When insulating your attic the contractor can either spray the attic floor to keep a vented attic or spray the roof deck for an unvented system.
Vented vs unvented roof.
Vented roofs serve a number of different purposes and their roles vary from climate to climate.
A secondary goal is to vent moisture that infiltrates the attic from the conditioned home.
Enhancing roofing material life span by reducing sheathing temperature.
The choice of the venting approach is up to the designer.
Note that this would not apply where an unvented roof assembly is used as indicated in section r806 4.
A vent space clearance of at least 1 must be maintained at the location of the vent and between insulation and roof sheathing.
Unvented roofs vented roof.
These assemblies are created by eliminating ventilation openings and moving the thermal moisture and air control boundaries to the plane of the roof deck.
In colder climates the main purpose of a vented roof is to keep the roof cold and reduce the formation of ice dams.
Unvented roof assemblies such as conditioned attics and unvented cathedral ceilings are becoming common in north american construction.
In this case you can learn a lot from foam tech s article vented vs.
Moisture content in roof structure must be less than 18 prior to covering.
There are traditionally four main reasons for venting a roof.
You re here to figure out which attic system is best for your home but it s also important to understand how each system works.
Control of ice dams moisture accumulation and heat gain can be successfully addressed by both vented and unvented attic or roof design.
Vented vs unvented attic.
This section outlines the conditions for unvented attic roof assemblies.
Controlling ice damming by keeping the roof cold.
Must vent to the outside.
Basically the term cold roof refers to a traditional roof or vented roof while hot roof refers to a roof that is not ventilated and which has foam insulation attached directly to the roof sheathing.
Both vented and unvented attic roof designs can be used in all hygro thermal regions.
Control construction moisture content with tenting or temporary roofing when necessary.
Because the drying capacity of unvented roof assemblies is inherently lower than vented ones it is especially critical to control built in moisture during construction.
Unvented roofs which provides a detailed explanation of each.
When it comes to a vented gas fireplace it produces a realistic flame because the temperature is controlled.
If realism is important to you vented will always beat ventless.
Removing moisture from roof cavities structural members sheathing and insulation.
Vented gas fireplaces do require a way to vent to the outside.
Unvented roofs gba editor posted in energy efficiency and durability on august 16 2010 04 51am i just talked to an insulation contractor who told me that if i do a proper job air sealing my house i would be better off not venting the roof this is with cellulose not foam.
