Replacing roof nails with screws

Replacing roof nails with screws

This is a question often brought up by DIYers, usually when trying to fix a broken piece of furniture, rebuilding part of a decking platform, or simply rejoining two pieces of wood that have somehow come loose with time – an age-old debate that started from before our time and continues until this day.


Both methods have proved its worth having survived for centuries, though none more so than the other, and we believe that it is down to choosing the best method to suit your needs.


When done manually, the difference in speed and precision between nails and screws installation was quite obvious.  Nails were easier and faster to drive but had less precision, and screws offered pinpoint precision but was slow and laborious.  However, the advancement of pneumatic and electric power tools for nail guns and screw guns have rendered the comparison pointless, as the tools made installation a breeze.


If speed and precision is out of the equation, one might wonder what else is left to compare?  As a fastener manufacturer selling under our own brand name, it is imperative we provide accurate information to our customers.  The choice between nails and screws of the same caliber all comes down the Shear strength, Tensile Strength, and Holding Strength.


  • Shear Strength: The shear load required to break the screw, the ability to resist the pressure of two joined pieces “sliding” past each other.
  • Tensile Strength: The tensile load required to break the screw, the ability to resist being pulled part, breaking under pressure.
  • Holding Strength: How well the jointed substrates hold up against each other.


Nails tend to have better shear strength compared to screws, which means more flexibility, a very important feature suited for structural joining, framing, exterior wall sheathing, or hardwood floor installation.  Nails made with correct materials will bend to a large angle and less likely to snap compared with screws.


Screws are better for delicate jobs and because the installation process involves less vibration, does not mar the surface, are easy to remove, and can be installed with precision.  The tapping process during installation creates a tighter bond when reusing the original nail hole.


To summarize, use nails when joined surfaces are more likely to slide, and use screws for joined area which are more likely to pull apart, and on holes that previously had nails in them.




Strongest screws for wood

Strongest screws for wood

What defines a strong screw, and can be categorized among the strongest screws for wood?  Answers may vary, as the versatility is based on the application and its intended purpose.


Screws for wood can be used for smaller jobs such as joining cabinet and furniture parts, mounting hardware or accessories, or simply connecting parts.  In the past, simple, old fashioned slot recessed screws were used but can easily fail during the drill drive process due to the slot unable to handle larger torque from electric hand-tools, and was replace by either Philips, Square, or Torx drives.


For timber framing, log home building, mass and heavy timber construction however, larger diameter structural timber screws are used and require a totally different set of mechanical properties, test standards among other differences.


Wood, as with all organic materials on planet Earth, is unique in a way that though we are able to tell between different types of wood from its texture, none of the fibers are identical, meaning the composition in relation to strength varies, which is the main challenge when designing a strong screw.  Below are main areas to look out for when designing strongest screws for wood.


Head type – Flush or Protruding

Screw Head type Flush or Protruding


Regardless of gauge, thread, or length, screws for wood come in all kinds of head types, though they can mainly be divided into two groups, one that sits flush against the surface, the other which protrudes and stands out.  Neither is superior to the other, and the choice depends on the application.


Heads that sink flush against with the surface are normally chosen when used standalone to join other pieces of wood, such as decking or when no protrusion is allowed such as fixing door hinges to wooden framing.  Doors wouldn’t be able to close properly if screw heads were protruding from the holes.  Depending on the screw gauge, heads that sink flush or sits flat normally have smaller heads with less contact area, and better suited for which does not require great holding force.


For outdoor applications such as fixing metal roofing sheets or wall cladding sheets to wooden purlins or frames, head types such as BDN’s hex washer flange head that sits tall against the surface, will withstand much more drive-in torque compared to flush and countersunk type heads which has the potential of breaking under heavy torque due the recessed drill and drive system.


A very common design among flush or protruding threads is the addition of nibs underneath the head to either create a perfect countersunk hole and extra grip to prevent slippage.


Screw gauge to head size ratio – Increased screw diameter also requires increase in its washer head diameter to provide adequate holding strength


Thread design

As mentioned above, natural wood fibers differ in texture, grain, and vary in hardness; a properly made thread should pierce through the surface of the wood, pull the screw in without creating any splits or splinters, while hold itself and the joined substrate firmly without fail.


Common knowledge among woodworkers has been fine threads for hardwoods, and coarse threads for softwood, though through improvements in thread rolling machinery, dies and computer aided design, threads have become more sophisticated and specialized to included knurls, hi-lo threads, cross cutting, serrated edges among others.


Drill Point

Drill Point

Eliminating the pilot-hole drilling process when drilling through timber wood saves a huge amount of time and labor but does come with caveats.   Though technically not as complicated compared to self-drilling screw drilling points, a good sharp point design is still critical in the strongest screw for wood competition.


The perfect sharp timber screw point should quickly penetrate wooden surfaces and create perfectly sized entry holes for the threads to follow through.  This would normally require features such as BDN TIMBER-Tite’s proprietary Type 17 Sharp Point, which is not only sharp, but has self-tapping flutes to clear off sawdust, allowing fast and smooth operation.

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

BDN Fasteners offers an extensive range of premium quality self-tapping and self-tapping timber, drywall, and decking screws for timber to timber or steel to timber applications.  For more information, contact us through email or a simple phone call today.


Recommended Reading: TIMBER-Tite™ Self-drilling timber screws


Self-Drilling Screw Manufacturer_BDN FASTENERS-Made in Taiwan

When deciding what screws to use for metal roofing, it is important to understand the choice of metal sheet material and available options, and  also check its compatibility against the environment, and if complies with local building regulations.  Many might see their choice limited by budget or price sensitive biddings, though it is always wise to think ahead see things in a broader sense.


Below is a simple checklist that will determine the type of screws to use for metal roofing.

  • Sheet material and thickness: This will determine the gauge, and drilling tip type. The thicker the sheet, the larger the gauge, and longer the drilling tip.
  • Sheet color: This will determine whether or not to go for painted head screws and the matching color.
  • Measurements of the profile: Water always finds its way to the lowest point, and it is imperative to avoid creating holes at lower areas of sheets.  Which means that screws should always be fixed at the corrugation crest of any metal roofing sheet.  The height of the corrugation will determine the screw length required.
  • Is it an insulated panel? If so, what is the thickness of the insulated portion? – The insulation thickness will determine the screw length required.
  • Will there be skylight panels involved during installation? – Skylight panels and metal roofing sheet when used in combination, is a totally different breed. Skylight panels can be installed as single panel or multi-panel runs, or framed independently of the metal sheets, all of which require different overlapping methods and fixtures.
  • Purlin and Truss material: Self-drilling screws are required for steel purlins and trusses, and sharp-tipped screws are required for timber.  There is also screws that are designed to do both, such as the BDN DUAL-Tite™ 2-IN-1 roofing screws, suited for hard timber and up to 3mm light metal fixing.
  • Corrosion resistance coating: 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. For rural areas, inland, or indoors, the demand for high corrosion resistant screws will be less.


The cost of screws is normally a fraction of the whole metal roofing setup, but is detrimental to the lifespan and safety of the covered area.  Roofing sheets have to hold up against rain, wind, and shine to protect what is underneath, and screws are what keeps substrates securely fastened.   There will always be cheaper alternatives when it comes to building materials, though at what cost?  Short-term savings at the risk sacrificing safety and stability is never a good choice in the long-term.


Further Reading: Step by step tutorial on choosing the correct roofing screw types

Are screws recyclable

Earth, which is essentially a closed system, has a finite amount of matter on the planet and within its atmosphere. Of the list of Earth’s finite resources, iron ore, the main raw materials to making steel is undoubtedly one of them.   Although the Law of Conservation of Mass states that matter cannot be created nor destroyed, but can be formed into different materials, there is a huge risk of our natural resources being altered to the extent where it becomes irreversible, taking up space in the form of un-reusable “trash”, and as some might say, polluting the environment.


Are screws recyclable


Scrap metals from hardware such as screws, nails, nuts and bolts, are ferrous metals that can be soldered down to create secondary metals and made into new products, which is beneficial to both the seller/user and to the environment.


In short, screws are recyclable.  The recycling process can be split into two stages – during production and after usage.


As a manufacturer, each stage of the post processing such as heading, threading and pinch pointing of BDN Fasteners creates a significant amount of scrap metal.  These are normally collected and trucked to the yard of a local recycling company in exchange for some cash, charged by weight.


Recycling a used screw however, can be a bit more complicated.  Although screws generally made from low to medium carbon steel wire, a couple of post processes and additional assembled parts are sometimes involved in creating the final product.  First and foremost is the surface treatment on the screws.  As the majority of steel screws are either fully or semi-exposed to the elements, the need for surface treatments such as basic zinc-nickel alloy plating to the more sophisticated and superior anti-corrosion coating such as Ruspert or Mechanical Zinc plating arise, which can create a huge impact on the environment if used the wrong ingredients.  Added assembled parts such as rubber washers should also be considered when recycling used screws.


Due to the arise of environmental awareness around the globe and among manufacturers, hazardous substances such as hexavalent chromium, trivalent chromium, lead, cadmium and mercury among other materials have become less prevalent, and thanks to advancement in technology, environmentally friendly substitutes material are developed to be used in place of the hazardous substances without compromise in performance.


BDN is well aware of the environmental impact of hazardous materials to our beloved Earth and to future generations, and use only environmentally friendly materials and production methods to manufacture and package BDN Fasteners.  When asked “Are screws recyclable?”, we can reply “Yes” with our heads held high.


As with fixing metal roofing sheets to steel or wooden substrates, fixing polycarbonate sheets is no different, and the basic guidelines when using fasteners remain the same and can be found in the following articles.

4 common causes of metal roof leaks around screws

How to use self-drilling screws


Compared to fixing metal roofing sheets, the biggest differences when fixing polycarbonate sheets is the high coefficient of thermal expansion rate.  Common among most thermoplastics, allowances and extra spacing should be reserved on frames or purlins, and dedicated screws such as BDN POLY-FAST™ and PolyXpand™ fasteners which creates an expansion hole whilst drilling should also be used.


Preparations Prior to Installation:

  1. Avoid placing polycarbonate sheets directly on rough surfaces or lean against bare walls.
  2. Make sure that frames are clean, and surface of the insert groove flat.
  3. Choose a matching thickness for the required bending radius.
  4. Leave margin for expansion and contraction, and depth when inserting the sheets.
  5. Use only neutral cure silicone or gasket material for gap-filling. Do not use any PVC materials.
  6. Use electric cutters (blades should be made of tungsten carbide). Sheets should be securely fixed to avoid vibration the protective should not be removed while cutting.
  7. Use electric cutters (blades should be made of tungsten carbide). Sheets should be securely fixed to avoid vibration the protective should not be removed while cutting.
  8. Protective films should remain until the installation is completed.
  9. Protective film should face the sun.


Polycarbonate roofing fixing instructions

Corrugated polycarbonate profiles are suitable for single or multi-panel skylights or side lights in roofs and walls of metal-clad structures. They can also be used independently as a roofing or cladding material on Shed, Gable, Hip or Dome type arrangements.  Solid flat polycarbonate profiles are equally suitable for roofing skylights and is a great alternative to glass skylights due to its significant weight reduction and being virtually unbreakable.


Roof fixing Installation & Fastening Tips:

  1. Roof Pitch – Polycarbonate roofing fixing should be installed at pitch rates of 10% or more. If installed at a lower pitch, additional sealing should be applied to insure weather resistance. A minimum slope of more than 5% is recommended when installing.
  2. For single panel runs, the long side outermost crests of the polycarbonate panel should lap over matching adjacent crests of metal panels on both sides.
  3. For multi-panel runs, begin installation on the side away from wind and rain direction. The middle panels should be installed with the short crest edge overlapping the top of a longer one. The outermost panels on both length sides will lap over the adjacent matching metal panels, as in a single panel run, unless designed otherwise.
  4. Allow for expansion & contraction at fasteners – using BDN POLY-FAST™ and PolyXpand™ fasteners will eliminate the need for pre-drilling an expansion hole. The thermal expansion hole drilling and screw fixing are completed in one-go.
  5. Drive fasteners perpendicular to the polycarbonate roofing sheet.
  6. Start the installation from the bottom up, on one side, and work your way to the left or right. Never start working from both ends to the middle. The Top panel always lap over the lower one.
  7. Start fastening screws on the lower edge purlin (end-lap), through every 2nd crest. Fasten screws at the internal and upper edge purlins through every 3rd crest, starting from the same side as the lower edge purlin.
  8. Do not over-tighten or under-tighten screws. Doing so may undermine the integrity and weathering resistance of the polycarbonate roof fixing.


Recommended Reading:

POLY-FAST™ – Polycarbonate Roofing Fasteners

POLYXPAND™ – Fixing Polycarbonate Sheeting to Metal


Collated Screws - autofeed screws (25mm drywall screws)-BDN Fasteners

BDN Collated Screws - Taiwan

Collated screws are screws that are held together with a durable plastic strip designed to fit perfectly into all leading brand auto-feed screw-guns.  The collating process is fully automated to ensure that the screws and plastic strip are mated perfectly to prevent jamming in the auto feeder system.


Look up the word collate on any dictionary and you’ll see the definition – “bring together”.   One of the most common collated screw types are bugle head drywall screws. Bugle head drywall screws are used to secure drywall sheets to ceiling joists, wall studs, wood, metal tracks and more.


BDN Collated Screws - Packaging


Difference between Loose Screws and Collated Screw Packaging

What are collated screws, and what differs between collated, and loose, uncollated bugle head drywall screws?  The difference is not in the screws themselves, but how the screws are presented.


Depending on the target customer, loose screws are normally packaged in either small boxes or blister packs, which are then packaged into larger bulk cartons.


Collated screws however, are often rolled and packed neatly in tubs or laid flat in wide boxes, which are easy to carry around and handle.


While single screws systems can be operated with a simple screwdriver or electric drywall screwdriver for the average do-it-yourself type person, it may not be as cost effective when hundreds or even thousands have to be installed every day for professional builders, especially when they are trying to fish out screws from small boxes or blister packs.


Difference between Loose Screws and Collated Screw Installation

Before the invention of collated screws and automatic feeding screwdrivers, handling loose screws presented a challenge to installers while they positioned drywalls with one hand, and then tried to place the screws perpendicular to the drywall, driving them, but not over-driving them with the other.


This is where collated screws really shine.


Drywall contractors were overjoyed with the introduction of the auto-feed system, which came in the form of either an attachment to a standard loose screw-gun, or a dedicated screw-gun system with an integrated, oftentimes adjustable, auto-feeder. Auto-feed systems not only increased speed (up to four times faster than installing loose screws) and efficiency, but also improved workplace safety. Gone are the days of fumbling clumsily through bulk packages, fighting to keep screws to stay on top of the Philips drive bit, while balancing your arm over the drywall trying to pinpoint the drill and drive location.


BDN Fasteners - Collated Screws

BDN Collated Screws

BDN Fasteners is proud to announce that we’ve now added collated bugle head screws in fine and coarse thread options to our product line.


Kindly check the attached DM and introduction video link below:


With 100% Made in Taiwan being an inherent part of the BDN Fasteners DNA, our collated screws are no different – everything from the screws to the collating of strips are all done in our facilities.


construction worker drilling metal

Screws, especially self-drilling screws, among other building materials, will only perform to its maximum potential only when chosen correctly, and then installed properly.

construction worker drilling metal

The “how to” part of using self- drilling screws can be broken down in two parts – How to “choose” the correct screw for the job, and how to “use” the screw correctly.


How to choose the correct self-drilling screw is explained in detail on our Step by step tutorial on choosing the correct roofing screw types.  Simply put, it is the process of trying to determine the type of material that will be drilled through, and also the material and structure the self-drilling screws are affixed to.  BDN Fasteners offer a complete range of self-drilling screws in different gauges, length, corrosion resistance, and unique designs to enhance mechanical properties and performance.


Recommended Reading: BDN Fasteners Types of screws for metal


Once we have set aside the matter of making the correct choice, the second and equally important aspect of how to use self-drilling screws is the installation. The importance being that it correlates with the longevity of not only the self-drilling screws in itself, but the structural integrity of the joined material, and lifespan of the structure as a whole.


Basic guidelines on how to use self-drilling screws are:

  1. Following the instructions on the packaging or from your dealer/distributor. When in doubt, stop what you’re doing, go through the instructions or talk to the dealer again.
  2. Check the maximum drilling capacity of the screws. If the thickness of the metal substrate exceeds the maximum capacity, you should choose a longer screw.
  3. Check if the corrosion resistant level is suited for your environment. For example, if you bought a simple, yellow zinc plated screw and expect it to last in coastal areas, think again.
  4. Check the maximum recommended RPM (Rounds Per Minute) allowed during drill & drive. Exceeding the maximum RPM recommend by manufacturers during drill & drive is a recipe for disaster, as it will most definitely result in tip burnout and failure.  Always err on the safe end and use a hand-tool with a torque limiter.
  5. To not over-drive screws. Over-driven screws have a tendency to crush the EPDM washers or rubber gaskets intended to create a tight weather seal over the hole between the screw head and affixed metal substrate.
  6. To not under-drive screws. Aside from not able to fasten substrates tightly together, under-driven screws fail to provide sufficient pressure over the over the hole between the screw head and affixed metal substrate to create a weather-tight seal.
  7. Always check the perpendicularity of the screws in relation to the drilled substrate during the drill and drive process. The is little to no chance of correcting a crooked driven screw and normally a new hole has to be driven somewhere alongside the failed one.  Washers on the skewed screw may also damage the substrate itself if it happens to be of a softer material such as plastic.


Recommended Reading: 4 common causes of metal roof leaks around screws

BDN Fasteners Types of screws for metal

Although the origin of screws is up for debate and was known to be used as early as the first century B.C., and has evolved to a plethora of length, sizes, and specific usage, the basic function has remained to be affixing two objects together, securely.  BDN Fasteners specializes in manufacturing self-drilling and self-tapping screws, and a wide selection of types of screws for metal fixing.

BDN Fasteners Types of screws for metal

Due to the ever-changing building regulations and codes which also differs from country to country, BDN Fasteners have developed 9 types of screws for metal which are split into 5 categories.  Regardless of the design and purpose these screws are aimed for, BDN Fasteners for metal include basic and proprietary designs which are manufactured to the highest standards, no corners cut.

  • Basic Designs
    1. Mechanical Properties – Follow AS3566 standards for Self-drilling screws for the building and construction industries.
    2. Corrosion Resistant Properties – Surface coating designed to withstand the elements and can be adjusted to cope with specific weathering conditions.
  • Proprietary Designs – Specific designs offer unique properties that provide superior performance for all BDN types of screws for metal.
    1. Trident Drill Point (Pat.) – Provides fast, steady and pinpoint precision drilling performance, effectively clears swarf and drills through 6mm thick steel.
    2. “S” Swirl Drilling Tip – Creates a larger area of engagement from the initial drill drive.
    3. Improved “Cutting Edge” Design – Larger, curved cutting blade edge lower manual load required.
    4. Scratshank / Double Scratshank – Effectively cuts and break out metal filings around the drill hole, keeping it free of damage to sealing washers during installation.


The types of screws for metal include but are not limited to the following series:

BDN Fasteners Types of screws for metal: METAL-Tite™ METAL-Tite™

  • Fixing Cladding to Metal
  • Fixing to Thick Steel
  • Insulated Sandwich Panel Screws for fixing to metal
  • Crest Fixing Fasteners for Fixing Roof Sheeting to Metal
  • Concealed fixing for brackets or fixing clips for wall cladding.
BDN Fasteners Types of screws for metal: DUAL-Tite™ DUAL-Tite™

Duofix 2 IN 1 Roofing Screw for Fixing Roof Sheeting to Light Metal and Timber.

BDN Fasteners Types of screws for metal: TRUSS-Tite™ TRUSS-Tite™

For the assembly of metal truss components through pre-punched holes.

BDN Fasteners Types of screws for metal: FRAME-Tite™ FRAME-Tite™

Flat topped frame screw designed for stud to plate connections and connection lintels to plate without pre-punched holes.

BDN Fasteners Types of screws for metal: POLYXPAND™ POLYXPAND™

Fixing Polycarbonate Sheeting to Metal.  Offered in Crest Fixing and Valley Fixing screws for metal versions.


BDN Fasteners Types of screws for metal: POLY-FAST™ POLY-FAST™

Features a fail-safe thermal expansion hole cutting washer design for fixing Polycarbonate Sheeting to Metal.


For more information on BDN types of screw for metal, please contact the dealer near you, or send us an email at

What are self-tapping screws used for

To begin with, self-tapping screws, as its name suggests, is a screw capable of tapping threads and securing various types of material such as wood, metal, plastics, drywall, bricks, cement and so on and so forth.  It is not to be confused with self-drilling screw in that self-tapping screws usually come with a pointed tip instead of an integrated drill bit, meaning that while being able to drill through thin gauged metal sheets, though on thicker material, it normally requires pre-drilling a pilot hole.

What are self-tapping screws used for

Self-tapping screw threads come in two different types: forming or cutting.  Thread-forming means that threads are formed over the course of drilling into the material, with softer materials such as plastics being the most common.  Thread-cutting types are mostly used on metal, wood, bricks; which requires threads to “cut” into the harder material for an adequate fix.   As with all screws, especially ones that self-tap threads onto material, it is imperative to not apply too much pressure during the process, and take extra care to follow the same track when disassembling or re-assembling the screws to avoid stripping.


What are self-tapping screws used for you may ask? Although self-tapping screws usage varies from country to country, they are mainly used for securing single or double layers of thin gauge sheet metal (which is the reason why people also call it sheet metal screws), fixing brackets into wood, fastening aluminum sections to each other, drilling into plastic housings or plastic plugs.


Learn more about BDN Fasteners >>

How to use self tapping screws for metal?

What’s the Difference Between Self-Drilling and Self-Tapping Screws?

Self-Drilling Screws METAL-Tite™ – HEAVY SECTION(No5)-BDN Fasteners® Made in Taiwan

There will come a time when you will encounter a seemingly impossible task, a piece of steel so thick and heavy duty that even your already awesome BDN No.3 point TEK screws in the toolkit cannot handle.  There will come a time when you the piece of steel in front of you may be tagged as “mild steel”, but in fact is composed of complex, unevenly distributed alloys, which creates a big challenge for regular self-drilling tips, and almost impenetrable.


One of the most important job a self-drilling screw has to muster, is clearing out excess material, or swarf, while drilling.  Having a hardened drilling point and sharp cutting blades only helps with the initial drill and drive, but without a flute long enough and designed correctly to bring out the excess during the spiraling action, iron shavings left in the hole are heated easily from all the spinning, causing the drill to burn out.  Once this happens, there is little to no chance of penetration with the screw, and you’ll have to start all over again.


A lot of big brand names are marketing their screws as either self- as TEK screws for thick steel, heavy duty self-drilling metal screws, or self-drilling screws for thick steel, capable of drilling through 12.5mm steel and above, though not many can perform as advertised.


Not for BDN METAL-Tite™ Heavy Section Fasteners.  Ours perform flawlessly, without fail.


Self-Drilling Screws METAL-Tite™ – HEAVY SECTION(No5)-BDN Fasteners® Made in Taiwan


BDN METAL-Tite™ heavy section, penetrates 12.5mm thick steel with ease.  The patented Thunder-Shot drill point prevents wandering during the initial drill drive, clears out swarf swiftly and efficiently.  The whole screw is coated with BN3 silver coating, which consists of multiple layers of specially formulated, corrosion resistant chemicals, and can easily withstand 1000hrs of salt spray test (ASTM B117), and 7 Kesternich cycles (DIN50018 2.0 SFW).


BDN METAL-Tite™ heavy section screws are also offered in a special 16mm thick steel penetration version.  Designed to not only drill through thick, hardened, or complex alloy steel, but can also pass stringent 1mm + 2mm + 9mm, and 2mm + 12mm penetration tests.  The most demanding part of these two tests is to withstand the impact force on the drilling tip when it passes through the first and/or second sheet, and hits the final thick hardened layer of steel.  Imagine the wear and tear, plus heat buildup of the drilling tip during the first and/or second process.  Nevertheless, BDN Heavy duty self-drilling metal screws pass these two stringent tests with flying colors.



Please contact your nearest BDN Fasteners dealer for further information.