Insulate Tin Roof Without Decking

Lay insulation on paper liner one of the most common mistakes that diy homeowners make with their metal roof is that they do not lay down any type of paper wrap on the sheathing.

Insulate tin roof without decking.

Talking about metal roof insulation this thing is one of the most challenging things people work in this field is facing it demands and requires excellent skill and expertise which you may only get from a reputable roofing contractor. The moisture is held in place by the insulation which allows for damage to the framing and other building components. First nail 1x2s to the rafter sides up against the roof strapping. If there is a roof leak the insulation will be damaged by the water leaving you with less insulating value.

In warm climates zones 1 through 4 low density open cell spray foam insulation is the typical choice since it is vapor permeable and will allow drying of the exterior sheathing and roof framing if they happen to get wet via diffusion into the interior of the building. This will provide an air space above the foam insulation to improve ventilation on the underside of the metal roofing. The problem arises with moisture. If you choose to omit the plywood from a residential construction install a vapor barrier between the purlins and the metal roof or plan to spray closed cell foam insulation between the rafters to eliminate the temperature differential between the air in the building and the metal.

It is possible to insulate from below as you suggest with rigid polystyrene insulation. This paper wrap is important to the health of the home by not allowing water to build up in the space between the sheathing and the metal roof. Some homeowners choose to use unfaced fiberglass insulation batts.