Kare George Roofing Screws

M-Bolt – The Self-Tapping Concrete Anchor

G Thom — Fri, 28 Nov 2025 09:04:27 +0000

Today’s focus is on the M-Bolt Self-Tapping Anchor which most commonly refers to a type of heavy-duty, self-tapping anchor bolt for fixing into a wide range of materials.

Function: A heavy-duty anchor bolt that taps its own thread into materials like concrete, brick, stone, and wood.
Key feature: Its “triple fillet thread” allows for a fast, low-torque installation with high pull-out resistance.
Application: Ideal for fixing brackets, machinery, shelving, and other heavy-duty items.
Benefit: It’s a non-expansion fixing, meaning it can be installed closer to edges without putting tension on the material.

M-Bolt – The heavy duty non-expansion anchor for all materials.

M-BOLT’s unique triple fillet thread is designed to tap its own thread and provides a rapid, low torque installation with exceptional pull-out resistance. This stress free, non-expansion through fixing is the solution for heavy duty anchoring and can be installed closer to edges, nearer together and at varying embedment depths.

Installation is quick and easy, making the M-BOLT ideal for general purpose fixing, even for temporary jobs as it is adjustable and removable.

The M-BOLT is suitable for use in concrete, brick, stone, concrete block, hollow brick and wood, replacing the need for traditional anchors such as through bolts, shield and sleeve anchors.

M-BOLTS are ideally suited for fixing wall angles, balustrades, frames, industrial machinery, brackets, racking, shelving, electrical trays, etc.

Benefits

Fast and easy to install
Triple filet thread is designed to ensure a secure fixing
Fixes along the entire thread length to enable fixing into hollow block and brick
M-Bolt applies no tension to the base material, making it possible to reduce spacing’s between fixings and edge distances
Silver Ruspert coating ensures high resistance to corrosion
Cost effective
Suitable for use in concrete, stone, brick, block and wood.

Available M-Bolt Sizes

7.5x60mm 7.5x80mm 7.5x100mm

10.5x60mm 10.5x80mm 10.5x100mm

12.5x80mm 12.5x100mm 12.5x120mm

1-2-3 EASY INSTALLATION

Close-Up View of M-Bolt

To ensure proper anchoring it is recommended you use the M-Bolt in conjunction with Square Washers

For more information call

082 886 4114

Or email

george@karegeorge.co.za

Screws for Timber Projects

G Thom — Thu, 13 Nov 2025 07:22:04 +0000

Timber screws are a type of fastener that are specifically designed for use with wood. They are commonly used in construction, carpentry, and woodworking projects. Examples of the most popular timber screws in South Africa are:

* Timbermate Screws

* Jetting Screws

* Timber Construction Screws

Let’s take a closer look.

Timbermate Screws

The Timbermate screw is a great overall performance screw. The saw-tooth point and square drive recess reduce the amount of torque required to install these screws, making them ideally suited for use with battery operated power tools.

Available in Class 2 coating. Sizes range from 3.0x12mm to 5.0x75mm. `

One of the main benefits of using timber screws is that they provide a strong, secure hold in wood. They are also relatively easy to install, making them a popular choice for DIY projects.

When choosing timber screws, it is important to consider the size and length of the screw, as well as the type of wood that you will be using. For example, if you are working with softwood (SA Pine), you will likely want to use a smaller screw, whereas hardwood may require a larger screw for a secure hold.

Another important consideration is the thread of the screw. Coarse thread screws are typically used for softwood, while fine thread screws are better suited for hardwood. This is because the coarse thread provides a better grip in softwood, while the fine thread is less likely to split hardwood.

It’s also important to pay attention to the head of the screw. For example, if you want a screw to be flush with the surface of the wood, you should use a countersunk head (CSK). If you want the screw to sit above the surface, you should use a raised head.

Jetting (Jet-In) Screw

The Jetting (Jet-In) Screws self-cutting drill point eliminates the need for predrilling in hard woods, ensuring quick installation into all, types of timber products.

The convex cutting ribs between the threads reduces the torque required to drive the screw into timber making the Jetting Screw ideally suited for use with battery operated power tools.

These screws are available in Class 2 and Class 3 corrosion resistant coatings. Available in 3.0, 3.5, 4.0, 5.0 and 5.5 dia. Lengths rangrange from 12mm up to 100mm

Timber Construction Screw

This screw was discussed in a previous post, read here

Screw Gauge, TPI – What They All Mean

G Thom — Wed, 05 Nov 2025 10:55:11 +0000

There are three main screw measurements: gauge, length, and threads per inch (TPI). But in the case of our roof fasteners there is another measurement, namely the screw drill point size.

When shopping for roofing fasteners at Kare George you’ll most likely find screws labelled like this: #10-24 x 22 Wafer #1 Point. So, what do all these figures mean?

#10 indicates the screw gauge
24 indicates the TPI
22 is the screw length and
#1 is the drill point type/size

I’ll explain each measurement individually.

Screw Gauge

The first number (#10) is the screw gauge, which refers to the outside thread diameter. This is also known as “major diameter.” Screws with a major diameter less than 6.35mm are typically labelled in sizes #0 to #14.

Threads Per Inch (TPI)

TPI is a measurement of the number of threads in a one-inch section of screw. The TPI measurement occasionally follows the screw gauge with a hyphen. The above example, labelled #10-24″ has a #10 gauge with 24 threads per inch. You may have heard the term “thread pitch,” which refers to the number of threads per unit of measurement.

Screw Length

The example wafer head screw is 22mm long, a measurement taken from the bottom of the head to the point.

Drill Point Type and Size

The drill point diameter is in correlation with the thread diameter and influences the pull-out values obtained in different steel thicknesses.

When fixing into timber, a Type 17 point is used

If fixing into steel, use a screw with a drill point that has the correct drilling capacity.
- No 1 (#1) Point. Stitching of thin gauge material (i.e. flashing and sheeting; end laps and side laps) and fixing into thin gauge metal battens.

No 2 (#2) Point. 2.5mm drilling capacity in cold rolled steel.

No 3 (#3) Point. 5mm drilling capacity. This is by far the most popular drill point and commonly used for fixing sheeting to 2.5mm cold rolled lip channel.

No 5 (#5) Point. 5mm drilling capacity. This drill point is used on hot rolled steel sections.

When fixing fibreglass, polycarbonate and fibre cement sheeting, an oversized hole in the sheeting is required to allow for expansion and contraction of the sheeting. By using a winged self-drilling screw, the reaming process can be done while fixing the fastener.

To summarise, if we look at our example screw, #10-24x22mm Wafer #1 it says that

It is Wafer head screw
With #10 gauge
And 24 TPI
With a No1 Point for drilling into thin gauge metal sheeting.

Crest Fixing or Valley Fixing?

G Thom — Wed, 29 Oct 2025 12:59:47 +0000

When fastening profiled metal sheeting, crest fixing means securing the sheet through the upper ridges (crests), while valley fixing secures it through the lower channels (valleys or pans). The primary difference is how effectively each method prevents water leakage.

Crest fixing

What it is: Fastening through the high points (crests) of the metal sheets.
Best for: Roofing applications, especially corrugated roofing.

Advantages:

More weathertight as the fastener is less exposed to water and debris.
Eliminates the risk of a screw head acting as a dam in a valley, which can cause leaks if the washer fails.

Disadvantages:

Can create an indent around the screw, causing water to pool around the screw

In general crest fixing is the standard and most watertight method for installing metal roofing sheets.

Mechanism: Fasteners, with a waterproof washer, are driven through the highest part of the metal profile into the support structure beneath.
Water-tightness: By fixing on the crest, the fastener is elevated above the primary water channel. Even if the washer fails, the water will likely flow down the valley and away from the fastener hole, minimizing the risk of leaks.
Application: Used for roofing installations where maximum water-tightness is critical.

Valley fixing

What it is: Fastening through the low points (valleys or pans) of the metal sheets.

Best for: Walling applications where a clean aesthetic is desired and the fasteners are less visible.

Advantages:

Provides a cleaner, less visible fastener line, as the fasteners are hidden in the valleys.
The sheet rests flat against the support structure, which can prevent deformation.

Disadvantages:

More prone to leaks, as the fastener is in a location where water and debris can collect. Regular roof maintenance however eliminates this risk.

This method is generally not recommended for roofing due to a high risk of possible leaks but is suitable for wall cladding.

Mechanism: Fasteners are driven through the lowest part of the metal profile (the valley or pan).
Water-tightness: Because the fastener is in the path of draining water, any failure in the washer or sealant will cause water to pool around the fastener and eventually leak into the building.
Application: Reserved for vertical wall cladding, where water simply runs down the surface and does not pool.

Comparison table

Feature	Crest Fixing	Valley Fixing
Location	The upper ridges or crests of the metal profile.	The lower channels or valleys (pans) of the metal profile.
Risk of Leaks	Low, as the fastener is above the water line.	High, as water flows directly over the fastener.
Best For	Roofing applications to ensure maximum water-tightness.	Vertical wall cladding applications.
Fastener	Uses a self-drilling fastener with a waterproof EPDM washer.	May use a full-threaded screw, but leaks are still a major risk on roofs.

Which one to choose?

You decide. 6 of the one, half a dozen of the other… My personal choice is Valley Fixing because if you do regular roof maintenance, no debris will accumulate around the fastener thus eliminating the only disadvantage of this type of fixing. The big advantage of Valley Fixing is that, even if you (or your labourer) do overtighten the fastener, you cannot create an indent causing water to pool around the screw and leak. Second benefit is that you can use #12x50mm (instead of #12×65/85mm) for fixing into Timber or #12x38mm (instead of #12×65/85mm) for fixing onto Metal – a huge cost saving factor.

But that is only me.

Polycarbonate Roofing Screws

G Thom — Mon, 27 Oct 2025 10:32:23 +0000

As with fixing all types of roofing material, there are certain guidelines to follow on how to screw polycarbonate roofing, some of which; are rules that work in general, and others which are specific to polycarbonate sheets.

Challenges in Using Screws for Polycarbonate Roofing

Dealing with screws for polycarbonate roofing poses a significant challenge due to the material’s relatively high coefficient of thermal expansion. Current industry practice is to ream a hole in a non-metallic roofing profile to install a #12 (4.5mm diameter) screw. This requires two tools, two operations and a reasonable amount of time, effort and skill. It is a significant time-consuming procedure. Oftentimes, screws are positioned at one side of the hole, instead of in the centre, which can result in insufficient clearance for expansion in the relevant direction.

Another challenge encountered during the installation of sheet roofing profiles involves issues with screws for polycarbonate roofing, specifically the problem of over-tightening of fixing screws such that there is a squashing of the raised profile through which the screw is passed. It is quite common for even professional installers to overdrive a fastening screw, squashing the relevant ridge in the profile, and requiring them to reverse the screw rotation in a secondary operation to bring it to the correct position. Not only does this procedure take more time than necessary, but it may also damage the sheets.

The Art…..

To comprehend the art of fixing polycarbonate roofing, familiarizing oneself with techniques that account for thermal expansion and counteract over-tightening was standard practice. Dive into the realm of advanced fastener choices, such as screws for polycarbonate roofing – the ZAP S/D Polycarb Screw. These fasteners are meticulously designed to overcome installation obstacles.

Our polycarb fasteners were invented and designed for affixing to an underlying structure, in most cases steel and/or timber purlins and battens.

During the drill and drive process, the winged shaft creates an expansion hole, which is then completely covered by the extremely durable and pliable BAZ EPDM washer.

When working with our Polycarb Fasteners it is absolutely critical to drive the screw perpendicular to the sheets, and not to the point that the washer is squished.

Our ZAP S/D #12x75mm Hex Head with Wings for Timber or Metal Class 4

The perfect screw for Polycarbonate Roofing

Timber Construction Screw – We Take a Deeper Look

G Thom — Wed, 22 Oct 2025 10:33:27 +0000

Timber construction screws – types and applications

Unlike ordinary wood screws, which come in handy when performing assembly work, for instance, setting up furniture or building garden structures, construction screws are intended for working in structural timber, used in the construction of buildings, e.g. roof framing components. This is precisely why they are typically longer and thicker, which enables them to form durable, effective, and secure joints.

The wide selection of screws dedicated to timber structures includes models of diverse characteristics. They can be classified according to the following characteristics:

screw head type: conical (countersunk), flat (wafer being the most common), cylindrical,
thread type – featuring full or partial, as well as double threads,
material – they can be made of stainless or zinc-plated (being the most common)

Did you know that…?

Construction screws are sometimes interchangeably referred to as purlin (or joinery) screws
Some manufacturers use a color-coding system for their screws to identify their size, eg the 160mm screw might have a blue head, the 120mm a yellow head, and the 80mm a white head. The screw colour coded heads assure correct installation, particularly to identify length and size of the fastener which is not visible once they are installed.

Applications for construction screws

Timber construction screws are used most typically in jobs such as the following:

Construction of timber frame houses – timber screws are crucial when it comes to joining the structural components of timber frame houses.
Installation of roof trusses – they are commonly used to join roof truss framework members.
Installation of beams and columns in timber structures – timber screws are used to fix floor beams, ceiling beams, and columns.
Refurbishment and renovation work – timber construction screws are used in renovation and structural reinforcement works in existing buildings, where additional stability and mechanical strength are required.
Interior load bearing structures – they are also used to reinforce load bearing structures inside buildings, for example, when building partition walls or stairs.
Terrace and deck construction – these screws prove perfect for fixing decking boards to the supporting structure.
Fencing construction – e.g. for fixing panels and boards to wooden posts.
Construction of garden furniture and building exterior development – on account of their strength and resistance to external conditions, they are used in the construction of garden furniture, gazebos, tool houses, and other outdoor structures.

The construction screws are normally available with large wafer head providing maximised setting force and pull-through capacity and comes in two diameter variants: 6.0 or 8.0 mm, and lengths ranging from 40 to 400 mm.

What makes the Timber Construction Screw so unique?

Patented thread ribs that cause no damage to wood structure.
High-precision rolled thread seamlessly converting into the sharp tip for instantaneous driving start after the screw is set against the base material, making work easier and faster.
Conical geometry of the Torx drive socket formed to match the lower range of dimensional tolerance, triggering a mechanical bonding effect.
Milling point directly adjacent to the screw shank to increase the hole diameter past the thread, preparing the hole for the rolling resistance to be reduced along the shank.
Torx bits that come in a reduced number of sizes (T30 & T40) matching the diameters available in the range, making it possible to cut down on the number of required bits and tools. Star-shaped drives also prevent screws from slipping while they are being driven.
Innovative screwing technique which prevents wood from cracking and protects the thread and hole from getting fouled with drillings. This reduces the diameter of the hole in the wood and improves the joint’s load capacity and strength even further.
Perfect bit and socket fit, making driving the screws easy.

Fastener Corrosion

G Thom — Thu, 16 Jan 2025 06:54:38 +0000

Kare Industrial’s Zap roof and cladding fasteners and our coating process has been proven to stand the test of time in South Africa’s harsh coastal environment, providing superior corrosion protection.

Each container of screws come with a coating data sheet ensuring our Zap screws conform to SANS 1273 standard

Kare Industrial Warranty

The Kare Industrial warranty gives you peace of mind against screw damage, roof failure and expensive call backs.

Download Kare Industrial Suppliers Warranty

Superior Screw and Cladding Compatibility

Our coating procedure ensures superior compatibility between fastener coating and roof sheet which helps ensure the fastener does not cause corrosion of the roof, so you avoid expensive rectification costs.

Help prevent under roof corrosion

Under roof corrosion of roofing screws is the great hidden danger. Our ZAP Fastener shank protection feature minimises the coating removed from the screw during installation, ensuring maximum protection from corrosion. The shank protection feature (see picture below) enlarges the hole making it larger than the screw shank following behind so that the protective coating is not scraped off when passing through the roof profile.

Selecting the Right Corrosion Protection for your Fasteners – Southern Cape Region

CORROSION RESISTANCE CLASS

MINIMUM POROSITY RATING

COATING TYPE

COATING

COMPOSITION

(BY MASS)

MINIMUM LOCAL METALLIC COATING THICKNESS

(μm)

Mechanically plated Zinc/Tin

20-23% Tin.

Balance Zinc

Mechanically plated Zinc/Tin

20-23% Tin.

Balance Zinc

Note: For Class 5 environment we recommend S/steel screws

When Roofing Fasteners Show Their True Colours

G Thom — Sun, 28 Apr 2024 09:30:23 +0000

Many claims are made by importers and distributors of roofing fasteners about the

wonderful corrosion resistance of their fasteners and how their fasteners conform

to various standards.

Kare Industrial Suppliers decided to put these claims to the test and submitted the nine

most popular roofing fasteners used in South Africa for testing at the S.A. Bureau of Standards.

The tests were monitored by two independent experts; one a doctor in metallurgical

engineering and the other a professor in material science.

One of the tests fasteners have to pass in order to comply with SANS1273 Class 3

requirements is a 1000 hour salt fog test. After the completion of the test, red rust on the fastener head and shank cannot exceed 5%.

Out of the nine samples submitted, five were Class 3 screws and four were Class 4 screws. The photos below show the nine fasteners (in random order) after the 1000 hour Class 3 test was completed.

Kare Industrial Suppliers supplied four of the nine fasteners that were tested. – Two Class 3 brands and two Class 4 brands

BASED ON THE RESULTS OF THIS TEST AND OTHERS THAT ARE DONE ON A REGULAR VASIS, WE CAN UNEQUIVOCALLY STATE THE FOLLOWING:

Our Zap® self drilling screws outperformed ALL other product offerings tested
One competitor’s claim that their Class 4 screws offer double Class 4 protection did not even pass Class 3 requirements
Another competitor claiming compliance with international standards on their proprietry coating also failed the basic 1 000 hour salt fog test

ASK YOURSELF THE FOLLOWINFG QUESTIONS:

As a Specifying Professional, are you willing to risk your reputation on substandard fasteners with dubious performance claims?
As a Roofing Contractor, are you sure the fasteners that you sue won’t result in expensive call-backs and repairs due to fastener failure?
As a Procurement Officer, are you really getting the true Class 3 & Class 4 coated fasteners you paid for? Or are you getting cheap imitations?

With a proven track record of supplying quality fasteners to the South African roofing industry for 32 years, offering the trusted Zap brand, Kare Industrial Suppliers offers you:

True value for money
The widest range of roofing fasteners available in S.A.
Fasteners conforming to SANS1273 standard
Nationwide distribution
Expert technical advice

Atmospheric Corrosion Map – SA Coastline

G Thom — Fri, 22 Mar 2024 12:09:56 +0000

How To Select The Correct Fastener Type & Length

G Thom — Fri, 02 Feb 2024 11:13:50 +0000

How To Select The Correct Fastener Type & Length

1. Determine whether the fasteners are going to be used for crest fixing or concealed fixing.

For concealed fixing use a wafer head self drilling screw on Brownbuilt and Kliplock. (Make allowances for insulation material)
For KingKlip, Saflock and Kraftlock the wafer head or hex head self drilling screws can be used. (Make allowances for insulation material )

2. When crest fixing determine the profile height of the sheeting to be fixed.

B.R. Profile = 38mm
Corrugated iron profile = 19mm

Add the compressed thickness of any insulation material to the profile height.
Establish whether the sheeting is to be fixed onto timber or steel.
If fixed to timber add a minimum of 30mm to the figure obtained in 3. above, to calculate the required fastener length.
Use a Type 17 self-drilling screw (preferred) or a self-tapping roofing screw (not preferred).
If fixed to steel purlins, determine the thickness of the purlins.
For cold rolled purlins up to 4mm thick use:

- A self-drilling screw with a no. 3 drill point
- A self-tapping roofing screw in a pre-drilled hole (5.5mm Dia.)

For hot rolled purlins from 4mm up to 12.5mm use:

- A self drilling screw with a no. 5 drill point (Super Teks Series 500)
- A self-tapping roofing screw in a pre-drilled hole (5.8mm Dia.)

The minimum screw length for a self-drilling screw is calculated by adding the figure obtained in 2. above, the purlin thickness, the length of the drill point and 6mm for penetration through the purlin.
The minimum screw length for a self-tapping screw is calculated by adding the figure obtained in 2. above, the purlin thickness and 15mm for penetration through the purlin.