Substrates
Standing seam roofs can be installed on a vented cold substrate or a non vented warm substrate.
Warm non-vented roofs
Cold vented roofs
Advantages
The non-ventilated substrates reduce thermal bridges and increases air tightness within the buildup.
Advantages
Cold vented substrates have a long and established track record and have existed since the first zinc roof was installed in 1809. This type of build-up can be used on roofs ranging from 1:12 pitches to vertical walls as well as soffits.
Definition of a warm roof in North America
Warm non-ventilated and cold ventilated roofs are two terms which do not always denote the same ideas to all building professionals. In order to put the warm non-ventilated roof system into context, we will refer to it as a roof where there is absolutely no vented space within the roof build-up and furthermore the entire roof structure is on the warm side of the insulation. Whilst there are a few very limited exceptions in North America this means that the roof structure is generally below the insulation.
Definition of a cold roof in North America
Cold ventilated roofs and warm non-ventilated roofs are two terms which do not always denote the same ideas to all building professionals. In order to put the cold ventilated roof system into context, we will refer to it as a roof where there is a continuous air space of at least 2” between the substrate supporting the zinc and the insulation. This air space must be a vented space with openings generally at the eaves and the ridge. Linear air vents must be at least ⅜” wide and are commonly protected by insect mesh. It is always good practice to include a vapor control layer in the build up and this should be installed on the warm side of the insulation.