The Plywood Under Your Shingles


If your home was built in the last year 20 years you most likely have a plywood as the first layer of your roof. The plywood on your roof should be 1/2 inch to 3/4 of an inch thick. If your plywood is only a 1/4 of an inch thick it will degrade faster. If you notice when you are walking on your roof that there is a lot of crunching underneath that is a sign the plywood is deteriorating. Here are some reasons your plywood would be deteriorating.

  1. If your attic is poorly ventilated it will cause a build up of moisture that could lead to the plywood sagging. When it’s hot the plywood expands and then when it’s cold the plywood condenses. The constant back and forth can over time can cause the plywood to sag or feel spongy.
  2. The plywood could delaminate and in that case the plywood could crack and split.
  3. Having a leak in your roof structure can lead to the plywood deteriorating but the plywood would does dry quickly if moisture was to get in.

If your roof is starting to sag or the plywood feels spongy stay off your roof. The structure may be strong enough to get the weather out but not strong enough to hold you up. Call the professionals, as they have the necessary tools to ensure safety when getting on roofs.