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The Range£7.14Visit shop Unifix Grade 4.8 Mushroom Head Roofing Bolts And Sq Nuts Bright Zinc Plated - M6 X 25 (Box Of 100) - Silver
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The Unifix Grade 4.8 Mushroom Head Roofing Bolts and Square Nuts are essential fasteners designed for professionals and DIY enthusiasts requiring reliable, heavy-duty fixing for roofing and construction projects. These M8 x 140 bolts provide excellent structural integrity, though they are specifically engineered for metal-to-metal and sheet roofing applications, meaning they may not be suitable for high-vibration machinery environments where vibration-proof fasteners are required.
| Colour | Silver |
|---|---|
| Model Part Number | 1426412 |
| Brand | Unifix |
Yes, the bright zinc plating provides significant protection against standard atmospheric corrosion for outdoor use.
They are primarily designed for metal-to-metal fixings, though they can be used in timber if appropriate washers are added to prevent the head from sinking.
This is an M8 bolt with a length of 140mm.
While the mushroom head acts as a large bearing surface, you may add a rubber-backed washer if waterproofing is required for roofing.
Grade 4.8 indicates the tensile strength of the steel; it is a standard grade suitable for general-purpose construction fastening.
Ensure the hole is pre-drilled to at least 8.5mm to allow for clearance and prevent thread binding.
Use a pair of pliers or a dedicated square-nut wrench to firmly hold the nut flush against the mounting surface.
For proper installation, use a standard open-ended or adjustable wrench to hold the square nut in place while tightening the bolt from the mushroom-head side. No special lubricants are typically required, but applying a small amount of anti-seize compound can be beneficial if installed in highly damp areas to facilitate easier removal later. To maintain the integrity of the zinc coating, avoid using high-impact power tools that may strip the thread or chip the plating. Periodically inspect the connections for any signs of loosening due to thermal expansion or contraction.
