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  • Writer's pictureEcorattic Insulation

Understanding insulation

Updated: Feb 2, 2022

What is insulation?

Insulation refers to a material that blocks or resists heat energy. Insulation is used to prevent heat from escaping from the home in winter and heat from outside from entering the home in summer.

The type and location you choose for insulation depends on the climate of your area and whether heat is being kept out or in. Understanding how your climate affects insulation is the first step to achieving a great result.

Good passive design is essential for insulation to work effectively. If insulation is installed in a house that is not adequately shaded in summer, it can trap heat inside, creating an "oven" effect.

Why is insulation so important?

Insulation is crucial for keeping your home cool and warm in the summer and winter. It acts as a heat barrier and prevents heat flow.Well-designed homes are comfortable all year, reducing cooling and heating costs, as well as reducing greenhouse gas emissions.

Typical heat losses and gains without insulation in a temperate climate

Source: SEAV (2002), updated in Energy Smart Housing Manual (2018)

Insulation R values

The R value is the measure of how well insulation products resist heat flow. The higher it is, the better insulation properties it has. The climate, the type of building, and whether cooling or heating are to be used will determine the appropriate level of insulation.

There are many factors that can lower the R value. These include thermal bridging and compression of bulk insulation, dust settle on reflective insulation, and the absence of an adequate air gap for reflective surfaces.To ensure that your insulation works as it should, you must follow the specifications, or use a help of professional installers.

Types of insulation

Insulation products can be divided into two main categories: bulk and reflective. Sometimes, they are combined to make a composite material.

Bulk insulation

Bulk insulation is made up of pockets of trapped air that resists the transfer of convection and conducted heat. Its thermal resistance does not change with the direction heat flows through it.

Bulk insulation products have a R value for a given thickness and can be made from materials like:

  • Glass wool, batts, and rolls are often made from recycled materials.

  • Wool, wool batts and loose fill

  • Loose fill with cellulose fibre (often made of recycled paper fibres).

  • Polyester, rolls and batts (often made of recycled materials)

  • Polystyrene expanded (EPS), or extruded to (XPS) as rigid boards

  • Polyisocyanurate (PIR) as rigid boards

  • Polyurethane (PUR), as rigid boards.

Bulk insulation traps air in still layers

Source: SEAV 2002

Reflective insulation

Reflective insulation is able to resist radiant heat flow due to its high reflectivity and low ability to re-radiate heat. The thickness of the air layer must be at least 25mm near the shiny surface to ensure insulation. Reflective insulation's thermal resistance varies according to the direction heat flows through it.

Reflective insulation is typically made from shiny aluminium foil laminated onto plastic or paper. It is available in sheets (sarking), batts-type batts, and multi-cell batts. These products are called reflective foil laminates (RFL).

Reflective insulation and heat flow

Source: SEAV 2002

Roof and ceiling insulation

Ceiling insulation and roof insulation can reduce heating and cooling costs by up to 45%

Types of roof construction

Most roofs are ventilated. They should have air gaps to allow for condensation to evaporate or dry out.

Unventilated roofs must have a hygrothermal assessment done by a qualified consultant in order to prove compliance with the National Construction Code.


Ceiling insulation can be placed between the joists in most climates.Bulk insulation options include batts, rigid foam boards and loose-fill.

It is very important to follow the manufacturer's instructions to install insulation. Insulation values can be significantly reduced if you do not follow the manufacturer's instructions.

Ceiling joists that are covered with insulation will be difficult to see when attempting to access the roof space. Platforms or access planks must be installed. Bulk insulation is often used to insulate ceiling joists and roof trusses so that they are not covered. However, this can reduce the insulation slightly.

Installing bulk insulation

Bulk insulation should not be compressed as this can reduce its effectiveness. It is important to make sure there is enough space so that the insulation can maintain its normal thickness.

If bulk insulation is exposed to moisture, its performance can be affected (unless it is water-resistant). If there is a chance of condensation, use a vapor control coating (vapor barrier).

Installing reflective insulation

Reflective foil insulation must always be placed on the warm side in any building system or Attic.

Keep at least 1 inch of air space between the reflective insulation's shiny surface and the roof.It only works by radiation and not-emittance so contact with other building elements will decrease its insulation properties to zero.

A qualified professional should install reflective foil insulation.

For a Professional Attic Insulation Installation, call ECORATTIC™ at 818-492-1090.


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