Attention to Detail: Solidly Sheathed Decking

Continuing our series regarding attention to roofing details for those in the Wichita, KS metro area, we will be discussing the importance of solidly sheathed decking.

What is a solidly sheathed deck?

A solidly sheathed deck means the roof has a solid wood surface to which asphalt (and other types of roofing materials) shingles can be fastened. This is code but also just good practice. Pursuant to 2006 IBC R905.2.1, “Asphalt shingles must be fastened to solidly sheathed decks.”

Why is solidly sheathed decking important?

If your home was constructed prior to 1970, there is a good possibility it will have 1”x6”, 1”x8”, 1”x10”, or 1”x12” board decking. Plywood was not common in construction until after this time. However, this board lumber was not usually kiln-dried before it was installed. So when the roof was originally nailed on it was likely solid, but as the wood dried over time it would typically shrink between 5%-10%, creating upwards of ½” gaps.

If I have gaps or insufficient decking, how can this be remedied?

In most cases where the above conditions are met, 7/16” OSB is mechanically fastened over the board decking. Plywood can be used for this application as well, but it is more expensive than 7/16” OSB (Oriented Strand Board) that is commonly used in new construction.

Why is an attic inspection important before replacing my roof?

An attic inspection will let you know if decking will be required for the roof replacement. Decking installation as of July 27, 2017, is running at approximately $125 per square. If you have an average roof size of 27 squares, this could potentially be a $3,375 cost added to your roof replacement. If your home is subject to an insurance claim and you have building ordinance coverage (or code upgrade coverage), this could potentially be funded by your insurance provider. 

Are there any exceptions to the code?

Some municipalities will still allow board decking as long as gaps are not greater than ¼”. However, since there are voids that are very prevalent across the roof, it is impossible to guarantee that nails will not end up in these voids. The result? Leaks that will appear immediately or in the near future. We recommend calling your local code enforcement office to determine what applicable building codes are present in your area. For the Wichita, KS metro area building codes, visit roofing materials, such as wood shingles, wood shake, and metal panel roofing systems, may also be installed on spaced decking. This is still an acceptable practice an approved by most building code.

Looking for a new roof or need a roof inspection in the Wichita KS Area?

If you are seeking a roof replacement and would like have an inspection of your existing roof system, please do not hesitate to reach us at (316) 665-4882 or request a quote online. Otherwise, if you have any questions about new roofs in the Wichita, KS area, please consider S&A Roofing, and contact us any time.