How to choose polystyrene foam for insulating walls inside the house

Selecting the appropriate polystyrene foam for interior wall insulation is essential for enhancing comfort and energy efficiency. Known for its lightweight and thermal insulation qualities, polystyrene foam, also frequently referred to as EPS (Expanded Polystyrene) or XPS (Extruded Polystyrene), is a widely used insulation material.

Take into account the R-value, which indicates the thermal resistance of polystyrene foam, when making your choice. An elevated R-value denotes superior insulation efficacy. Selecting a foam with a balanced R-value is crucial for interior walls, where space may be more limited than for exterior applications. This will optimize insulation without sacrificing the size of the room.

Consideration should also be given to the kind of polystyrene foam—EPS or XPS. Since moisture isn’t a major concern, EPS is a flexible and affordable material that can be used for most interior applications. However, XPS is stronger and has a higher resistance to moisture, which makes it perfect for damp environments like bathrooms or basements.

Take into account the foam sheets’ thickness as well. Better insulation is provided by thicker sheets, but they might take up more room. Thinner polystyrene foam sheets can still provide substantial thermal benefits for interior walls without taking up too much space.

Finally, evaluate the installation procedure. Since polystyrene foam sheets are usually lightweight and manageable, many homeowners can accomplish the installation themselves. Make sure the right adhesives and methods are applied to adhere the foam sheets to the wall surface in an efficient manner, minimizing any gaps that might lower the insulation’s effectiveness.

Insulation of walls outside and inside – which is better??

It is highly recommended by all experts to use external wall insulation. The dew point, or the temperature at which moisture in the air starts to condense and settle on cold surfaces, moves when insulating walls. This is explained by the peculiarities of physical processes. The wall will continuously get wet with all the unfavorable effects if the dew point is on the interior surface of the wall. This issue is resolved by external insulation, which pushes the dew point deeper into the material.

The insulation gets wet when it is insulated from the inside because the dew point is between it and the wall. Furthermore, the interior atmosphere of the house gets oversaturated with water vapor, necessitating more forced ventilation and having a negative impact on occupants’ well-being.

Nevertheless, installing interior insulation is frequently required. This occurs because doing outside work is not feasible for the reasons listed below:

• The height of the building does not allow work to be carried out.
• There is no possibility of insulation due to dense neighboring buildings.
• Climatic conditions or weather do not allow working outside.

For these reasons, we are forced to use the only solution available: insulating the walls from the inside out. There are benefits to this approach:

• Ability to carry out work at any time of the year and in any weather.
• There is access to all sections of the walls without the construction of scaffolding, platforms, etc.d.
• Sound insulation of the room increases.

But there are some serious drawbacks:

• The volume of rooms is reduced.
• The presence of insulation reduces the possibility of using hanging furniture.
• Air humidity increases.
• Transfer of the dew point to the inner surface of the wall, which will sooner or later cause it to get wet.

Situations like this call for a unique strategy to solve the issue, specifically a careful and methodical selection of insulation material that can function well under particular circumstances. The most popular and efficient insulating material for interior walls is foam plastic, which is frequently utilized for this purpose.

Foam plastic – advantages and disadvantages

The most beneficial insulating material is polystyrene foam because of its many beneficial properties.

Among them are:

• Low thermal conductivity.
• The material is very light – 98% of it consists of gases.
• It cuts well, has convenient sizes – length, width and thickness of sheets.
• Individual foam granules are completely neutral to the effects of water; for an array there is a slight absorption, but it is insignificant.
• Polystyrene foam is a good vapor barrier.
• Practically non-flammable, in any case, polystyrene foam will not cause a fire.
• The price of the material is the lowest of all similar ones.

But there are drawbacks as well:

• The material cannot withstand any deformation – it breaks immediately.
• Absolutely unresistant to solvents such as acetone or gasoline.
• Requires increased accuracy in work, as crumbles a lot in case of careless actions.

Foam comes in different densities. Various densities of brands are produced by the industry:

• PSB-S-15.
• PSB-S-25.
• PSB-S-35.
• PSB-S-50.

The material has a higher density the higher the number.

The material with the highest density would be the best option for internal insulation because it allows the least amount of steam to pass through.

Apart from ordinary polystyrene foam, extruded polystyrene foam is a more robust and compact variant. It is made somewhat differently, as it is a single foamed monolith rather than a collection of individually welded granules. It costs roughly three times as much as regular polystyrene foam, but it is ideal for internal insulation.

You have the option of selecting polystyrene foam or any of the following insulation materials, depending on its benefits and drawbacks:

• mineral wool;
• penoizol;
• extruded polystyrene foam;
• penoplex;
• penofol;
• polyurethane foam.

Internal insulation wall cake

The internal wall insulation cake’s structure is not overly complicated. The following is the composition:

• Wall surface.
• A small leveling layer of primer.
• Foam glued or nailed onto dowels.
• Internal lining.

The pie’s structure can be altered or complicated, but adhering to this guideline is essential:

The vapor permeability of the layers of the pie from the inside should be in descending order.

This indicates that the foam’s vapor permeability ought to be less than the wall’s. To accomplish this, select the densest material.

According to this rule, steam will be easier to release outside if it is released from a denser material onto a looser one. If this isn’t the case, steam will start to build up and condense at the intersection of layers—in our case, the wall’s surface.

By the way, the preparatory primer layer also acts as an intermediary layer, smoothing the transition to low wall temperatures and eliminating significant variations in the material’s characteristics.

How to calculate the thickness of insulation?

Several issues are resolved when insulation thickness is calculated correctly. It first aids in the removal of undesirable effects, such as elevated indoor humidity, wall material failure, and swelling.

There are also strictly practical duties, like measuring the width of window sills, window slopes, and other components that require replacement while accounting for foam thickness.

The process of determining the material’s thickness involves intricate computations using formulas that involve a number of different quantities, including the material’s thermal resistance, thermal conductivity coefficients, and other knowledge.

Finding information on a particular material can become so complicated (you’ll need to look for values for current concrete grades or other wall materials) that the final result might not match the actual circumstances at all. The truth is that a proper computation necessitates accounting for a wide range of minute effects, all of which together provide the true picture of the object’s physical state.

Simultaneously, obtaining the necessary values is considerably simpler – all you need to do is locate multiple online calculators on the Internet, which are widely available, and enter the available data to obtain the desired outcome. Such computations are performed on multiple independent resources for increased reliability, allowing for a comparison and clarification of the data collected.

In practice, in the vast majority of cases, a foam thickness of 50 mm is used.

Regardless, the computation must be closed at this thickness by rounding the computed data to match the real dimensions of the material that is sold commercially.

It’s important to take into account aspects like moisture resistance, ease of installation, and R-value when choosing polystyrene foam for interior wall insulation. Making the appropriate choice can greatly improve your home’s comfort and energy efficiency. This guide will examine the various varieties of polystyrene foam, their advantages, and helpful hints for selecting the ideal option to meet your insulation requirements and create a more comfortable and sustainable living space.

Preparing the wall surface

Surface preparation is the first step in insulating walls with foam plastic. The preparatory work includes scraping off old paint or wallpaper, checking the surface for flaws that need to be fixed, such as cracks, and removing any flaking or crumbling areas.

Examine the wall’s plane for any dents, irregularities, or depressions. If required, remove any flaws by local leveling or plastering over the affected area. One centimeter is allowed deviation for each linear meter.

Subsequently, a deep penetration primer layer is applied to the wall surface to improve the wall material’s adhesion to adhesives.

Is vapor barrier and waterproofing under foam plastic necessary??

Foam made of polystyrene is a great vapor barrier. This characteristic is beneficial for internal insulation but may be detrimental in other situations. As a result, no extra film supplies are needed.

Because of this situation, labor costs can be greatly simplified and decreased when doing work, mostly to cosmetic surface finishing.

Installation of sheathing

If the sheathing material—such as linings, wall panels, etc.—cannot be mechanically fastened to the foam, lathing might be the only option. In these situations, a wooden block measuring 50 by 50 mm is used, and it is arranged on the wall in horizontal rows before the insulation is attached.

Following the installation of the foam, these bars are affixed with vertical counter-lattice strips, which are subsequently attached to the sheathing.

Methods for attaching foam to the wall

Three techniques are employed:

• Dry mixes. Materials such as tile adhesive, diluted to the desired consistency with water.
• Special glue. Most often it is produced in cylinders, similar to polyurethane foam.
• Dowels with a wide head – fungi.

The foam is directly coated with the adhesive. Usually, stripes are applied to the central portion and the perimeter of the slab, leaving the remaining surface uncovered. Additionally, joints are filled with polyurethane foam or, in certain situations, coated with adhesive.

Using polyurethane foam to secure

Selecting the proper polystyrene foam to insulate your home’s walls is essential for both comfort and energy economy. Take into account the R-value, which represents the thermal resistance of polystyrene foam, when making your choice. Better insulation has higher R-values. Examine the foam sheets’ thickness as well, since thicker sheets often offer better insulation.

The kind of polystyrene foam used is another crucial consideration. The two primary varieties are extruded polystyrene (XPS) and expanded polystyrene (EPS). While XPS offers greater moisture resistance and compressive strength, making it ideal for areas prone to moisture, EPS is more cost-effective and suitable for the majority of applications.

Polystyrene foam selection should take installation procedure into account. Because EPS foam boards are lightweight and simple to cut, installation is made easier. Although XPS foam is denser and necessitates precise cutting instruments, it provides greater stability and durability over time.

Finally, consider sustainability and the impact on the environment. Certain polystyrene foams can support your sustainability objectives because they are recyclable or made of recycled materials. Selecting the proper polystyrene foam will guarantee that your house is energy-efficient, comfortable, and sustainable for many years to come.