Roofing Screw Types

9 Simple steps to choosing the correct roofing screw type

When selecting fasteners for specific projects, it is important for the builder, designer and even installer to understand or be involved in the process to understand not only the material and available options, but to also check compatibility against the environment, and the most important of all, building regulations.  Many might see their choice limited by budget or price sensitive biddings, though we always remind decision makers to see it in a broader sense.


The cost of fixtures normally accounts for a fraction of the total budget, but play a significant role in the overall safety and longevity of the structure, as a chain is only as strong as its weakest link – meaning a roofing sheet will have to remain in place be it rain, wind, or shine to protect what is underneath, and the main purpose of screws is to keep substrates securely joined or fastened to one another.   There will always be cheaper alternatives when it comes to building material choices, though one should always ask – what is the compromise?  Are you willing to, in exchange of short-term savings, risk sacrificing safety and stability of the whole project in the long-term?


Below are questions we ask customers to determine the correct screw type for roofing.

  1. Determine the type of roofing sheet are we dealing with.
    • What material is the sheet made of?
    • What profile is the sheet?
    • What is the color?
    • Thickness of the sheet?
    • Is it an insulated panel? If so, what is the thickness of the insulated portion?
    • Will there be skylight panels involved during installation?
  2. Determine the structure it is affixed to.
  • Are the purlins steel or timber?
  • Thickness of the steel purlins?
  • Are there any trusses involved?


Upon understanding what we are dealing with, below are questions we ask ourselves to choose the correct screw type for the job.

  1. Should I choose as self-drilling point or sharp-pointed screw?
    • Steel purlins or trusses require self-drilling points and timber requires sharp tipped screws.
  2. What head type does the job require?
    • Hex profiles are usually the head type of choice for roofing screws, though some may choose a flatter profile which comes with recessed Philips, square or Torx sockets.
  3. What screw gauge size does it require?
    • Screw gauge size, or simply gauge, refers to the major diameter of the screw – the larger the number, the larger the diameter. Although factors such as choice of wire material, surface and core hardness after heat treatment, and thread pitch and depth are all contributors to the properties of the final product, it is still safe to say that harder and thicker steel, more often than not, require larger gauge screws.
  4. What thread count (TPI) should I specify?
    • Fasteners are often driven first through thinner substrates (i.e. metal roofing sheets), and then through thicker material (i.e. steel purlins or structures), pulling in, fixing the substrates together.

TPI selection is usually determined by the thickness of the thicker material, though some come with special designs such as a larger diameter upper thread to increase pullout values on a thinner top ply.

  1. How long does the fastener need to be?
    • The fastener length should cover the thickness of the sheet plus full height of the corrugation (crest fastening on roofs), and should have at least 2 to 3 full thread penetration on the bottom substrate (i.e. steel purlins or structures).
  2. What is the required drilling capacity and choice of drilling tip?
    • Drilling tip choice correlates directly with the drilling capacity of a self-drilling screw. Thicker substrates will most definitely require longer drilling tips, and harder substrates normally requires wider tips.
    • A reputable distributor or manufacturer should be able to provide sufficient details of the product and its intended use for you to make the correct choice.
  3. What category of corrosion resistance coating should I use?
    • Understand your environment. For example, areas close to the coast will be at high risk to corrosion due to high salt content in the atmosphere compared to the inland, and therefore would require high weathering resistant fasteners on structures.
    • There are multiple choices on the market when it comes to corrosion resistant coatings, and products are normally priced according the number of years the screws can remain rust proof.

Since it is impossible to tell from the naked eye how effective the coatings really are, a reputable company will provide accredited 3rd party test lab reports as proof of compliance.

  1. Does it need to be painted?
    • This normally comes down to personal preference. Some would like head colors to match the roofing sheets, while others simply don’t care.
    • Paint is another topic which deserves an article of its own, as the weathering process when exposed to the elements sometimes contribute to delamination or chipping of itself and coatings underneath, resulting in catastrophic disasters such as galvanic corrosion in the long run.
  2. Do I need a washer? If so, what material should I use?
    • Washers should be considered an accessory to fasteners, and can be used with or without depending on where it is used. The main purpose of washers is to help prevent leaks and normally not required for structural applications such as steel truss or frame connections.
    • Bonded EPDM (ethylene propylene diene monomer) washers offers superior resistance to Ozone, UV, sunlight, extremely pliable, and highly recommended for use with fasteners.
    • PVC washers, though significantly cheaper compared to EPDM washers, are quite stiff, have lower temperature resistance and cannot come in contact with plastic skylights. Due to lack pliability, PVC washers are prone to leakage when used standalone, and should be sealed off with silicone.


Fasteners are normally manufactured according to standards such as AS, DIN, ASTM or JIS to name a few.  These standards provide specific sets of rules and regulations, and should be seen as minimum standards on how products should be manufactured.  Choosing a reputable brand that adheres to the standards should prevent any unexpected surprised during and after installation.


Roofing Screw - self-drilling screws BDN FASTENERS®


BDN Fasteners offer roofing screws in multiple sizes and specifications to meet different requirements; are all manufactured to Australian AS3566 standards, and backed by matching 3rd party lab reports and real-world testimonials from projects worldwide.

Screws for metal roof installation

Choosing the correct screws for metal roofing sheets installation.

The majority of BDN self-drilling screws are designed for either metal roofing or wall cladding installations, with the exception of proprietary designs for specific purposes such as PolyXpand™ for plastic skylight fixings, or TRUSS-Tite™ for joining truss components on steel framing.


Common issues we see on high quality, expensive metal roofing sheets fixings are:

  1. Incorrect selection of screws, with issues ranging from length, drilling capacity, thread type, gasket, and more.
  2. Poor quality screws which are unfit for the location and environment installed in.
  3. Improper installation – the majority of issues stem from insufficient knowledge of the product, not following installation guides and instructions, and most of all, carelessness. Don’t forget that choosing the correct tool for the job also plays an important part in proper installation.



Before any installation, understand the type of structure, material, and environment we are dealing with.  Since we are talking about metal roof installation, determining the type of metal roof will be first priority.

  1. Is it a single sheet insulated panel?
  2. Are there any skylight panels installed in between sheets, and if so, what type of material are the skylights?
  3. What is the thickness of the sheet, and how thick is the insulated portion underneath?
  4. Color of the sheet and should the screws have to come with matching head colors?


Upon determining the type of sheet used, we then have to understand the type of structure it is affixed to.

  1. Are the purlins steel or timber?
  2. Thickness of the steel purlins?
  3. Are there any trusses involved?


We should then determine the kind of environment the building structure is built on.  Here at BDN Fasteners, we have categorized the kind of environments to the following based on its characteristics.  Scope of warranty for our products are also based on the category the environment is classified to.

  • Dry, Rural Areas – Areas remote from the coast and sources of pollution; as well as all of the areas listed below.
  • Mild Urban or Rural Areas –
    • Areas with little to no chemical pollution, including but not limited to natural chemicals such as ammonia from livestock or carbon monoxide from log-fire.
    • Areas far from the coast with no impact from salt water spray.
    • Areas at least 2 kilometers away from any type of industry, light or heavy.
  • Light Industrial or Urban Areas
    • Light industrial zones, light manufacturing, warehousing, distribution, or limited light intensity activity areas.
    • Built up areas constituted of high human population and infrastructures.
    • Areas at least 1~2 kilometers away from light industrial or urban areas.
  • Small Industrial Zones
    • Areas located in or adjacent to small industrial zones.
  • Coastal Areas
    • Areas located approximately 2 kilometers from the coast.



Lastly, choosing the correct product and tool is only half the job done, and it all comes down to how the installer completes the final touch, as an improperly installed screw is worse than none installed at all.


Above are basic guidelines for the novice builder or contractor to follow when making the correct fastener selection.   Since building sites differ from one another, additional factors may be required to take into consideration; it is best to contact an experienced salesperson or technician for on-site checks before making final decisions.


Properly driven screw

Common mistakes which cause leaks around screws.


Metal roof leaks around screws:

There are lots of contributing factors when it comes to roofing leaks.  A properly driven screw will have achieved the following steps and as a result, provide the perfect weather seal.

Driven straight, perpendicular to the material it is fastened on to.

Adequate, clean penetration with no excess swarf protruding or overhanging from the drilled hole.

Driven until the gasket is compressed firmly against the surface.


Below is a list of common causes of metal roof leaks.


1. Choosing an incorrect screw:

Metal roofing screws are usually designed for fixing thin roofing sheets onto steel purlins, trusses or timber underneath.  Depending on the thickness of steel underneath, correct drilling point sizes must be chosen in order to penetrate.  Most suppliers will provide a list with corresponding drilling capacities to their screws.  Read through the list carefully and don’t hesitate to ask questions.

The length of the screw is also important. The length of screw required can be calculated by adding the depth of the roofing sheet corrugation, plus the thickness of the purlin/truss underneath plus at least 2 to 3 full thread lengths to ensure proper fastening.  Don’t forget that the thickness of the bonded EPDM washer or Domed BAZ washer should also be taken into consideration.

Thread type should be considered.  A rule of thumb is, coarse threads for thinner sheets (<4.5mm), and fine threads for thicker sheets (>4.5mm).  This will ensure the fixing to have adequate pullout values against pressure from high winds or snow.


2. Overdriven screws:

The rubber gasket should seat firmly but not over compressed against the surface.  The rule of thumb is, the gasket should not be bulging at the sides of the washer flange, or even to the point of being squished.  Workers should take extra care while making an attempt to ensure a tight seal between the metal roofing and the screw head because an over-torqued washer loses its elasticity, breaks down prematurely, and oftentimes disintegrate due to over-exposure to the elements.


3. Under-driven screws:

This is an easy one.  An under-driven screw does not provide sufficient pressure to the washer to create a firm seal against the surface.  This may happen due to incorrect drilling tip capacity selection and therefore could not adequately penetrate the metal substrate underneath to reach the desired depth.


4. Misaligned or skewed drilling:

A misaligned or crooked driven screw will result in the rubber washers not seating properly against the surface, which means insufficient seal of the hole, or one side over compressed, resulting in premature damage to the gasket.  Another sometimes overlooked risk is the skewed side of the steel washer or hex washer flange digging in, deforming or sometimes even cracking the surface, which also contributes to leakage.


Properly driven screw


Some screws have extra features built in to enhance performance; oftentimes poor choice of fixings become the weakest link in a seemingly strong building structure.  BDN Metal-Tite® series roofing screws come with an enlarged hex washer flange, anti-static EPDM washer, double thread, Scratshank, and Ruspert anti-corrosive coating.

  • The large washer flange is designed so that the EPDM washer will remain fully covered after compressed.
  • Anti-static EPDM washers prevent galvanic corrosion.
  • The larger diameter upper thread close to the hex washer flange increases pullout values on thin metal sheets.
  • Scratshank clears out excess swarf, smooths out the drilled hole, and prevents damages to the EPDM.
  • Ruspert anti-corrosive coating fully protects the screw from weathering and extends the lifespan of the screw and the sheets it is affixed to.
BDN Fasteners offers TIMBER-Tite™ and TRUSS-Tite™ self-tapping screws

How to use self tapping screws for metal?

Self-Tapping and Self-Drilling screws are the bread and butter of our business and the most commonly known and used for fastening two different kinds of material, be it steel, timber, or plastic, and the list goes on.

BDN Fasteners offers TIMBER-Tite™ and TRUSS-Tite™ self-tapping screws. TIMBER-Tite screws are designed for fixing metal roofing sheets or wall claddings to timber, whereas TRUSS-Tite™ is designed to fix steel roofs and floor trusses.

Basically, all self-drilling and self-tapping screws are able to tap threads, where the main difference is that self-tapping screws normally come with either a blunt head, sharp point, or a reduced drill point.


Blunt headed screws such as the TRUSS-Tite™ is designed for truss components assembly, fixing into steel. These types of steel normally come with pre-punched or pre-drilled holes, and the blunt, slightly tapered leading threads makes it easier to fix the sheets down.

Frame Screw - TRUSS-Tite™ Fixing to steel roof and floor trusses, BDN FASTENERS®


Our sharp pointed TIMBER-Tite™ are designed for fixing roof sheeting to timber. The longer versions such as the T17CG1265C3N or T17CG1250C3N are designed for crest fixing and shorter versions such as the T17H1020C3N are designed for valley fixing. People ask why screws should be fixed down on the crest but not the valley. The main reason being water runs by gravity and flows to the lowest point, and if fixed on the valleys on rooftops, might increase the risk of water pooling around the screws and with time, cause rust.

Type 17 Timber Screws TIMBER-Tite™ Fixing roof sheeting to Timber and light metal. BDN FASTENERS®

Application - Fixing roof sheeting to timber (type 17 timber screws)




Shorter self-tapping screws which come with what we call a “reduced” drilling point, provides the same function as a sharp drilling point, but drills faster through thin metal sheeting, and is much more effective at clearing off excess swarf, as it is difficult if impossible to add flutes on smaller sharp pointed screws to due manufacturing limitations.

For roofing sheet fixing screws, always check if they come with a knurled, fluted, or slotted shank, and if the upper threads are larger in diameter compared to the lower threads. You might notice that the majority of BDN self-drilling and self-tapping roofing screws are equipped with both. The larger diameter upper threads provide good pullout strength for the whole setup under high winds and the slotted Scratshank design clears out excess swarf which might damage EPDM washers if leftover, which could result in leaks.

Self-tapping screw head types

10 Different Self-Tapping screw head types


Self-tapping screw head types

A self-tapping screw has the ability to tap threads as it is driven into the material. It is often used only to describe a specific type of thread-cutting screw intended to produce threads in various types of materials, with sheet metal and wood being the most common.

BDN Fasteners offers a range of self-tapping screws.  The screws come with either a self-drilling tip for metal or pointed tip for timber.  After the tip creates a pilot hole, the thread then taps the metal or wood the screw is affixed to.


On head types.  Screws are available in many different head types.  Some head types are very application specific, and others for more varied and general applications.  Head types are usually manufactured according to set standards according to the region used, though some might tweak or even tailer the design here and there in order to meet special requirements.


BDN Fasteners are manufactured according to the tried-and-true Australian AS standards, offering a good balance between cost and performance, and backed with an industry leading warranty.




In the smaller gauges up to 8gauge, this head style is generally used for plasterboard as it does not damage the face of the sheet. The 14-gauge screws with this head style are often used for landscaping and fixing heavy duty decking boards


Screws with this head type are used for stitching thin steel together and the large head provides a good clamping force on the materials being fixed.


This head style is used in a broad range of timber applications where a flush finish is required for the fixing, and the ribs countersink the screw into the timber. It also comes in a variety of drive types depending on the application.


This head style is generally used with screws that are fixing steel, where a countersunk recess has been pre-drilled.


This head style is a low-profile type typically used where cladding is to be fixed over the top, including where plasterboard is fixed to a steel house frame. It is imperative that the head sits absolutely flat


This head style is used for a broad range of applications including roofing, cladding and timber fabrication, and comes in a range of gauges for heavier duty applications.


This head style is used with general purpose fasteners for fixing thin steel to steel or timber substrate.


This head style is mainly used for fixing 3-6mm thick cladding such as Cement Sheet or Blue Board, and the ribs under the head countersink the screw into the material for a flush finish.


This head style is normally used for decking or picket applications where a smaller head is required to avoid splitting the timber when it is installed.


This head style is mainly used for fixing a variety of generally lighter materials to a steel or timber substrate.

Self-Drilling Screw Manufacturer. BDN FASTENERS®

Self-drilling screws – commonly known as Tek screws – are some of the most widely used metal fasteners in the building and construction industry.

Tek screws or self-drilling screws come with an additional pair of bladed flutes which extends from the threaded portion of the body all the way to the drilling tip.  The purpose of this is to combine the drilling and tapping function onto the same screw, thus eliminating the need to pre-drill pilot holes and tap threads.  Drill, tap and fasten are completed in one go, saving time and money.  The best Tek screws come with various types of surface treatments to cope with the environment and provide weathering resistance to itself and the fastened substrate.

Tek screws are popular for many general sheet metal applications like roofing, cladding, and HVAC, etc.

Larger Tek screws (No.3 Tek and above) are strong enough to penetrate 12~20-gauge galvanized steel, as well as 3/8” to ½” (10~12.5 mm) structural steel and can be used on various civil and naval engineering applications.

What is the best way to use Tek Screws?

To ensure optimum use and extended lifetime, here are some tips and recommendations for fastening Tek screws successfully onto various kinds of metal material.

  • Choose the right size Tek screw to match the material you are working with.
    Make sure that the Tek screw drill point capacity exceeds the thickness of the material to be drilled.  Failing to do so may result in burnt out or broken drilling tips.
  • Power drills with adjustable clutch settings are better suited for use with Tek screws on light sheet metal than Impact drills.
    The hammering action generated by impact drills can cause metal dimpling or oil canning deformations on lightweight metal sheets.
  • Do not overtighten the Tek screw and washer when fastening them onto sheet metal. The washers should be compressed just enough to fill any uneven surface to provide a perfect seal.
    Two things can happen if the washers are over-compressed. One, the sheet panel may deform from overtightening, and two, the exposed portion will be exposed to the sun and the elements, which accelerates the weathering process and reduces lifespan.
  • When fastening Tek screws onto hardened galvanized or structural steel, set your (cordless) power drill clutch speed to approx. 1500 rpm, and apply steady, consistent, pressure throughout the process.
    Drill speed exceeding 2300 rpm or more can result in premature drill point wear or burnout, causing it to lose its function.

Do not compromise the quality and workmanship of your construction projects.  Your building is only as strong as its weakest fastener.  Choose only quality self-drilling screws from a reliable Tek screw manufacturer – Choose BDN Fasteners today, every day.

Self-Drilling Screws, Self-Tapping Screws. BDN FASTENERS®

Despite their widespread availability and usage in commercial, industrial, and construction applications, many still confuse self-tapping screws with self-drilling screws.

Part of the reason this happens is that self-drilling screws are a subtype of self-tapping screws.

Let’s go through these two products separately to clarify these differences.

Self-Tapping Screws

Self-tapping screws have various names. They’re often called metal screws, sheet metal screws, tapping screws, or tapper screws.

Their tips come in different shapes: pointed (like a pencil), blunt, or flat, and they are described as thread-forming, thread-cutting, or thread rolling. If the screw is pointed, it will be thread-cutting – tapping and creating threads in a pre-drilled hole. If the tip is flat, it is thread-rolling – rolling or extruding threads and creating zero clearance between screw and material.

The most important difference between self-tapping and self-drilling screws is that self-tapping screws cannot go through metal without a pilot hole, which must be pre-drilled or pre-punched.

Exact drill or punch hole size is also important. The screw will become loose and not thread properly and securely if the hole’s too big. If the hole’s too small, the screw can break or cause the material to split or crack.

Self-tapping screws are good for use with metals, various types of plastics (plywood, fiberglass, polycarbonates), and cast or forged material, like iron, aluminum, brass or bronze. Self-tapping screws also work for surfaces where you can’t secure the rear end with a nut. Common applications include fastening aluminum sections, attaching metal brackets onto wood, or inserting screws into plastic housings.

Self-Drilling Screws

Self-drilling screws are easy to distinguish if you look at their point, which curves gently at the end and is shaped like a twist drill. They’re often called Tek Screws, after the brand name that popularized them.

Screw lengths vary, but drill points are standardized, identifiable by number (1 to 5), which determines their length and thickness. Head and drive styles vary; self-drilling screws are most commonly Phillips, hex, or square.

Unlike self-tapping screws, self-drilling screws need no pilot hole to cut and fasten; they can drill, tap, and fasten in one go, which saves you the extra step of drilling, then fastening.

These screws can fasten metal to metal, wood to metal, and work well with light, low-density materials. In general, they have more specialized applications than self-tapping screws. They are good for metal building and light gauge metal assemblies; Point #5 is already capable of fastening half-inch steel sheets.

Self-drilling screws are useful in HVAC applications, cladding, metal roofing, steel framing, and other general construction tasks.

Similarities and Differences

What’s most similar about these two types of screws is that both form threads as they penetrate the material being worked with. Both attach steel on steel and steel on wood when rivets or nuts and bolts cannot do the job.

Between these two, however, self-drilling screws offer two distinct advantages: time and costs saved at assembly time, and reduced error in installation, which often happens if one pre-drills holes in the wrong size.

Consult with self-drilling screw manufacturers you can trust – contact BDN Fasteners today.

Self-Drilling Screw Manufacturer. BDN FASTENERS®

Fastening sheet metal is a technical process that not only requires expertise, but also the most optimal screws – specifically self-drilling sheet metal screws. These screws feature sharp threaded shanks and tips that pierce easily through solid metal surfaces and other sturdy materials.

Self-drilling sheet metal screws come with pointed drilling tips designed to penetrate metal without the need for pre-drilled pilot holes.

Without the need for pilot holes, self-drilling screws save installation time, eliminates the extra cost for labor and drill bits. This cost-saving feature and additional advantages make them an excellent choice for metal building construction.

Features to Look Out for When Purchasing Self-Drilling Sheet Metal Screws

Like any hardware, self-drilling sheet metal screws come with various features. But whatever type of self-drilling sheet metal screw you need for your project, it’s best to go for screws that have:

  • Corrosion-Resistant capability

As many tradies know, rusty screws are a real pain to deal with, not to mention an eyesore. Rust significantly reduces the strength of metal structural elements, reducing the thickness, and even leaving holes in components. It is also difficult to contain rust once it starts to spread, which is why self-drilling sheet metal screws with Corrosion-Resistant capabilities are in high demand.

As part of our quality assurance policy, all BDN Fasteners self-drilling screws are sent to SGS for regular Kesternich (7 cycles) and Spray Salt Tests (1000hrs).  Going through regular testing demonstrates our commitment to quality and the results prove consistent product quality.

  • Corrosion-Resistant surface treatment

Self-drilling sheet metal screws with proper Corrosion-Resistant surface treatments last longer against the deteriorating effects that occur from weathering.  Such exposure can negatively affect the performance of various components and increase the possibility of failure in the long term.

BDN Fasteners self-drilling sheet metal screws come with Class 3 Corrosion-Resistant coating – designed to cope with even the most challenging of environments.

  • Corrosion-Resistant accessories

Self-drilling sheet metal screws should also come with accessories that prevent the possibility of rust.  BDN Fasteners self-drilling screws come with optional pre-assembled weatherproof washers such as DEKS Dekseal® Trueblue®, 100% weather sealed washers.  These washers provide the perfect seal between the screw and sheet metal, are anti-static to reduce the possibility of rust, and come with a 20-year warranty that will outlast the life of most sheets – a must for construction projects.

Find High-Quality Corrosion-Resistant Sheet Metal Screws at BDN Fasteners

Roofing Screw-BDN FASTENERS-Packaging


At BDN Fasteners, we say that your sheet metal is only as long-lasting as the fasteners it is affixed to, which makes all the difference between a good or mediocre project.

BDN Fasteners offer an extensive range of Corrosion-Resistant self-drilling sheet metal screws in various lengths, sizes, and specifications, suitable for a host of applications.

Special features of our self-drilling sheet metal screws include:

  • Patented Trident Self-Drilling Point.
  • Designed to work with DEKS Dekseal® Trueblue® 100% Weather-Sealed Washers.
  • AS3566 Class 3 Corrosion-Resistant surface treatment.
  • SGS Certified: 1000hrs Spray Salt Test and 7 Kesternich Cycles.

As a leading supplier of sheet metal screws in Asia, we maintain strong relationships with dealers, distributors, and project managers, providing the correct fastening solutions for their needs.

For more information and inquiries about our products, contact us today.