Insulating A Non Vented Flat Roof

Preventing moisture is essential for having a properly functioning un vented roof.

Insulating a non vented flat roof.

For such constructions the principles and benefits of unvented attic construction are similar to that occurring in a single family residence. Insulation and air barrier are applied directly to the underside of the roof deck are common in applications where designers are seeking cost effective and energy efficient roof assemblies. Insulation mineral wool rests on the interior ceiling and is approx 4 thick and provides minimal insulation r 11. A non vented flat roof.

However in many situations the insulation may need to be primarily or entirely below the flat roof membrane and between the roof joists if so what are the best options. This space is currently accessible only by removing facia rim joist on soffit. In an un vented roof foam can serve as the air barrier and vapor retarder and prevent moisture from getting in to the roof cavities. However architects of these compact roof assemblies must consider vapor permeance and arrangement of the materials to produce acceptable hygrothermal performance and low risk of condensation in the resulting conditioned attic space.

The answer depends on the type of roof you have. In a vented roof foam can seal the openings and serve as an air barrier and a vapor retarder in addition to its insulating function. Mid century modern home has flat torch down roof. Low slope and steep slope unvented roof systems i e.

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. Cold roofs have insulation beneath the. A cold roof or hot 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.

Nail 1 furring along every rafter side against the roof deck. How much ventilation does a flat roof need. There are about 10 between roof decking to interior ceiling. Foam insulation can play an important role in both vented and un vented roof assemblies.

If you don t want to use sips or nailbase read this article tolearn the four basic approaches to insulating unvented roof assemblies. Flat roofs have often been built with the insulation all on top of the vapor closed drainage plane as this avoids dew point condensation issues inboard of the roofing. Hot roofs have the roof deck then insulation then the roofing material. 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.

It depends on where the insulation is installed. Any type of roof from tpo to epdm can be either hot or cold.