Performing the task of external insulation of a home is a labour-intensive process that takes several days. However, in reality, it is easy, and even a person with minimal experience in repair or construction can cope with this job.
When insulating the exterior of multi-story buildings with polystyrene foam, doing it yourself becomes almost impossible. In this case, involving specialists using sophisticated equipment will be necessary. However, insulating a private house with your own hands presents no particular difficulties. You will not need specific tools, and performing this task will be affordable. This way, you will not only save money but also be sure that the job was done correctly.
In this article, we will look at the basic principles of insulating house facades using polystyrene foam and provide answers to the most common questions.
Polystyrene foam is the most common and preferred choice when choosing a material for external insulation. However, it has competitors such as polyurethane foam, mineral wool and glass wool.
Internal insulation of a house using polystyrene foam is rare. This is because the thermal insulation properties of polystyrene foam manifest themselves best as its thickness increases. When insulating from the inside, the usable space inside the premises is significantly reduced. However, an alternative solution may be to use thin foil insulation, which saves space but has a higher cost.
Polyfoam has excellent heat and sound insulation properties and does not absorb water. Additionally, additives increase the flash point to 220°C, making it less susceptible to fire.
The technical properties of polystyrene foam are directly related to its production process. The main component is styrene, which forms granules when foaming. Inside these granules are cavities with carbon dioxide, which leads to reduced thermal conductivity of the foam.
In the building materials market, “foam” usually refers to two different materials: polystyrene and extruded polystyrene. Both materials are created based on the same substance but using other technologies.
Foam insulation technology
The technology of insulating a house with polystyrene foam can include both external and internal insulation. A combination of both approaches is most effective. However, many companies recommend choosing external insulation if you plan to protect only one side of your home. This is due to several reasons:
Space saving: external insulation does not occupy the internal space of the room.
Moving the dew point to the outside: External insulation will place the dew point outside, which helps prevent humidity inside the home from increasing and causing mould to develop.
No need to vacate the premises: when externally insulating a house, there is no need to temporarily leave the premises since the work is carried out outside.
Possibility of using thick layers of insulation: External insulation allows the use of thicker layers, improving energy efficiency.
Foam insulation of facades is suitable for various types of houses, including brick, wood, and cinder blocks. Covering the walls with foam plastic around the entire perimeter without leaving gaps is essential. Partial insulation can create cracks between “warm” and “cold” walls. This is due to temperature deformations: the insulated part expands more than the cold part, which can lead to the formation of microcracks. Water can get into these cracks, which freezes and widens the gap. The problem may not appear in the initial years, but it can damage the walls over time. Therefore, it is recommended to carry out foam insulation over the entire area of the walls without gaps.
The preparatory steps before insulating walls with foam plastic in private homes include the following steps:
- Surface cleaning: Remove old plaster or coat from the wall surfaces. You can use a hammer drill with a flat chisel to do this.
- Repairing cracks: If there are cracks on the surface of the walls, they need to be repaired. Make sure there are no seams or irregularities.
- Checking the evenness of the walls: use a building level to match the evenness of the walls. They must be levelled if the height references the height of being more levelled. To do this, it is recommended to use a wide facade spatula.
- Priming: after the putty has dried, the surface of the walls must be primed. The primer is necessary so the adhesive mixture adheres well to the surface.
- Installation of the starting profile: the starting profile is screwed onto the bottom line of the insulation. Make sure the profile is level.
- External wall insulation with foam plastic can sometimes be done directly on old plaster. A wooden sheathing is used to fasten the insulation sheets in this case. However, this fastening method can increase heat loss through gaps and joints of guide beams and insulation. Therefore, adhering to the correct technology is recommended and takes advantage of time and materials.
To insulate the facade of a house with polystyrene foam, you will need the following materials:
- Deep penetration primer prepares the surface before applying glue and insulation.
- Base profile: installed at the bottom of the facade to protect against moisture and mechanical damage.
- Adhesive solution for foam plastic: the primary material for attaching foam boards to the surface of the walls.
- Reinforcing mesh: used to strengthen and stabilize the insulating layer.
- Adhesive for reinforcing mesh: used to apply mesh to the surface of insulated walls and secure it.
- Finishing primer: applied before finishing work to create a uniform surface and improve the adhesion of finishing materials.
- Finishing materials for cladding: selected depending on preferences and design, may include paint, plaster, clinker tiles, siding and others.
- Dowels are used to fasten the profile and foam sheets. The profile must be secured with at least two points per meter. Sheets of foam plastic are attached in the centre and corners, and special umbrella dowels are used to ensure reliable fastening.
The cost of materials will depend on the selected brands, scope of work and region. You should contact specialists or material suppliers to obtain more accurate information about the cost and quantity of materials required for a specific project.
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To carry out work on insulating a house with foam plastic, you will need the following tools:
- Building level: used to check the surface’s evenness and the walls’ alignment.
- Tape measure: necessary for measuring dimensions and calculating quantities of materials.
- Wide spatula: used for applying glue and plaster to the surface of the walls.
- Roller: used for applying primer, paint or finishing.
- Construction knife: necessary for cutting foam and reinforcing mesh.
- Rotary Hammer or Impact Drill: Used for drilling holes and attaching dowels to walls.
- Drills are selected considering the thickness of the insulation and the depth to which they must penetrate the wall.
In addition to the listed tools, you may need additional devices, consumables and protective equipment, such as goggles, gloves, a mask, etc.It is important to choose tools and equipment that match the insulation tasks and ensure safety and quality of work.
Insulation of the facade step-by-step
Steps for insulating the facade of a house with polystyrene foam can be as follows:
- Start laying the foam from the corner of the facade, for example, near a door or window. Place the first row of foam on the profile.
- Cut holes in the foam for communication outlets, if necessary. Also, cut the foam at a 45° angle at the corners of the walls to create a tight joint.
- Apply glue with a notched trowel. The adhesive should cover the area of the entire sheet of foam and should also be applied to the joint between individual sheets. Place the beacons in the centre of the foam.
- Press the foam firmly against the wall surface and hold for about 1 minute. Remove excess glue that squeezes out of the joints.
- After the glue has initially hardened, make holes for the dowels.
It is important to remember that the following rows of foam must be laid offset. The joints in the vertical direction of adjacent rows should not coincide, as when laying bricks.
After laying the foam:
- Apply a primer.
- Apply a layer of glue and lay down the reinforcing fibreglass mesh (corners are used in the corners).
- Apply another layer of glue on top.
- Apply putty to the surface. In most cases, bark beetle is used.
- The final stage is finishing the facade. This could be painting or using decorative plaster. If decorative plaster is chosen, then additional processing may not be required. For painting, you can use an air compressor and a spray gun.
- An alternative option for finishing the facade is to use facade tiles. In this case, you may need a specialized tile cutter or an angle grinder with a diamond blade to cut the tiles.