Depends on what you are factoring in all the insulation the coating a roof replacement if needed air sealing new or existing the hot roof will usually run more but it generally doesn t need any ongoing maintenance.
Hot roof foam insulation.
The movement of air into indirect conditioning of an unvented attic is a slow gradual process that will not be noticeable by occupants and typically will not put any strain on the hvac system.
A hot roof is one where there is no ventilation required as the insulation is directly attached to the roof sheathing.
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.
This product is suitable for use in wall sheathing applications in new.
The benefits of a conditioned attic.
Which is more expensive.
If you don t want to use sips or nailbase read this article tolearn the four basic approaches to insulating unvented roof assemblies.
Rigid foam board roof insulation there are a couple of scenarios in which it would be recommended that you install insulation in the slopes roof assembly of a home rather than on the attic floor as is so commonly done.
Moisture from indoors can diffuse through the foam and find the cold roof sheathing where it accumulates and eventually rots the roof.
But spray foam insulation used at the underside of the roof deck would need to be covered by a thermal barrier and intumescent coatings are commonly used.
Unvented roofs which provides a detailed explanation of each.
How hot roofs differ from traditional roofs.
In this case you can learn a lot from foam tech s article vented vs.
In the next section we will discuss the process of installing rigid foam board insulation in the roof deck.
The term hot roof comes in because the spray foam insulation is being affixed directly to the roof sheathing which removes the need for ventilation.
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.
R matte plus 3 thermasheath 3 is rigid foam plastic thermal insulation r matte plus 3 thermasheath 3 is rigid foam plastic thermal insulation board composed of environmentally sound closed cell polyisocyanurate foam bonded to a durable white matte non glare aluminum facer and a reflective reinforced aluminum facer.
Open cell spray foam insulation is risky in all climate zones we already know open cell spray foam is risky in cold climates.
While some try to do this with fiberglass or cellulose their efforts are for naught and quite simply it is not allowed by any legitimate building code out there.