Residential Roof Decking
Roof decking and roof sheathing are two terms for the same thing; the load-bearing portion of your roof system. It is installed between the roof rafters and trusses and can be made out of plywood, oriented strand board (“OSB”), wood planks, tongue-and-groove boards, and metal.
Plywood and OSB are the primary choices for homeowners because of their flexibility, strength, and affordability.
OSB Sheathing
The most commonly used roof decking material, OSB is material made of wood chips and strips compressed together under extreme pressure to form a flat sheet. It is very affordable, ranging between $16-57.
Plywood Sheathing
Available in 8ft and 9ft, plywood is offered in several thicknesses (3/8″, 7/16″, 15/32″, 19/32″, and 23/32) and the price ranges between $21-57.
Radiant Barrier for OSB and Plywood
OSB and plywood roof decking has the option to come with a radiant barrier where one side is covered with aluminum foil that is installed face down (into the attic). The barrier is an excellent bonus to have in the Carolinas with our warmer climates because it blocks up to 97% of roof-absorbed heat and reduces attic temperatures by up to 30 degrees Fahrenheit which help reduce cooling costs up to 17%.
When installed correctly, the decking can last 80-100 years!
Wood Planks
Wood plank decking is comprised of 1×6 or 1×8 boards and can be installed 3 ways:
- Straight/closed where the planks are laid side-by-side, used for asphalt or wood shingles.
- Skip/spaced planks for usually for wood shakes and are installed with gaps for ventilation.
- Diagonal planks are installed at 45-degree angles for added shear strength*.
This decking type is commonly found in home built before the 1960s and the gaps may require additional OSB and plywood to cover the planks.
Tongue and Groove
Many homeowners will recognize this style of decking from their trips to flooring departments. Tongue and groove is a specialty lumber product with the patterned side facing down (into the house), the tongues pointed up on sloped/pitched roofs and out on flat roofs.
This decking is an option for exposed ceilings for its aesthetics. Due to its nature of being a specialty lumber the sizes and pricing will vary from manufacturer.
Industrial Metal Roof Decking
“Why wouldn’t I use metal decking for a metal roof? Makes sense to have a metal deck for a metal roof.“
Metal decking is the toughest sheathing material out there which is why it is used in industrial complexes where the building’s structural supports are predominantly metal. Our homes are made using wood supports which benefit greatly from metal roofing because it’s lightweight —about half the weight of an asphalt shingle roof— add too much metal, however, and you’re weighing down on those supports.
Industrial sheathing comes up in the search results when looking for DIY metal roof installations and while you don’t want to use it on your house it’s still great information to have, making YOU the expert in metal decking, so let’s get into it!
The 3 Types of Metal Roof Decking
There are 3 types of 1.5″ metal roof decking —1.5″ refers to the depth of the decking, the two depth currently available are 1.5″ and 3″ with the latter being used when the distance between your roof supports is longer.
Let’s break down the types of 1.5″ metal decking.
Type A
Also known as the “narrow rib“, Type A decking is 1.5″ deep and has narrow spacing between the ribs at approximately 1”. This spacing will vary slightly between manufacturers who have their own version of the A Deck. Of metal roofing decks, this is the oldest profile and is used mostly on repair jobs.
It’s important to note that newer Type A decks are incompatible with older versions. There have been modifications to the Type A decks over the years making nesting the two difficult.
Type A roof deck should only be used in repairing and patchwork when it matches the existing style. New construction uses Type B for its strength and economic value.
Type F
Developed after the Type A deck, the rib spacing is wider at approximately 1 7/8″, and is known at the “Intermediate Rib“. Once again, the exact spacing will depend on the manufacturer as each has their own version of the Type F deck.
Structurally this roof decking is not as strong as Type B, Type F should be used in repairing or patch work only.
Type B
“Wide Rib“, as the Type B is commonly called, is the most modern, economical, and widely used of the three 1.5″ types of metal roof decking. It is spaced at approximately 2 1/2″, measure to verify when you’re looking at decking from different manufacturers as each will have their own spacing variations and allowances.
The Deep Roof Deck
There is a 4th roof decking profile!
Used in projects with supports that span between six to sixteen feet, the Type N deck is 3″ deep and comes in either a 24″ wide panel (N-24) or a 32″ wide panel (HSN-32). This type is the strongest metal decking, this depth is needed when there is wide spacing between the roof’s structural support beams.
Which decking material is right for me?
OSB is the top choice for roofing contractors and the DIY homeowner. Offered at local home improvement stores, it’s ease of accessibility and affordability make it the top contender for roof decking.
The thickness and size of decking you need will depend on the existing materials and your future plans —adding rooms in the future may call for skylights or additional vents that when planned ahead can get your next home improvement project off the ground and running!
Final Thoughts
When in doubt, give us a call or email us and we’ll come out and inspect your existing materials and get an estimate prepared for you. We live and breathe metal roofing, match the decking to the needs of the project and home, and take immense pride in our materials and installation services.
👉 Call us today for your free estimate.
👉 Check out our Facebook page for metal roofing success stories!
* Shear strength is a material’s capacity to resist sliding failure along a plane when subjected to opposing parallel forces.
