Pitched Roof Insulation Between Rafters

An efficient room in a roof in a new build property where over rafter insulation is not desirable.

Pitched roof insulation between rafters.

In this blog post we will be looking at insulating pitched roofs and why putting insulation just between the rafters isn t a viable solution. The roof will typically be insulated above the rafter line creating what is most commonly known as a warm roof. If 180mm is to be installed then 100mm board might be introduced between the rafters there has to be a minimum 25mm air gap between the insulation and the underside of. The thickness of roof insulation is determined by the u value requirements.

To create a warm pitched roof insulation such as kingspan kooltherm k7 pitched roof board should be fitted between and over the rafters. Utilising a pitched roof as a usable living space is an effective way to maximise the square meterage of a residential development. This roof type will require a breathable membrane like kingspan nilvent to be. This popular application requires some careful design considerations to minimise the risk of interstitial condensation and guidance on how to meet.

The general advice we give is that you should always insulate between and above the rafters or between and under the rafters on our u value calculator we don t give an option for putting insulation between the rafters. The benefits of insulating a building around the outside protecting the structure and effectively creating a tea cosy effect are well publicised. Both products are high performance pir insulation boards which have been specifically designed for this type of roof construction. Its versatility is the key to its popularity whether being used to achieve.

Kingspan kooltherm k7 pitched roof board is a premium performance rafter level insulation for ventilated or unventilated pitched roofs. For this method of pitched roof insulation we recommend using quinn therm qr roof insulation boards between the rafters and quinn therm ql kraft insulation boards below the rafters. Kingspan with a warm roof the usual process is to split the insulation into two layers. There will also be kooltherm k7 pitched roof board between the rafters image credit.

As this requires fitting insulation above the rafters the roof covering will have to be removed in order to fit the insulation. It is common to use the same thickness of insulation between the rafters as you have used above the rafters. Arguably the most popular pitched roof solution installing insulation between and under the rafters uses the depth of the structural timbers to best effect. The table below is based on a typical warm roof construction with insulation above and between the rafters.

When it comes to pitched roofs however adding a thick layer of insulation to the rafters can result in a depth of roof construction that may.