4 Things Homeowners Need To Know About Roof Decking


Chances are, the shingles on your roof were attached on top of a plywood base. Sometimes referred to as roof sheathing or a roof deck, this plywood acts as a foundation for the layers of underlay and the shingles on your roof and connects the roof to the frame of the house. Even though it isn’t visible, it is very important to the structure of your home.

Unfortunately, because the roof sheathing isn’t normally visible, damage can go unnoticed by homeowners. By the time you’re aware of the problem, catastrophic repairs can be expensive. However, by being proactive, you can save your home from the same fate. Continue reading to learn the importance of inspecting your roof’s plywood base, and the warning signs that it may be time to replace it.

1) What Does Roof Decking Do?

Roof decking serves several important purposes, including but not limited to:

  • Supporting Shingles: Asphalt shingles are heavier than you might expect, with a single shingle weighing in at 2.5lbs. In addition, there are other layers between the shingles and decking, such as tar paper or felt. All of this weight adds up, and decking provides support for all of the weight on a roof.
  • Fire Prevention: Although plywood decking cannot fully protect against a fire, flame retardants are often sprayed on the plywood as an extra line of defense. Talk to your roofer about their policies on this practice, as some believe that flame retardants decrease the decking’s overall performance.
  • Weather Protection: Decking helps distribute weight throughout the structure of your home, and can help your roof stand up to fallen branches, and severe weather. Mother nature can strike your home at any time, so it’s best to have as much support as possible.
  • Fewer Leaks: Water leaks can and will happen. While, shingles are primarily responsible for keeping moisture out, sturdy plywood decking is another line of defense against leaks.

2) Why Is Rotted Plywood Decking An Issue?

Rotted plywood can cause a number of issues. Rotted plywood cannot support the weight of a roof the way healthy wood can, nor can it safely grip the nails put into the roof and keep them held firm.

  • Moisture causes wood to rot, and rotten wood absorbs water even more readily than fresh wood. If there is rotten decking, the shingles are most likely letting moisture in. If it isn’t already, it’s only a matter of time until that rotten wood lets water into your attic and ceilings.
  • Trying to apply shingles on rotten wood can cause the roof to shift, which can in turn lead to more leaks.

3) Do I Have To Replace Damaged Decking?

If you are getting a new roof, while you may not necessarily need to have the plywood decking replaced, you should have it carefully inspected by a qualified roofing contractor. The inspection should take place when the old shingles have been removed.

While the added cost of replacing plywood can be expensive, it will still be far less expensive than the problems that rotting or leaking sheathing will cause. It’s best to absorb the cost now to save money and prevent damage down the road.

When considering a contractor for your project, be sure to address the subject of plywood replacement, and what the cost per plank will be. You want no surprises going into your project.

4) Attic Moisture And Roof Decking

Excess moisture in your attic can cause the sheathing to become excessively moist. The hotter temperatures rising from the attic can then make your roof’s sheathing a breeding ground for mold and mildew.

Your roofer should do an attic inspection to evaluate the roof ventilation and any potential issues that could arise from excess moisture content.

Your roof protects your home, and plywood sheathing protects your roof. For your next roofing project, make sure you get a roofer that knows all of the best practices and procedures for inspecting, removing, and re-applying roof sheathing. Your home will thank you.

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