Self-drilling roofing screws with a 19mm EPDM bonded metal washer. Available in 5.5mm and 6.3mm diameters. Supplied in bags of 100, these are a staple fixing for metal roofing and cladding sheets.
The 19mm washer roofing screw is the fixing that keeps your roof watertight. It sounds simple enough, and in some ways it is, but get the wrong screw and you will be back up that roof fixing leaks before the year is out. These screws combine a hardened self-drilling point with a bonded EPDM rubber and metal washer, creating a compression seal around the fixing hole the moment the washer seats down. No separate washers to drop, no fiddling around at height. Available in 5.5mm and 6.3mm shank diameters to suit different purlin gauges and sheet profiles.
The EPDM rubber in the washer is the important part here. EPDM handles UV exposure and temperature cycling far better than standard rubber, which cracks and hardens over time, eventually allowing water to work its way in around the fixing point. A failed washer on a profiled metal roof is one of those slow, infuriating leaks that takes a while to trace. These washers resist that degradation, staying pliable and maintaining their seal across the seasons.
Where 19mm Washer Roofing Screws Get Used
The 19mm washer diameter is well suited to profiled metal sheets, box profile cladding, and corrugated roofing panels. The washer is large enough to bridge minor misalignments without distorting the sheet, and the bonded construction means the rubber and metal move together under the drill, rather than the rubber spinning off or bunching up before the screw seats. Roofers know that second scenario all too well.
Shank Size Selection
The 5.5mm shank suits lighter gauge purlins and secondary steel work. The 6.3mm is the go-to for fixing into heavier structural sections where you need more thread engagement and pull-out resistance. If you are fixing into cold-rolled steel purlins, the 6.3mm is usually the safer choice. Supplied in bags of 100, the pack size is practical for a day’s work on a small roof or as a top-up when you run short mid-job.
Pro Tip: Always check your drill speed when running these in: too fast and the EPDM washer overheats and distorts before it seats, leaving you with a compromised seal that looks fine until the first heavy rain.
These roofing screws are used primarily for fixing profiled metal roofing sheets and cladding panels to steel or timber purlins. They appear regularly on agricultural buildings, industrial units, portal frame warehouses, and commercial roofing projects. The self-drilling point removes the need for pre-drilling in lighter gauge steel, speeding up the fixing process considerably on large roof areas.
Beyond primary roofing, they are also used for fixing ridge cappings, flashings, and translucent roof sheets where a weathertight fixing point is needed. Installers working on re-roofing projects often use them for securing new sheets over existing frameworks where the original fixings have failed or corroded.
Best For
Profiled metal roofing sheets
Box profile cladding panels
Corrugated roof sheets
Ridge cappings and flashings
Agricultural and industrial buildings
Compatible With
Steel purlins (light and heavy gauge)
Timber purlins
Cold-rolled structural sections
Translucent roof sheet fixings
Key Specifications
Washer diameter: 19mm
Washer type: EPDM bonded metal
Available shank sizes: 5.5mm and 6.3mm
Self-drilling point
Supplied in bags of 100
Not suitable for: Not suitable for fixing into concrete, masonry, or timber-to-timber applications where a roofing screw profile is not appropriate. The 19mm washer size is not ideal for very fine sheet profiles where a smaller seating diameter is specified.
Fit a suitable hex driver bit to your drill or screwdriver, matching the head recess on the screw. Use a controlled, consistent speed: fast enough to drive the self-drill point through the sheet and into the purlin cleanly, but slow enough that the EPDM washer compresses gradually rather than overheating. Drive the screw until the washer seats firmly against the sheet surface with a slight, even compression visible around the perimeter.
Do not over-drive. The washer should be snug and flat, not deformed or buckled. An over-driven screw distorts the seal and can dimple the sheet, which causes water to pool. If you are working along a full roof run, it is worth checking the first few fixings before committing to a rhythm, since drill speed and technique vary between operatives.
Select the correct shank diameter for your purlin gauge: 5.5mm for lighter sections, 6.3mm for heavier structural steel
Fit the appropriate hex driver bit to your drill, ensuring a secure fit to avoid cam-out on the screw head
Position the screw on the crown of the sheet profile at your marked fixing centres
Drive at a controlled speed, applying steady downward pressure as the self-drill point engages the sheet
Continue driving until the EPDM washer makes full contact with the sheet surface
Stop driving when the washer shows a slight, even compression all the way around, with no deformation or buckling
Visually inspect each fixing: the washer should sit flat and flush, with no gaps or lifted edges
What is the difference between the 5.5mm and 6.3mm shank sizes?
The 5.5mm is suited to lighter gauge steel purlins and secondary steelwork. The 6.3mm provides greater thread engagement and pull-out resistance, making it the better choice for fixing into heavier cold-rolled or structural steel sections. If in doubt, the 6.3mm is generally the safer option for main purlin fixings.
Why use EPDM rather than standard rubber washers?
EPDM resists UV degradation and temperature cycling far better than standard rubber. Ordinary rubber hardens and cracks over time when exposed to sunlight and outdoor conditions, which eventually breaks the seal at the fixing point. EPDM stays pliable over many years, keeping the weathertight seal intact for the long term.
These screws use a hardened carbon steel shank with a self-drilling point designed to penetrate light to medium gauge steel without pre-drilling. The washer is a bonded assembly combining a metal plate with a vulcanised EPDM rubber facing. EPDM offers good resistance to ozone, UV radiation, and a wide temperature range, making it well suited to outdoor roofing applications where standard rubber compounds would degrade prematurely.
Washer Diameter
19mm
Washer Construction
EPDM bonded metal
Available Shank Diameters
5.5mm, 6.3mm
Drive Type
Hex head, self-drilling
Pack Quantity
100
Application
Metal roofing and cladding fixings
SKU
TFW19
Size
5.5mm, 6.3mm
Box Quantity
100
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