Spacing Between Insulation And Roof

The gaps do not have to be more than 1 8 inch but they are important to the health of the roof the insulation and the house as a whole.

Spacing between insulation and roof.

Common spacing for trusses on this type of building is often between 2 and 4 feet but trusses built with advanced designs may allow spacing as great as 8 or 12 feet. By leaving an air space between the insulation and the sheathing we can have air flow over the framing. In the winter humidity from the house s interior will get past the insulation and come in contact with the cold roof sheathing where it will condense into water. For such constructions the principles and benefits of unvented attic construction are similar to that occurring in a single family residence.

If there is a leak the air flow ventilation will help dry out the moisture. Place between purlins if using them. In vented cathedral ceiling assemblies a minimum 2 inch clear airspace is recommended between the underside of the roof deck and the top of the cavity insulation. When there are gaps or channels between the pieces of insulation you allow the air to flow between each one.

A roof must be able to breathe. An air space between the insulation and the bottom of the roof sheathing is desirable. The idea here is after you have your high quality metal roof installed you will want to prevent the space underneath from heating up. The same concept holds true for roof trusses.

The code calls for a minimum of 1 in. Instead a dead space exists between the roof system and the top floor ceiling typically comprising of an acoustic tile system and no roof ventilation is provided. This not a code requirement but ought to be only 1 inch is typically specified. The solution is not to ignore the insulation but to add one component.

Of airspace between the top of the insulation and the back of the roof sheathing. Roof decking insulation is a common method of providing yet another insulating barrier between the metal on top and the attic space below.