Steel Building and Metal Roofing

Steel buildings and their metal roof and wall cladding put two very different demands on fasteners: self-drilling screws must drill through hardened sheet steel, clamp the sheet firmly to the purlin and keep the joint watertight for decades, while structural bolts carry the frame itself. Getting both disciplines right is what keeps a portal-frame warehouse dry, stable and inspectable for its whole design life.

Why Fastener Selection Matters in Metal Roofing

Up to 80% of metal roof leaks trace back to the fastening point, not the sheet itself. An under-sized point burns out before penetrating the purlin; an over-drilling point strips the thread and loses clamp load; a washer that is over-compressed cracks within a few seasons. Choosing a matched drill point, thread and washer combination for the total steel thickness in your build-up is therefore the single most important specification decision on a metal roof.

Recommended Fastening Solutions

• Hex Washer Self-Drilling Screws with EPDM Washer - the industry standard for fixing trapezoidal and corrugated roof sheets to steel purlins; the bonded EPDM washer seals the drilled hole against wind-driven rain.
• Zinc-Tin Alloy Coated Roofing Screws - a sacrificial coating that protects the carbon-steel screw even where the coating is damaged by drilling, ideal for agricultural and industrial buildings.
• Ruspert Coated 304 Stainless Steel Bi-Metal Screws - for coastal or high-corrosion sites where ordinary coated screws cannot guarantee the design life of the roof.
• EPDM Sealing Washers - replacement and upsize washers for refurbishment and over-cladding projects.

Structural Bolting with DIN933

DIN933 fully-threaded hex bolts, paired with nuts and washers to matching property classes (typically 8.8 and 10.9), are the workhorse of steel-to-steel connections: beam-to-column splices, base plates, bracing and purlin cleats. Fully threaded shanks simplify detailing where grip lengths vary, and the property-class marking on the head makes every connection traceable to its strength grade.

Pre-Installation & Torque Control

• Assemble with clean, undamaged threads; wire-brush re-used galvanised threads and re-lubricate them to keep the torque-tension relationship predictable.
• Tighten in stages - 30%, 70%, 100% of specified torque - working from the stiffest part of the joint (usually the centre of a bolt group) outwards.
• Use hardened washers under both head and nut to protect the connected ply and prevent rotation galling.
• On slip-critical connections, follow the specified surface class; paint or overspray on faying surfaces destroys slip resistance.

Typical Applications

• Trapezoidal and corrugated steel roof sheeting on portal-frame warehouses and factories
• Standing seam and composite panel side and end laps
• Flashings, ridge caps, gutters and eave closures
• Over-roofing and refurbishment of existing profiled roofs
• Wall cladding and liner panels
• Portal-frame warehouse and factory structures
• Beam splices, base plates and haunch connections
• Bracing systems, towers and masts

Surface Protection & Corrosion

Hot-dip galvanised or zinc-flake coated bolts suit most external and humid environments; for immersion, coastal or chemical exposure we supply Duplex systems (galvanised plus painted) and stainless structural fasteners. Remember that the coating of the bolt must be compatible with the coating of the steel it touches - mixed metallic coatings can set up galvanic cells at the connection.

Installation Guidelines

• Always match the drill point (#2, #3, #4 or #5) to the combined thickness of sheet plus purlin - the point must protrude at least three full threads beyond the steel before threading starts.
• Drive with a depth-setting nose cone: the EPDM washer should be compressed to roughly half its original thickness, visibly squeezing slightly at the edges, but not cut or rolled over.
• Keep screws perpendicular to the sheet; an angled screw cuts an oval hole that will leak.
• Do not exceed the recommended maximum fastening spacing for the wind zone, and add extra fixings at sheet ends, corners and perimeter zones.

Why Choose BuildFastener

We manufacture roofing screws with points and threads matched to the steel thicknesses common in your market, and supply structural bolts with batch-traceable property-class certification and consistent head markings that match standard nuts without cross-threading. Every batch is tested for drill performance, torsional strength and salt-spray resistance and supported with full mill certificates and test reports - the details that keep site erection on schedule and inspection painless.