Understanding Roof Decking: A Comprehensive Guide

by MidSouth Construction Roofing Contractors

Your roof is not just for looks – it’s a system that protects your home from the weather. The roof decking is a crucial part of the system, as it provides the foundation for the entire roofing structure.

Whether you’re considering a roof replacement or just some repairs, it’s crucial to understand the role and importance of your roof’s decking. At MidSouth Construction Roofing Contractors, we help homeowners understand their roofing systems and replacement costs. We are committed to providing this information.

Roof Decking - A Comprehensive GuideWhat Exactly is Roof Decking?

Roof decking, also known as roof sheathing, consists of wooden boards that form the frame of your roof. These boards are the base on which shingles and other roofing materials are installed.

Types of Roof Decking

There are two primary types of wood roof decking: plank decking or space decking, and sheet decking.

  • Space Decking:

Plank decking, also called space decking, was commonly used for roofs in homes from the early to mid-20th century. It was a popular choice during that time. Residential buildings often had this type of decking for their roofs.

Space Decking on Older Nashville Home

Builders used wooden planks to create a sturdy base for the roof. They placed the planks on the roof beams. This provided support for materials such as shingles or metal panels.

Builders no longer use plank decking for roof decks because plywood and OSB are more durable and cost-effective options. However, you can still find plank decking in older homes and historic buildings. Plank decking is made from long rectangular wooden boards, typically sized 1×6 or 1×8.

  • Sheet Decking:

Sheet decking includes flat sheets of wood, primarily plywood and OSB (oriented strand board). OSB is commonly used for roof decking in construction because it is cost-effective, durable, moisture-resistant, and consistently high-quality. It is a popular choice due to its affordability.

Plank Decking covered with new OSB to meet building codes


It also has a reputation for being strong and resistant to moisture. Additionally, it is valued for its consistent quality. OSB is comprised of compressed wood strips or chips, forming a durable 7/16” thick panel.

Plywood, available in various thicknesses like ⅜”, ½”, ⅝”, and ¾”, is still widely used based on structural requirements and budget.

When to Replace Roof Decking

Gap size of this existing plank decking will require new OSB to be installed over the roof deck to meet codesThe first step is having a roof inspection completed! They will evaluate and possibly determine if you will need to replace your roof decking during a full roof replacement. If the roof decking integrity is compromised or signs of rotting are evident, you must replace these boards.

Our seasoned roofing specialists can inspect the roof deck from the attic before removing the roof. This inspection will disclose obvious issues with gaps in plank decking.

We also look for roof deck thickness from the rakes and eves. In some homes, we have to remove the existing roof first. This allows us to assess how much of the decking needs to be replaced.

Cost of Roof Decking

The cost of roof decking varies due to fluctuating wood prices. For instance, plank decking is sold per linearThe cost to replace your roof decking may be covered by insurance foot, whereas sheet decking is priced per sheet. Depending on the type and extent of damage, replacing plank decking with OSB or plywood can be more cost-effective.

Right now, the cost to replace sheet decking for a retail agreement is $60 per sheet, covering both labor and materials. This price can suddenly change based on material prices.

Is Roof Decking Covered by Insurance?

If you have an insurance claim roof replacement, your homeowner’s insurance typically covers roof decking if your policy includes code endorsements. Roof decking comprised of space decking with gaps wider than 1/4 inch, thin decking, or sheet decking is delaminated, it must be replaced to comply with local building codes. The total roof replacement cost should include the cost to bring your decking up to codes!

Check with your insurance agent. See if your policy includes code endorsements for residential roofing. These endorsements cover roofing repairs or roofing installation.

Compliance with Roofing Codes

Roof decking must comply with specific building codes, like the 2018 International Residential Code R905.2.1, which mandates that asphalt shingles be fastened to solidly sheathed decks. This ensures your roof can support the new materials and pass inspections.

Nashville Davidson County TN has adopted the 2018 IRC Building Codes for roofingThe 2018 International Residential Code (IRC) 903.1 mandates that roof decks must be covered with approved roof coverings, which are securely attached to the building in accordance with this chapter’s provisions. Roof assemblies must also be designed and installed in line with the code and the manufacturer’s approved instructions to ensure they adequately protect the structure.

Roofing manufacturers specify precise requirements for decking to ensure their systems function effectively and qualify for a warranty. For instance, according to GAF guidelines, gaps in space decking should be no more than 1/4 inch between boards. Sheet decking should be a minimum of 3/8 inch thick to ensure the roofing system’s integrity and warranty. In order to meet current building codes, roofs with space decking with gaps exceeding 1/4 inch would require replacement.

Is Roof Decking Covered By Insurance?

Roof decking is typically covered by your homeowner’s insurance if your policy includes code endorsements. If your roof has space decking with gaps wider than 1/4 inch, or if the sheet decking is thin or delaminated, it must be replaced to comply with local building codes.

Talk to your insurance agent. Confirm if your policy includes code endorsements. This will ensure that any needed roofing repairs or roof replacements are covered.

Further Roofing Insights

Beyond roof decking, other crucial materials comprise the roofing system. Understanding all these components is vital for any homeowner considering roof work.

At MidSouth Construction Roofing Contractors, we pride ourselves on thorough, high-quality roofing services. We don’t just sell roofs, we make sure every homeowner in Nashville has a strong and long-lasting roof. We also provide extended workmanship warranties up to 25 years that you can transfer! Our goal is to provided peace of mind for every customer who hires MidSouth Construction to replace their roof!

MidSouth Construction Team - Nashville Roofing Contractor specializing in residential and commercial roofing servicesDiscover More About Your Roof

Our blog provides a wealth of information on roofing systems and roof materials available today! Read our blog that discusses the impact of high quality roofing materials on your residential home value. With your local Nashville Roofers, MidSouth Construction, your roof is in expert hands.