Building a new house or changing the entire decking of your roof? Well, there are a few considerations you’ll have to think about before starting your construction work. Namely, you’ll have to choose the type of decking, and most importantly, its thickness.
If you’re not sure whether you should go for ½” or 5/8″ roof sheathing, let us be your guide. In this article, we’ll tell you which thickness may be a better choice based on several factors. We’ll also answer more questions that might be on your mind concerning roof decking. Let’s dive in!
Should I Use ½ or 5/8-Inch Roof Sheathing?
Before we dive into the answer to this question in-depth, you should know that most experts recommend going for 5/8-inch decking right away. Thanks to its added thickness, it’s generally more durable than its ½-inch sibling. Thus, you can never go wrong with 5/8-inch decking.
Still, not everyone can afford to buy boards of 5/8-inch roof sheathing without knowing that they need it. This decking tends to be pricier than its ½-inch counterpart, and its installation will cost you more as well.
To make sure that your investment is well-placed, you’ll have to consider the following factors first.
Factors to Consider When Choosing Roof Sheathing
Weather
An important aspect that you need to think about is the climate of the place you’ll build your house in.
See, if you live somewhere with mild weather, you can go for ½-inch roof sheathing. This is because you won’t need all the extra durability that the 5/8-inch decking has to offer.
On the other hand, houses, where extreme weather is the norm will require you to install a sturdier alternative. For example, if you reside somewhere prone to large snowfalls, heavy rain, or hurricanes, 5/8-inch roof decking will be the wiser choice.
Rafter Spacing
Besides the weather, the space between the rafters that make up the roof framework is another major factor that’ll help you determine the right thickness for your decking.
The standard rafter spacing of 24 inches will require you to install 5/8-inch sheathing. This way, the decking should be solid enough to withstand the roof loads without bending or falling apart.
On the contrary, ½-inch sheathing may be a good option if the space between the rafters is less, say 16 inches.
While not as common as 16 and 24 inches of rafter spacing, a space of 20 inches can sometimes be found in house roofing. If that’s the case with you, you could use both decking thicknesses here with confidence.
Choosing one over another will only rely on the weather conditions and your budget.
Your Budget
As we’ve previously mentioned, 5/8-inch roof decking is considerably pricier than ½-inch sheathing. Plus, the thicker and heavier boards are more time-consuming to install.
As a result, a roofing professional will charge you more in exchange for his time and workmanship.
Therefore, if you’re on a tight budget, consider going for a 1/2-inch decking unless your region’s weather or rafter spacing requires otherwise. Of course, if money isn’t an issue, we’ll always recommend picking 5/8-inch thick sheathing boards instead.
What Is the Minimum Thickness for Roof Decking?
The minimum thickness for a roof sheathing material is 3/8th of an inch. Of course, this thickness won’t be compatible with most roofs in the country, but it has specific requirements.
For instance, this kind of decking can work fine with roofs that have minimal loads. In other words, 3/8-inch decking may be a good candidate for steep roofs since they have a lesser load per square foot.
Also, this decking thickness needs no more than 16 inches as the space between rafters.
As you can see, these conditions don’t apply to the majority of houses out there. Furthermore, some towns or cities don’t allow roof decking thicknesses under the typical ½ and 5/8-inch.
For roofs that need to battle some extra load, like those subject to heavy snowfall and ice accumulation, consider switching to ¾-inch decking.
OSB vs. Plywood Decking – Which Type Does My Roof Need?
Now that you’ve determined the best thickness for your roof sheathing, you might as well start thinking about the right material. As you probably know, the most common decking materials are OSB (Oriented Strand Board) and plywood.
In this section, we’ll discuss the pros and cons of each type of decking to help you make up your mind.
Oriented Strand Board
While not as popular as plywood, OSB is steadily getting more appreciation as a roofing decking material. OSB refers to a type of wood consisting of strands compressed together with adhesive to give you its final board form. But what makes it so special anyway?
The cool thing about OSB boards is that they’re much cheaper than their plywood siblings. Better still, they meet most standards of plywood sheets, which is good news for people on small budgets.
However, nothing comes without a price.
One of the disadvantages of OSB is that it doesn’t hold nails as effectively as plywood does. As a result, the overall structural strength of the roof may be reduced, but it’s still not that huge of a difference in durability.
You should also know that OSB tends to absorb moisture in a different way than plywood does. So, sure, OSB will take longer to do so, but it won’t let go of the absorbed moisture as fast as plywood will.
In some states, like Florida, OSB in roofing has been prohibited entirely because of the way it contains moisture. This decision came after the county noted Hurricane Andrew’s effects on houses that had this material as roof decking.
Even after the boards dried down, they swelled around their middle and stayed dry around the edges.
The bottom line is, if you’re somewhere with extreme weather, using OSB for your roof decking may not be a good idea.
Plywood
To keep things simple, plywood consists of layers of wood that are adhered together. In each layer, the grains of wood run in alternate directions to keep the boards from bending.
In most cases, plywood roofing may be the best option, especially if your budget allows it. However, even the prices of plywood boards will vary according to the thickness you’ll be using, which we’ve discussed earlier.
Most importantly, plywood is more durable than OSB, not to mention that it works in sync with nails.
Plus, plywood boards don’t keep moisture as long as OSB does, giving the former extra points for use in places where snow, rain, and hurricanes are common occurrences.
See, unlike OSB, plywood performs fantastically when faced with moisture. Because of the way that its layers are stacked together, plywood expands evenly along its length. Also, when it dries out, every area of the board returns to its original size all at once and with the same shrinkage degree.
Therefore, if you’re looking for a sturdier roof structure, more resistance to the natural elements, and better handling of moisture absorption, plywood should be your best bet.
To Wrap It Up
When considering whether you should go for ½” or ⅝” roof sheathing, you must keep a few factors in mind before deciding. Those main points include the weather conditions, the space between the rafters, and your budget.
Once you ensure that all these aspects work with your needs perfectly, you can finally pick the best decking thickness for your roof. Remember to also consider the right material for the sheathing to ensure that the structure of your roof remains in good shape for as long as possible.
Now, are you ready to give your old roof a new look?