Build Daily


October 05, 2016 23:15

Thermal insulation with polyurethane foam pros and cons

bona fide owner of your own home insulation of their housing issues always refer to the primary.And it is - absolutely correct position.A well-planned and high-quality insulation made performs several important functions.It significantly reduces heat loss of the building, which makes it possible with a minimum of energy in a building by creating an efficient heating system.Thermal insulation is very good in the summer hot days - in the house will not be hot, and the installation of air conditioning will not work with the excessive load.Finally, the insulation of all the basic elements of the structure - is the key to their long-term operation, reduction of destructive external influences on the building materials of walls, floors, foundations.

Thermal insulation with polyurethane foam pros and cons

Thermal insulation with polyurethane foam pros and cons

However, you must bear in mind the fact that a wrong insulation is fully capable to cause serious harm to the building.Choice insulating materials - an extremely important issue, since not all of the

m permissible in certain cases.One of the most promising modern thermal isolator polyurethane considered.But.And around this material does not subside heated debate - someone considers his material with little or no shortcomings, and there are those who exposed him to ruthless criticism.Let's try to understand this question - polyurethane foam insulation pros and cons, some to generalize and systematize the information with numerous construction sites and forums.

What is polyurethane

Article Contents

  • 1 What is polyurethane
  • 2 As applied polyurethane foam on the thermally insulated construction
    • 2.1 Video: wall insulation sprayed polyurethane foam
    • 2.2 Video: illustrative example of filling the cavity with polyurethane foam construction design
  • 3 Actual flimsy and advantages and disadvantages of polyurethane foam insulation
    • 3.1 low coefficient of thermal conductivity?
    • 3.2 Excellent adhesion to any surface?
    • 3.3 process of applying the polyurethane foam insulation - fast and easy?
    • 3.4 Very high service life of polyurethane foam insulation?
    • 3.5 Biological resistance - does not appear on the foam mold, it does not bite mouse?
    • 3.6 Polyurethane - absolutely environmentally friendly material?
    • 3.7 Use foam eliminates the steam and waterproofing?
    • 3.8 material has fire safety?
  • 4 calculator for calculating the thickness of the insulation layer

In practice, private housing polyurethane foam in our area began to be widely used not so long ago.But, for sure, all this material is known since early childhood: foam - and this is also one of the varieties of polyurethane foam, was the manufacture of sponges for the adoption of hygienic procedures, and used it as a stuffing for stuffed toys and children's furniture.

Anyone familiar foam - this is also one of the varieties of polyurethane foam

Anyone familiar foam - this is also one of the varieties of polyurethane

course, for insulation of building structures using different types of polyurethane, but the basic chemical composition and the principle of obtaining the material remain the same.A characteristic feature of polyurethane - a gas-filled high, reaching 90% of the total volume of the frozen mass.

Thus, polyurethane refers to a gas-filled porous polymers based on polyurethane components.Depending on the particular components used, can be obtained on the entrance elastic flexible structure (the same foam) or rigid, such that the ground and is used in the insulating events.

When insulation of various building structures can be applied polyurethane foam insulation finished parts such as panels, blocks, half-cylinders (shells for piping), etc.However, the maximum demand have compositions which are applied to the surface of the thermally insulated (or poured into the cavity) in liquid form, but possess a self-foaming ability and rapidly polymerize and solidify.Thus, in essence, the preparation of the desired composition occurs directly at the site of insulating works.

  • two-component compositions are used for large-scale works.Typically, current technology requires use as component "A" of the polyol, and as "B" - polyisocyanate.
Бочки с компонентами "А" и "Б"

Barrels of components "A" and "B»

mixture of these components with a small amount of water results in a polymer synthesis reaction with an active gas (in this case - carbon dioxide), which creates a foamed, porous rigidstructure.Such polyurethane foams have closed cell structure - the vast majority of the air bubbles are completely isolated from its neighbors.

Structure of closed cell foam

structure of polyurethane foam with closed cell

thermal conductivity of carbon dioxide, the filling of the cell, with all other things being equal, is considerably lower by about a third than that of air (0.016 W / m × ° C against 0.026 W / m × °C), which is another significant advantage for closed-cell polyurethane foam, it is as an effective insulation.

Some professional high-quality systems as a blowing agent used CFCs.

  • At the household level, as well as for the limited area and volume of operations (filling gaps, small openings, repairs, etc.) are more commonly used one-component polyurethane foam compositions, better known under the name of all of polyurethane foam.
Polyurethane foams

Polyurethane foams

In fact, the components are pre-mixed, and required for the polymerization composition is bottled under pressure.But for the final reaction, foaming and curing requires contact with atmospheric oxygen and water (moisture and surface water vapor contained in the air).The result is a porous foam structure whose cells are open.

The structure of hardened foam - not so dense and homogeneous

structure of hardened foam - not so dense and homogeneous

gas involved in the forced foaming - Freon gradually disappears and is replaced by normal air, and compete for the thermal conductivity of polyurethane foam with a degree of closed-cell - can not.He plays it in strength, resilience.So seriously consider such compositions as major for the insulation of the building is not necessary - they have their own, and very high demand, the scope of application.The only criterion by which wins such a structure with open cells - is sound absorption and sound insulation.

For comparison, the table below shows the basic physical and operational parameters of polyurethane foams both types:

main parameters of materials Comparative characteristics
polyurethane foam with closed cell structure (two-sprayed) polyurethane foam with open structure (foam)
Thermal conductivity, W / m × ° C 0,019 ÷ 0,035 0,025 ÷ 0,045
number of closed cells More90% Less than 50%
Extension (foam rise) compared with the initial volume 1: 40 1: 70 ÷ 90
density, kg / m ³ 20 ÷ 200 8 ÷ 18
Water vapor permeability 0,02 ÷ 0,05 0,07 ÷ 0,15
Dehumidification 1 ÷ 3% 10 ÷ 60%
waterproofing properties yes no
properties absorption good high

As applied polyurethane foam on the thermally insulated construction

since the subject of the article is directly linked it with the thermal insulation measures, in the future we will consider mainlytwo-component polyurethane foam with a closed cell structure, leaving aside foams.

Create insulated structures or elements of the building giving the insulating qualities can be carried out using two different technologies - spraying or filling cavities (filled).

  • for spraying uses special processing plants.complex layout may be different, but in any case, the process is to ensure that the components of "A" and "B" are collected from regular containers or tanks built, pre-filled before starting work.Further, under the influence of pressure created by the compressor components in transit through the control station are input to the spray gun.
An example of a set of spraying equipment

Example sets of spraying equipment

Mixing components takes place already at the final stage - in the mixing chamber of the gun, and then under high pressure through a nozzle liquid mixture reaches the insulated surface.In fact, the bulk of the polymer synthesis reaction, with evolution of heat and a large amount of carbon dioxide, resulting in copious foaming occurs already on the treated surface.

From the gun nozzle under high pressure fed spray cone mixed components

They are under great pressure nozzle gun is fed cone jet mixed components

Both the composition of the resulting foam and applying it under high pressure contribute to excellent adhesion of insulation to almost any surface - a distinctive feature and one of the key advantages of this material.

Video: wall insulation foam spraying

Governing Bodies process unit can accurately adjust the percentage of the components in the mixture - this is largely performance of the coating depend.Setting up amenable to pressure at the outlet, the maximum amount of material on the nozzle gun.

Despite the seeming simplicity of the technology, it has the weight of subtleties that are known only to experienced professionals.Independently carry out spraying, even if you can rent a set of equipment - task difficult, unless, of course, the priority is the quality of the insulation and rational expenditure of materials.By the way, very many of today's so-called "master", offering their services in this area are also often guilty of low professionalism.Buy own apparatus for polyurethane foam spraying - does not mean the right to become a qualified professional, in direct analogy to, for example, buying a car can not immediately make the new owner an experienced driver.By the way, in Europe installation for spraying foam operator falls into the category of highly skilled workers, this specialty training takes even one year, and in the course of not less than once in 6 months, it is considered mandatory passage of the control attestation.So, choosing a contractor for insulation of their own home, it requires considerable caution - better to give preference to its proven company that guarantees quality, even if services will be slightly more expensive than that of an unknown private owners.

leader in production equipment for polyurethane foam spraying is an American company GRACO, producing a lineup of special installations «REACTOR» various capacities.And in the production of high-quality component formulations for foams maximum ratings deserves the products of concern "BASF".It can also be taken into account when choosing a manufacturer works by reading e its technical equipment.

  • second option polyurethane insulation of building structures - a filling mixture in a specially set aside for this cavity.A striking example - frame house, built on the "sandwich" -technology.
Something like this is performed with polyurethane foam filling of cavities

Approximately performed Fill cavities with polyurethane foam

Such work also requires knowledge of certain nuances and highly experienced professionals.Components also fed under pressure, but it is considerably lower than during the deposition on the wall.Mixing is done in a special gun chamber from which the mixture is already being output, the feed tube.The equipment can be used is the same as during deposition, but with certain parameters reconfiguration.However, for high-quality execution of work and there are special aspic installation, which provided for the use of special components with the options a kind of "delayed start" foam, so as to allow sufficient time to make the mixture into the cavity (form) prior to the change in composition of the active structure.

To fill the cavity in the building structure are left in advance or doing technological holes

to fill the cavity in the building structure are left in advance or doing technological holes

in filling foam structure are left to advance or to make holes for the entry into the cavity feed tube, as well as for visual control of the fill level.Qualification master here is critical - requires a good understanding of the characteristics of the prepared mixture: its estimated volume expansion, a complete set amount of time and the beginning of solidification.The operator must strike a balance between the subtle incomplete or not properly filled cavity and possible breaks or deformation insulated design.A full visual control in such situations are usually impossible, and then admitted flaws can be detected only during the operation of the building or by means of special equipment - Imager.

for insulation of external enclosing structures used exclusively polyurethane foam with a closed cellular structure.To create a sound-proof barriers in the internal walls or ceilings is acceptable from the point of view of efficiency, to use the cheaper foam with an open cell.

Video: illustrative example of filling the cavity with polyurethane foam construction design

Actual flimsy and advantages and disadvantages of polyurethane foam insulation

It's time to talk about the advantages and disadvantages of polyurethane foam used for insulation of building structures.To start with, we present a table with the main characteristics of closed cell material, the manufacturer, and then analyze the main parameters in more detail.

Key Features polyurethane Indicators
Compressive strength (N / mm ²) 0.18
flexural strength (N / mm²) 0.59
Water absorption (% volume) max.1 ÷ 3
Thermal conductivity (W / m × ° K) 0,019 ÷ 0,035
Content of closed cells (%) to 96
frother SO₂
Flammability class B2
Fire class F2
application temperature not less +10 ° C
application temperature from -150 ° C to +220 ° C
applications Thermo and hydro insulation of residential and industrial buildings, tanks, cars, boats, cars
effective lifetime 30 ÷ 50 years
moisture, aggressive media Resistant
Environmentally friendly Once fully cured - is safe.Approved for use in residential buildings.Used in the production of refrigerators for food
Pour Time (seconds) 25 ÷ 75
Water vapor permeability (mg / m × h × Pa) 0,05 ÷ 0,07