SLE Cladding Limited

Sometimes When roofing it is necessary to cut both profiled and flat sheets, particularly in cases where hip roofs and valleys are involved. There are various tools available. For a small amount of cutting particularly on flat sheets a pair of tin snips is suitable. Do purchase a good quality pair the cheaper ones being a waste of time and money. For flat sheets a jig saw with a metal cutting blade can be used.

For cutting profiled sheets, many people including roofers us a fibre cutting disc for metal. These can be obtained to fit small angle grinders or the larger specialist disc cutting tools as seen on building sites. There are drawbacks, the thin edge of the sheets wear the disc out very rapidly and the heat generated burns back the plastic coating and leaves very sharp edges which rust, so they tend to be used only where the cut edge is hidden by say the ridge or barge and the client isn't looking.

Diamond & tungsten tipped blades are available, these make a better finished than the fibre discs but it is still not perfect. For that you would have to go to a very expensive specialist tool and blade.

For making a neat job the best tool is a nibbler which can be hired from good tool hire firms. It is the size of a small angle grinder and works by punching out half moon shaped pieces of metal. It will even cut up and over profiles if used with care. Do first practice on a spare piece of sheet as at first it can be difficult to follow a straight line. They are usually available in both 110 and 200-240 volt AC. and for compressed air operation.

The general industry practice for fixing corrugated sheets is at the ends of sheets (including laps), fix at the top of every other corrugation. Where the middle of the sheet rests on intermediate bearers, fix at the top of every third corrugation. There must be a fixing in the first and last lap. Note in the drawings above the fixing points are marked by a cross and show an unusual combination of every other and every third lap, which achieves the every other fixing in total. For added security the side laps can be stitched using seam stitchers, (a small self drilling Tek screw). SLE Cladding recommend at 12" to 18" centres.

Fixings. All fixings for corrugated sheets must be fixed into the top of the corrugation. A variety of fixings are available from Galvanised Drive Screws with a Diamond Curved or Round Curved Washer to the cheaper Spring Head Nails with a Black Spat Washer. Diamond Washers should have a matching felt washer fitted under it. No one seems to bother to fit them and manufacturers are now stopping manufacturing felt washer, making supplies difficult to obtain.

We notice that some people are now using the longer type AB Tek screws for fixing to wood through the top of the profile. These stand proud of the sheet and tend to look rather ugly compared with the more rounded appearance of drive screws or spring head nails and if colour caps are fitted, they do not seat down into the curve of the corrugation.


Galvanised Drive Screw	Gash Point Type AB (Wood) Tek Screw	Galv. Diamond Curved Washer	Galv. Round Curved Washer
Awaiting Drawing
Spring Head Nail	Spat washer	Colour Cap

All the fixing mentioned above and more can be viewed by CLICKING HERE to visit the Fixings Page.

Box profile (Trapezoidal)

Individual Box Profiles are usually named by their profile depth and their cover width. i.e. the above profile is a 32/1000 profile. The method of fixing through the top of the profile has long been superseded by the "Self Drill & Tap Screw, commonly known as a TEK screw, a generic name.

Above a type AB Tek screw for wood

The matter of fixing points is more straight forward than with corrugated sheets. The British standards specify that at the ends of sheets (including the laps) a fixing in each valley. Where the middle of the sheet rests on an intermediate bearer fix in every other valley. There must be a fixing in the first and last valleys. Tek screws are available with a variety of self drill points to suit the material to which the sheet is to be secured.

Fixing Tek Screws.

Tek screws must be drilled in at right angles to the sheets and must not be overtightened. Tighten until the fibre washer just starts to bulge. Overtightening is as bad as undertightening. Tek screws for wood (Type AB) have a standard wood screw point. This will drill through the thinner roofing sheets of 0.5mm and maybe 0.55mm. but they will not drill through 0.7mm (22 SWG) or thicker. For this pre-drill a pilot hole.

Fixing to Metal Purlins

Tek screws for drilling into Angle Iron or Z Purlins have their own drill point attached, and this will drill though the sheets and the purlins. Angle Iron can vary in its degree of hardness, depending on the amount of carbon that it contains. Occasionally when fixing to it, the drill point might not be good enough to drill it's own hole and the Tex screw drill point will snap off. In these cases pre-drill a pilot hole. Afterwards always take care and remove all the swarf from the drilling as this will rust and eat into the sheet coating.

ROOF PITCHES of 10 Degrees and below.

In the cases of roof pitches of 10 degrees and below. Before fixing, all laps (both side and end) should be sealed by placing a bead of Butyl Sealant (Like putty on a roll) between the two lapping sheets and the laps secured with Seam Stitchers a 12 - 18" centres. (see below) This prevents wind driven rain from being driven up the slope under the top sheet and penetrating the building. This also applies to Corrosive Industrial Locations and Coastal Locations where corrosive salt spray can be driven between the sheets. In these conditions consider using a cut edge lacquer to prevent rusting of the cut edge. This is not necessary under normal conditions.

Above a Seam Stitcher and it's fixing position

Colour Caps. A range of push on "Colour Caps" to fit over the heads of the Tek screws are available in colours to match the profile sheets.

For further information please contact SLE Cladding Ltd. Tel. 01948 666 321. Fax. 01948 66 55 32