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Construction: types of insulation

Insulation is the main component used to provide the thermal qualities or thermal resistance to the fabric of a building, to reduce the flow of heat in or out of a building. Insulation has not always been as we now know it, the Ancient Egyptians used stone and thick mud to block the heat of the desert, the Greeks pioneered air gaps in wall to provide a thermal break and in the industrial revolution asbestos was used as the main form of insulation on engine pipes to improve efficiency.

In modern construction insulation can be provided in a number of different ways, such as the use of boards, spray foam, blown in, or blanket. When developing the proposals for a new home or extension the method of insulation is one of the considerations and will have an impact on the approach to construction for the slab, walls and roof.

The thermal properties of the fabric of the building, including the insulation, are often expressed as a U-value where all aspects of the fabric, including air gaps are considered. A U-value value is indicated in units of W/m²·K, indicating the ability of an element to transmit heat from a warm space to a cold space in a building, and vice versa. The lower the U-value, the better insulated the building element. These are some of the main type of insulation found in modern construction:

  • Glass wool insulation

The most common type of insulation which is used in the home is blanket insulation which usually comes in rolls and is often the type found in loft spaces, laid over the ceiling rafters. The material normally used is glass wool made from recycled bottles which gives the material a good environmental rating. Due to its flexibility, it is one of the easiest materials to install cutting down on labour costs and can be a cost-effective option.

  • Rock mineral wool

This insulation is often produced as a semi-rigid material when compared to glass wool and can be produced as a denser board and can provide the benefit of no sagging or slumping, and is often found in roof and wall construction. Rock mineral wool is a very effective fire safety measure as it is resilient to heat and fire.

  • Loose fill or blown insulation

Often used to fill existing cavity wall construction as the oose-fill takes the form of small particles that will fill a space when installed under pressure without disturbing structures. This form of insulation is also widely used in timber frame construction and is installed once the frame has been erected, with the insulation being able to fill all the gaps between the timber studs, but care must be given to not using a material that will sump or compress. The most commonly used material for this type of insulation is cellulose, fibreglass and mineral rock wool which are all produced from recycled material.

  • Sprayed foam insulation

Sprayed foam is a common insulation and works in a similar way to loose fill / blown insulation, where a liquid foam is poured or injected into wall cavities. In residential projects it is used more on retrofits and refurbishments rather than new builds. Sprayed in foam is installed using a foaming agent and will expand and become solid as the mixture cures. Slow curing foams are available which will flow around any obstructions inside the wall cavity before hardening. This has lots of benefits when working with refurbishments as the insulation can over come difficult detail and shapes whilst providing a continuous line of insulation, particularly in projects where cutting insulation boards to fit in difficult spaces may end up with gaps in the insulation.

  • Rigid foam

There are three main types of rigid insulation boards: Polyisocyanurate known as Polyiso (PIR), Extruded Polystyrene (XPS) – often called Styrofoam – and Expanded Polystyrene (EPS), and are typically petroleum-based, they have good thermal resistance compared to other insulations of the same thickness, but the ecological impact should also be considered prior to using these.

  • Sheep’s wool

There are lots of benefits of using sheep’s wool, particularly as it is a natural product it is one of the more sustainable forms of insulation and is versatile.

It is important to consider the qualities of each type of insulation an how it can be integrated into a project. We’d be happy to help with your architectural plans and discuss ways we can work together. Check out our contact page here.


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