How does Pitched Roof
Insulation Work?

There are two terms to be aware off when thinking of pitched roof insulation – ‘cold roof’ and ‘warm roof’ insulation. The term ‘cold roof’ is used to describe insulation in a pitched roof that installed at the level of a horizontal ceiling of the top floor. This leaves the loft space unheated above the installed insulation. Alternatively, ‘warm roof’ insulation describes the insulation that is installed between or under the timber roof rafters. This ensures that the entire space under the roof is heated.

There are four ways to insulate a pitched roof, and this is done either at ceiling level or rafter level.
The first method is an ‘installation from above’ where the roof coverings are temporarily removed above the sloping ceiling. The insulation is then installed between the roof rafters whilst maintaining an air gap between the insulation and the roof covering. The insulation used here can be the same insulation used within the existing roof space. This method provides effective and compatible insulation as well as providing full access and opportunity to achieve the highest standard of installation.

Alternatively, we can install your insulation by pushing it downwards from the roof space. This maintains an air gap between the sarking and the insulation. Rigid foam boards are the easiest to install in this instance. However, this would make it difficult to achieve a full, airtight fit and they do not have the same thermal performance that mineral wool can provide.

If that doesn’t sound right for you, we can remove your existing sloping ceilings and replace them with insulated ceilings. This helps to maintain a ventilating air gap between the roof sarking felt and insulation. This method ensures minimal disruption to your family life and offers a reduced cost. However, it can be difficult to work from the underside of the ceiling and the tightest fit can’t be guaranteed.

Finally, we can apply insulation boards to the underside of the existing sloping ceiling. This is less expensive than removing the ceiling or roof coverings and the remaining air gaps can be preserved. Although, it should be considered that future removal can cause extensive damage and the thickness of the insulation will be limited due to the floor to ceiling height and the presence of current windows and doors.

Should I insulate my
Pitched Roof?

We would usually advise that the insulation is installed both between and above the rafters or alternatively, between and under the rafters.

It is beneficial to insulate the underside of a pitched roof to conserve heat when the space is intended to be used for anything other than storage. Prior to the installation of insulation to the sides of a pitched roof, any repairs that require attention should be inspected. This is because once the insulation is fitted it will be difficult to identify leaks or damage to the roof and you run the risk of the leak soaking into the insulation. The addition of another layer of insulation provides an extra advantage in which it minimises the effect of cold bridging through the rafters as heat will be lost at a faster rate through the rafters than it will be through the insulation itself.