General Specifications

Sing Core Professional Large Trapezoid Pivot Door Blanks are 40 ft. tall,18 ft. wide at the top 12 ft. wide at the bottom, and 3.5 in. thick and manufactured utilizing patented Sing Core material as the base interior substrate of the door. Size to be adjusted to varying specifications. The Sing Core substrate material is created using a vertical grain natural wood torsion box design while the traditionally empty voids are filled wall to wall with recycled foam. The foam material is available in various forms depending on your specification. The default is recycled EPS foam. Natural wood lock blocks can be positioned at locations as necessary for locking mechanism placement and/or as pivot hardware anchor points. The core material is framed by 1.25-inch wood stiles and rails for finishing strength and attaching hardware. The torsion box is completed by adhering .25 in. marine grade birch paint grade ply as exterior material (skin) or other material according to your specifications.

1/4 in. Marine Grade Birch Ply Pivot Door Stress Skin

The trapezoid pivot door blank surface material is made of .25″ marine grade birch ply paint grade stress skin unless otherwise specified. Bonding agent used in adhesion of the entire composite material is formaldehyde-free.

Click here for tips on How to Create the Right Sing Panel for your specific project.

Every Sing Core manufactured trapezoid pivot door blank is unfinished (unless specified otherwise) and professional grade is guaranteed for 50 years for warp-free and structural integrity.

Detailed Specifications:

Scope: Subject to local building codes, the Sing Core trapezoid pivot door blank is intended for use in:

  • Single family dwelling interior applications
  • Multifamily dwelling, low-rise professional office, library and low-rise motel interior applications
  • Lighter use industrial building and factory, hotel and retail sales building interior applications


Large Trapezoid Pivot Door Materials: Sing Core large trapezoid pivot door blanks are manufactured using Eco-friendly cold-press process. Composite materials include:

  • Sing Core vertical wood-grain torsion substrate filled with recycled EPS foam
  • Professional grad composite stiffeners are included for long lasting warp-free performance
  • Core material is framed with solid wood stiles and rails
  • Stress skins are .25 in. marine grade paint grade birch ply
  • Formaldehyde-free bonding agent is used for adhesion of all components

Architectural Specifications Substitutes

For information on some of our architectural substitutes click here.

Interior Blocking: Solid wood implants can be inserted as lock blocks or anchor points. Also additional stiles (vertical wood implants) or rails (horizontal wood implants) can be positioned at any desired location inside the large trapezoid pivot door. (Note: Depending on your expectations, solid wood implants should be supported by at least 12 inches of Sing Core material to maintain true flatness.)

Delivery: Reasonable care is taken to ensure safe transportation of your Sing Core large trapezoid pivot door from factory to your location including proper crating to protect the natural beauty of your pivot doors during transport.

Storage and Protection: Store your Sing Core large trapezoid pivot doors in an upright position and allow to acclimate to room temperature following shipment receipt or prior to finishing or installation.

Preparation: Per manufacturer’s specifications, ensure that openings or attachment walls are constructed plumb, true and level prior to installation. Select fasteners of adequate type, number and quality to assure proper function.

Installation: Installer shall be specialized in the installation of the type of work that is associated with the project and will comply with manufacturer’s installation policies and procedures to ensure proper end use.

Verify that attachment, hinging and latching assemblies operate freely and correctly

Finishing: The finishing of the Sing Core large trapezoid pivot doors are the responsibility of the client due to the product being delivered in unfinished condition unless specified otherwise in writing for use in interior applications only. Any exterior use must be approved in advance to avoid warranty exception and sealing must be in accordance with manufacturer’s specifications to protect against a variety of environmental conditions as necessary. In reference to exterior applications:

  • Seal all 6 surfaces with two coat minimum on operable panel(s)
  • Finishing or re-finishing must be completed following acclimatization and installed within 7 days
  • Avoid finishing after rain (or damp) or during periods of higher than average humidity
  • At least once a year, conduct periodic inspections of coating to ensure no wall panel components are exposed
  • Reseal the surface as necessary

Machining: Sing Core large trapezoid pivot doors are easy to work with in the millwork or standard woodworking shop for CNC work or on-site for finishing, and fastening.

Strength Performance: Patented Sing Core has an unsurpassed strength as compared to other lightweight substrate materials tested at 660 PSI (based on 2″ x 2″ grids and 3/4″ thick) for superior structural integrity and is resistant to warp, twist and crack when compared to other materials.

Light Weight Performance: Sing Core weighs much less than other traditional building materials, as much as 50% less; or more, as little as 4 lbs. per sq. ft. yet sustainable and true green technology.

Insulation Performance: Sing Core large trapezoid door pivot blanks feature built-in insulation value with an R3 (can be upgraded to to R6.5 or more) rating per inch, depending on architect’s specifications.

Acoustical Performance: Sing Core trapezoid pivot door blanks have a natural sound-deadening quality for noise control. Standard sound transmission class (STC) is 30*. Additional noise control specifications can be met at the behest of the customer or designer and must be noted in advance.

Eco-friendly: Sing Core is manufactured using natural wood fibers, no formaldehyde, or toxic chemicals, is created using less energy than any other core material with little or no waste. The structure of Sing Core is 100% renewable (nature-grown) clean wood fiber and/or recycled material.

Warranty: Sing Core professional large trapezoid pivot door blanks can be structurally guaranteed and warp-free for 50 years under normal conditions.

Basic Sing Door Spec Drawings: Click here

Custom-cut Window/Lite Openings: Lite openings for glass inserts can be custom cut per your specifications (drawings above show examples of standard openings) for glass insertion.

Door Specifications

Door Width
Rough Opening Width
Rough Opening Height 6/8
2/0 (Single) 26″ 82-1/2″
2/4 (Single) 30″ 82-1/2″
2/6 (Single) 32″ 82-1/2″
2/8 (Single) 34″ 82-1/2″
3/0 (Single) 38″ 82-1/2″
4/0 (Double) *50″ 82-1/2″
4/8 (Double) *58″ 82-1/2″
5/0 (Double) *62″ 82-1/2″
5/4 (Double) *66″ 82-1/2″
6/0 (Doulble) *74″ 82-1/2″

See also: Door Technical Information

Appearing regularly in Contemporary Architecture Design

* Note: STC rating varies according to size, thickness, skin, and other factors. Sing Core does not rate doors, although we are fortunate enough to have one of the best sound testing labs in the world, here in the Pacific Northwest. If you require a specific STC rating, Sing Core can build a door to your architectural specifications and have the resulting door tested at our rating facility for an official rating.