Insulation Against Roof Sheathing

You must meet the same minimum code requirements for the spray foam layer and the total assembly as for the rigid foam plus air permeable insulation approach.

Insulation against roof sheathing. If there is a roof leak the insulation will be damaged by the water leaving you with less insulating value. Senior engineer manager at icynene john broniek makes the case for the unvented attic assembly and why insulating the underside of the roof makes sense. It creates a breeding ground for mold and mildew and ruins the air trapping pockets that block heat flow. Exterior has a 1 2 thick drainage board and building paper against the sheathing where the thinstone veneer is attached to this specialized system designed for stone.

In climate zones 2b and 3b you can install fiberglass insulation against the underside of your roof sheathing without a ventilation channel or rigid foam above the sheathing but only if you install tile roofing. Remove existing roofing and non adhered underlayment to expose roof sheathing. Look for water stains on the roof sheathing or damp or moldy spots on attic joists and existing insulation as a clue to where leaks might be. A layer of spray polyurethane foam can be installed against the underside of the roof sheathing with the rest of the rafter cavity filled with air permeable insulation.

T he problem with the insulation against the sheathing expands. This retrofit assembly is appropriate for homes with conditioned attics or where the retrofit is intended to create a conditioned attic. The moisture is held in place by the insulation which allows for damage to the framing and other building components. Use rigid foam insulation to cover wider spans of roof sheathing between joists.

Cut each sheet to the desired size using a utility knife then fasten it in place using staples or adhesive. Water is insulation s enemy. Avoids nails or screws which could penetrate the metal roof and cause leaks. The quest for greater energy efficiency in buildings has led to increasing interest and need for insulation improvements in hvac equipment more airtight construction new materials and assemblies.

Radiant barriers are utilized to reduce summer heat gain in attics and help to improve the efficiency of green building envelopes. The problem arises with moisture. This system works. The home builder used 1 2 polyisocyanurate as an interior vapor barrier under 1 2 drywall.

Box out light fixtures. Install insulating sheathing above the roof deck on existing homes.