction,
  • agriculture,
  • medicine,
  • food industry,
  • oil refining,
  • production of cryogenic equipment.

Perlite as an insulation material can withstand temperatures varying in the range from -200°C to +900°C. The material has a high moisture-absorbing ability - it can absorb liquid up to 400% of its weight. Perlite is chemically neutral to the action of weak acids and alkalis and does not contain heavy metals. The environmental friendliness of the insulation allows its use in insulating residential buildings without risk to human health. This material is not only completely safe for humans, it does not cause allergies and helps create a favorable microclimate in the house. In addition, this material is quite simple and easy to work with.

The low bulk density of the material (100 kg/m3) explains the high acoustic properties of the insulation produced from it. Plaster mixtures containing expanded perlite sand also play the role of insulation.

A plaster layer 3 cm thick in its thermal insulation characteristics is equivalent to a 15 cm layer brickwork. The high heat and sound insulation qualities of insulation are well manifested in the installation of “floating” plank and concrete floors, asphalt floors, for leveling and increasing the sound insulation characteristics of floors between floors, between walls and floors, and in insulating pipeline systems.

The neutral pH of perlite eliminates the formation of corrosion of pipelines and wiring electrical networks located in the floor area. Perlite is especially popular as insulation when implementing “warm” floor systems, since it is not prone to expansion when heated, does not shrink, and is absolutely non-flammable. In addition, it does not die and does not cause interest among insects and rodents. To enhance sound and thermal insulation properties concrete mortar, perlite is also added to it. Such a wide range of uses of this material perfectly confirms its high physical and technical properties.

Options for using expanded perlite as insulation

  • Perlite sand (backfill insulation)
  • Roof thermal insulation

Backfill perlite insulation

One of the effective solutions to lighten the structure of a house, along with increasing its thermal conductivity characteristics, is the use of backfill insulation based on perlite sand. This step allows you to reduce heat loss by almost 50%. Backfill can be used in layers between external and internal wall plaster, interior finishing and wall plaster, in all voids of wall masonry.

The largest amount of perlite in world practice is used in the manufacture of molded thermal insulation products(more than 60%). The binder is bitumen, cement, gypsum, liquid glass, clay, lime, polymers. Considering the high hygroscopicity of perlite, materials based on it are best used for internal insulation, however, there are techniques that allow the use of thermal insulation materials based on foamed perlite in external insulation.

Thermal insulation boards are widely used for insulation of residential and outbuildings. The thermal conductivity of the material reaches 0.118 W/(m-°C).

The main advantages of using perlite slabs are their low weight and high sound and heat insulation characteristics. In addition, structures insulated with this material are reliably protected from rotting, are not damaged by rodents, and are not affected by mold and fungi.

Perlite sand, mixed dry with cement or gypsum, is dissolved with water directly on the construction site. The resulting composition is used to fill cavities in bricks, concrete, walls, and to grout cracks and seams. Expanded perlite is used in the preparation of adhesive and putty mixtures, self-leveling floors, solutions for repair work, in the installation of “warm” floors, etc. The thermal conductivity of mixtures averages 0.2 W/(m-°C). Based on the type of binder, perlite compositions are classified into cement-perlite, gypsum-perlite, and lime-perlite.

Roof thermal insulation

Bitumen-perlite is especially popular in thermal insulation of roofs and ceilings. With its participation, high-strength insulating layers of the required shape are created. In addition, the material can be combined with bituminized cover layers and insulating boards. Bitumen-perlite does not need to be heated before application. The thermal conductivity of bitumen perlite is 0.067 W/(m-°C). Using perlite as insulation, you choose a safe, economical, durable, non-flammable material with high physical and technical characteristics.

In many countries around the world, perlite backfills are used to create warm sloping roofs. In addition, such an effective heat insulator as perlite concrete is used in roof insulation. It is highly wind and fire resistant, and when combined with perlite magnesia insulating boards it acquires high thermal resistance.

Perlite is a rock of volcanic origin, which, when heated to 900-1100 ° C, expands according to the “popcorn” principle. This is due to the fact that perlite sand contains bound water, which, when heated to high temperatures, expands the base rock - due to which “expanded perlite” is formed, which is already used in various industries. The size of expanded perlite granules ranges from 1 mm to 5 mm, bulk density from 50 kg/m3 to 150 kg/m3. It is these small numerous pores that provide the lightness and unique heat and sound insulation properties of perlite, its fire resistance, chemical inertness, lack of influence from pests, etc.

Perlite is widely used in construction, metallurgy, cryogenic technology, agriculture, and the food industry.

PERLITE IN CONSTRUCTION

Dry building mixtures based on perlite.

The main area of ​​application of perlite now is the production of dry construction mixtures, where perlite acts as a heat-insulating filler. Perlite plasters based on perlite have won their strong place in the thermal insulation of houses, thermal insulation of ceilings and heated floors. A layer of external perlite plaster of 5-10 cm allows you to solve the problem of insulation of both new and old buildings and structures. At the same time, unlike foam plastic and mineral wool, perlite plaster does not emit harmful substances and retains its structure and performance characteristics.

Thermal insulation of floors

Poured perlite floor


To make this type of floor, you need to mix M-100 grade perlite, M-400 grade cement and water. When the mixture is ready, it must be poured onto the floor with a thickness of 5 cm to 30 cm. If you are pouring the floor in the basement, we first recommend laying a waterproofing pad (hydrozol).

Three-layer concrete floor with perlite insulation

This type of floor is made of 2 layers of concrete, laying a perlite heat insulator between them. By the way, the latter was not chosen as insulation by chance. After all, perlite is an ultra-light, environmentally friendly material with very low thermal conductivity.

So, to prepare a perlite heat insulator, it is necessary to combine perlite, cement and water, mix thoroughly, while achieving “plasticity” of the mixture. This mixture must be laid in a several-centimeter layer on the concrete floor. The heat insulator should dry out within a week, after which concrete or ceramic tiles. Accordingly, perlite with hydrophobic and dust-absorbing properties is best suited for floor insulation.
This type of floor can be used not only at home, but also during the installation of baths.

Floating floor


If you have chosen an electrically heated floor to insulate the room, then you cannot do without a “floating floor”. This type of floor compensates for the thermal deformation of the concrete floor due to its heating and cooling, and is therefore optimal.

As you know, objects have the ability to expand when heated. So, when in concrete field Heating and cooling modes constantly alternate, pressure is formed, as a result of which such a floor can crack. To avoid this, it is necessary to use the “compensator” principle. Namely: perlite is poured onto an old concrete floor, floor slabs or other so-called “subfloor” that no longer needs to be leveled. If the concrete layer is higher than 10 cm, then the perlite backfill must be compacted. After this, chipboard is laid around the perimeter of the room where the heated floor is laid. Please note that the height of the chipboard must match the height of the concrete floor that is being poured. After this, a cord is laid on the perlite heating element and the entire surface is filled concrete mortar. After 3-7 days, when the concrete has dried, the chipboard must be removed from the cracks between the wall and the floor.

Monolithic floor using perlite


Perlite is also used to insulate a monolithic floor with a hard surface. To do this, perlite is poured onto the base and distributed with leveling slats so that the thickness of perlite sand exceeds the desired thickness by 20% ( minimum thickness laying - 1 cm). If pipes or other uneven components need to be placed in the floor, they can be easily accommodated in this bulk insulation material. After this, the entire surface is covered with slabs, on top of which a monolithic floor is made.

If this type of floor is not installed in a basement, then it is recommended to use drainage pipes to collect and eliminate moisture, and an absorbent protective pad under the layer, such as kraft paper (not film).

If you are dealing with a wooden floor, then expanded perlite is laid without compaction. Since perlite is a non-flammable material, this significantly increases the fire safety of the room.

If during work there is a need to reduce dust and insulate top layer perlite, it can be sprinkled with cement and then moistened a little with water. Another way to insulate the perlite layer can be to cover it diffusely open materials, such as corrugated cardboard, kraft paper, chipboard, etc. To increase the load-bearing properties of bulk, heat-insulating material, perlite granules can be treated with wax. This compacted perlite forms a durable insulating layer for a dry screed floor.

Thermal insulation of walls

Perlite sand is used as backfill thermal insulation in layered enclosing structures:

    in the layers between internal and external wall masonry;

    between wall masonry and interior decoration;

    in wall structures made of hollow small-piece products;

    in all voids of wall masonry;

    as a substitute for quartz sand in cement screeds roofs and floors

In this case, it is possible to reduce heat loss by 50% or more.

To maintain heat inside the house, as well as to protect the room from the penetration of cold, it is best to use perlite. To do this, it needs to be poured into the cavity between the walls. In this case, perlite insulation is poured directly from the bag (or through a hopper) into the wall from above at any convenient interval (no more than 6 m). By the time the window sill is installed, the cavities under the door and window openings should already be filled. If necessary, you can pour perlite, wait until it “settles down” and add more. All openings that may be in the wall and through which perlite insulation can spill out must be closed by the time the insulation is poured. Copper, galvanized steel or fiberglass can be used to construct drainage systems. At the same time, the perlite insulation must remain dry.

Perlite filling of the cavity between the carrier and facing masonry poured in layers after laying 3-4 rows of bricks. In order to avoid shrinkage, the backfill layer is filled to approximately 10%. Waterproofing gaskets are placed at working breaks in the insulation. If necessary, the insulating layer can be made of any kind required thickness. Since construction is a long-term process, when working with perlite insulation, the cavities between the walls should be protected from rain.

Having high heat-protective properties, expanded perlite does not age and is not destroyed by pests of animals and plant origin. It is worth noting that perlite backfills are used to insulate walls made of wood and frame structures. Such insulating gaskets do not burn, and therefore increase the fire safety of houses.

Perlite roof insulation

In world practice, perlite backfills are often used in the construction of warm sloping roofs.

1 .Perlite roof backfill

First, diffusely penetrating, bottom covering boards (e.g. plasterboards). Perlite is poured into the cavity between the “cladding” and the “grid” and compacted by 10%.

During the installation of the lower roofing layer from the “lining”, a waterproof seal made of glassine or film is laid over it. The connection points with the gutter, as well as the points of passage through the roof, are hermetically sealed with thick and adhesive tape.

In addition, bitumen perlite and perlite concrete can be used for thermal insulation of the roof.

2. Perlite concrete roof insulation

Compared to other insulating materials, perlite concrete thermal insulation has high wind and fire resistance. Moreover, in combination with heat-insulating perlite-magnesium slabs or slabs covered with perlite concrete, it has high thermal resistance.

Properties of perlite concrete

Directions for use
The following materials can be used for perlite concrete roof insulation: expanded perlite, Portland cement, water, air duct impurities, etc. If fire protection characteristics require reinforcement, the roof can be reinforced with reinforcing mesh.

If it is fairly dry and the perlite concrete insulation can withstand the load of workers on it without damaging the surface, layers of perlite concrete insulation can be installed every 48 to 72 hours.
The minimum recommended roof slope for normal water drainage is 1/8. The most economical way to tilt perlite concrete insulation is through the stepped arrangement of heat-insulating slabs (see Fig. %%).

3. Bitumen-perlite roof insulation

Bitumen perlite is a dry granular material that consists of perlite particles coated with bitumen. This is a ready-to-use material (filled from bags) and does not require additional mixing or any other impurities.
A bitumen-perlite mixture can be prepared by mechanically mixing expanded perlite sand and hot bitumen.
Properties of bitumen perlite

Scope of application
New construction. Bitumen perlite can be used directly on hard surfaces (for example, concrete) to which cold bitumen adheres well. If bitumen perlite is used over wooden base, you must first use roofing felt attached to the tree.

Roof repair.

Bitumen perlite is the most optimal material for repair existing roof, since it can be used on structurally sound surfaces, free of dirt and peeling, covered with a layer of cold bitumen. Moreover, by arranging slopes to the funnels/watering cans of the internal drainage system or along the perimeter of the roof, it is possible to provide not only additional insulation of the existing base, but also to avoid stagnation of water on the roof.

Method of use
Before laying the bitumen-perlite base, the roof must first be prepared. The dry granular bitumen perlite is then poured out of the bags, spread and leveled to a thickness 40% higher than the final desired thickness with the desired slope. For compaction, sheets of plywood placed on the material and a roller weighing 180 kg are used. Final compaction is achieved by laying bitumen perlite with a roller directly over the material, without plywood.

Using bitumen perlite, you can form monolithic bases for different types roofs. Since there is no need to waste time drying and hardening bitumen perlite, immediately after laying and compacting it, you can lay it roll roofing using hot bitumen.

As a result of increasing production technology, more and more thermal insulation materials are appearing. Thus, relatively recently, volcanic rocks, which have many advantages, began to be actively used. One of the most popular materials using this raw material is Perlite, which will be discussed below.

Perlite is obtained as a result of the production of both rocks and volcanic rocks. Such feedstock is capable of increasing in size when heated (this action is called swelling). During the production process, raw materials are subjected to heat treatment and the addition of special additives that help improve technical characteristics. The output is a material that can serve as heat or sound insulation.

Characteristics of Perlite in the form of sand

Basic properties - they are also advantages

It is worth noting the main advantages that perlite insulation has:

  • Light weight. Despite the fact that rocks and volcanic rocks are used as raw materials, Perlite is quite light (this is achieved through heat treatment). As a result, there is no need to construct a particularly strong frame.
  • Increased temperature resistance. It can withstand temperature changes from −220 to +900 degrees. Therefore, it can be freely used for external insulation even in the far north.

Important! In this aspect, it beats all its competitors. No other insulation can boast of a permissible amplitude of over 1100 degrees.

  • Environmental safety. Even when heated, this material does not emit any toxic substances or carcinogens.
  • Chemical neutrality to most acids and alkalis. This eliminates the possibility of corrosion and other unpleasant formations. It should also be noted that it is completely hypoallergenic.
  • High sound-absorbing properties, which are achieved due to low bulk density. As a result, when using this insulation, there is no need to lay an additional soundproofing layer.
  • Does not deform as a result of heating. Therefore, Perlite is often used in underfloor heating systems.
  • High efficiency. In general, stating the features presented above, we can note the impressive efficiency of this material. Despite the fact that it is not very popular (relative to Penoplex and mineral wool), its use seems to be very rational. At the same time, the cost of this material is in the average range.

Where is this material used?

Such an impressive list of advantages predetermined the wide range of application of this insulation:

  • External plastering of buildings. Here frost resistance comes to the fore.
  • Any interior work associated with leveling and increasing thermal conductivity properties.
  • Interior roof finishing.
  • Thermal insulation of pipelines (including hot water supply).
  • Warm floor systems.

Above are only the most extensive construction fields. The substance itself, called Perlite, is used in medicine, metallurgy, energy, agriculture, oil refining and even the food industry.

We study all known varieties

In total, there are 4 forms of release of this insulation: backfill (it is also called sand), slabs (outwardly similar to penoplex), roofing models and dry building mixtures. These varieties have some features that you should know.

Backfill insulation

The first form factor of Perlite to emerge was loose insulation. The main task of this material in the construction of houses is to lighten the structure (it is lighter than a standard cement-sand mixture) and increase its thermal insulation qualities. This layer is usually used for backfilling floors and interfloor layers. It is also often used to fill voids in wall masonry. Less often it is used in combination with (or instead of) warm plaster.

The most convenient and practical form is slabs

According to official statistics, about 60% of all Perlite produced on the planet goes to create thermal insulation boards. They are obtained by hydraulic pressing, making them very convenient to use. The binder may differ depending on the specific type (bitumen, lime, polymer compounds, cement, liquid glass, etc.).

This category of materials has quite high hygroscopicity. Therefore, it is mostly used for interior decoration. However, when laying an additional moisture-proof layer, it can also be used for exterior finishing. However, this is not very justified from an economic point of view.

Roofing models

From the name, it is obvious that such analogues are used primarily for roof finishing. For this task, the so-called bitumen perlite is used. This material allows you to create a thermal insulation layer of any shape, so it is often used for buildings of unusual design.

Important! There is no need to heat this coating before use!

The average thermal conductivity for this variety is 0.067 W (m*C), which is a very worthy result. This coefficient allows the use of this coating even in northern regions. It is also worth noting the non-flammability of this insulation, which provides general security buildings.

Dry building mixtures based on Perlite

As a result of mixing cement and perlite sand, a very effective dry mortar. The solution is prepared very simply - just add water (that is, no additional additives such as APG or gypsum are required). Basically, a similar composition is used for filling cavities in brickwork, grouting seams and cracks, as well as creating a plaster layer with increased thermal insulation characteristics. At the same time, it allows you to easily level the surface.

Today we will tell you about bulk insulation, which is represented by eight different types. The variety is simply impressive, as they are made from paper, stone, resin, polymers and even clay. Each material has its own strengths and weaknesses, although there are also those that there is nothing to praise for, even if one would like to. All bulk insulation can be installed using two methods: manually or using a compressor. Such materials are good because they fill all the cracks and voids. A to negative qualities This can be attributed to shrinkage, which is inherent in all insulation materials from this cohort.

Expanded polystyrene crumbs

Styrofoam crumbs.

Bulk insulation for walls made from foam spheres is used only when it is necessary to fill the cavities of already built structures. The crumbs are simply blown out using a special machine, trying to achieve maximum density. The disadvantage of crumbs is that the insulation can shrink. In addition, the material:

  • burns;
  • emits toxic smoke;
  • Rodents feel great in it.

This bulk wall insulation is transported to plastic bags. Can be used to insulate floors, ceilings, and pitched roofs.

Loose penoizol

Penoizol flakes have a random shape.

In appearance, penoizol looks like foam chips, but if you look more closely, the difference is obvious. Despite the visual similarity, these are two completely different materials. Penoizol is more reminiscent of snow flakes, it does not have an ideal ball shape, this material is softer. Penoizol is used as backfill insulation for walls and horizontal ceilings. In addition, it is also available in sheets, but is mainly used in liquid form. Unlike polystyrene foam, penoizol:

  • does not burn;
  • does not smoke;
  • allows moisture to pass through, but does not absorb it.

The thermal conductivity characteristics of both materials are almost equal.

Penoizol backfill insulation for walls is made from resin. The quality of the material primarily depends on the quality of the resin used for production.

First, the liquid substance is poured into blocks, about a meter by meter. Then the blocks are cut into sheets, and only then the sheets are crumbled. Installation is carried out using a blowing machine or manually. When working, you need to control the degree of density of the material.

Foam glass in granules

Foam glass fractions are different sizes, right down to rubble.

It is made from broken glass, which is crushed into smallest fractions, melted and mixed with coal. As a result, carbon dioxide begins to escape from the material, which forms air spheres in the structure of the foam glass. This is a very expensive material, it is used for industrial facilities or during the construction of high-rise buildings. It is used extremely rarely in private construction, since not everyone can afford such a cost. They are used as bulk insulation for ceilings, floors and walls, and in the form of slabs or blocks. Bulk comes in different fractions, based on this, it looks like:

  • granules;
  • crushed stone

Bulk has the following characteristics:

  • does not absorb water;
  • does not burn;
  • thermal conductivity 0.04–0.08 W/m*C;
  • does not allow steam to pass through;
  • high compressive strength 4 MPa;
  • bending strength is even more than 0.6 MPa;
  • operating temperature range from -250 to +500 degrees.

Application Feature bulk insulation for the floor is that foam glass can be included in the composition cement mortars, with which the screed is poured. The same is true when pouring foundations; instead of ordinary crushed stone, you can use foam glass.

Expanded clay

Expanded clay is ugly, but time-tested.

Probably the oldest and most well-known fill-in insulation is expanded clay. Made from clay by firing. Depending on the size of the fractions, it can be in the form of:

  • gravel;
  • crushed stone;
  • sand (dropouts).

It should be noted that expanded clay is much cheaper than its competitors, namely perlite and vermiculite, which we will talk about a little later. The density of the material can vary between 250-800 kg/m. cube The degree of thermal conductivity ranges from 0.10 to 0.18 W/m*C.

Expanded clay practically does not absorb moisture; this process occurs very slowly. But, having filled up with water, he is very reluctant to part with it, which cannot but affect his characteristics.

It is used as bulk insulation for walls, floors, ceilings and roofs. Also read ““. He does not enter into any chemical reactions, mold does not grow in it, and mice do not live in it. Since the starting material for manufacturing is clay, expanded clay has all its positive qualities:

  • does not harm health;
  • does not burn;
  • does not contain poisons.

Expanded clay can be mixed with sawdust, but the insulation layer should be slightly larger, since wood has a slightly lower resistance to heat transfer.

Loose thermal insulation ecowool

Ecowool was developed as part of a waste recycling program.

This type of insulation was developed in Europe as part of a recycling program. That is, the main goal is to profitably recycle waste. It is made exclusively from newspapers; no more than 10% cardboard is allowed. To prevent ecowool from burning, microorganisms from growing in it, and mice not gnawing on it, borax and boric acid are added to the detailed newsprint.

It is used as bulk insulation for floors and walls, installation is carried out using dry and wet methods. The density when blown by machine is 65 kg/m in the wall. cube, on floors 45 kg/m. cube, density for manual laying - up to 90 kg/m. cube Thanks to fire retardants, the material does not burn, but smolders successfully.

The service life of ecowool produced in the Omsk and Tomsk regions is 10–12 years. Western manufacturers claim that the material will last 50 years. But they make such forecasts based on climatic conditions your region, where temperature differences are smaller and, accordingly, less moisture settles in the insulation (due to the dew point). For Russia, with its cold and humidity, these forecasts are unlikely to come true.

The thermal conductivity of ecowool is 0.037–0.042 W/m*C. It easily absorbs moisture and releases it just as easily.

When wet, it becomes heavier, which leads to shrinkage, which is inevitable. In fact, ecowool has nothing to do with environmental friendliness. It is simply stuffed with chemicals and we do not recommend using it.

Bulk perlite insulation

Perlite is always white.

Perlite is a volcanic ore (acidic glass). For insulation, construction perlite is used, the fraction of which varies from 0.16 to 1.25 mm. After ore is mined, it is crushed and heated to 1 thousand degrees. It is important that the heating is carried out sharply, and the water that is in the structure of the rock begins to evaporate. As a result of this process, perlite swells and reaches a porosity of 70–90%.

Material characteristics:

  • thermal conductivity 0.04–0.05 W/m*K;
  • does not burn;
  • does not absorb moisture;
  • allows steam to pass through;
  • chemically inert.

The density of insulation in the wall varies from 60 to 100 kg/m. cube Membranes cannot be used during installation, as they quickly become clogged during operation. For laying on pitched roofs Perlite treated with bitumen is used. After a solvent is added to bituminized perlite, it becomes sticky, and after it hardens, it forms a single insulating layer of any shape.

Vermiculite backfill insulation

Vermiculite has become very popular recently.

Loose thermal insulation vermiculite is made from mica - an ore that is mined in quarries. The ore is broken into small fractions, which are subsequently intensively heated to 700 degrees and due to the evaporation of moisture, swelling occurs; naturally, the fractions increase in volume. If you gradually heat the mica fractions, the moisture will slowly evaporate and swelling will not occur.

The service life of the material is unlimited, because there are no adhesive impurities in it, there is simply nothing there to spoil. Material characteristics:

  • thermal conductivity 0.048-0.06 W/m*K;
  • density 65-150 kg/m. cube;
  • does not burn;
  • non-toxic;
  • allows steam to pass through;
  • when moistened by 15%, it does not lose its thermal insulation properties.

Vermiculite transports and distributes liquids well. This means that even with intensive, deliberate moistening of a separate area, perlite will evenly distribute moisture over all its areas, and then completely remove it outside. This property allows you to minimize the consequences of getting the insulation wet. Vermiculite costs almost the same as ecowool (about 4,500 rubles per cubic meter). It can be mixed with sawdust in a 50/50 ratio.

Wood sawdust

Thermal conductivity sawdust 0.07–0.08 W/m*S. Sawdust is rarely used as an independent insulation material, as it is prone to absorbing moisture and further rotting. Therefore, they are mixed with other materials:

  • clay;
  • expanded clay;
  • perlite;
  • vermiculite

The ability of these materials to remove moisture prevents sawdust from being blocked even when laid in a thick layer. By the way, you can only use small sawdust, which is obtained when processing wood on modern machines with high speeds.

Having examined all types of bulk insulation, we can conclude that heat insulators made from rocks and clay. In terms of price/practicality/heat transfer resistance best option- penoizol. An outsider in our rating, ecowool is poison in pure form, not otherwise.