CORNELL CORPORATION
808 South 3rd Street
P.O. Box 338
Cornell , Wisconsin 54732
Tel: (888) 439-6411
Fax: (800) 267-8368
E-Mail: cornell@cornellcorporation.com
Web site: www.cornellcorporation.com
CVRS is ventilated roof sheathing designed for use with shingles and metal roofing. The factory made panels are built from oriented strand board (OSB) with wood spacer blocks that provide a 1” deep open space (1-1/2” optional) to allow air flow below the sheathing in all directions. The standard OSB sheathing is 7/16”. 5/8” and ¾” OSB is also available.
Shingle manufacturers require ventilation between the roof sheathing and the insulation. Cornell Ventilated Roof Sheathing provides the sheathing and the ventilation space in one product. It is used above the roof deck and insulation. This is particularly useful when re-roofing buildings where the existing insulation is sufficient. Eave and ridge vents (by others) are used to allow air flow through the ventilated space.
Cornell Ventilated Roof Sheathing allows ventilation in all directions, which is most important on buildings with hips and valleys or other obstructions. Small solid wood spacers occupy only 8% of the panel area, leaving 92% ventilated.
The spacers are less than 12" apart in both directions, which greatly reduces the flexibility of the sheathing. Cornell Ventilated Roof Sheathing provides over 10 sq. in. of Net Free Area per Lineal Foot of sheathing after deducting for the spacer blocks. This exceeds the standard 18 sq. in. per foot (9 sq. in. per foot each side) used in the ridge vent industry.
The oriented strand board used is approved as roof sheathing by all major code bodies and conforms to APA rated sheathing standard PRP 108, Exposure 1 and HUD/FHA-918. 7/16" OSB is accepted as roof sheathing under Class A shingles approved by Underwriters Laboratories. The Ventilated Roof Sheathing shall be securely fastened to the supporting roof deck through any insulation that is between them. See separate installation instructions.
NOTE: Eave and ridge vents (by others) should be included in other parts of the specifications.
An engineer should determine that the roof deck is structurally sound for the spans involved and that it will securely hold the fasteners that are used to attach the Ventilated Roof Sheathing. On some buildings a vapor retarder may be needed below the insulation.
The roof sheathing shall be Cornell Ventilated Roof Sheathing manufactured
by Cornell Corporation, P.O. Box 338, Cornell, Wl 54732, Tele: 888-439-6411.
It shall consist of 7/16" (optional 5/8" or 3/4") oriented strand board sheathing with 1" deep wood spacers secured to the underside of each 4' x 8' panel. The wood spacers shall not be more than 12" apart in either direction.
The unobstructed air space shall be over 90% of the panel area and shall allow air flow both up the slope and horizontally. The air space shall provide 10 Sq. In. of Net Free Area per Lineal Foot of sheathing after deducting for the spacers.
Please see the attached table for a quick selection guide to Cornell’s roof sheathing and insulation products.
If insulation below the vented sheathing is required we recommend our isocyanurate ventilated roof insulations, Vent-Top ThermaCal 1 or 2 or our extruded polystyrene roof insulations, Vent-Top ThermaCal X1 or X2. For these products see our catalog in Sweets or our web page www.cornellcorporation.com.
Catalogs, detail drawings, draft specifications and installation instructions are available. Call 888-439-6411 or FAX 800-267-8368.
Cornell Corporation has been a leading roof insulation manufacturer since 1954. In response to the need for nailable insulation above the structural roof deck in cathedral or vaulted ceiling applications, Cornell Corporation introduced ThermaCal® in 1979, which started the nail base roof insulation industry.
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