An understanding approach is required to ensure effective insulation, which includes considering the roof, walls, and floor. There must be no gaps in the insulation; doing so would result in thermal bridges and condensation problems of their own.

Insulation installation stands out as a highly influential improvement in enhancing your homes energy efficiency. Insulating your walls can substantially reduce winter heat loss and summer heat gain. This increases the convenience of your home while decreasing its heating and cooling energy costs. 

This post will explain which insulation would be best for your home, depending on the type of home you live in. 

Identify your wall type

Assessing the construction of your external walls is a critical initial stage in devising insulation enhancement strategies. Numerous prevalent wall varieties warrant consideration. In many residences, wood-framed walls with structural cavities are the norm. As a result, installing batt insulation between the joists is simplified. 

Without built-in voids for insulation, masonry walls such as brick or concrete blocks would require the installation of rigid boards or insulated sheathing on the external or internal. Certain residences have double walls that have an air cavity in between. Insulation that has been blown in can occupy this space. 

The insulation strategy will also influence whether the structure comprises solid masonry or a brick veneer affixed to a wood framework. 

Knocking on the wall and examining the headers above windows and doors makes it possible to ascertain the presence of timber framing beneath. If uncertain, consulting building plans or a professional can assist in accurately identifying your wall construction. 

What wall insulation is available? – Further useful information

External wall insulation

Insulating a homes external walls is called external wall insulation. Insulating external walls with rigid foam planks adhered to the external wall surface beneath the siding is the most prevalent method.

Frequently employed rigid insulation boards consist of extruded polystyrene (XPS), expanded polystyrene (EPS), or mineral wool. These boards are affixed to the wall through mechanical fasteners and adhesives to create an impermeable insulation layer.

The boards are subsequently coated with a reinforced base varnish and finish render to safeguard the insulation system. Alternate hues and textures can be applied to the render to create a contemporary facade. In contrast to uninsulated walls, external wall insulation offers superior thermal insulation, thereby diminishing heat loss and enhancing energy efficiency.

Advantages of external wall insulation 

  • No living space: There is no reduction in living space. By insulating from the external, usable floor space inside is not occupied.
  • Heat loss prevention: The complete surface of the wall is covered. External insulation envelops the entire wall and prevents heat loss caused by thermal bridging.
  • Stops mould growth: It renders the structure secure. Insulating the external wall structure mitigates moisture-related issues such as mould growth and structural decay during the winter.
  • Increased R-value: A denser insulation layer can be applied by external insulation, increasing R-value.
  • No air leaks: External insulation simplifies air leak sealing around windows, doors, and other penetrations.

Insulation around obstructions is avoided. Insulate over obstructions such as electrical outlets and plumbing that may be present on the external.

However, the cost of incorporating external insulation is higher than that of internal alternatives. Additionally, you will need to install new sheathing over the existing one, increasing the price.

Disadvantages 

  • Cost: External insulation is among the most costly methods of home insulation. Installation, materials, and specialised labour can add up.
  • Appearance: Some individuals detest how external insulation alters the aesthetics of a house externally. It conceals siding or masonry.
  • Moisture hazards: Inadequate installation may result in moisture-related problems within the wall or permit water ingress. Appropriate detailing is critical.
  • Wall space reduction: This reduction may occur due to relocating appliances or furniture away from external walls to accommodate thicker insulation layers. The amount of living space is reduced.

Internal wall insulation

Insulation is applied to the internal area of external floors and walls. By implementing this additional layer of insulation in the living space, heat loss through the building’s surfaces is mitigated, and heated air from the internal is prevented from reaching the colder external temperatures.

In most instances, insulating walls from the internal is simpler and less expensive. Typical methods for insulating internal walls include:

  • Batts or coils: Batts or coils of insulation made of mineral wool or fibreglass are affixed between the studs of a wall.
  • Blown-in insulation: Using specialised apparatus, loose-fill insulation or flakes of cellulose or fibreglass is blown into the wall cavity.
  • Spray foam insulation: Spray foam insulation establishes a seamless air barrier by being injected into the cavities.
  • Insulating panels: Between studs, rigid foam or fibre insulation planks can be cut to size.

Advantages of internal wall insulation

  • Lower expenses: DIYing internal insulation typically costs about half the cost of external insulation. Likewise, no additional sheathing is required.
  • Simple installation: The installation is simplified. Internal access to the wall cavities is more convenient. Specialised equipment is not required.
  • Minimal disruption: External disruption is minimal. You refrain from modifying the external appearance of your residence.
  • Scheduling: Adaptable scheduling. Incorporating insulation gradually is feasible, given the constraints of time and budget. 

Disadvantages 

  • Less living space: Eliminates living space. Plumbing, wiring, and framing consume internal space that could be utilised otherwise.
  • Difficulty: It is more difficult to insulate irregular surfaces. It is challenging to insulate around impediments within the wall cavity.
  • Reduced insulation capacity: Due to framing, internal insulation cannot encompass the entire wall surface.
  • Potential moisture-related problems: As the wall structure cools, the risk of condensation increases. Effective vapour barriers are vital.
  • Continuous air: Establishing a continuous air barrier is challenging. It is difficult to seal every crevice around internal wall penetrations.

Which is better?

Providing insulation for the external walls improves their thermal performance and reduces your heating and cooling expenses. However, it does incur higher initial costs. Frequently, internal wall insulation offers the greatest return on investment for do-it-yourselfers on a budget.

Blown-in cellulose provides comparable insulation value to external foam but at a significantly reduced cost.

Combining external and internal insulation is one alternative. Incorporate fibreglass batts or blown-in insulation from the internal into the stud cavities. Adhere 1-2 inches of rigid polystyrene to the external surface. This combines the air-sealing and performance advantages of external insulation with the convenience of internal insulation.

Insulation analysis

  • Insulating walls enhances indoor comfort and reduces heating and cooling expenses.
  • Energy efficiency is enhanced by external insulation, while internal insulation is less expensive and simpler to install.
  • A cost-effective strategy incorporates both internal and external insulation.
  • Obtain an energy audit to determine which areas of your one-of-a-kind property to insulate.
  • Utilise insulation of superior quality and implement it correctly for maximum efficiency.

Final Thoughts 

Internal and external wall insulation have advantages, and an optimal insulation strategy may incorporate both. External insulation maintains internal space, reduces thermal bridging, and improves thermal performance. However, it entails greater initial investment and external cosmetic considerations. 

Internal insulation is more cost-effective and enhances the comfort of a living space. However, it has a lesser impact on thermal bridges and may even reduce room size. Ultimately, climate, wall construction, budget, and aesthetic preferences should determine whether a home should be insulated internally, externally, or through a combination. 

It is recommended to consult with a certified expert and be familiar with local building codes to ascertain the most effective wall insulation strategy.