Roof insulation: polystyrene, polyurethane foam, foamyx

The comfort and energy efficiency of your home can be greatly affected by the insulation you choose for your roof. Today’s popular options include foamyx, polystyrene, and polyurethane foam. Every material has special qualities that meet a range of demands and price points.

Expanded (EPS) or extruded (XPS) polystyrene are two common forms of polystyrene insulation that are renowned for being lightweight and rigid. Because of its excellent thermal insulation qualities, EPS is inexpensive and frequently used. Contrarily, XPS has a higher compressive strength and superior moisture resistance, making it appropriate for moist environments.

Insulation made of polyurethane foam is preferred because of its superior heat resistance per inch of thickness. There are two varieties available: open-cell and closed-cell. While closed-cell polyurethane foam is denser and has a higher R-value per inch, which makes it effective in a thinner layer, open-cell foam is less dense and lets moisture vapor pass through.

Foamyx, a relatively recent addition to the insulation market, is renowned for its environmentally friendly and sustainable qualities. Foamyx is lightweight and simple to install, with good thermal insulation qualities thanks to its recycled material construction. It appeals to homeowners who are concerned about the environment and are looking for efficient insulation options.

Advantages and disadvantages of foaming for roof insulation

You must exercise extreme caution when selecting insulation. If everything is done right, your home will always be cozy and warm, you won’t need as much gas or firewood for heating, and condensation won’t collect on the roof’s details and damage them.

These days, the ceilings and roof are insulated with time-tested and contemporary materials:

  • embankment expanded clay (with excellent hydro and fire resistance), which is covered with a layer of about 15 centimeters;
  • the so -called Saman – clay mixed with finely lamp, this is a very dense and elastic heat insulator with excellent fire resistance;
  • sawdust – with excellent thermal insulation properties, but high fire hazard;
  • sawdust with cement or sawdust with clay – with much less fire hazard;
  • foam concrete, which is poured onto the ceiling (it has good heat -insulating properties, but very hygroscopic);
  • mineral and basalt wool in the form of mats and plates.

However, what should be done with the roof’s exterior and interior surfaces? In complex roof configurations, fixing the insulation is often required beneath the roof, which is why polystyrene (also known as polystyrene foam), foam, and polyurethane foam spraying are part of daily life.

  • They are much easier than all of the above materials;
  • They hold heat much better;
  • practically do not rot;
  • have good hydrophobic.
  • They are not heat -resistant – they refer to high temperatures, secreting harmful substances;
  • Very fire hazard.

The selection of insulation from these three options is influenced by numerous factors:

  • from the type of roof;
  • from whether the attic is residential;
  • From the frequency of use of the house: constantly or only in the summer season;
  • from geographical latitude;
  • From the budget.

Comparison and advice on choosing a heater from foam

All these materials have a lot in common, but they also differ greatly from one another. Take a closer look at them.


Foam is made of foamed polystyrene (which is a byproduct of styrene polymerization), slabs from seeding granules with millions of voids and air bubbles in between. Since air is the best heat insulator, this accounts for the foam’s opulent thermal insulation qualities. The material has a higher density and is less permeable to water and steam the denser the granules are sprinkled with.

One of the most widely used heaters is foam. True, because it releases toxic gas, it has long been thought to be dangerous in residential buildings, both during regular operation and when heating. However, this is old information. PSB foam is now used as insulation because it is resistant to temperature fluctuations and fire, and it has the ability to self-adjust when it catches fire. It is made in sheets up to 20 centimeters thick and used in all climate zones.

Foam insulation benefits include:

  • A little weighs due to the bubble structure-the key advantage of the foam;
  • has extremely good heat -insulating properties;
  • resistant to minus and high plus temperatures, as well as sharp weather changes;
  • does not heat up in the summer;
  • almost never gets wet;
  • Winning, does not freeze;
  • environmentally neutral;
  • does not deform;
  • simply processed (cut) and easily mounted, often simply on special tile glue;
  • durable;
  • has excellent soundproofing properties;
  • Hypoallergenic.
  • for insulation of the “loud” – and therefore, flexible – metal roofs, it is poorly suitable, since it is hard and does not bend;
  • For the same reason, it can be poorly combined, creating voids – “cold bridges” in which condensation forms;
  • fungi and mold can start in it;
  • Crushes strongly, so rodents make holes in it;
  • With a strong fire, the foam still burns – and then the fire becomes even stronger.


A new generation of light insulation made of polystyrene foam and shaped like plates is called Foamyplex. However, they are produced by extrusion at high temperatures and pressures. The plates are homogeneous, mechanically very durable, and receive a uniform structure with small air bubbles. In terms of thermal insulation, a five-centimeter layer of foam is not less effective than a fifteen-centimeter brick wall. Every climate zone uses it.

  • almost never gets wet;
  • resistant to minus and high plus temperatures, as well as sharp weather oscillations;
  • environmentally neutral;
  • resistant to fire and high temperature;
  • has very good heat -insulating and soundproofing properties;
  • durable;
  • simply processed (cut) and easily mounted, often just on a special tile glue.

The drawbacks are identical to those of foam.

Let’s attempt a rough comparison of the key indicators between foam and polystyrene.

Table: Comparison of the foam and foam for key indicators:

Position Characteristic Styrofoam Foam Note
1 Thermal conductivity 0.04 W/MK 0.032 W/MK Foam plate of 20 mm corresponds to a 25 mm foam plate.
2 Water absorption 0.4 % 2% This means that the foam can be laid without vapor barrier, and the foam is undesirable.
3 Compressive strength 0.5 MPa 0.2 MPa Penoplex is possible even for insulation of floors and any structures with high loads, and foam is not.
4 Price The price of the foam is higher than the price of the foam is about one and a half times.

The foamine’s purpose is indicated by its brands:

  1. “Comfort” (foamyplex 31C) – very frost -resistant, used to warm apartments, loggias and foundations.
  2. “Wall” (Penoplex 31) has the highest heat -insulating properties from all brands, therefore it is used to warm the leeward walls and in rigid climatic conditions.
  3. The "foundation" has the largest compression strength and is used to warm the floors and foundations.
  4. “Foamplex 45” has the highest density, used for railways and runways.
  5. And finally – "roof" (polystyrex 35) has the highest fire resistance. It is he who is used to warm any types of roofs.

Poliuretan foam

It is a member of the gas-filled plastics family as well, but the insulating principle is entirely different. When liquid polyol and polyisostal are combined at high temperatures and pressures, a rapidly-fast-fastening elastic foam is produced.

It is separated into several types based on density:

  • stiff polyurethane foam (from 30 to 85 kg/m 3 with poor vapor permeability indicators) – can serve as a waterproofer, more often used for flat roofs;
  • Semi-burning polyurethane foam (below 30 kg/m 3)- requires additional layers of steam and waterproofing, used for the roof;
  • liquid (below 20 kg/m 3) – used to fill the voids.
  • very good heat -insulating and soundproofing properties;
  • good waterproofing qualities;
  • It can perfectly adhere to any materials on which it is applied, and they do not need to be pre -processed;
  • just applied, it does not need to be cut and glue;
  • very light;
  • gives the design strength;
  • applied without cracks and seams;
  • does not rot and is not subject to infection with fungi and mold;
  • does not attract mice;
  • ecological (after hardening);
  • withstands temperatures from -150 to +150 o C.
  • poor vapor permeability;
  • Sensitivity to ultraviolet, needs to be protected from light (cladding) immediately after hardening;
  • expensive equipment for spraying.

In conclusion, every material under consideration is exceptional for insulating roofs. Your financial situation, the insulation’s functionality, your addictions and skills, and its attributes all play a role in the decision. Keep in mind that:

  • For the pitched roofs, you can take a foam with a thickness of 50-100 millimeters;
  • For flat roofs, a foam is needed under load;
  • Polyuertan foam is suitable for any application.

The type of roof—pitched or flat—determines the insulation techniques. If it’s flat, you should ascertain how it will be utilized from above (e.g., a penthouse terrace or summer garden). Nothing is dependent on the type of roof.

Roof insulation with foam

There are some differences in the complexity of the process: if the insulation is installed after the roof is constructed, then the steps will need to fit the foam plates very precisely and thoroughly, and there will need to be very precise sealing; otherwise, cold bridges will form in the cracks, causing condensate to occur, which will lead to rot and rust in the metal parts.

The composition of the roof pie

The following elements make up the insulation structure:

  • waterproofing layer (hydropower);
  • insulation;
  • vapor barrier layer;
  • interior or roofing.

A few requirements are as follows:

  1. It is advisable to lay foam slabs in two layers with a shift in order to close the seams of the first.
  2. It is desirable that the thickness of the rafters be calculated in advance. It should correspond to the thickness of the foam.
  3. If you have a wooden house, then the roof can be insulated six months after its full shrinkage, so that all defects and deformations are eliminated before insulation.
  4. It is necessary to carefully examine the overlapping and replace the rotten parts, then treat everything well with an antiseptic and a pyrozhoz composition. Then it will be too late.
  5. The method of insulation depends on the purpose of the attic: for a cold attic, only thermal insulation of the floors of living rooms is needed. If it is the attic, then you need to thermal insulation and the roof.
  6. It is required to clean and dry the places where thermal insulation will be installed.
  7. It is necessary to think through ventilation gaps between rafters and insulation so that the rafters do not rot.
Position Appointment Mark Density Thickness Note
1 For insulation of the pitched roof PSB-15 15 kg/m 3 50–100 mm Residential attic, attic, ceiling
2 For insulation of the pitched roof and walls PSB-25 25 kg/m 3 50–100 mm Residential attic, attic, ceiling, walls
3 For insulation of flat roofs and attic floors PSB-35 35 kg/m 3 50–100 mm Residential attic, attic, ceiling, flat roof

Foam fastening

Methods for foam consolidation include the following:

  • laying pieces of foam between rafters;
  • pushing polystyrene with a continuous “carpet” with gaps between them;
  • gluing (facade frost -resistant glue or liquid nails);
  • Using special fasteners (anchor bolts, nails or screws).

Warming of the pitched roof

Tools needed and extra supplies needed:

  • Styrofoam;
  • waterproofing film;
  • membrane for vapor barrier;
  • Stapler for fixing the film;
  • knife;
  • scissors;
  • rails for fixing polystyrene (if necessary);
  • mounting foam;
  • screwdriver;
  • hammer;
  • drill;
  • nails;
  • Self -tapping screws.

Insulation from the inside

  1. The waterproofing is attached by the stapler to the crate in the intervals between the rafters.
  2. On the roof, we mount the crate so that there is an air gap for ventilation between it and the foam. Another option: we drive out nails into the rafters and pull the grid from the twine along them, and put the foam on it.
  3. We cut the foam with sheets of such a size that they are slightly wider than the distance between the rafters.
  4. Between the rafters with an effort, insert the foam. We darken the joints.
  5. We fasten it with the racks of the crate (then they are parallel to the floor in a pitch of about half a meter), a grin grid or nail nails.
  6. Then, on the rafters, we strengthen the vapor barrier with a stapler (without pulling it, it is better even so that it sagging slightly).
  7. Then we are sheathed with material for finishing: drywall, lining – also with some gap from foam.

Video: roof insulation with foam from the inside

Insulation from the outside

  1. The vapor barrier is attached by the stapler to the rafters.
  2. We mount a crate with an air gap for ventilation in the same way as in the previous case.
  3. We cut the foam with sheets of such a size that they are slightly wider than the distance between the rafters.
  4. Between the rafters with an effort, insert the foam. We darken the joints.
  5. We fasten it with the racks of the crate (then they are stuffed with a step of about half a meter), a grin grid or nail nails.
  6. We put waterproofing on top of the foam (ordinary roofing material, foil or polyethylene) without pulling it.
  7. We stuff the crate.
  8. Put and fix the roofing.

Insulation of a flat roof

Heavy loads are typically placed on flat roofs. As a result, using foam is advised in this situation, though foam will work just fine.

There are two other ways to insulate a flat roof.

Insulation from the outside, or "Non -handed ceiling"

  1. Prepare the surface of the roof, clean and level.
  2. We lay a vapor barrier membrane.
  3. Put the foam – on glue or mastic.
  4. Swifts are displeased.
  5. We lay waterproofing (roofing material or geotextiles), seal the seams.
  6. We fall asleep everything with gravel to a thickness of 5 cm, or lay with paving slabs.
  7. Next, you can lay geotextiles, on top of it a cement screed and already fuse the bitumen roof on it. Recently, “hanging gardens” has come into fashion – a reinforced coating has been laid on the insulation, then a special membrane, geotextiles and fertile land. And already there you can plant plants with short roots.

Insulation from the inside, or "fascinating ceiling"

  1. We carry out the work in exactly the same way as when warming the pitched roof from the inside.
  2. On top of vapor barrier and crate, we mount the finish ceiling – from boards, lines, chipboard or drywall.

It is challenging to overestimate when it comes to polystyrene roof insulation, as such a property is not achievable! In this case, vapor-proof film is required in addition to roofing. Water seeping through the roof allows the insulation to effectively drain away without altering its thermal insulation qualities. Polystyrene cannot be wet on top when there is a leak in the roof; however, it must be shielded from below water vapors from the house, which form over a household’s lifetime, using materials such as cotton wool. Vapor polystyrol is allowed. Vodcinea Online at www.Mastergrad.COM/Forums/T42311-A-CheM-PENOPLAST-PLOH-Dlya-Utepleniya-Mansardy/

Roofing with polyurethane foam

  1. We put on a protective suit and respirator.
  2. Run the device for filling, a stream of foam appears from the nozzle. In this method there is no need to specially prepare the surfaces.
  3. Smoothly apply foam on the inner surface of the crate of the roof, starting from the far corner.
  4. We make sure that the insulation does not get out for the crate.
  5. If you need to switch to another place, turn off the device, and before the start of the new "session", we change the exhaust nozzle.
  6. If you need to apply the second layer, then first we let it completely polymerize the first.
  7. Cut the frozen foam with a knife, if necessary.
  8. We reinforce the frozen foam with a net to continue work: plaster, coloring, installation of roof or siding.

Polyurethane foam can be applied on the top of the crate from the outside as well as the inside of the pitched roof.

Video: Roofing Roof polyurethane foam from the inside

This technique functions flawlessly on both flat and pitched roofs.

Video: applying polyurethane foam to a flat roof

Because of the PPU’s quick installation, lack of cold bridges, moisture adsorption, and ability to resist shrinking over time, he insulated both the floor and the roof. For the money, it’s a little pricey, but it comes with fewer hemorrhoids and happens faster—the brigade arrived and went after half a day, and my gender and roof are ready. As far as I can tell, everything has been tidy for a while. exclusively for me. Banderes Antonio This is the URL. View = comments

Maintaining comfort and energy efficiency in your home depends on the insulation you choose for your roof. Three common options—polystyrene, polyurethane foam, and Foamyx—each with distinct advantages.

Whether it is extruded (XPS) or expanded (EPS), polystyrene insulation is lightweight, moisture-resistant, and has good heat resistance. For many homeowners, it’s an affordable option that offers respectable insulation qualities without going over budget.

Known for its superior thermal performance, polyurethane foam creates a seamless insulation layer that successfully plugs gaps and cracks. It works well in smaller spaces where maximizing insulation thickness because it provides high R-values per inch of thickness.

A more recent addition to the insulation market, Foamyx combines the advantages of polyurethane and polystyrene foam. It is environmentally friendly, made from recycled materials, and has remarkable heat resistance. Additionally lightweight and simple to install, Foamyx appeals to green-minded homeowners searching for efficient insulation options.

The decision between Foamyx, polystyrene, and polyurethane foam ultimately comes down to budget, desired level of insulation, and environmental factors. You can choose the best course of action based on your unique needs and the local climate by speaking with an expert.

Selecting the appropriate roof insulation—polystyrene, polyurethane foam, or the cutting-edge Foamyx—can have a big impact on the comfort and energy efficiency of your house. Every substance has particular advantages: Foamyx combines lightweight construction with remarkable thermal performance, polystyrene offers cost-effective thermal resistance, and polyurethane foam excels in versatility and moisture resistance. Knowing these choices enables homeowners to improve their living areas while reducing their energy expenses."

Video on the topic

Insulation of PPU. I threw the stone cotton wool and flooded all Ecotermix. Everything is according to the mind

Preparation of the attic for insulation of PPU (polyurethane foam)

What do you think, which element is the most important for a reliable and durable roof?
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Alexandra Fedorova

Journalist, author of articles on construction and repair. I will help you understand the complex issues related to the choice and installation of the roof.

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