Warm Roof of Cold Roof. Whats the difference?
Dan Simpson
Dan represents the 3rd generation of M Simspon and Sons. With over 18 years in the trade, Dan carries out our client site surveys, liaises with customers as well as managing all the contracts.
Few people know the difference of each insulation method and even fewer people know the benefits of each. In this handy guide, we highlight the two methods and the benefits of each.
Warm Roof
During the construction, rigid insulation boards are installed over the timber joists and underneath the flat roof covering of choice e.g. Felt, EPDM rubber or Fibreglass.
Layers that make up a warm roof system:
What are the benefits?
More energy efficient compared to a traditional cold roof. In the event of a new build project it is likely the architect will insist on a warm roof system.
Cold Roof
A cold roof construction is the traditional method of laying glass wool insulation between the timber joists. A timber deck is then fixed to the joists followed by the chosen flat roof covering system. Because the insulation does not cover the entire flat roof area, there is a small amount of heat loss. This is known as thermal bridging. An air gap between the insulation and the under-side of the timber deck is necessary to prevent contact therefore causing subsequent condensation.
Layers that make up a warm roof system:
What are the benefits?
Less labour and materials needed for the method resulting in lower costings for the home-owner.
Our Advice
In relation to a new build build project, we would recommend a warm roof system. Due to the thickness of the layers, this would not be possible if you have an obstacle e.g. patio doors leading to a balcony area.
In the event of a renovation to an existing living area, a cold roof should suffice. Especially if the area won't be lived in on a regular basis. Thermal bridging is an issue, but, with the advances of efficiency regarding modern glass wool insulation this isn't too much of a concern.
