Super Insulated Roof Design

The amount of roof cavity ventilation is specified by numerous ratios of free vent area to insulated ceiling area ranging from 1 150 to 1 600 depending on which building code is consulted the 1 300 ratio being the most common.

Super insulated roof design.

Reformulate or coat black membranes to make them reflective. Control of ice dams moisture accumulation and heat gain can also be facilitated by unvented roof design. Built up roofs consist of a base sheet fabric reinforcement layers and usually a dark protective. Polyisocyanurate insulation above the sheathing and approximately 91 4 in.

Of cellulose insulation in the rafter cavities the roof shown here has an r value of approximately 63. The walls of this house are 2 8 construction with dense pack cellulose insulation r 27 zip sheathing for the air barrier and 6 roxul insulation r 24 for a total insulation value of r 43. Deck for a thick roof rigid foam insulation installed above the roof assembly can create an energy smart roof. Blow insulation onto a flat ceiling.

However there is one tight spot that needs special attention. In 1979 steve kropper and the rowell energy group undertook the retrofit of a 1911 triple decker a three family home design nearly identical to the estimated 18 000 triple deckers in the city of boston. The vapor and dew point profiles for our climate showed the potential for condensation on the inside face of the exterior sheathing. With three layers of 11 2 in.

There are three methods for insulating the top side of the building envelope box. To maintain a continuous air barrier the stego wrap is connected to the zip sheathing on the walls which doubles as the air barrier. The kropper house was the first super insulated retrofit in the us. How they can be made cool.

Interior wall and roof condensation was also a concern during design of the monument house because of the very thick walls 12 and roof 18. Ample vertical space about 22 inches is ideal exists under most roof slopes to achieve r 60 insulation. Single ply membranes are pre fabricated sheets rolled onto the roof and attached with mechanical fasteners adhered with chemical adhesives or held in place with ballast gravel stones or pavers. Highly insulated ceiling or roof.

They typically consist of a conventionally framed 2 4 exterior wall sheathed with 1 2 in. In general this level will also be the most. Unfaced insulation is simply cut to fit the girt spacings and then impaled onto fast r rigid insulation hangers which prevents the insulation from sagging. A second non load bearing 2 4 stud wall is built on the interior.

Double walls have been built since the early days of super insulated houses.