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Deck Type Flat Roofing | New York Roof Pro Contractor

(Deck Type Roofs)

There are multiple products that are used in a flat roof environment to create the deck surface of the roof assembly. These deck roof types are the most popular designs in the Tri-State area.


  • (Steel “B” Deck )– This is usually a corrugated, galvanized or painted steel panel that comes in 36” wide x 18’ lengths.  This is the most typical “modern day” method of creating decks. The decking is installed and attached to the structural trusses. Insulation boards are generally screwed or glued to the decking to provide a roofable surface and “R” value for the roof assembly. Prolonged exposure to water from a leaking roof can cause deterioration of a steel deck and should be changed if this condition is present.
  • (Wood Deck) – This is generally a plywood or tongue and groove sheathing installed over some type of wood framing.  This was typically used for buildings built prior to 1940, but is still used to this day. These decks are much more prone to water damage by comparison to steel and extremely dangerous when torch applied roof systems are being used.


  • (Concrete Deck) – These decks are used when high levels of strength and fireproofing are necessary. These decks are either poured into forms with rebar or they are set on roofs in pre-cast planks over steel framing.  It is common to see “poured” concrete decks installed “dead level”.  These decks will generally need to be pitched with a tapered insulation system to move water to the designed drain locations. Adhering insulation on concrete decks requires either masonry type fasteners or adhesives.
  • (Poured Gypsum Deck) – This deck product became popular during WWII when metal was at a premium for war efforts.  This was cheap and available to install on large flat roofing areas in New York.  It is lightweight and does not expand and contract as much as other decking materials.  This deck is constructed by using “T” purlins between structural joists.  Sheetrock is very similar it is placed into “T” purlins and liquid gypsum is poured over the roof surface.  Steel mesh is installed into the gypsum for strength. When cured this deck is usually 4” thick and very strong. This deck does have a few shortcomings such a these below.

           a.  When exposed to water it becomes very unstable and is difficult to repair. b.  It also is usually set “dead level” and needs to be pitched to move water to drain locations. c.  It can also be difficult to adhere insulation or recovery boards to the surface.


  • (Tectum Deck) – This material is a composite strand board that is structurally sound and has good sound absorbing properties (this product is commonly used in gyms and auditoriums).  It can present issues when water damaged and needs special fasteners to adhere insulations.

Understanding what type of deck is present on your building and what the proper design for your roof assembly is crucial. We see many roofs on Long Island that are not installed correctly to the deck that is on the building. This will usually lead to wind uplift and blow off of the roof system, ponding water or water intrusion.

If you have any questions about deck types or Roof Pro, contact your local New York Roof Contractors online or give us a call.

Call Us Today: 1-800-766-3773

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