Polyethylene foil insulation became so widespread that the name of the famous brand - "Penofol" - became a household name. But often homeowners and unfortunate craftsmen use the material thoughtlessly, violating the thermal and humidity conditions of operation of a country house. Sellers are also cunning, greatly overestimating the real performance of this heat insulator. Let’s clarify the situation: we will tell you where Penofol insulation is used effectively and we will describe the technology in detail according to the manufacturer’s instructions.
What is Penofol and its analogues
Thin polymer insulation is made of the following materials:
- The main insulating layer is foamed polyethylene 3 ... 10 mm thick with closed air pores. The thermal conductivity coefficient λ of this layer is in the range of 0.037-0.051 W / (m • ° С) depending on the operating conditions.
- The external reflective layer is aluminum micron with a thickness of 14 microns, securely glued to the polymer base.
- The third layer on the reverse side of the polyethylene can be adhesive for ease of installation or the same aluminum.
Reference. All specifications are taken from the official website of the manufacturer. Thermal insulation options of other brands may vary. For example, the thickness of a similar material from Tepofol reaches 150 mm.
The peculiarity of the material is impermeability to moisture, the declared indicator is just miserable - 0.001 mg / m • h • Pa. The insulation is quite light - the density is in the range of 16 ... 35 kg / m³, sold in rolls. Thanks to these parameters, the material serves well as an internal vapor barrier.
Penofol is available in 3 versions:
- two-layer type A;
- three-layer - the base is coated with aluminum on both sides (type B);
- the same with the adhesive layer - Type C.
The foil side acts as a reflector of the radiant (infrared) component; polyethylene foam resists direct heat transfer. For wall cladding, a perforated version of Penofol is shown on the outside, shown in the photo. Many small holes are designed to exit water vapor from the thickness of building structures.
Real characteristics of thermal insulation
At the beginning of the publication, we mentioned the overestimation of the operational parameters of the material by unscrupulous sellers. Common myths about the properties of an insulator look like this:
- The innovative insulation "Penofol" has the best thermal insulation characteristics. The thermal resistance R of a sheet with a thickness of 4 mm reaches 1.2 m² • ° C / W, which is comparable with the laying of red brick 0.67 meters or 46 mm expanded polystyrene.
- The Penofola layer serves as excellent sound insulation.
- The insulation can be freely poured with a cement-sand screed, unfolding the foil up.
Reference. The manufacturer claims: for the most effective operation, the heat insulator must be placed inside a closed air gap. When mounted close to other materials, the aluminum coating will not fulfill its function of reflecting radiant heat. Infrared waves can overcome open space, but not the thickness of concrete.
The heat transfer resistance of one insulation layer can be easily calculated using the classical formula from the course of building thermophysics:
- R is the thermal resistance of the material, m² • ° C / W;
- δ is the insulation thickness, m;
- λ is the coefficient of specific thermal conductivity, W / (m • ° С).
Substituting the manufacturer's data in the formula (we take the best option), we obtain R = 0.004 mm / 0.037 W / (m • ° C) ≈ 0.11 m² • ° C / W.Knowing the thermal conductivity of the foam (λ = 0.043), it is easy to determine the corresponding layer thickness: 0.11 x 0.043 = 0.0047 m = 4.7 mm. Roughly speaking, 5 mm of expanded polystyrene and 4 mm of foamed polyethylene will hold the same amount of heat, there is no question of any 46 mm.
Closed pores do not allow Penofol to become a complete soundproofing material. Sound waves are only partially absorbed by the soft surface of the polymer.
For effective sound insulation, acoustic building materials with an open structure are needed:
- mineral wool;
- cork sheathing;
- foam sheets;
- cellulose ecowool.
It is categorically not recommended to lay Penofol under a cement screed for underfloor heating for the following reasons:
- Under the weight of the solution, soft polyethylene foam is crushed, air (or an inert gas) is squeezed out of the chambers, the insulation becomes twice as thin. Thermal resistance is reduced to a minimum.
- Aluminum foil in the thickness of concrete does not work as a reflector of infrared waves.
- Monoliths thinner than 6 mm shrink and crack together with tiles.
Note. A full-fledged radiant heat reflector, laid under the screed, is a rolled multifoil. Structure - large air cells that do not crumple under the load of concrete.
Under the monolith, the usual Penofol quickly loses its foil due to the aggressive effects of Portland cement, which is clearly demonstrated below in the video. The manufacturer suggests laying a special type of insulation under the screed - “Penofol ALP”, laminated with a protective polymer film. True, the issue of compression and destruction of closed pores from the weight of the monolith remains unresolved.
Conclusion. Foil products made of polyethylene are not inferior in terms of thermal insulation properties to Penoplex and sprayed polyurethane. The weaknesses of Penofol are its small thickness and soft structure. The material must be used in certain places, observing the technology and manufacturer's instructions.
Scope of application
Using Penofol, you can significantly increase the energy efficiency of any home - a private house or apartment. Where is the material used:
- thermal insulation of the roof of the attic or cold attic;
- cladding of ceilings and walls from the inside - as an addition to the “pie” of the main insulation;
- under the final floor covering laid on logs;
- strengthening of the outer heat-insulating layer;
- internal warming of balconies and loggias;
- coating of heating pipes and ventilation ducts.
Addition. "Penofol" type C (adhesive surface), many drivers insulate the car body - interior floors, doors and roof. Cut blanks are glued to metal over bitumen vibration isolation.
It is undesirable to use the material as an independent insulation of external fencing - you will not achieve the desired effect, only protect the building from blowing by the wind. An exception - products of large thickness from 20 to 150 mm of the Tepofol brand, suitable for full insulation of the house.
Insulation technology
Knowledge of the proper use of the material will come in handy in any case - are you going to isolate the house with your own hands or hire a team of performers. It is important to observe 2 conditions:
- An air gap is made between the foil side of the insulation and the adjacent surface. Then Penofol will reflect about 95% of infrared thermal radiation.
- The porous base of the polyethylene must not be squeezed by an external static load. Short-term dynamic effects are permissible. Example: laying material under a laminate as a heat and sound insulation substrate.
Note. The requirement for an air gap is important to observe when warming a wooden house. It is well known that the porous and "breathing" structure of wood does not tolerate prolonged contact with any moisture-proof polymers and gradually begins to rot. The interlayer acts as a ventilation duct, which removes water vapor.
Now we will separately analyze the thermal insulation of various building structures using Penofol.
Ceiling and roof cladding
Preliminary warming of the slopes of the attic roof is proposed to be done according to the following scheme (presented above in the drawing):
- Waterproofing is placed horizontally on top of the rafters - a diffusion membrane, the minimum overlap is 100 mm. The order of fastening the paintings - from bottom to top.
- The membrane is pressed to the beams with bars of a counter-lattice, horizontal boards of the main crate are nailed to them. Top mounted roofing - metal, slate, profiled sheet and so on.
- From the inside, horizontal rails of 50-60 mm thick are attached to the rafters, the installation step is 60 cm.
- Three-layer “Penofol” of type B with two foil surfaces is aimed at the bars. Note that a thin insulation bypasses the rafters so that there is clearance on both sides.
- The inner lining is vertically screwed to the ends of the bars - lining, moisture-proof drywall, chipboard panels or other finishing materials.
Attention! The Penofol roll is rolled vertically along the surface, adjacent sheets are stacked end-to-end, and not lapped. We carefully glue the seams with aluminum tape.
In this case, the insulation reflects heat fluxes from both sides, which is very useful in the summer, when the metal roof is very hot. The inner layer remains unventilated, moisture from the outer air is removed through the membrane. Since Penofol serves as a barrier to a couple, it is necessary to organize a natural hood in the attic through a separate ventilation duct.
Please note that there is an inaccuracy in the drawing above - there is no external counter-lattice creating a ventilation duct above the superdiffusion membrane. In the next version of the diagram, which shows the heat-insulating “pie” of the attic roof, the crate frame is clearly visible. What is the difference between this method of plating:
- Between the rafters is a powerful layer of the main insulation - 120-200 mm of mineral wool.
- Bottom of the mineral wool is hemmed with a two-layer "Penofol" type A directly at the ends of the beams. Aluminum is turned inside the attic room, the paintings are deployed horizontally.
- A gap of 2-3 cm was left between the polyethylene and mineral wool insulation, about 4 cm from the side of the foil.
- We stick the bars for interior decoration to the ends of the beams directly through a layer of polyethylene.
It is clearly seen in the section that Penofol plays the role of an additional insulator and a vapor barrier - the traditional film is not used from the inside. The moisture formed in the mineral wool is discharged through the upper air duct and the waterproofing membrane. Vapors from the life of people are removed by supply and exhaust ventilation.
Tip. When working with Penofol, it is important to understand the essence: always leave a layer in front of the foil, we lay the polyethylene base close to the building structures. We connect the canvases only end-to-end.
The ceilings are insulated according to a similar principle:
- If from the attic side the wooden floor is covered with expanded clay, sawdust or reeds, it is enough to lay 1 layer of “Penofol” type B, arranging the gaps with the help of the crate.
- Type C material can be glued directly to the concrete ceiling, with foil down. Next, mount the frame for attaching GKL or another finish.
- When capital insulation of the ceiling is necessary, use the attic scheme, only without a membrane and an external crate. Install the frame from beams or galvanized profiles, between them, by surprise, insert the main insulation, then hem the bottom with type A foam.
If Penofol is the only heat flux insulator (which is not always correct), choose the maximum material thickness - 8 ... 10 mm. In tandem with other heaters, a sheet with a thickness of 3-4 mm works well. In detail about the device of the attic roof, see the video:
Wall insulation
If you carefully studied the previous section, you will quickly understand how to insulate walls with Peonofol. As a rule, the material is used for internal lining in 3 ways:
- with one air gap over a timber frame 2-3 cm thick;
- with two vents on the crate of timber 40-50 mm;
- as an internal vapor barrier as part of a full-fledged “pie”.
An important point. For wall insulation from the inside, it is better to use moisture-proof materials - extruded polystyrene foam or sprayed polyurethane foam. The dew point will surely fall into the thickness of the insulator, but the vapor will never come out of the smallest closed pores. By the way, it is better not to buy polystyrene - it is able to pass moisture.
In timber, log and frame houses, Penofol must be attached with a stapler to the crate in order to ensure a void of 2-3 cm from the aluminum side. Open cell pore foam and aerated railings are sheathed using a similar technology.
If you want to mount an external thermal insulation with your own hands, consider these recommendations:
- The walls of stone dwellings insulated with polymers are sheathed with a one-sided “Penofol” foil to the outside.
- If the brick house is sheathed with mineral wool on the frame, use only the perforated version of the insulation on the outside.
- Thermal insulation of wooden dwellings should be carried out with materials permeable to steam - polystyrene foam, mineral wool, ecowool and so on. Accordingly, to release moisture from the insulation, you need to take a perforated Penofol.
Comment. To provide clearance from the foil side, you will need a frame. The technology of insulation of stone buildings “wet facade” does not provide for the installation of crates; polyethylene foam cannot be used. Another thing is the “ventilated facade” system, where the material can be used as wind protection.
Floors and floors
We want to warn you right away: when insulating an existing wooden floor, it will not do without opening. You need to remove the finish and get to the lag in order to properly lay reflective thermal insulation. Overlapping can be insulated according to a simplified scheme that repeats the insulation of the roof:
- Across the lag, a rolled Penofol of type B is rolled up with a thickness of 8-10 mm. The material is aimed at the beams in such a way that 2 layers are formed on the top and bottom.
- The second cloth is laid end-to-end with the first, fixed with a stapler, and then glued with metallic tape.
- On top of the lag, a rough floor and a finish coating are laid.
An important nuance. Theoretically, a roll can be rolled right under a laminate or linoleum. But the whole point of reflective insulation is lost - the aluminum coating will not work.
The second option involves laying a single-sided Penofol Type A under the rough floors with a foil layer down. Note: under the thin insulator there remains a large cavity equal to the width of the log. If the room is located above a cold basement or an unheated room, be sure to lay mineral wool between 10-15 cm thick between the beams. Do not forget to provide a layer of 20-30 mm between polyethylene foam and mineral wool.
User reviews about Penofol
I must admit that on popular forums there are very diverse responses and opinions of homeowners about reflective polyethylene insulation. We dare to assume that the negative or positive in the comments depends on the correct use of the material.
Here are a few examples, discarding obviously purchased reviews:
Vyacheslav, Donetsk, Ukraine.
Recently, for the purpose of repair, I had to open the plasterboard wall lining inside the room. Behind her, a foiled Penofol was discovered covering a plastered cinder block wall. There was dampness and black mold under the heater; I had to dismantle all the casing and dry the walls.
Ivan, Veliky Ustyug, Russian Federation.
Lined with "Penofolom" 5 mm cold veranda, hammered together from a tez.Stapled it to the walls and ceilings, laying sheets of chipboard. This winter, the door to the veranda was calmly opened without fear of getting a house, the temperature outside is minus 40 degrees. Sometimes he drowned an extension with a potbelly stove to dry the walls.
Natalia, Lipetsk, Russian Federation
Than they did not insulate the northern wall of my private house, I could not get rid of mold. We tried cotton wool, polystyrene, any waterproofing. The father-in-law, a builder, came to visit, redid everything and lined it with this brilliant material. The result after opening (a year later) - the wall is dry.
Looking for video material for publication, we came across an interesting point confirming our assumptions. The installers are well aware of the recommended methods of using Penofol, but in practice the technology is constantly being violated. The reason is clear: the installation of a double crate for the sake of a thin layer of insulation is not economically feasible. It’s better to mount on the subsystem full insulation from basalt wool or “Penoplex” without any frame.
Finally about other use cases
Insulated foam polyethylene home craftsmen use for a wide variety of purposes:
- protection of heating pipes and hot water supply from freezing;
- interior decoration of the entrance door leaf;
- a reflective screen glued to the outer wall behind the heating batteries;
- inexpensive thermal insulation of farm buildings - sheds, workshops, garages;
- exotic - shoe insoles from a thin-sheet heater of 3 mm.
Penofol polymer insulator is a material that deserves attention. When applied according to the instructions, it will serve as a good insulation. But do not try to save and solve all thermal insulation problems at the expense of one thin polyethylene, use other effective heaters.