Unvented Shed Roof With Above Deck Installation

Unvented roof here again the choice of what insulation to use and whether to install it over or under the roof deck depends on the condition of the present roof the depth of rafters the r value you must attain and cost.

Unvented shed roof with above deck installation. You can install all of the insulation above the roof sheathing but the foam has to be thick enough to meet minimum code requirements for ceiling r value. Drying of unvented roofing assemblies is by definition only provided to the interior. In unvented flat or low slope roofs with parapets perform a full flood test to ensure leak free installation of roofing membrane. Photograph 2 above right.

Unvented roof diagram i know this is a very basic example so if you want to read more on the topic i ve put some additional reading for unvented roofs at the end of this article. New shingles were installed over a fully adhered membrane applied directly to the original roof decking. Unvented roofs also make a lot of sense in high wind or high fire areas where vents might admit drenching rains or embers. Br br we ll show you how to build this shed and.

Simply put unvented roofs get rid of the vents and move the thermal air control and moisture boundaries to the roof deck. If the upper edge of a low slope shed roof intersects a vertical wall the most logical approach in my opinion is to detail the roof as an unvented roof. Dallas tx is located in a mixed humid climate region. Test roofing membranes for integrity prior to covering from below.

Figure 4 shows the potential for condensation of an unvented roof assembly in dallas tx. Br you may also want to install an outdoor light if you plan on using the space during the evening. This roof assembly has no insulating sheathing installed above the roof deck. Note that this roof assembly has rigid insulation installed above the roof deck in order to control the condensation potential.

Most unvented attics incorporate spray polyurethane foam spf on the underside of the roof deck and attic walls. Finished roof back then looked pretty good seventeen years ago. Yes unvented roof assemblies can be insulated with fiberglass a wufi post and not just in climate zones 2b amp. Another approach is to build a cupola or ventilated doghouse in the middle of the low slope roof an approach championed by joe lstiburek.

Martin s post focuses on the marketing of owens corning 039 s propink unvented attic insulation system. Four options for building an unvented roof assembly. The rigid foam will be fairly thick see sidebar how much insulation.