1. Performance Roofing ProductsPerformance Roofing ProductsPerformance Roofing Products
www.cornellcorporation.com
• The largest vent cross section available -
10 sq. in. per ft. run
• Over 86% open for up the slope ventilation
• Over 50% open area for lateral ventilation
• Over 92% open area - spacers occupy only 8% of
panel area
• Solid wood spacers less than 12" apart in both
directions minimize deflection of top sheathing
• Sheathing pre-spaced for thermal expansion
For Slate, Tile and
Maximum Loading
• Two layers of sheathing
For Shingles and Metal Roofing
• Single layer of sheathing
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IINNNNOOVVAATTIIVVEE RROOOOFFIINNGG PPRROODDUUCCTTSS SSIINNCCEE 11995544IINNNNOOVVAATTIIVVEE RROOOOFFIINNGG PPRROODDUUCCTTSS SSIINNCCEE 11995544
TONGUE & GROOVE
EDGES GREATLY
REDUCE
HEAT LOSS!
PolystyrenePolystyrenePolystyrenetrudedtrudedEE
NN AA II LL BB AA SS EE RR OO OO FF II NN SS UU LL AA TT II OO NNNN AA II LL BB AA SS EE RR OO OO FF II NN SS UU LL AA TT II OO NN
a d v a n t a g e
actoractorththe
Catalog
CORX-2005

2. PPRROODDUUCCTTPPRROODDUUCCTT
PPRREESSEENNTTAATTIIOONNPPRREESSEENNTTAATTIIOONN
Vent-Top ThermaCalX is a ventilated nail base roof
insulation which combines oriented strand board and
extruded polystyrene insulation. Vent-Top
ThermaCalX1 has one layer of O.S.B. and Vent-Top
ThermaCalX2 has two layers of O.S.B. The nail base
is APA performance rated O.S.B. consisting of
hardwood wafers bonded under heat and pressure with
waterproof resin. 7/16" O.S.B. is standard and 5/8"
O.S.B or plywood is available for special applications.
The standard vent space is 1" deep and 1-1/2"
depth is available as an option. The layout of the small
wood spacers leaves over 92% of the area open for air
movement. This allows air flow in all directions to
give improved cooling and ventilation throughout
the roof area, especially at hips and valleys.
PPRROODDUUCCTT DDEESSCCRRIIPPTTIIOONNPPRROODDUUCCTT DDEESSCCRRIIPPTTIIOONN
Vent-Top ThermaCalX1 has one layer of oriented strand
board. It is manufactured with one layer of 7/16" O.S.B. and
extruded polystyrene insulation with a ventilation space
between them. The 1" deep ventilation space is maintained by
solid wood spacers. Tongue and groove foam edges are
available when specified. The layout of the small internal
spacers leaves over 92% of the area open for air movement.
Spacers are not over 12" apart to minimize deflection of the
sheathing. The short wood spacers allow air flow in all
directions to give improved cooling and ventilation throughout
the roof area, especially at hips and valleys.
DDAATTAA TTAABBLLEEDDAATTAA TTAABBLLEE
Nom. Size 4' x 8' (32 s.f./panel)
1215 mm x 2430mm (2.95M
2
)
APPROX. OVERALL WEIGHT LTTR
THICKNESS P.S.F. R-VALUE*
3" 75 mm 1.9 9
31/2" 89 mm 2.0 12
4" 102 mm 2.1 14
41/2" 114 mm 2.2 17
5" 127 mm 2.3 20
51/2 140 mm 2.4 23
6" 152 mm 2.5 25
61/2” 165 mm 2.6 28
7” 178 mm 2.7 31
71/2” 190 mm 2.8 33
8” 203 mm 2.9 36
*For comparison with Long Term Thermal Resistance (LTTR) values used in the
Polystyrene Foam Association (OCF, Dow and Pactiv) provided foam aged R
values generated per CAN/ULC S770 by a third party laboratory. The nominal
thickness is 1/2” less than the overall thickness.
TTyyppiiccaall RRiiddggee DDeettaaiillTTyyppiiccaall RRiiddggee DDeettaaiill
2
RIDGE
VENT 2" SHINGLES
VENTILATED
NAIL BASE
INSULATION
ROOF DECK—
MTL. OR WOOD
STL. JST.
OR TRUSS
PP..OO.. BBooxx 333388PP..OO.. BBooxx 333388 CCoorrnneellll,, WWII 5544773322CCoorrnneellll,, WWII 5544773322
Cornell Corporation has been a leading roof
insulation manufacturer since 1955. In response to
the shingle manufacturers’ requests for ventilation,
we introduced Vent-Top ThermaCal in 1987, which
started the ventilated roof insulation industry.
Cornell Corporation - your ventilated roof insulation
specialist!
5511 YYEEAARRSS5511 YYEEAARRSS
OOFF EEXXPPEERRIIEENNCCEE!!OOFF EEXXPPEERRIIEENNCCEE!!
FFUULLLLYY MMAACCHHIINNEEDDFFUULLLLYY MMAACCHHIINNEEDD
CCOOMMPPOOSSIITTEE PPAANNEELLCCOOMMPPOOSSIITTEE PPAANNEELL
For Shingles and Metal Roofing
• Single layer of sheathing

3. ROOF DECK—
MTL. OR WOOD
PPRROODDUUCCTT DDEESSCCRRIIPPTTIIOONNPPRROODDUUCCTT DDEESSCCRRIIPPTTIIOONN
Offers the highest degree of compression resistance in the
industry. It is a ventilated nail base insulation with 1" deep wood
spacers between the two layers of sheathing. Tongue and groove
foam edges are available when specified (see photo on cover).
The layout of the small internal spacers leaves over 92% of the
area open for air movement. Spacers are not over 12" apart to
minimize deflection of the sheathing. The short wood spacers
allow air flow in all directions to give improved cooling and
ventilation throughout the roof area, especially at hips and
valleys.
UUSSEESS,, AAPPPPLLIICCAATTIIOONNSSUUSSEESS,, AAPPPPLLIICCAATTIIOONNSS
Ventilated roof insulation is used when you want to insulate
outside the structural roof deck. This occurs in many buildings
with cathedral ceilings or where the attic is partially heated to
protect sprinklers from freezing. The roof deck may be steel,
wood or concrete. Vent-Top ThermaCal X1 and X2 provide
excellent insulation values combined with a ventilated area
below the roof sheathing.
Shingles, shakes or metal roofing are installed over the
ventilated roof insulation. Eave and ridge vents (by others) are
used to allow air flow through the ventilated space. A minimum
slope of 3" in 12" is recommended.
Re-Roofing—The application of asphalt shingles direct to
insulated sheathing has contributed to many premature roof
failures. Ventilated roof insulation is a solution to the ventilation
problem when re-roofing buildings with cathedral ceilings.
AADDVVAANNTTAAGGEESSAADDVVAANNTTAAGGEESS
Ventilated Surface—Vent-Top ThermaCalX provides the
ventilated top surface that many contractors and shingle
manufacturers require. In hot weather this cools the sheathing
and shingles. It also allows any moisture to escape. In severe
winter weather it provides a cold air space below the top
sheathing. This cold roof reduces snow melting and the
possibility of run-off forming ice dams and causing leakage
above the walls.
Ventilated Space—The air space provides over 10 sq. in. of
Net Free Area per Lineal Foot of insulation after deducting
for the spacer blocks. This gives 20 sq. in. of Net Free Area
per lineal foot of ridge (insulation on both sides) and exceeds
the standard 18 sq. in. per foot used in the ridge vent
industry.
Spacers are solid wood to resist compression and
occupy only 8% of the panel area. They leave 50% open
for lateral (across the slope) ventilation.
VVEENNTT SSPPAACCEE PPRROOPPEERRTTIIEESSVVEENNTT SSPPAACCEE PPRROOPPEERRTTIIEESS
Depth 1" (25 mm)
Cross Section 10 Sq. In. of Net Free
Area/Lin.Ft.
(212 Sq.Cm./meter).
Open Area Not less than 92% of plan area
Max. Spacer Separation Less than 12" (300 mm)
PPHHYYSSIICCAALL PPRROOPPEERRTTIIEESSPPHHYYSSIICCAALL PPRROOPPEERRTTIIEESS
O.S.B. Sheathing Conforms to APA rated sheathing standard
PRP 108, Exposure 1 and HUD/FHA-918.
Foam
Flame Spread
(extruded polystyrene) E84 5 or less
k Factor at 75° E512 0.20
Vapor Permeance E96 approx. 1.1 perm
DDEESSIIGGNN AASSSSIISSTTAANNCCEEDDEESSIIGGNN AASSSSIISSTTAANNCCEE
Additional Architectural Details and a full Draft Specification on
email or hard copy are available. Call Cornell Corporation for
venting design assistance - 715-239-6411, or fax 800-267-8368.
Email: cornell@centurytel.net
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VENTILATION BEHIND FASCIA
GGEENNEERRAALL IINNFFOORRMMAATTIIOONNGGEENNEERRAALL IINNFFOORRMMAATTIIOONN
The following information applies to both
Vent-Top ThermaCalX1 and X2
3
ROOFING
1-1/2" x 1-1/2"
FURRING
INSECT
SCREEN LAM
BEAM
VENTILATED NAIL BASE
INSULATION
AIR
FLOW
*For comparison with Long Term Thermal Resistance (LTTR) values used in the
Polystyrene Foam Association (OCF, Dow and Pactiv) provided foam aged R
values generated per CAN/ULC S770 by a third party laboratory. The nominal
thickness is 1/2” less than the overall thickness.
DDAATTAA TTAABBLLEEDDAATTAA TTAABBLLEE
Nom. Size 4' x 8' (32 s.f./panel)
1215 mm x 2430mm (2.95M
2
)
APPROX. OVERALL WEIGHT LTTR
THICKNESS P.S.F. R-VALUE*
31/2" 89 mm 3.3 10
4" 102 mm 3.4 13
41/2" 114 mm 3.5 15
5" 127 mm 3.6 18
51/2 140 mm 3.7 21
6" 152 mm 3.8 24
61/2” 165 mm 3.9 26
7” 178 mm 4.0 29
71/2” 190 mm 4.1 32
8” 203 mm 4.2 40
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For Slate, Tile and Maximum Loading
• Two layers of sheathing

4. CORX-2005 Printed in U.S.A. Copyright 2005 Cornell Corp.
CODE ACCEPTCODE ACCEPTABILITY CERTIFICAABILITY CERTIFICATIONTION
CODES - O.S.B. is approved by CABO, ICBO, BOCA, SBC,
ARMA and the APA as roof sheathing. The foam used in Vent-
Top ThermaCalX1 and 2 has a Flame Spread Rating of 5.
Plastic foam must be protected from flame on the inside by a
suitable barrier. Some codes require a 15 minute barrier.
Generally, wood decking or drywall is acceptable and plywood
or metal decking are allowed in certain roofing applications.
CHECK LOCAL CODES.
**This numeric Flame Spread Rating is not intended to reflect
hazards presented by this or any other material under actual
fire conditions.
UUNNDDEERRWWRRIITTEERRSS LLAABBOORRAATTOORRIIEESSUUNNDDEERRWWRRIITTEERRSS LLAABBOORRAATTOORRIIEESS
The foam used complies with ASTM C578 and UL Roof Deck
Construction #457 for use directly over metal deck.
CCOODDEESS AANNDD CCOOMMPPLLIIAANNCCEESSCCOODDEESS AANNDD CCOOMMPPLLIIAANNCCEESS
FEDERAL SPECIFICATION - foam meets HUD/FHA Use of
Materials Bulletin No. UM71a, ASTM C578 and AASHTO M230.
MODEL CODES-foam insulation is in compliance with:
BOCA- Section 2603.0
ICBO- Section 2602
SBCCI- Section 2603.2
IINNSSTTAALLLLAATTIIOONNIINNSSTTAALLLLAATTIIOONN
Installation instructions for Vent-Top ThermaCalX1 and 2 are
available from Cornell Corporation and are attached to all
shipments. Fasten to structural deck using pole barn ring shank
nails or roof insulation screws - see instructions. Cornell Corp.
can supply nails or screws if requested.
Vent-Top ThermaCal X should be kept dry during installation. If
it should become wet it should be dried out before roofing is
applied. The roofing should be applied as soon as possible in
accordance with the roofing manufacturer's recommendations.
Manufacturer’s installation instructions include fire precautions,
shipping and storage information.
OOTTHHEERR PPRROODDUUCCTTSS AAVVAAIILLAABBLLEEOOTTHHEERR PPRROODDUUCCTTSS AAVVAAIILLAABBLLEE
ThermaCalX is a non-vented nail base roof insulation without
a vent space. It has a 7/16" O.S.B. top surface adhered to
extruded polystyrene foam insulation. 5/8" or 3/4” O.S.B. or
plywood optional. ThermaCal X is available in nominal
4' x 8' sheets with rabbeted edges and is installed over a
structural deck. Tongue and groove foam edges on all four
sides are available when specified. Call for separate literature.
Cornell Ventilated Roof Sheathing is a ventilated sheathing
product without any insulation. It is used where the existing
insulation is sufficient. Call for separate literature.
DDRRAAFFTT SSPPEECCIIFFIICCAATTIIOONN--SSHHOORRTT FFOORRMMDDRRAAFFTT SSPPEECCIIFFIICCAATTIIOONN--SSHHOORRTT FFOORRMM
Note to Specification Writer: This draft spec can be used
for Vent-Top ThermaCalX1 (with one layer of oriented strand
board) or for Vent-Top ThermaCalX2 (with two layers of
oriented strand board). This spec is usually placed in
Section 07220. It can be downloaded from our website
www.cornellcorporation.com.
1. VENTILATED ROOF INSULATION
A. Description of system:
1. The ventilated roof insulation shall be a factory
assembled panel consisting of one or two layers
(Spec writer to choose) of 7/16" oriented strand
board top surface, a built-in ventilation space
maintained by 1" wood spacer blocks, and
extruded polystyrene insulation on the bottom.
2. The Long Term Thermal Resistance (LTTR)
R-Value of the ventilated roof insulation shall
be no less than ______.
3. Wood panel edges shall be rabbeted to allow the foam
edges to fit together while providing clearance
between the wood sheathing on adjoining panels.
4. Foam sides and ends shall have a tongue and groove
profile to reduce heat loss at the joints.
5. The wood spacer blocks shall not exceed 8% of the
panel area and shall have 50% open for lateral (across
the slope) ventilation. Spacer blocks shall not be over
12" apart in either direction.
6. The vent space shall provide a minimum of 10 sq. in. of
Net Free Area per lineal foot of insulation after deducting
for the spacer blocks or strips.
2. SUBMITTALS
A. The following will be submitted to the architect for
approval: Copies of the manufacturer’s product
information and installation instructions. A sample with
the edge profile specified and large enough to show
the actual lateral spacing of the vent space supports. A
manufacturer’s dimensioned drawing showing how the
50% lateral ventilation is achieved. Calculations of spacer
block percentage of panel area and the Net Free Area
per Lin. Ft. of insulation after deducting for spacers.
3. PRODUCTS
A. Products shown below are acceptable provided they
meet the requirements of this specification.
Vent-Top ThermaCalX1 or X2 (Spec writer to choose)
by Cornell Corporation, Cornell, WI
Tele: (715) 239-6411 Fax: (800) 267-8368
TTEECCHHNNIICCAALL SSUUPPPPOORRTTTTEECCHHNNIICCAALL SSUUPPPPOORRTT
DESIGN CONSIDERATIONS
VAPOR RETARDERS
The designer should determine if a vapor retarder is
required between the deck and the insulation. A vapor
retarder should always be specified in buildings with high
humidity conditions, such as swimming pools.
4
PPrroodduucctt SSppeecciiffiiccaattiioonnssPPrroodduucctt SSppeecciiffiiccaattiioonnss
OOnnlliinnee:: wwwwww..ccoorrnneellllccoorrppoorraattiioonn..ccoomm eemmaaiill:: ccoorrnneellll@@cceennttuurryytteell..nneettOOnnlliinnee:: wwwwww..ccoorrnneellllccoorrppoorraattiioonn..ccoomm eemmaaiill:: ccoorrnneellll@@cceennttuurryytteell..nneett
Tele: 715-239-6411 (Central Time)
Fax: 800-267-8368
P.O. BOX 338, CORNELL, WISCONSIN 54732
ThermaCal
®
is a Registered Trademark of Cornell Corporation