Single Skin Corrugated Sheeting


The following details are a guide to aid during the installation of single skin sheeting, it is not meant to be a definitive guide as many different factors can contribute to the fixing of sheets.


Sealants & Fixings

  1. Number Of Fixings Per Sheet It is recommended that 3 fixings per sheet width per purlin are used. At the eaves it is recommended that additional fixings are used.
  2. Side Lap Stitching The side laps should be stitched at maximum 450mm centres (if required).
  3. Side & End Lap Sealing Both the side and end laps should be sealed using a 6mm x 5mm butyl mastic.
  4. Main Fixings For the roof a corrugated (sinusoidal) sheet should always be fixed through the crest of the sheet and should incorporate an M6 or M8 sealer washer (dependent on purlin material). The head of the fixing should ideally then be covered using a shallow or deep cap (option not available for all fixings). For a wall the above installation can be utilised, however some people may prefer to use a standard fixing with a 16mm or 19m moulded head but be aware that the washer may not form a fully water tight seal.
  5. Side Lap Fixings The side laps can be sealed using stitcher fixings or rivets.
  6. Rooflight Fixings Any rooflights should be fixed in the same manner as the main sheeting, however the side laps must be sealed using rubber sleeved ‘Lapfix’ fixings and not stitchers.



To install carbon steel self drilling / self-tapping fasteners you will need a variable speed general purpose

screw driver that will run from approx, 0-2500 RPM. If installing a large area using heavy steel it may be beneficial to use a heavy-duty screwdriver. It is imperative when installing all types of self drilling and / or self-tapping fasteners that the nosepiece of the screwdriver is used and correctly adjusted. Care should be taken not to over tighten fasteners / washer combinations as this may cause water ingress. It can also contribute towards increased air leakage and reduced pull-over as a result of washer inversion. The following speeds are for guidance only as each installation will vary but the slower a fastener is installed the higher the mechanical performance obtained. Do not put your full body weight on the screwdriver when installing fasteners as this may cause the fastener point to burn out.

Light Section Rail         1800 – 2500 RPM
Heavy Section Rail         MAX – 1800 RPM
Stitcher 0.7mm x 2         1800 – 2500 RPM

When installing either carbon steel or self-tapping fasteners with correctly sized holes a powerful single speed screwdriver is preferred. The diagram below shows the correct installation when using a fixing with a sealer washer.