Seeing buckling or warping on your roof can be alarming. You may immediately think the worse, but sometimes it may be simply the roofing material that appears to be warped and not the roof deck itself. However, even a warped roof deck can be repaired. Although there may be many different reasons for buckling or warping to occur, here are a few of the more common causes.
•Movement of the roof deck: An improperly installed roof deck (or the sheets of plywood that are underneath your roofing material) could result in the plywood shifting. The plywood might also become warped itself if it becomes wet, which could happen in the case of a roof leak.
•Underlayment not lying flat: If the underlayment (or the vapor barrier) underneath your roofing material becomes wrinkled, it might result in your roof taking on a buckled appearance. This most commonly occurs when the underlayment was improperly installed.
•Felt not lying flat: In much the same way that poorly installed underlayment can cause roofing material to take on a warped shape, improperly installed felt can do the same thing.
•Inadequate roof ventilation: Never underestimate the importance of a well-ventilated roof. If your roof doesn’t have proper ventilation, moisture can build up in the attic space. Over time, that moisture can seep into your roof deck, causing it to become warped.
•New roof tiles installed over existing roof: One of the most common causes of a buckled roof is when new tiles or shingles are installed over an existing roof. Although this is a cost-cutting measure, it can easily result in buckling. •Avoid this by always having your old roof removed before having a new one installed.
Source: Patton Contracting http://www.pattoncontracting.com/roofing-buckling.htm
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