A strong and durable roof depends on selecting the appropriate fasteners when sheathing is attached to rafters. Picking between self-tapping screws and nails can be difficult with so many options available. Knowing the benefits and drawbacks of each will enable you to make an informed choice.
Self-tapping screws are well-liked because of their firm grip and long-term resistance to loosening. They have a strong grip and are less prone to come loose under pressure. They are therefore a dependable option for locations with strong winds or fluctuating loads. Nevertheless, compared to nails, installation can take longer with them.
Conversely, nails can be less expensive and can be installed more quickly. They have long been a part of roofing tradition and, when applied properly, can create a strong bond. However, in high-stress areas, they might not provide the same level of security as screws.
It is essential to comprehend the unique requirements of your project as well as the features of each type of fastener in order to get the best results. In the sections that follow, we’ll go over how to securely and long-lastingly fasten sheathing to rafters with self-tapping screws and nails.
| Criteria | Self-Tapping Screws | Nails |
| Strength | High, provides strong hold | Moderate, less secure than screws |
| Ease of Use | Requires a drill, easy to install | Hammer needed, simple to use |
| Durability | Resistant to loosening over time | May loosen with wood movement |
| Cost | Generally more expensive | Usually cheaper |
| Best For | Heavy-duty and precise work | Quick and less critical tasks |
- Features of the wooden “skeleton” of the roof
- What to choose – screws or nails
- Resistance to vertical loads
- Resistance to lateral loads
- Why are nails better?
- Types of nails for fastening sheathing
- Smooth
- Yerent
- Screw
- Selecting nails by length
- Video on the topic
- Fasteners for frame houses. Nails or screws. Construction of a country house with Build Your Own House.
- How to attach the sheathing and counter-lattice
- how to attach the sheathing and counter-lattice to the rafters
Features of the wooden “skeleton” of the roof
When working with wood, consideration must be given to both the material’s properties and the direction of loads acting on different structural components.
Wood has softer, more elastic qualities than metal or concrete, but these qualities can fluctuate depending on humidity. When it rains outside, the wooden components of the under-roofing system absorb moisture from the air and water vapor rising from the inside of the house. The opposite movement takes place in dry weather conditions, when the tree releases extra moisture into the atmosphere. Simultaneously, the material undergoes expansion or contraction, causing changes in the elasticity and spacing between its fibers, ultimately affecting its capacity to retain fasteners.
Thus, you must choose the appropriate hardware before fastening the sheathing to the rafters or creating nodal connections to the structure. The loads affecting them must be identified in order to accomplish this. This considers:
- roofing weight;
- stresses that arise in the material when its humidity changes;
- snow load, which can cause deflection of the sheathing;
- wind loads.
The force applied to the fastener can cause bending, tensile, pulling, and shear loads, depending on which way the force is applied.
In the event that the snow load is vertical, the wind load will be dependent upon the direction of air flow and will act either horizontally (lateral shear load) or vertically (pull-out load).
Let’s observe how self-tapping screws and nails perform under challenging circumstances before determining which method is best for attaching the sheathing to the rafters.
What to choose – screws or nails
An extended steel rod with a pointy tip is called a nail. Driven into wood, it wedges the fibers, which compress the rod from all sides as they attempt to revert to their original position. It is held in the material by this pressure.
When screwed into wood, the spiral-shaped protrusion on the screw rod creates grooves in the thickness of the wood. The resistance of these groove walls holds this fastener in place in wood in addition to lateral compressive forces.
Let’s examine how well these hardware resists lateral (shearing and bending) and vertical (tearing) loads.
Resistance to vertical loads
Propping and threaded hardware are unquestionably stronger when viewed through the lens of pull-out loads. The elastic forces holding a nail’s rod must be overcome in order to remove it from wood. This alone won’t remove the screw; you also need to obliterate the grooves that restrict the thread.
A self-tapping screw with the same thickness and length, 22 mm, can only be removed by applying a force equal to 74 kg.Similarly, a 40 mm long nail driven into a pine beam will pull out of it with a force of 32 kg.
As a result, many people prefer to use self-tapping screws rather than nails to fasten the roof sheathing because they correctly assume that the connection is stronger.
However, lateral loads—which happen when wooden parts are displaced relative to each other owing to wind pressure or uneven swelling of the wood—also have an impact on the fastening elements in addition to vertical loads.
Resistance to lateral loads
The dynamic nature of lateral loads acting on fasteners causes them to either increase or decrease. The nail can withstand them with ease because of its relative flexibility; it bends when the parts move.
The truth is that heat treatment is not used in the cold forging process used to create nails from steel wire. Additionally, the steel used to make the self-tapping screws has been chemically and thermally treated to give it the high hardness required to cut threads. However, because of their increased hardness, they shatter under shear load because they are unable to bend and move with the material.
You must consider the fact that wood swells from absorbing moisture, increasing the thickness of the fastened elements, before using self-tapping screws to fasten the sheathing. In this instance, the screws break frequently at the base, directly under the head, because they are held in place by thread and are unable to move, while the nails are squeezed out of the channel they punched.
Why are nails better?
The pulling forces have a far smaller effect on the sheathing-to-rafter connection than they do on the lateral ones. They may be important if the area beneath the roof is exposed to wind gusts that are aimed at the slopes’ inner walls. Canopies, open terrace roofs, and pavilions are a few examples. However, they primarily affect sheet roofing, which can cause the rafters and inadequately fastened sheathing to come loose.
More often than not, fasteners are unable to endure long-term operation’s multidirectional displacement of wooden structure parts and the impact of atmospheric conditions. Nails withstand these kinds of "wave" influences quite well.
Note: You will need to use stainless steel or galvanized hardware that is protected against corrosion in order to install the roof.
Types of nails for fastening sheathing
Because it only examined the fastening characteristics of common construction nails with a smooth shaft, the comparison between nails and self-tapping screws is not totally accurate. Other species, such as screw and ruff, exhibit a significantly greater resistance to tearing loads. Selecting the nails required for the roof’s chatter will be simpler.
Smooth
The compounds with smooth nails have the lowest reliability. Their primary issue is that the fastener is forced out by swollen wood, and the hat sticking above the surface may harm the coating that is on the crate.
However, these tools are essential for building temporary structures because they make dismantling them the simplest.
Yerent
The truncated cones that make up the "rod" of these nails are arranged one above the other, base upward. There’s also ring nails. When clogging, they enter the wood easily, but when it swells and dries out, they are not released or squeezed out because the fibers of the wood squeeze the area above the protrusions.
This kind of hardware is thought to be the most dependable when it comes to installing roofing systems and constructing frame homes. However, handling them calls for a high level of skill and accuracy because it is nearly hard to disassemble a mistaken connection without damaging the material.
For informational purposes only! Many people choose self-tapping screws over nails for rafters and sheathing because of how quick and simple they are to use; screwing in fasteners with a screwdriver is far more convenient and easier than hammering. However, a nailer is a specialized tool that can be used for the quick installation of rough nails.
Screw
In terms of structure, screw nails and wood screws are comparable. Both have a thread that stops short of the head, but the thread is less frequent and sharp. Such a nail rotates around its own axis when hammered, much like a screw does. The wood fibers separate unevenly at the same time, creating a lot of friction and strong attachment to the hardware.
These fasteners are also very resistant to being pulled taut. It will require many times more effort to remove from wood than it would to remove a typical, smooth nail. As a result, buildings put together with its assistance endure for decades.
Counseling! It is also preferable to use screws or rough nails rather than self-tapping screws when choosing how to fasten the rafters.
The choice you make regarding self-tapping screws vs nails for sheathing attachment to rafters can significantly impact the strength and longevity of your roof. Self-tapping screws are perfect for making sure the sheathing stays firmly in place because they offer a better hold and are less likely to loosen over time. However, for larger projects, nails can be more economical and easier to install. You can ensure a strong, long-lasting attachment for your roofing project by making the best decision by being aware of the advantages and disadvantages of each option. For both approaches, using the right installation techniques is essential to getting the best results.
Selecting nails by length
The consistency of the connection depends on the nail length. It is chosen with consideration for the sheathing’s thickness so that the fasteners pass straight through it and penetrate the rafters an additional 1.5–2 times deeper. As an illustration:
- sheathing thickness 20 mm – nail length 60 mm;
- sheathing thickness 30 mm – nail length 70 mm;
- sheathing thickness 40 mm – nail length 90-100 mm.
Each method of fastening sheathing to rafters—self-tapping screws and nails—has advantages and disadvantages. The conditions of the project and your unique needs will determine which is best.
A classic option, nails are renowned for their quickness and flexibility. They work well for extensive projects where you have to move fast over large areas. But with time, they may loosen and need to be tightened again, which could mean more maintenance.
Conversely, self-tapping screws provide better durability and holding power. They’re perfect for long-term stability because they’re less likely to come loose. The drawback is that installing them can take longer, and you’ll need the appropriate tools to finish the task quickly.
The optimal decision ultimately comes down to your priorities. Nails could be the best option if speed and ease of use are important to you. Self-tapping screws are a good option if you’re willing to put in a little more time and are searching for strength that lasts.
Whichever option you select, make sure you’re attaching the sheathing correctly by adhering to the recommended alignment and spacing standards. This will give your project the best results while preserving the structural integrity of your roof.
