27 May WHY IS DECKING IMPORTANT?
Decking is the most important component of a roof. If the decking is not strong or supportive, neither will your roof be. Shingles need to lay flat and must be nailed firmly to the decking. If they’re not, they simply will not last.
Decking is important because:
1. It provides a nail-able surface
2. Shingles conform to the decking
3. It needs to hold up in a storm
4. Manufacturers specifications detail decking requirements
Nail-able Surface – If I said, “Nails need to hold the shingles down,” you would be like, “Duh! Everyone knows that.” But did you know that some decking is too thin, and some decking has gaps between each board, causing it to be unsuitable to have shingles nailed to it? Let’s look at a few examples. Decking on new construction houses nowadays is 7/16” OSB plywood at a minimum. Decades ago, the construction industry used 3/8” plywood or wood plank boards, also called 1×6. 7/16” is the new code minimum for decking thickness, so if your home has only 3/8,” this would leave you far short of minimum thickness. When plank boards were installed, sometimes the spacing between the boards would exceed ¼.” This might seem insignificant, but sometimes nails would be driven into this gap, completely missing the wood boards altogether. Both of those would not be considered a good nail-able surface. Contacting the local building code office will allow you to find out what the minimum building requirements are in your area.
Shingles conform to the decking – Shingles are flexible when warm; thus, they conform to the surface that is under them. That includes decking. Replacing boards that are soft and sagging is extremely important. Plank style boards that are wider than 6” can curve upwards overtime. Plywood should be installed overtop to correct this issue. A transition point from one pitch of a roof to another can have a height difference that can cause a shingle to not lay properly, thus requiring added material to make a smoother transition. These three areas that we just talked about can cause shingles to not lay flat if not addressed. Now you might say, “What’s the big deal?” Well, if shingles don’t lay flat, they tend to not seal properly, and eventually, they blow off. Decking that is not flat but wavy creates the same wavy pattern in shingles. This wavy pattern will create little dam-like areas where the water is not able to run off. Instead, the water will start to run horizontally. Water running horizontally creates leaks.
Decking needs to hold up in storms – You need a roof that holds up to everything that is thrown at it. If the roof cannot, then what’s the point? More than likely, we all have seen pictures of a storm that has come through and blown off not only shingles but also plywood as well. Having the right size of plywood and making sure that plywood is fully secured to the rafters is extremely important. After the roof is torn off, make sure that all loose plywood is re-nailed. Shingles are only as good as the surface to which they are nailed. If loose plywood is not addressed, the roof can become susceptible to storms that blow through.
Manufacturers Specifications – Shingle manufacturers know how important decking is and how it affects the shingle they make. Some building codes will say decking has to meet manufacturers specifications, or “specs” for short. If the decking issues that we talked about here were not addressed when you installed your new roof, there is a great chance that if you ever needed to file a claim because of a defect in the shingles themselves, the warranty that came with the shingles can be voided out because they were not installed to the specs that they required. Always check what the minimum requirements are. Double-check with the roofing company you are using to make sure they are meeting these requirements.
Decking is the base of the whole roofing system. At Robert Moore Construction, we always make sure that your roof meets these requirements and never shy away from getting in the attic if needed. We also make sure that all damaged wood is replaced and re-nailed where needed. If you have any questions about decking in addition to what we talked about here, please reach out to us and let us know. If you about to embark on getting a new roof and are not sure about the size and style of decking that you have, we’ll come out and take a look because it’s always better to know before getting your new roof installed than after.