Roof Repair: Damaged Decking
Decking is the plywood sheathing that makes up your main roof surface. The rest of the roof, from shingles to vent covers, are all installed atop the decking. Decking damage may not be noticed immediately since the decking is covered by a layer of shingles.
Types of Damage
Decking damage falls under two main categories. There is external and internal damage. External damage is usually caused by impact. A fallen tree branch may puncture the decking, for example, or an animal like a raccoon may pry up the corner of the decking to gain access to the attic. With external damage, the wood is in good condition except for the puncture area.
Internal damage means that the wood itself is compromised. The most common cause of this is due to rotting from moisture exposure. You will find internal damage when damaged shingles or a roof leak isn't addressed properly, so the decking absorbs all the moisture and begins to rot. Internally damaged decking boards will have water stains, and they will also warp and develop soft spots.
External damage can usually be patched. The puncture or chewed-up area of the board is cut away so that there is a square or rectangular hole. Then, a piece of decking board is cut to the exact dimensions of the hole. A support board is installed underneath the decking to span the hole; then, the patch is nailed to the support board and caulk is used to create a waterproof seal around all joints. Finally, the area is reshingled.
Internal damage that has lead to decking rot can't be patched. Fortunately, repair is an option if only one piece of decking is affected. The damaged board is removed and replaced with new decking. Then new shingles are installed over the damaged site.
When to Replace
Sometimes repair isn't recommended or even possible. Severe punctures that span several lengths of decking, for example, are often more cost-effective to repair by simply removing the old roof and installing a completely new roof. This is especially true if other damage may have occurred, such as to the roof trusses. A fallen tree on the roof is the common cause of such extensive external damage.
Severe water damage that has affected multiple sheets of decking is another reason to consider a full replacement, and for similar reasons as above. By replacing all the decking, you can be sure there are no rotten boards still in place that could spread the damage to the new decking.
Contact a roof repair service if there is damage to your roof decking.