Unvented roof assemblies should be insulated either with air impermeable insulation rigid foam or spray polyurethane foam or with a combination of foam and air permeable insulation.
Unvented roof assembly detail.
If not properly detailed partial penetrations into the unvented roof assembly for things like can lights or ceiling fans can undermine the insulation and or air tightness strategies alluded to above.
This is a mis interpretation of the code.
It s not and so code doesn t require r value ratios.
Yes unvented roof assemblies can be insulated with fiberglass a wufi post and not just in climate zones 2b amp.
Martin s post focuses on the marketing of owens corning 039 s propink unvented attic insulation system.
This is how to detail an unvented roof assembly for flat and low slope roofs.
Currently have a standing seam metal room installed over synthetic felt over osb.
However as the future owner i m beginning maybe a bit too.
They are designed without ventilation openings and the attic is conditioned like the rest of the living space.
The point is that the inner face of that first layer the air barrier layer of insulation should always be warmer than the dew point or you ll get water in your roof.
Read all of r806 5 carefully.
Unvented roofs operate by the principle that venting is not necessary to control moisture accumulation.
Unvented roof assemblies are becoming an increasingly common construction alternative to traditional vented roofs.
The key detail is that the air impermeable insulation must be suitably thick to stop condensation in the assembly.
This document provides a brief description of different types of unvented roof assemblies and the benefits of unvented roof construction.
No insulation installed yet.
If you don t want to use sips or nailbase there are four basic approaches.
If it all sounds simple there is certainly room for error.
Unvented roof assemblies such as conditioned attics and unvented cathedral ceilings are becoming common in north american construction.
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 the process of construction.
Figure 6 describes open cell spray foam as air permeable.
This is the recommendation of all three local insulation installers.
Before constructing a flat roof assembly please refer to the unvented roof assembly comments under 6 2 vented and unvented roof assemblies and if applicable 6 3 parapet walls.
The unvented attic space is completely contained within the building thermal envelope.
Recent building codes only allow unvented roof assemblies for pitches 3 12 and greater irc 2015 section r806 5 2 7.
Insufficient fill below the impermeable insulation layer.
There will be ducting and other hvac equipment in the attic.