Is it possible to insulate a wooden house from the outside with penoplex and how to comply with the technology?

Most private developers are trying to find simple, reliable and the most inexpensive construction technologies that make it possible to erect buildings that are relatively cheap to install and operate. For our climate, the most expensive item of operating costs is heating during the cold season, don't you agree? So the search for the optimal insulation has always remained an urgent problem.

Nowadays, penoplex is very popular, which has proven itself perfectly for warming foundations, plinths and concrete structures. Experienced developers have convinced themselves of the excellent characteristics of this material, but the owners of wooden houses doubt whether it is possible to insulate a wooden house with penoplex from the outside, and if so, what is the optimal technology of this process.

To understand, one should, first of all, understand in what cases such an undertaking is necessary, what criteria should the insulation meet, and what is the mechanism of such a costly and troublesome event. It is these questions that we will consider in detail in our article.

When is insulation of wooden houses required?

Wood itself is an excellent heat insulator. And a high-quality wooden house, if we talk about traditional log technology, does not require additional insulation. But this is in a perfect world.

In practice, a wooden building may turn out to be uncomfortable or completely unsuitable for habitation due to technological errors, for example:

• a triangular longitudinal groove in the log instead of a semicircular one, cutting off part of the caulk over time and therefore easily blown;
• insufficient thickness of lumber used in construction;
• converting non-residential premises into residential ones;
• an attempt to stop age-related changes in the structure of the house with little blood - the tree sooner or later undergoes biological damage and its heat-insulating properties drop sharply.

That's when the owners think about additional wall insulation.

Of course, ideally, it is still not to insulate a wooden house, but to correct flaws in its design. But for a variety of reasons, this path is not always possible. Therefore, the developer still decides to carry out insulation.

Requirements for the heat-insulating circuit

Let's break down the big picture into a few basic points. First, wood is a material susceptible to biological damage (fungus, mold, woodworm, etc.). Part of the problem can be stopped by using chemical biosecurity methods. But this path is not always effective, and it can only be considered as part of a general complex, and not a self-sufficient means.

Main protection of wooden structures - moisture protection and natural ventilation. Consequently, the additional heat-insulating circuit should in no way interfere with the normal ventilation of the walls and should not interfere with the removal of moisture from the wall array.

The second important point is flammability of wood. Impregnation with fire retardants (substances that protect wood from fire), as in the case of chemical biosecurity, is only part of the solution to a common problem. It is also important to minimize the spread of fire. What should also be taken into account when installing the insulation - if ventilation gaps are formed, then they should be arranged accordingly, which will be discussed below.

Third, it is important observe the general installation rules heat insulator. But everything is simple here: no internal insulation wooden house. Any competent builder will say that the heat-insulating circuit is always mounted outside the protected structure. There is a simple explanation - Dew point.

In simple terms, moisture can condense directly from the air - when temperatures change. And therefore condensation on the border of warm and cold is inevitable - physics. Accordingly, the dew point must be artificially displaced either to the outer surface, or removed in depth heat insulator - if it is dense and not hygroscopic. And you cannot do so that condensation falls out in the room itself or in an array that is capable of retaining moisture. And the tree is just one of them.

Fourthly, facade cladding required. Since we are talking about the external insulation of a wooden house, then you should think about an affordable way to improve the facade after carrying out warming measures - all the same, the existing insulation does not belong to the number of decorative materials. And here the properties of the insulation must correspond to the design of the facade.

How to comply with the requirements in practice?

The ideal insulation for wood should be considered one that roughly corresponds to it in terms of vapor permeability and hygroscopicity. This can be considered ecowool made from recycled waste paper or (with some stretch) mineral mats based on basalt fibers.

The subtleties of using penoplex

But here considerations of the total cost of the project and the ease of installation of the structure often come to the fore, and it was then that many remember penoplex - boards made of extruded expanded polystyrene. A material with unique thermal insulation properties, practically zero water absorption and a host of other useful qualities. Moreover, the Internet is full of tips and tricks for its use. Unfortunately, even the manufacturer does not always correctly indicate the areas of application of this material.

Penoplex is sometimes used in frame construction, since the material is vapor-tight and keeps heat well. Nevertheless, it should only be used in combination with kiln-dried wood. EPPS does not work well with damp wood or naturally dried wood.

In order for the penoplex, or rather, the shell from it, built around the walls, to meet all of the above requirements, you need to provide a lot of nuances. So that there is no threat of biological damage, it is necessary to provide normal ventilation.

If the foam block is permeable to steam, then a separate plate is not (it is just that there are gaps between the plates, which, even when filled with assembly compounds, do not provide the necessary tightness). So in the array of insulation, areas with a high vapor conduction voltage will be created, that is, all the steam that is somehow formed in room, will begin to pass through the walls not through the entire surface, but only on some point areas, which will cause condensate. And, as a result, there are problems of focal accumulation of moisture - in places where steam may pass through the walls.

The problem can be partially solved by creating a ventilation gap between the wooden wall and the EPSP layer. But this option is not possible due to fire safety reasons. Yes, the manufacturer assures that extruded polystyrene foam is fire safe, because it is bad lights up, but in the vicinity of a combustible material it supports combustion well, so they are neighbors with a tree bad. More details technical characteristics of EPS we covered in this article.

In general, it is strictly forbidden to build ventilation gaps with the use of flammable materials with wooden walls - such a gap plays the role of a chimney with excellent draft and therefore contributes to the immediate spread of fire in the event of fire.

Since the option with observance of the gap disappears, you have to think about the tight fit of the EPS to the walls of the house. That is possible only in timber or frame construction. A blockhouse made of round logs cannot be protected in this way.

But at the same time, additional measures will have to be taken to improve the ventilation of the interior of the house - in order to get rid of the thermos effect (although here the comparison with a greenhouse is more correct). And an increase in the power of supply and exhaust ventilation can affect the decrease in the efficiency of the heating system.

To remove such a negative, you will have to think about recovery schemes - mainly we are talking about preheating the air coming from the street due to the air that is removed from the room) in the ventilation system. And this will lead to additional costs, so that the primary visible savings on house insulation in this way can reduce all budget bonuses to zero.

Thin sheets EPPS in principle, cannot be used for facade insulation. Due to the same dew point. It should be located in the thickness of the polystyrene itself or on its outer surface. Shifting it to the middle of the total massif is unacceptable - the tree should be protected in every possible way from the ingress of water.

In prefabricated frame structures, this problem is solved by almost complete sealing. solid walls and the use of kiln-dried wood, but in artisanal conditions this is simply impossible. Therefore, only increased ventilation.

Exterior finish on top of insulation

Expanded polystyrene has a fairly high coefficient of thermal expansion. Accordingly, the linear expansion of its massif with daily and seasonal temperature fluctuations will reach serious values. Therefore, the use of a wet facade, for the creation of which technologies are used that use hydraulic binders, in other words, putties and plasters, is excluded.

In theory, it is possible to create around expanded polystyrene shell of some basic reinforcing layer, which will become the load-bearing. But this solution is by no means optimal. Therefore, only the frame sheathing method remains.

Facade insulation tips EPPS

If our arguments have not convinced the skeptics and they continue to insist on the insulation of a wooden house with slabs penoplex, we will give a few tips to somehow level out the shortcomings of such a solution.

So, mount the slabs on walls without a gap. It is best to use a mounting adhesive based on polyurethane foam. Additionally, the plates are fixed with plastic "fungi" or self-tapping screws with reinforced mounting washers.

When choosing a material, preference should be given to plates that have a quarter along the edge - for a greater density of the connection. And all the same, the joints of the plates after installation should be carefully filled with polyurethane foam. The thickness of the slabs is ideally from cm - with a lower layer of protection, problems can begin with the same notorious dew point.

Particular attention should be paid to window and door slopes. They should be carried out as tight as possible..

It is better to carry out work in the winter, as paradoxical as it may sound. Since installation in cold weather will help to get rid of fragmentation (separation of monolithic insulating the shell of the house into separate slabs) of the protective layer due to the large CTE (coefficient of thermal expansion).

Conclusions and useful video on the topic

We recommend watching a video where a specialist with a construction education explains in detail the disadvantages of insulating a residential building with slabs EPPS:

This video addresses issues of technology compliance during installation penoplex:

EPPS cannot be considered the optimal insulation for the outer walls of a wooden house. Yes, it has excellent heat-insulating properties, has a low specific weight and a relatively low price. And yet, for external walls, in addition to the ability to retain heat well, other equally important requirements are put forward. Which, unfortunately, penoplex cannot provide.

Do you still have questions about the intricacies of exterior wall insulation with Penoplex? Or would you like to share your own experience in EPPS installation and give recommendations to our readers? Ask questions to our experts, participate in the discussion - the feedback form is located below.